space travel time change

Is Time Travel Possible?

We all travel in time! We travel one year in time between birthdays, for example. And we are all traveling in time at approximately the same speed: 1 second per second.

We typically experience time at one second per second. Credit: NASA/JPL-Caltech

NASA's space telescopes also give us a way to look back in time. Telescopes help us see stars and galaxies that are very far away . It takes a long time for the light from faraway galaxies to reach us. So, when we look into the sky with a telescope, we are seeing what those stars and galaxies looked like a very long time ago.

However, when we think of the phrase "time travel," we are usually thinking of traveling faster than 1 second per second. That kind of time travel sounds like something you'd only see in movies or science fiction books. Could it be real? Science says yes!

This image from the Hubble Space Telescope shows galaxies that are very far away as they existed a very long time ago. Credit: NASA, ESA and R. Thompson (Univ. Arizona)

How do we know that time travel is possible?

More than 100 years ago, a famous scientist named Albert Einstein came up with an idea about how time works. He called it relativity. This theory says that time and space are linked together. Einstein also said our universe has a speed limit: nothing can travel faster than the speed of light (186,000 miles per second).

Einstein's theory of relativity says that space and time are linked together. Credit: NASA/JPL-Caltech

What does this mean for time travel? Well, according to this theory, the faster you travel, the slower you experience time. Scientists have done some experiments to show that this is true.

For example, there was an experiment that used two clocks set to the exact same time. One clock stayed on Earth, while the other flew in an airplane (going in the same direction Earth rotates).

After the airplane flew around the world, scientists compared the two clocks. The clock on the fast-moving airplane was slightly behind the clock on the ground. So, the clock on the airplane was traveling slightly slower in time than 1 second per second.

Credit: NASA/JPL-Caltech

Can we use time travel in everyday life?

We can't use a time machine to travel hundreds of years into the past or future. That kind of time travel only happens in books and movies. But the math of time travel does affect the things we use every day.

For example, we use GPS satellites to help us figure out how to get to new places. (Check out our video about how GPS satellites work .) NASA scientists also use a high-accuracy version of GPS to keep track of where satellites are in space. But did you know that GPS relies on time-travel calculations to help you get around town?

GPS satellites orbit around Earth very quickly at about 8,700 miles (14,000 kilometers) per hour. This slows down GPS satellite clocks by a small fraction of a second (similar to the airplane example above).

GPS satellites orbit around Earth at about 8,700 miles (14,000 kilometers) per hour. Credit: GPS.gov

However, the satellites are also orbiting Earth about 12,550 miles (20,200 km) above the surface. This actually speeds up GPS satellite clocks by a slighter larger fraction of a second.

Here's how: Einstein's theory also says that gravity curves space and time, causing the passage of time to slow down. High up where the satellites orbit, Earth's gravity is much weaker. This causes the clocks on GPS satellites to run faster than clocks on the ground.

The combined result is that the clocks on GPS satellites experience time at a rate slightly faster than 1 second per second. Luckily, scientists can use math to correct these differences in time.

If scientists didn't correct the GPS clocks, there would be big problems. GPS satellites wouldn't be able to correctly calculate their position or yours. The errors would add up to a few miles each day, which is a big deal. GPS maps might think your home is nowhere near where it actually is!

In Summary:

Yes, time travel is indeed a real thing. But it's not quite what you've probably seen in the movies. Under certain conditions, it is possible to experience time passing at a different rate than 1 second per second. And there are important reasons why we need to understand this real-world form of time travel.

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Time Dilation

What Is Time Dilation?

An accurate clock for one observer may be measured as ticking at a different rate when compared to a second observer’s own equally accurate clock. This effect is not a result of the clocks’ technical properties but of the nature of spacetime itself. [i] Clocks on the International Space Station (ISS), for example, run marginally more slowly than reference clocks back on Earth. This explains why astronauts on the ISS age more slowly, being 0.007 seconds behind for every six months. This is known as time dilation, and it has been frequently confirmed and validated by slight differences between atomic clocks in space and those on Earth, even though all were functioning flawlessly. The laws of nature are such that time itself will bend because of differences in either gravity or velocity, each of which affects time in distinctive ways. This phenomenon will have significant implications for interstellar or intergalactic travel.

What Causes Time Dilation?

Time dilation is triggered by disparities in both gravity and relative velocity. Together these two factors are at constant play in the case of a spacecraft’s crew. When two observers are in relatively uniform motion and not influenced by any gravitational mass, the point of view of each observer will be that the other’s clock is ticking at a slower rate than his or her own. Furthermore, the faster the relative velocity, the larger will be the magnitude of time dilation. This case is occasionally termed special relativistic time dilation.

The Spacecraft Scenario

Two spacecraft moving past each other in space would experience time dilation. If the crew inside each one could somehow have an unobstructed view into the other’s spacecraft, it would see the other craft’s clocks as ticking more slowly than its own. In other words, from Spacecraft A’s frame of reference its clocks are ticking normally, while Spacecraft B’s clocks appear to be ticking more slowly (and vice versa). From a local standpoint, time registered by clocks that are at rest with respect to the local frame of reference always seems to pass at the same rate. For example, if a new spacecraft, Spacecraft C, travels next to Spacecraft A, it is “at rest” relative to Spacecraft A. From Spacecraft A’s point of view, Spacecraft C’s time would also appear normal. Here arises a thought-provoking question. If both Spacecraft A and Spacecraft B think that each other’s clocks are ticking more slowly than the other’s, who’s time is correct, and who would have aged more?

Time Dilation and Interstellar Space Flight

Time dilation would make it conceivable for the crew of a fast-moving interstellar spacecraft to travel further into the future while aging much more slowly, because enormous speed significantly slows down the rate of on-board time’s passage. [ii] That is, the spacecraft’s clock would display less elapsed time than the clocks back on Earth. For extremely high speeds during a journey, the effect would be more dramatic. For example, one year of interstellar travel might correspond to ten years back on Earth. Therefore, constant acceleration at one G would theoretically allow a human crew to travel through the entire known universe in one lifetime. Unfortunately, the crew could return to Earth billions of years in the future. Interstellar travel at high speeds thus would have huge implications from both an anthropological and sociological perspective. The crew volunteering for a mission of this magnitude and speed would have to accept the fact that their loved ones, and perhaps even their home planet or star system, would have died long ago. [iii] Because of this effect, humans might wish to travel to nearby stars without spending their entire lives aboard an interstellar spacecraft.

The Twins Paradox

In this paradox one twin makes an interstellar trip in a fast-moving spacecraft but upon return to Earth finds that the other twin who remained there passed away hundreds or thousands of years ago. [iv] This result appears bewildering because each twin sees the other twin as traveling; therefore, each should find the other to have aged more slowly. The paradox can be resolved, however, within the framework of special relativity. The siblings are not equivalent because the twin on the interstellar trip experienced additional acceleration when switching direction to return back to Earth.

Consider by way of illustration an interstellar spacecraft traveling from Earth to Proxima Centauri, the nearest star system outside our solar system and four light years away. At a speed of 80% of the speed of light, the twins will observe the situation as described in the following paragraphs. To make the math less complicated, the spacecraft is assumed to have reached its full speed instantly upon departure from Earth.

The twin on the interstellar spacecraft would see low-frequency (red-shifted) images for three years. During that portion of the trip he would see his counterpart on Earth in the images grow older by 3/3 = 1 year. On the return trip to Earth, he then sees high-frequency (blue-shifted) images for another three years. During that time he would see his twin on Earth in the images grow older by 3 × 3 = 9 years. When the interstellar trip is completed, the image of the twin on Earth will seem to have aged by 1 + 9 = 10 years.

On the other hand, for nine years the twin back on Earth sees slow (red-shifted) images of the spacecraft twin, during which time the spacecraft twin ages in the images by 9/3 = 3 years. The twin on Earth then sees fast (blue-shifted) images for the remaining one year until the spacecraft returns. In the fast images the spacecraft twin ages by 1 × 3 = 3 years. The total aging of the spacecraft twin in the images received by Earth is 3 + 3 = 6 years, so the spacecraft twin returns a bit younger.

To avoid misunderstanding, note the difference between what each twin actually sees versus what he actually calculates. Each sees an image of his twin that he knows originated at an earlier time and that he knows is Doppler-shifted. He does not take the elapsed time in the image as the age of his twin now. If he wants to estimate when his twin was the age shown in the image, he has to determine how far away his twin was when the signal was emitted. In other words, he has to consider simultaneity for a distant event. If he wants to calculate how fast his twin was aging when the image was transmitted, he tweaks for the Doppler shift. [v]

Time Dilation and Communications with Earth

In theory, time dilation will also affect scheduled meetings between the crew on an interstellar mission and the mission managers back on Earth. For example, the crew would have to set their clocks to count the precise number of years time has passed for them, whereas mission control back on Earth would need to count several years more to allow for time dilation. At the velocities currently possible, however, time dilation is too trivial to be a factor in communications between the ISS and Earth.

Implications for Interstellar Travel

Time dilation will have huge implications for both the crew of a spacecraft and mission managers back on Earth. We must consider, for example, the age of the mission managers for the crew returning to Earth (or for alleged extraterrestrials returning to their home planets) and whether or not an interstellar mission would be sociologically accepted. Consider, for example, a spacecraft traveling at 99% of the speed of light to the center of the Milky Way. If everything goes right, the crew would have aged about 21 years. However, back on Earth over 50,000 years would have passed (as observed from Earth). [vi] Obviously all those involved in the initial planning of the mission, as well as generations thereafter, would have died long ago.

[i] Ashby, Neil (2003). “Relativity in the Global Positioning System.” Living Reviews in Relativity. http://relativity.livingreviews.org/Articles/lrr-2003-1/download/lrr-2003-1Color.pdf.

[ii] Toothman, Jessika (2012). “How Do Humans Age in Space?” HowStuffWorks. Retrieved 2012-04-24.

[iii] Calder, Nigel (2006). Magic Universe: A Grand Tour of Modern Science . Oxford University Press.

[iv] Miller, Arthur I. (1981). “Albert Einstein’s Special Theory of Relativity: Emergence (1905) and Early Interpretation (1905–1911).” SOURCE?

[v] Wheeler, J.; and Taylor, E. (1992). Spacetime Physics . 2nd ed. New York: W. H. Freeman.

[vi] Interstellar Travel Calculator. http://spacetravel.nathangeffen.webfactional.com/spacetravel.php.

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Paradox-Free Time Travel Is Theoretically Possible, Researchers Say

Matthew S. Schwartz

A dog dressed as Marty McFly from Back to the Future attends the Tompkins Square Halloween Dog Parade in 2015. New research says time travel might be possible without the problems McFly encountered. Timothy A. Clary/AFP via Getty Images hide caption

A dog dressed as Marty McFly from Back to the Future attends the Tompkins Square Halloween Dog Parade in 2015. New research says time travel might be possible without the problems McFly encountered.

"The past is obdurate," Stephen King wrote in his book about a man who goes back in time to prevent the Kennedy assassination. "It doesn't want to be changed."

Turns out, King might have been on to something.

Countless science fiction tales have explored the paradox of what would happen if you went back in time and did something in the past that endangered the future. Perhaps one of the most famous pop culture examples is in Back to the Future , when Marty McFly goes back in time and accidentally stops his parents from meeting, putting his own existence in jeopardy.

But maybe McFly wasn't in much danger after all. According a new paper from researchers at the University of Queensland, even if time travel were possible, the paradox couldn't actually exist.

Researchers ran the numbers and determined that even if you made a change in the past, the timeline would essentially self-correct, ensuring that whatever happened to send you back in time would still happen.

"Say you traveled in time in an attempt to stop COVID-19's patient zero from being exposed to the virus," University of Queensland scientist Fabio Costa told the university's news service .

"However, if you stopped that individual from becoming infected, that would eliminate the motivation for you to go back and stop the pandemic in the first place," said Costa, who co-authored the paper with honors undergraduate student Germain Tobar.

"This is a paradox — an inconsistency that often leads people to think that time travel cannot occur in our universe."

A variation is known as the "grandfather paradox" — in which a time traveler kills their own grandfather, in the process preventing the time traveler's birth.

The logical paradox has given researchers a headache, in part because according to Einstein's theory of general relativity, "closed timelike curves" are possible, theoretically allowing an observer to travel back in time and interact with their past self — potentially endangering their own existence.

But these researchers say that such a paradox wouldn't necessarily exist, because events would adjust themselves.

Take the coronavirus patient zero example. "You might try and stop patient zero from becoming infected, but in doing so, you would catch the virus and become patient zero, or someone else would," Tobar told the university's news service.

In other words, a time traveler could make changes, but the original outcome would still find a way to happen — maybe not the same way it happened in the first timeline but close enough so that the time traveler would still exist and would still be motivated to go back in time.

"No matter what you did, the salient events would just recalibrate around you," Tobar said.

The paper, "Reversible dynamics with closed time-like curves and freedom of choice," was published last week in the peer-reviewed journal Classical and Quantum Gravity . The findings seem consistent with another time travel study published this summer in the peer-reviewed journal Physical Review Letters. That study found that changes made in the past won't drastically alter the future.

Bestselling science fiction author Blake Crouch, who has written extensively about time travel, said the new study seems to support what certain time travel tropes have posited all along.

"The universe is deterministic and attempts to alter Past Event X are destined to be the forces which bring Past Event X into being," Crouch told NPR via email. "So the future can affect the past. Or maybe time is just an illusion. But I guess it's cool that the math checks out."

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White House directs NASA to create a standard of time for the moon

The White House on Tuesday directed NASA to establish a unified standard of time for the moon and other celestial bodies, as the United States aims to set international norms in space amid a growing lunar race among nations and private companies.

The head of the White House Office of Science and Technology Policy (OSTP), according to a memo seen by Reuters, instructed the space agency to work with other parts of the U.S. government to devise a plan by the end of 2026 for setting what it called a Coordinated Lunar Time (LTC).

The differing gravitational force, and potentially other factors, on the moon and on other celestial bodies change how time unfolds relative to how it is perceived on Earth. Among other things, the LTC would provide a time-keeping benchmark for lunar spacecraft and satellites that require extreme precision for their missions.

“The same clock that we have on Earth would move at a different rate on the moon,” Kevin Coggins, NASA’s space communications and navigation chief, said in an interview.

OSTP chief Arati Prabhakar’s memo said that for a person on the moon, an Earth-based clock would appear to lose on average 58.7 microseconds per Earth-day and come with other periodic variations that would further drift moon time from Earth time.

“Think of the atomic clocks at the U.S. Naval Observatory (in Washington). They’re the heartbeat of the nation, synchronizing everything. You’re going to want a heartbeat on the moon,” Coggins said.

Under its  Artemis  program, NASA is aiming to send astronaut missions to the moon in the coming years and establish a scientific lunar base that could help set the stage for future missions to Mars. Dozens of companies, spacecraft and countries are involved in the effort.

An OSTP official said that without a unified lunar time standard it would be challenging to ensure that data transfers between spacecraft are secure and that communications between Earth, lunar satellites, bases and astronauts are synchronized.

Discrepancies in time also could lead to errors in mapping and locating positions on or orbiting the moon, the official said.

“Imagine if the world wasn’t syncing their clocks to the same time — how disruptive that might be and how challenging everyday things become,” the official said.

On Earth, most clocks and time zones are based on Coordinated Universal Time, or UTC. This internationally recognized standard relies on a vast global network of atomic clocks placed in different locations around the world. They measure changes in the state of atoms and generate an average that ultimately makes up a precise time.

Deployment of atomic clocks on the lunar surface may be needed, according to the OSTP official.

The official also said that as commercial activities expand to the moon, a unified time standard would be essential for coordinating operations, ensuring the reliability of transactions and managing the logistics of lunar commerce.

NASA in January said it has scheduled for September 2026 its first astronaut lunar landing since the end of the Apollo program in the 1970s, with a mission flying four astronauts around the moon and back scheduled for September 2025.

While the United States is the only country to have put astronauts on the moon, others have lunar ambitions. Countries have their eyes on potential mineral resources on the moon, and lunar bases could help support future crewed missions to Mars and elsewhere.

China said last year it aims to put its  first astronauts  on the moon by 2030. Japan in January became  the fifth country  to put a spacecraft on the moon. India last year became the first country to  land a spacecraft  near the unexplored lunar south pole, and it has announced plans to  send an astronaut  to the moon by 2040.

“U.S. leadership in defining a suitable standard — one that achieves the accuracy and resilience required for operating in the challenging lunar environment — will benefit all spacefaring nations,” the OSTP memo stated.

Defining how to implement Coordinated Lunar Time will require international agreements, the memo said, through “existing standards bodies” and among the 36 nations that have signed a pact called the Artemis Accords involving how countries act in space and on the moon. China and Russia, the two main U.S. rivals in space, have not signed the Artemis Accords.

Coordinated Universal Time might influence how Coordinated Lunar Time is implemented, the OSTP official said. The U.N.’s International Telecommunication Union defines Coordinated Universal Time as an international standard.

White House directs NASA to create unified time standard for the Moon and other celestial bodies

NASA will establish a unified standard of time for the Moon and other celestial bodies, as the White House aims to set international norms in space. 

The directive comes amid a growing lunar race among nations and private companies.

The head of the White House Office of Science and Technology Policy (OSTP) instructed the space agency to work with other parts of the US government to devise a plan by the end of 2026,  in a memo seen by Reuters.

The setting would be called Coordinated Lunar Time (LTC). 

The differing gravitational force on the Moon and on other celestial bodies change how time unfolds relative to how it is perceived on Earth. 

The LTC would provide a time-keeping benchmark for lunar spacecraft and satellites that require extreme precision for their missions, NASA's space communications and navigation chief Kevin Coggins says. 

"The same clock that we have on Earth would move at a different rate on the Moon," Mr Coggins said. 

"Think of the atomic clocks at the US Naval Observatory [in Washington]. They're the heartbeat of the nation, synchronising everything," Mr Coggins said.

"You're going to want a heartbeat on the Moon."

Under its Artemis program, NASA is aiming to send astronaut missions to the Moon in the coming years and establish a scientific lunar base that could help set the stage for future missions to Mars.

Dozens of companies, spacecraft and countries are involved in the effort.

An OSTP official said without a unified lunar time standard it would be challenging to ensure the data that transfers between spacecraft are secure and that communications between Earth, lunar satellites, bases and astronauts are synchronised.

Discrepancies in time also could lead to errors in mapping and locating positions on or orbiting the Moon, the official said.

On Earth, most clocks and time zones are based on Coordinated Universal Time, or UTC.

This internationally recognised standard relies on a vast global network of atomic clocks placed in different locations around the world.

They measure changes in the state of atoms and generate an average that ultimately makes up a precise time.

Deployment of atomic clocks on the lunar surface may be needed, according to the OSTP official.

While the US is the only country to have put astronauts on the Moon, others have lunar ambitions.

Countries have their eyes on potential mineral resources on the Moon, and lunar bases could help support future crewed missions to Mars and elsewhere.

In 2023, China said it aims to put its first astronauts on the Moon by 2030.

In January, Japan became the fifth country to put a spacecraft on the Moon.

India last year became the first country to land a spacecraft near the unexplored lunar south pole, and it has announced plans to send an astronaut to the Moon by 2040.

"US leadership in defining a suitable standard — one that achieves the accuracy and resilience required for operating in the challenging lunar environment — will benefit all space faring nations," the OSTP memo stated.

Defining how to implement Coordinated Lunar Time will require international agreements, the memo added.

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Why does time change when traveling close to the speed of light? A physicist explains

Assistant Professor of Physics and Astronomy, Rochester Institute of Technology

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Michael Lam does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

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Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected] .

Why does time change when traveling close to the speed of light? – Timothy, age 11, Shoreview, Minnesota

Imagine you’re in a car driving across the country watching the landscape. A tree in the distance gets closer to your car, passes right by you, then moves off again in the distance behind you.

Of course, you know that tree isn’t actually getting up and walking toward or away from you. It’s you in the car who’s moving toward the tree. The tree is moving only in comparison, or relative, to you – that’s what we physicists call relativity . If you had a friend standing by the tree, they would see you moving toward them at the same speed that you see them moving toward you.

In his 1632 book “ Dialogue Concerning the Two Chief World Systems ,” the astronomer Galileo Galilei first described the principle of relativity – the idea that the universe should behave the same way at all times, even if two people experience an event differently because one is moving in respect to the other.

If you are in a car and toss a ball up in the air, the physical laws acting on it, such as the force of gravity, should be the same as the ones acting on an observer watching from the side of the road. However, while you see the ball as moving up and back down, someone on the side of the road will see it moving toward or away from them as well as up and down.

Special relativity and the speed of light

Albert Einstein much later proposed the idea of what’s now known as special relativity to explain some confusing observations that didn’t have an intuitive explanation at the time. Einstein used the work of many physicists and astronomers in the late 1800s to put together his theory in 1905, starting with two key ingredients: the principle of relativity and the strange observation that the speed of light is the same for every observer and nothing can move faster. Everyone measuring the speed of light will get the same result, no matter where they are or how fast they are moving.

Let’s say you’re in the car driving at 60 miles per hour and your friend is standing by the tree. When they throw a ball toward you at a speed of what they perceive to be 60 miles per hour, you might logically think that you would observe your friend and the tree moving toward you at 60 miles per hour and the ball moving toward you at 120 miles per hour. While that’s really close to the correct value, it’s actually slightly wrong.

This discrepancy between what you might expect by adding the two numbers and the true answer grows as one or both of you move closer to the speed of light. If you were traveling in a rocket moving at 75% of the speed of light and your friend throws the ball at the same speed, you would not see the ball moving toward you at 150% of the speed of light. This is because nothing can move faster than light – the ball would still appear to be moving toward you at less than the speed of light. While this all may seem very strange, there is lots of experimental evidence to back up these observations.

Time dilation and the twin paradox

Speed is not the only factor that changes relative to who is making the observation. Another consequence of relativity is the concept of time dilation , whereby people measure different amounts of time passing depending on how fast they move relative to one another.

Each person experiences time normally relative to themselves. But the person moving faster experiences less time passing for them than the person moving slower. It’s only when they reconnect and compare their watches that they realize that one watch says less time has passed while the other says more.

This leads to one of the strangest results of relativity – the twin paradox , which says that if one of a pair of twins makes a trip into space on a high-speed rocket, they will return to Earth to find their twin has aged faster than they have. It’s important to note that time behaves “normally” as perceived by each twin (exactly as you are experiencing time now), even if their measurements disagree.

You might be wondering: If each twin sees themselves as stationary and the other as moving toward them, wouldn’t they each measure the other as aging faster? The answer is no, because they can’t both be older relative to the other twin.

The twin on the spaceship is not only moving at a particular speed where the frame of references stay the same but also accelerating compared with the twin on Earth. Unlike speeds that are relative to the observer, accelerations are absolute. If you step on a scale, the weight you are measuring is actually your acceleration due to gravity. This measurement stays the same regardless of the speed at which the Earth is moving through the solar system, or the solar system is moving through the galaxy or the galaxy through the universe.

Neither twin experiences any strangeness with their watches as one moves closer to the speed of light – they both experience time as normally as you or I do. It’s only when they meet up and compare their observations that they will see a difference – one that is perfectly defined by the mathematics of relativity.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to [email protected] . Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

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Moon Standard Time? Nasa to create lunar-centric time reference system

Space agency tasked with establishing Coordinated Lunar Time, partly to aid missions requiring extreme precision

The White House wants Nasa to figure out how to tell time on the moon.

A memo sent on Tuesday from the head of the US Office of Science and Technology Policy (OSTP) has asked the space agency to work with other US agencies and international agencies to establish a moon-centric time reference system. Nasa has until the end of 2026 to set up what is being called Coordinated Lunar Time (LTC).

It’s not quite a time zone like those on Earth, but an entire frame of time reference for the moon. Because there’s less gravity on the moon, time there moves a tad more quickly – 58.7 microseconds every day – compared with on Earth. Among other things, LTC would provide a time-keeping benchmark for lunar spacecraft and satellites that require extreme precision for their missions.

“An atomic clock on the moon will tick at a different rate than a clock on Earth,” said Kevin Coggins, Nasa’s top communications and navigation official. “It makes sense that when you go to another body, like the moon or Mars, that each one gets its own heartbeat.”

Nasa has plans to send astronaut missions to the lunar surface beginning in September 2026 through its Artemis program, which will also eventually establish a scientific lunar base that could help set the stage for future missions to Mars. Dozens of companies, spacecraft and countries are involved in the effort.

Without a unified lunar time standard, an OSTP official told Reuters, it would be challenging to ensure that data transfers between spacecraft are secure and that communications among Earth, lunar satellites, bases and astronauts are synchronized.

Discrepancies in time also could lead to errors in mapping and locating positions on or orbiting the moon, the official said.

“Imagine if the world wasn’t syncing their clocks to the same time, how disruptive that might be and how challenging everyday things become,” the official said.

Clocks and time zones on Earth operate on Universal Coordinated Time (UTC), which is internationally recognized. It relies on a vast global network of atomic clocks placed in different locations around the world. They measure changes in the state of atoms and generate an average that ultimately makes up a precise time.

Developing LTC may require atomic clocks to be placed on the moon.

Defining how to implement LTC will require international agreements, the memo said, through “existing standards bodies” and among the 36 nations that have signed a pact called the Artemis accords involving how countries act in space and on the moon. China and Russia, the two main US rivals in space, have not signed the Artemis accords.

UTC might influence how LTC is implemented, the official said. The UN’s International Telecommunication Union defines UTC as an international standard.

The International Space Station, being in low Earth orbit, will continue to use Universal Coordinated Time. But just where the new space time kicks in is something Nasa has to figure out. Even Earth’s time speeds up and slows down, requiring leap seconds.

Unlike on Earth, the moon will not have daylight saving time, Coggins said.

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Time Travel Is Real. Here Are the People and Spacecraft Who Have Done It

To get ahead in life, spend some time on the International Space Station. Why? Well, according to the theory of relativity, astronauts on the ISS age more slowly due to the spacecraft's high orbital speed. It's called time dilation, and it means that when they return they're a bit younger than they would have been—as if they've traveled into the future. (The effect is very small—it would take more than 100 years on the ISS to warp ahead by just one second.) But not all space travel will keep you young. Like speed, gravity also slows time, so your clock revs up as you get farther from a large mass like Earth. As a result, satellites in higher orbits age more quickly. Got your heart set on space travel but want to age at a normal, earthly pace? Good news! There's a sweet spot, 3,174 kilometers above Earth's surface, where the effects of increased speed and reduced gravity cancel each other out. You can hang out there as long as you like without fear of relativistic shenanigans.

Stephen Clark, Ars Technica

Reece Rogers

Eric Berger, Ars Technica

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'Coordinated Lunar Time': NASA asked to give the moon its own time zone

The White House wants the moon to have its own time zone.

On Tuesday, Arati Prabhakar, the head of the White House Office of Science and Technology Policy (OSTP), asked NASA to establish a unified standard time for the moon and other celestial bodies.

Prabhakar asked the space agency to coordinate with other government agencies to come up with a plan to create a Coordinated Lunar Time (LTC) by the end of 2026.

Time moves quicker on the moon

Time moves quicker (by 58.7 microseconds) every day on the moon relative to Earth because of the different gravitational field strength on the moon, the memo said.

"The same clock that we have on Earth would move at a different rate on the moon," Kevin Coggins, NASA's space communications and navigation chief, said in an interview with Reut ers .

The LTC would provide a time-keeping benchmark for lunar spacecraft and satellites that require extreme precision for their missions.

"Think of the atomic clocks at the U.S. Naval Observatory (in Washington). They're the heartbeat of the nation, synchronizing everything. You're going to want a heartbeat on the moon," Coggins said.

Artemis program: Here's why NASA's mission to put humans back on the moon likely won't happen on time

Synchronized time and lunar missions

In 2017, NASA formed the Artemis  program, to re-establish crewed lunar missions. The space agency aims to establish a scientific lunar base that could help set the stage for future missions to Mars. Dozens of companies, spacecraft and countries are involved in the effort.

An OSTP official told Reuters that without a unified lunar time standard it would be challenging to ensure that data transfers between spacecraft are secure and that communications between Earth, lunar satellites, bases and astronauts are synchronized.

Discrepancies in time also could lead to errors in mapping and locating positions on or orbiting the moon, the official said.

"Imagine if the world wasn't syncing their clocks to the same time - how disruptive that might be and how challenging everyday things become," the official said.

Contributing: Reuters

White House directs NASA to create a new time zone for the moon

The moon may have its own time zone by the end of 2026.

The White House has tasked NASA with creating a new time zone for the moon by the end of 2026, as part of the United States' broader goal to establish international norms in space. 

The direction to set up a lunar time zone comes amid growing global interest for humanity to establish a long-term presence on the moon in the coming years — a chief priority of NASA's Artemis program .

The new lunar standard, called "Coordinated Lunar Time (LTC)," is part of a broader effort to "establish time standards at and around celestial bodies other than Earth," according to an April 2 memo by the White House Office of Science and Technology Policy (OSTP). It was not immediately clear whether the moon would have multiple time zones, as Earth does.

Related: The moon: Everything you need to know about Earth's companion

"U.S. leadership in defining a suitable standard — one that achieves the accuracy and resilience required for operating in the challenging lunar environment — will benefit all spacefaring nations," the memo stated.

Because there is lower gravity on the moon than on Earth, time there moves slightly faster — 58.7 microseconds faster every day. Though minuscule, that difference would make it harder for the growing number of future missions to communicate with each other and for mission control to accurately track satellite and crew positions, among other issues. 

"As NASA, private companies and space agencies around the world launch missions to the moon, Mars and beyond, it’s important that we establish celestial time standards for safety and accuracy," Steve Welby, the OSTP deputy director for national security, said in a statement . 

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On Earth, time is measured by numerous atomic clocks placed in various locations around our planet. A similar ensemble of atomic clocks on the moon itself may be used for lunar timekeeping. 

"An atomic clock on the moon will tick at a different rate than a clock on Earth," Kevin Coggins, manager of NASA's Space Communications and Navigation Program, told the Guardian . "It makes sense that when you go to another body, like the moon or Mars, that each one gets its own heartbeat."

 — NASA's Artemis program: Everything you need to know

—   Mining the moon to help save life on Earth (op-ed)

 —  How China will land astronauts on the moon by 2030

In space, there are a couple of different ways in which space agencies keep time. Astronauts aboard the International Space Station , which is in low Earth orbit, follow Coordinated Universal Time (UTC). For spacecraft elsewhere, NASA uses " Spacecraft Event Time " to catalog key mission events, like science observations or engine burns.

To establish LTC on the moon, the space agency told NPR that "subject matter experts throughout the international community are discussing an approach to provide recommendations to the International Astronomical Union for lunar reference frame and time systems."

NASA's Artemis program currently plans to send humans to the moon no sooner than September 2026, three months prior to the deadline to establish LTC. China previously announced a lunar crewed mission before the end of this decade and India by 2040 .

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: [email protected].

Sharmila Kuthunur is a Seattle-based science journalist covering astronomy, astrophysics and space exploration. Follow her on X @skuthunur.

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• COLGeek I heard about this a couple days ago while listening to the radio. Makes sense from a consistency perspective, but this sort of forward thinking will drive some bonkers. Reply
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More From Forbes

As the universe expands, does space actually stretch.

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The fabric of expanding space as illustrated over cosmic time. One of the consequences of the ... [+] expansion is that the farther away a galaxy is, the faster it appears to recede from us, and that the farther away a light source is, the greater the redshift of the light's wavelength by the time we receive it.

It’s been almost 100 years since humanity first reached a revolutionary conclusion about our Universe: space itself doesn’t remain static, but rather evolves with time. One of the most unsettling predictions of Einstein’s General Relativity is that any Universe — so long as it’s evenly filled with one or more type of energy — cannot remain unchanging over time. Instead, it must either expand or contract, something initially derived independently by three separate people: Alexander Friedmann (1922), Georges Lemaitre (1927), Howard Robertson (1929), and then generalized by Arthur Walker (1936).

Concurrently, observations began to show that the spirals and ellipticals in our sky were galaxies. With these new, more powerful measurements, we could determine that the farther away a galaxy was from us, the greater the amounts its light arrived at our eyes redshifted, or at longer wavelengths, compared to when that light was emitted.

But what, exactly, is happening to the fabric of space itself while this process occurs? Is the space itself stretching, as though it’s getting thinner and thinner? Is more space constantly being created, as though it were “filling in the gaps” that the expansion creates? This is one of the toughest things to understand in modern astrophysics, but if we think hard about it, we can wrap our heads around it. Let’s explore what’s going on.

An animated look at how spacetime responds as a mass moves through it helps showcase exactly how, ... [+] qualitatively, it isn't merely a sheet of fabric. Instead all of 3D space itself gets curved by the presence and properties of the matter and energy within the Universe. Multiple masses in orbit around one another will cause the emission of gravitational waves.

The first thing you have to understand is what General Relativity does, and doesn’t, tell us about the Universe. General Relativity, at its core, is a framework that relates two things that might not obviously be related:

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• the amount, distribution, and types of energy — including matter, antimatter, dark matter, radiation, neutrinos, and anything else you can imagine — that are present all throughout the Universe,
• and the geometry of the underlying spacetime, including whether and how it’s curved and whether and how it will evolve.

If your Universe has nothing in it at all, no matter or energy of any form, you get the flat, unchanging, Newtonian space you’re intuitively used to: static, uncurved, and unchanging.

If instead you put down a point mass in the Universe, you get space that’s curved: Schwarzschild space. Any “test particle” you put into your Universe will be compelled to flow towards that mass along a particular trajectory.

And if you make it a little more complicated, by putting down a point mass that also rotates, you’ll get space that’s curved in a more complex way: according to the rules of the Kerr metric. It will have an event horizon, but instead of a point-like singularity, the singularity will get stretched out into a circular, one-dimensional ring. Again, any “test particle” you put down will follow the trajectory laid out by the underlying curvature of space.

In the vicinity of a black hole, space flows like either a moving walkway or a waterfall, depending ... [+] on how you want to visualize it. At the event horizon, even if you ran (or swam) at the speed of light, there would be no overcoming the flow of spacetime, which drags you into the singularity at the center. Outside the event horizon, though, other forces (like electromagnetism) can frequently overcome the pull of gravity, causing even infalling matter to escape.

These spacetimes, however, are static in the sense that any distance scales you might include — like the size of the event horizon — don’t change over time. If you stepped out of a Universe with this spacetime and came back later, whether a second, an hour, or a billion years later, its structure would be identical irrespective of time. In spacetimes like these, however, there’s no expansion. There’s no change in the distance or the light-travel-time between any points within this spacetime. With just one (or fewer) sources inside, and no other forms of energy, these “model Universes” really are static.

But it’s a very different game when you don’t put down isolated sources of mass or energy, but rather when your Universe is filled with “stuff” everywhere. In fact, the two criteria we normally assume, and which is strongly validated by large-scale observations, are called isotropy and homogeneity. Isotropy tells us that the Universe is the same in all directions: everywhere we look on cosmic scales, no “direction” looks particularly different or preferred from any other. Homogeneity, on the other hand, tells us that the Universe is the same in all locations: the same density, temperature, and expansion rate exist to better than 99.99% precision on the largest scales.

Our view of a small region of the Universe near the northern galactic cap, where each pixel in the ... [+] image represents a mapped galaxy. On the largest scales, the Universe is the same in all directions and at all measurable locations, with the major difference being that distant galaxies appear smaller, younger, denser, and less evolved than the ones we find nearby: evidence for cosmic evolution with time, but no changes in isotropy or homogeneity.

In this case, where your Universe is uniformly filled with some sort of energy (or multiple different types of energy), the rules of General Relativity tell us how that Universe will evolve. In fact, the equations that govern it are known as the Friedmann equations : derived by Alexander Friedmann all the way back in 1922, a year before we discovered that those spirals in the sky are actually galaxies outside of and beyond the Milky Way!

Your Universe must expand or contract according to these equations, and that’s what the mathematics tells us must occur.

But what, exactly, does that mean?

You see, space itself is not something that’s directly measurable. It’s not like you can go out and take some space and just perform an experiment on it. Instead, what we can do is observe the effects of space on observable things — like matter, antimatter, and light — and then use that information to figure out what the underlying space itself is doing.

When a star passes close to a supermassive black hole, it enters a region where space is more ... [+] severely curved, and hence the light emitted from it has a greater potential well to climb out of. The loss of energy results in a gravitational redshift, independent of and superimposed atop any doppler (velocity) redshifts we'd observe.

For example, if we go back to the black hole example (although it applies to any mass), we can calculate how severely space is curved in the vicinity of a black hole. If the black hole is spinning, we can can calculate how significantly space is “dragged” along with the black hole due to the effects of angular momentum. If we then measure what happens to objects in the vicinity of those objects, we can compare what we see with the predictions of General Relativity. In other words, we can see if space curves the way Einstein’s theory tells us it ought to.

And oh, does it do so to an incredible level of precision. Light blueshifts when it enters an area of extreme curvature and redshifts when it leaves. This gravitational redshift has been measured for stars orbiting black holes, for light traveling vertically in Earth’s gravitational field, from the light coming from the Sun, and even for light passing through growing galaxy clusters.

Similarly, gravitational time dilation, the bending of light by large masses, and the precession of everything from planetary orbits to rotating spheres sent up to space has demonstrated spectacular agreement with Einstein’s predictions.

A photon source, like a radioactive atom, will have a chance of being absorbed by the same material ... [+] if the wavelength of the photon doesn't change from its source to its destination. If you cause the photon to travel up or down in a gravitational field, you have to change the relative speeds of the source and receiver (such as driving it with a speaker cone) in order to compensate. This was the setup of the Pound-Rebka experiment from 1959.

But what about the Universe’s expansion? When you think about an expanding Universe, the question you should be asking is: “what, observably, changes about the measurable things in the Universe?” After all, that’s what we can predict, that’s what’s physically observable, and that’s what will inform us as to what’s going on.

Well, the simplest thing we can look at is density. If our Universe is filled with “stuff,” then as the Universe expands, its volume increases.

We normally think about matter as the “stuff” we’re thinking about. Matter is, at its simplest level, a fixed amount of massive “stuff” that lives within space. As the Universe expands, the total amount of stuff remains the same, but the total amount of space for the “stuff” to live within increases. For matter, density is just mass divided by volume, and so if your mass stays the same (or, for things like atoms, the number of particles stays the same) while your volume grows, your density should go down. When we do the General Relativity calculation, that’s exactly what we find for matter.

While matter and radiation become less dense as the Universe expands owing to its increasing volume, ... [+] dark energy is a form of energy inherent to space itself. As new space gets created in the expanding Universe, the dark energy density remains constant.

But even though we have multiple types of matter in the Universe — normal matter, black holes, dark matter, neutrinos, etc. — not everything in the Universe is matter.

For example, we also have radiation: quantized into individual particles, like matter, but massless, and with its energy defined by its wavelength. As the Universe expands, and as light travels through the expanding Universe, not only does the volume increase while the number of particles remains the same, but each quantum of radiation experiences a shift in its wavelength towards the redder end of the spectrum: longer wavelengths.

Meanwhile, our Universe also possesses dark energy, which is a form of energy that isn’t in the form of particles at all, but rather appears to be inherent to the fabric of space itself. While we cannot measure dark energy directly the same way we can measure the wavelength and/or energy of photons, there is a way to infer its value and properties: by looking at precisely how the light from distant objects redshifts. Remember that there’s a relationship between the different forms of energy in the Universe and the expansion rate. When we measure the distance and redshift of various objects throughout cosmic time, they can inform us as to how much dark energy there is, as well as what its properties are. What we find is that the Universe is about ⅔ dark energy today, and that the energy density of dark energy doesn’t change: as the Universe expands, the energy density remains constant.

When we plot out all the different objects we've measured at large distances versus their redshifts, ... [+] we find that the Universe cannot be made of matter-and-radiation only, but must include a form of dark energy: consistent with a cosmological constant, or an energy inherent to the fabric of space itself.

When we put the full picture together from all the different sources of data that we have, a single, consistent picture emerges. Our Universe today is expanding at somewhere around 70 km/s/Mpc, which means that for every megaparsec (about 3.26 million light-years) of distance an object is separated from another object, the expanding Universe contributes a redshift that’s equivalent to a recessional motion of 70 km/s.

That’s what it’s doing today, mind you. But by looking to greater and greater distances and measuring the redshifts there, we can learn how the expansion rate differed in the past, and hence, what the Universe is made of: not just today, but at any point in history. Today, our Universe is made of the following forms of energy:

• about 0.008% radiation in the form of photons, or electromagnetic radiation,
• about 0.1% neutrinos, which now behave like matter but behaved like radiation early on, when their mass was very small compared to the amount of (kinetic) energy they possessed,
• about 4.9% normal matter, which includes atoms, plasmas, black holes, and everything that was once made of protons, neutrons, or electrons,
• about 27% dark matter, whose nature is still unknown but which must be massive and clumps, clusters, and gravitates like matter,
• and about 68% dark energy, which behaves as though it’s energy inherent to space itself.

If we extrapolate backwards, based on what we infer about today, we can learn what type of energy dominated the expanding Universe at various epochs in cosmic history.

The relative importance of dark matter, dark energy, normal matter, and neutrinos and radiation in ... [+] the expanding Universe are illustrated here. While dark energy dominates today, it was negligible early on. Dark matter has been largely important for extremely long cosmic times, and we can see its signatures in even the Universe's earliest signals. Meanwhile, radiation was dominant for the first ~10,000 years of the Universe after the Big Bang.

Notice, very importantly, that the Universe responds in a fundamentally different way to these differing forms of energy. When we ask, “what is space doing while it’s expanding?” we’re actually asking which description of space makes sense for the phenomenon we’re considering. If you consider a Universe filled with radiation, because the wavelength lengthens as the Universe expands, the “space stretches” analogy works very well. If the Universe were to contract instead, “space compresses” would explain how the wavelength shortens (and energy increases) equally well.

On the other hand, when something stretches, it thins out, just like when something compresses, it thickens up. This is a reasonable thought for radiation, but not for dark energy, or any form of energy intrinsic to the fabric of space itself. When we consider dark energy, the energy density always remains constant. As the Universe expands, its volume is increasing while the energy density doesn’t change, and therefore the total energy increases. It’s as though new space is getting created due to the Universe’s expansion.

Neither explanation works universally well: it’s that one works to explain what happens to radiation (and other energetic particles) and one works to explain what happens to dark energy (and anything else that’s an intrinsic property of space, or a quantum field coupled directly to space).

An illustration of how spacetime expands when it’s dominated by Matter, Radiation or energy inherent ... [+] to space itself, such as dark energy. All three of these solutions are derivable from the Friedmann equations. Note that visualizing the expansion as either 'stretching' or 'creating new space' won't suffice in all instances.

Space, contrary to what you might think, isn’t some physical substance that you can treat the same way you’d treat particles or some other form of energy. Instead, space is simply the backdrop — a stage, if you will — against or upon which the Universe itself unfolds. We can measure what the properties of space are, and under the rules of General Relativity, if we can know what’s present within that space, we can predict how space will curve and evolve. That curvature and that evolution will then determine the future trajectory of every quantum of energy that exists.

The radiation within our Universe behaves as though space is stretching, although space itself isn’t getting any thinner. The dark energy within our Universe behaves as though new space is getting created, although there’s nothing we can measure to detect this creation. In reality, General Relativity can only tell us how space behaves, evolves, and affects the energy within it; it cannot fundamentally tell us what space actually is. In our attempts to make sense of the Universe, we cannot justify adding extraneous structures atop what is measurable. Space neither stretches nor gets created, but simply is. At least, with General Relativity, we can accurately learn “how” it is, even if we can’t know precisely “what” it is.

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Would you really age more slowly on a spaceship at close to light speed?

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Every week, the readers of our space newsletter, The Airlock , send in their questions for space reporter Neel V. Patel to answer. This week: time dilation during space travel. 

I heard that time dilation affects high-speed space travel and I am wondering the magnitude of that affect. If we were to launch a round-trip flight to a nearby exoplanet—let's say 10 or 50 light-years away––how would that affect time for humans on the spaceship versus humans on Earth? When the space travelers came back, will they be much younger or older relative to people who stayed on Earth? —Serge

Time dilation is a concept that pops up in lots of sci-fi, including Orson Scott Card’s Ender’s Game , where one character ages only eight years in space while 50 years pass on Earth. This is precisely the scenario outlined in the famous thought experiment the Twin Paradox : an astronaut with an identical twin at mission control makes a journey into space on a high-speed rocket and returns home to find that the twin has aged faster.

Time dilation goes back to Einstein’s theory of special relativity, which teaches us that motion through space actually creates alterations in the flow of time. The faster you move through the three dimensions that define physical space, the more slowly you’re moving through the fourth dimension, time––at least relative to another object. Time is measured differently for the twin who moved through space and the twin who stayed on Earth. The clock in motion will tick more slowly than the clocks we’re watching on Earth. If you’re able to travel near the speed of light, the effects are much more pronounced. 

Unlike the Twin Paradox, time dilation isn’t a thought experiment or a hypothetical concept––it’s real. The 1971 Hafele-Keating experiments proved as much, when two atomic clocks were flown on planes traveling in opposite directions. The relative motion actually had a measurable impact and created a time difference between the two clocks. This has also been confirmed in other physics experiments (e.g., fast-moving muon particles take longer to decay ). 

So in your question, an astronaut returning from a space journey at “relativistic speeds” (where the effects of relativity start to manifest—generally at least one-tenth the speed of light ) would, upon return, be younger than same-age friends and family who stayed on Earth. Exactly how much younger depends on exactly how fast the spacecraft had been moving and accelerating, so it’s not something we can readily answer. But if you’re trying to reach an exoplanet 10 to 50 light-years away and still make it home before you yourself die of old age, you’d have to be moving at close to light speed. 

There’s another wrinkle here worth mentioning: time dilation as a result of gravitational effects. You might have seen Christopher Nolan’s movie Interstellar , where the close proximity of a black hole causes time on another planet to slow down tremendously (one hour on that planet is seven Earth years).

This form of time dilation is also real, and it’s because in Einstein’s theory of general relativity, gravity can bend spacetime, and therefore time itself. The closer the clock is to the source of gravitation, the slower time passes; the farther away the clock is from gravity, the faster time will pass. (We can save the details of that explanation for a future Airlock.)

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Exploring how Interstellar became a timeless masterpiece embedded in time

C hristopher Nolan's space adventure film Interstellar has left a lasting impact on cinema since it was released in 2014. Nolan's ability to blend complex narratives with stunning visuals and the acting prowess of its talented cast took audiences on a transcendent journey through the cosmos.

The film is about a near future where famines have ravaged Earth, and the human population has plummeted, facing extinction. Joseph Cooper, a former NASA pilot turned farmer along with a team of scientists, embarks on a perilous mission through a wormhole near Saturn.

As Earth's resources dwindle and the planet becomes increasingly uninhabitable, their objective is to find a habitable planet for humanity to colonize. However, for the mission, they must give the ultimate sacrifice of time to their loved ones.

Interstellar , starring Matthew McConaughey, Anne Hathaway, Michael Caine, Jessica Chastain, and Matt Damon was praised by critics and audiences for its theme, ambition, and execution.

Interstellar 's storyline took the audience on an unforgettable journey

In 2067, humanity is on the brink of extinction due to ecocide. Former NASA pilot Joseph Cooper embarks on a daring journey through a wormhole near Saturn leading to three potentially habitable planets, each orbiting the supermassive black hole Gargantua. Copper and his team navigate the complexity of time dilation, relativity, cosmic uncertainty, and the mysteries of space to reach these planets.

The team makes the ultimate sacrifice of time with their loved ones, including Cooper who left his father and two children behind. They face perilous challenges and emotional trials, but the bond of love and sacrifice drives them forward.

During the mission, a few crew members die, some are left behind, and Cooper falls beyond the black hole's event horizon. However, the bond of love transcends space and time and gets Cooper back to his daughter after 89 years.

Interstellar provokes existential questions and explores humanity

It sensitively portrays a possible dystopia and warns about the desperate journey that humanity would have to take if we weren't cautious. The film also intrigued the future of human exploration, and the possibility and perhaps the necessity of interstellar travel.

Interstellar explores the interconnectedness of all existence and the lengths to which individuals would go to ensure the survival of their species and loved ones.

It engagingly blends science and humanity

Interstellar did not stay back from showcasing the rigor of science and mathematical complexity. To stay as true to science as possible, Nolan hired Kip Thorne, a theoretical physicist and Nobel Laureate as the scientific consultant and executive producer of the film.

The film kept the themes of love and humanity wrapped inside the wonders of scientific prowess. And eventually professed the use of science for progress but, with necessary caution.

Interstellar is inspired by several sci-fi books and films, most notably Stanley Kubrick's adaptation of the Arthur C. Clarke novel, 2001: A Space Odyssey .

Interstellar is an epic tale of love, loss, and redemption

Interstellar is not an action spectacle, it is a film about love and sacrifice. While it's set in space and has some of the most spectacular sequences put to film, at its heart the film is a love story between Cooper and his children.

The scientific complexity of the film is overwhelming, as it deals with the profound mysteries of the universe and the human condition. But Nolan seamlessly weaves it together with deeply emotional storytelling.

Cooper goes on a journey to save humanity but sacrifices the most important thing in his lifetime with his children. The perilous journey takes him to unknown worlds and puts him and his team against the ambiguity of space and time. But in the end, his special connection with his daughter Murph becomes the vessel to save humanity.

Love emerges as the central theme of the film, not just as a personal bond between characters, but as a cosmic force transcending space and time.

Interstellar's commitment to scientific accuracy

While Interstellar takes creative liberties for the sake of effective storytelling, it remains grounded in scientific theories and speculations. Caltech physicist and Nobel Laureate Kip Thorne and producer Lynda Obst conceived the scientific scenario and premise of the film.

Jonathan Nolan, after working on the script for four years, recommended his brother as a suitable director for the film. The result of these collaborations is a narrative that balances scientific realism with imaginative speculation, inviting audiences to contemplate the mysteries of the cosmos.

Interstellar utilizes Einstein's theory of relativity as the narrative cornerstone and references theories like Murphy's law , Tsiolkovsky Rocket Equation , time dilation, and the Einstein-Rosen bridge . It also features futuristic AI robots and spacecraft based on the International Space Station.

The final sequence of the film shows a human space habitat that resembles O'Neil's Cylinders , a theoretical space habitat model proposed by physicist Gerard K. O'Neil in 1976.

The film's scientific accuracy was praised by scientists like Neil DeGrasse Tyson, Michio Kaku, and several others.

Time Travel and exploring dimensions

Interstellar delves into the mind-bending concept of time travel with remarkable depth and ingenuity. The film uses the hypothetical concept of space travel through a wormhole and explores how time alters perception when astronauts venture near black holes.

Each minute spent on distant planets equates to days spent on Earth. Cooper's team mission on Dr. Miller's Ocean Planet lasted over a couple of hours, but in that time 23 years had passed on Earth. And Cooper is left crying in front of a screen playing video messages from his children, who are now grown adults.

The production teams also designed three spacecraft - the Endurance, a ranger, a lander, and two robots, CASE and TARS to showcase realistic machinery capable of exploring space and other dimensions. The works of renowned architect Ludwig Mies van der Rohe heavily inspired the designs of these machinery.

The making of Gargantua for Interstellar

The film features a rapidly spinning supermassive black hole called Gargantua. It is orbited by potentially habitable planets that Cooper and team are set to explore.

To bring Gargantua to life the visual effects team referenced several academic journals on black holes under Thorne's supervision. The effects were created in Double Negative studio where engineers wrote new CGI rendering software to create accurate stimulations. Some individual frames took up to 100 hours to render, totaling 800TB of data.

Kip Thorne in his book, The Science of Interstellar has explained Gargantua in detail and mentioned that several of the visual effects were toned down severely from what it would've actually looked like.

Impending apocalypse on Earth

As a film set in 2067, Interstellar paints a bleak picture of the future . In the film, humanity is facing an existential crisis due to The Blight, an agricultural phenomenon that has caused widespread failure of crops and famine. It would soon increase the Nitrogen level to such an extent that everyone would die of suffocation.

This was due to a combination of environmental factors such as climate change, soil degradation, overpopulation, and the depletion of natural resources. The film is a cautionary tale against ecocide.

How Hans Zimmer's score breathed life into the film

Interstellar had three primary settings, the uncertainty of life on Earth , the emptiness of space, and the unforgiving nature of the new worlds. Hans Zimmer's score masterfully conveys the humane feelings in each setting.

In an interview, Hans Zimmer said that Nolan did not tell him the story of the film, instead gave him a letter that told the story of a father leaving his child for work. This simple prompt was converted into an epic score with the use of unconventional instruments, such as a 1926 Harrison & Harrison organ.

Zimmer also uses simple melodies to convey the emotions of love, desperation, and loss of time. The ticking sound every 1.25 seconds on the ocean planet sequence denoting the passing of one day on Earth is a testament to his genius.

Apart from Zimmer, Academy Award-winning audio engineers Gregg Landaker and Gary Lizzo, and sound editor Richard King worked on enhancing the audio experience of the film.

How did the Nolan Brothers write Interstellar?

Christopher Nolan wrote the script of Interstellar with his brother and frequent collaborator Jonathan Nolan, who went to the California Institute of Technology for the necessary research, where he studied relativity. He drew inspiration from dystopian films like Wall-E and Avatar to write a story about a dystopian future.

Chris Nolan after joining the project, did his research and worked and reworked the script with his brother. Together they even went to NASA to understand the workings of the space agency.

In an interview with The Hollywood Reporter , Nolan said the project was originally developed by Lynda Obsta, an astrophysicist at CalTeach, who is friends with Kip Thorne.

"The project was originally developed by Lynda Obst. She's great friends with Kip Thorne, an astrophysicist at CalTech, and their dream was to make a science-fiction film where the more outlandish concepts were derived from real-world science. They originally developed the film with Steven Spielberg at Paramount and they hired my brother to come up with a story and a script. He and I talk about everything, whether or not we're working on it together, so I'd been hearing about it over the four years he worked on it, and I really felt that there was an extraordinary opportunity there to tell a very intimate story of human connection and relationships and contrast it with the cosmic scale of the overall events."

Nolan continued:

"So when I had the chance to get involved, I wanted to jump on it because I feel that those kinds of opportunities are very few and far between, where you really see what something could be, in terms of what the balance is between the emotional side of the story and the scale of the thing, the vastness of what the story tries to encompass."

Interstellar's visual mastery and spectacle

Visually stunning and meticulously crafted, Interstellar has some of the most incredible sequences ever put on film. Every frame, from the vast emptiness of space to the majestic beauty of distant planets , is a work of art.

Cinematographer Hoyte van Hoytema shot the film on 35mm film in Panavision anamorphic format and IMAX 70mm photography .

Nolan's use of miniatures, practical effects, and innovative techniques, combined with Hoytema's use of lenses, and the awe-inspiring work by the visual effects team, creates an immersive cinematic experience that lingers long after the credits roll.

Final thoughts

The portrayal of space travel in Interstellar is both thought-provoking and visually stunning, cementing its status as a seminal work of science fiction cinema. Nolan's intricate storytelling challenges viewers to contemplate the fluid nature of time, captivates them in the majestic visual spectacle, and immerses them in the humane quest for survival in the face of existential threats.

The film weaves together profound themes of love and loss with masterful performances to create an unforgettable cinematic odyssey.

20 Years On, How the Columbia Shuttle Disaster Changed Space Travel

F olks around NASA don’t much care for this time of year. It was 56 years ago last week—January 27, 1967—that astronauts Gus Grissom, Ed White, and Roger Chaffee lost their lives in a launch pad fire inside their Apollo 1 spacecraft as they were running a dress rehearsal for countdown. It was 37 years ago—on January 28, 1986—that the shuttle Challenger exploded during launch due to a faulty seal that caused one of the solid rocket boosters to ignite the external fuel tank. The pair of solid boosters flew on heedlessly, leaving a gruesome, two fingered fireball in the sky as seven astronauts perished, including New Hampshire school teacher Christa McAuliffe.

Seventeen years later, on January 28, 2003, astronaut Rick Husband, commander of the shuttle Columbia, which was then in orbit, marked the anniversaries. “They made the ultimate sacrifice,” he said, “giving their lives for their country and mankind. Their dedication was an inspiration to each of us.”

America would have to find a similar kind of grim inspiration just four days later, when, on February 1—20 years ago today—Columbia met an end similar to Challenger’s, breaking apart during reentry, when hot plasma tore through the spacecraft from a breach in the leading edge of the left wing. Husband and his crew of six were killed, as the shuttle, on its way to a landing at the Kennedy Space Center in Florida, left a debris trail that stretched from eastern Texas to Louisiana.

“A poisonous rain of broken shuttle pieces fell onto backyards and roadsides and parking lots, through the roof of a dentist’s office, bits of machinery in Nacogdoches, a hand and leg in San Augustine,” wrote TIME’s Nancy Gibbs , as part of the magazine’s cover package that week.

Then-President George W. Bush scheduled a call with the family members of the lost crew for later that day and spent part of his morning studying crew biographies to see which astronauts had spouses and children.

“Tough day, tough day,” was all Bush could mutter to himself as he prepared to place the call.

It was that, indeed. NASA reacted as NASA does in such circumstances, first with a certain minimalism and stoicism. As I reported in a piece that accompanied Nancy’s: “‘A space-shuttle contingency has been declared,’ the voice of Mission Control intoned in the arid argot of the space agency. It was an echo of the understated announcement 17 years ago, when the shuttle Challenger consumed itself in an awful fireball, and the stunned NASA narrator was left to declare, ‘Obviously a major malfunction.’”

But NASA has done other things too when faced with tragedy. It has searched for the cause of the problem and fixed it. In the case of the Apollo 1 fire, that meant redesigning the spacecraft from top to bottom to avoid the kind of errant spark that set off the blaze, as well as replacing the cockpit’s pure-oxygen atmosphere—which burns like gasoline—with an oxygen-nitrogen mix when the spacecraft was at high internal pressure on the ground. (In space, where the internal pressure is much lower due to the vacuum outside, the spacecraft could safely be filled with pure oxygen.) NASA also changed all of the fabric in the spacecraft, including the astronauts’ suits, to a burn-resistant beta cloth. In the case of Challenger, fixing what went wrong meant redesigning the solid fuel boosters and changing the launch rules, to prevent a liftoff in the uncharacteristic Florida freeze that January morning that had left the engine seals brittle.

In the case of Columbia, the job meant first pinpointing the cause of the breach in the shuttle that allowed the hot plasma to infiltrate the spacecraft. It was ultimately traced via liftoff footage to a suitcase-sized piece of hard insulating foam that fell off the external tank and struck the wing in the first moments of the spacecraft’s flight. That meant doing away with the insulating foam at the spot where the tank joins the shuttle—the region from which the deadly fragment fell—and replacing it with heaters. It also meant that on future flights to the International Space Station, shuttle pilots would do a sort of pirouette of their vehicle so that station astronauts could give it a visual inspection. NASA also kept another shuttle at the ready in case a mission had to be launched to rescue a crew aboard a ship that could not reenter safely.

But both Columbia and Challenger led to another kind of change too—a sort of back to the future reversal in spacecraft design. The rocketry revolution that the shuttle program sought to herald was intended to be the end of the old model of putting humans at the top of a booster, firing them into space, and throwing away the launch vehicle after a single use. The new shuttle would be reusable, with the spacecraft itself gliding gracefully back to Earth, the spent solid boosters dropping by parachute into the ocean and being recovered, and only the external tank—little more than a huge shell of metal and plumbing—being discarded.

But there was a lifesaving advantage in the old design that NASA was eschewing with the shuttles: that business of the crew being perched atop the pyrotechnics. Ever since the days of NASA’s first crewed flights, spacecraft-and-booster stacks were designed so that sensors would detect any impending problem in the rocket and either blast the crew-carrying capsule away from it by escape engines or, in the case of the 1960s’ two-man Gemini program, signal the commander to pull a D-shaped ring that would activate parachute-equipped ejection seats.

In the newer shuttle design, the crew was placed directly next to the pyrotechnics. Challenger’s tank explosion happened with the shuttle riding atop it like a human on a horse. Columbia’s wing could never have been damaged if it hadn’t been located below the spot on the tank from which foam fell. Even before the remaining three shuttles were retired in 2011, NASA vowed that in the future it would keep fuel and humans separate, returning to the old model of crew riding at the top of the missile—a model adopted by NASA’s new moon rocket, the Space Launch System ; SpaceX’s Falcon 9 and Starship rockets; and Boeing’s crew-carrying Starliner spacecraft . And in the case of SpaceX, most of the throwaway problem has been addressed, with the first stage of the Falcon 9, and both stages of the planned Starship rocket returning for upright landings, allowing them to be used again.

Now, two decades on from the most recent loss, and generations removed from the earlier ones, NASA does not let the memories of the missing men and women—or the sacrifice they made—fade. Each year, on the last Thursday of January, the space agency holds a NASA Day of Remembrance to celebrate their lives—and mourn their loss. We take space travel as a fixed fact of 20th and 21st century life. But crews take a big gamble—on physics, fate, and engineering—when they climb aboard a spacecraft. We all benefit from the fact that they do—and all are made poorer, more sorrowing, by the mercifully few times that gamble does not pay off.

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Russian cosmonaut Yuri Gagarin, the first man in space, completed a circuit of the Earth in the spaceship Vostok 1 on April 12, 1961.

5 Changes in Space Travel Since Yuri Gagarin's Flight

On Yuri's Night, space historians reflect on how far technologies have advanced.

A little over 50 years ago, no one on Earth knew what would happen when a human being was launched into space. That all changed on this day in 1961, when Yuri Gagarin , a Soviet military pilot and cosmonaut , hurtled into orbit aboard Vostok 1.

He circled the Earth once, reporting that he was feeling "excellent" and could see "rivers and folds in the terrain" and different kinds of clouds. "Beautiful" was his simple description of the view. Weightlessness, he said, felt "pleasant." (See pictures of Gagarin's flight .)

In the decades since Gagarin became the first person in space, what began as a politically fraught competition has yielded men on the moon, space walks, and visions of putting people on Mars . Here's a look at some of the important changes in space travel that occurred along the way.

Gagarin's flight represented a triumph for the Soviet Union during the heat of the Cold War, from which both the U.S. and Russian space programs were born. "The space race was partly about impressing the living daylights out of other nations because the science and technology are closely aligned with military capability," says Roger Launius, senior curator and space historian at the Smithsonian's National Air and Space Museum .

The Soviets, notes Launius, kept secret for years the fact that Gagarin had to bail out of his spacecraft with a parachute several miles above ground during the landing. The spherical Vostok capsule lacked thrusters to slow it down, and requiring Gagarin to eject before reaching the ground might have meant the mission didn't qualify as the first successful human space flight. "They had no idea what was going to happen—the capsule could have left a big hole in the ground," Launius says. (See pictures of space suit evolution .)

Nowadays the U.S. and Russia collaborate regularly, with cross-training and joint flights to the International Space Station (ISS). The launch pad from which Gagarin took off—Baikonur Cosmodrome in what is now Kazakhstan—is still used today, most recently to send two cosmonauts and a U.S. astronaut to the ISS in March.

Escaping Earth

Gagarin's mission required a rocket that could propel his spacecraft fast enough to sustain a speed of some 17,000 miles per hour (27,359 kilometers an hour), known as orbital velocity. Less than a decade later, NASA's Saturn V rocket achieved escape velocity—the speed required to escape Earth's gravitational pull (25,039 miles per hour or 40,320 kilometers per hour). This milestone made it possible to put men on the moon.

Saturn V stood taller than the Statue of Liberty and generated more power than 85 Hoover Dams. It was a thing of beauty, and resulted in the first human footsteps on extraterrestrial terrain, when Neil Armstrong stepped onto the moon in 1969. More Apollo missions followed, and Saturn V took its final bow in 1973, when it launched the Skylab space station into orbit.

Creature Comforts

Gagarin traveled in what was essentially a giant ball and didn't have the capacity to control his spacecraft. If he were to take a tour of the International Space Station today, he might be impressed with the amenities: exercise bikes, barbeque beef brisket—even a choice of toilet papers.

"There wasn't a lot of interest early on in making cosmonauts comfortable—they were there to do a task," says Launius. "It's only with longer-term missions that you have to worry about comfort."

Hence the memorable shower aboard Skylab , NASA's space station during the 1970's and first attempt to test the ability of humans to work and live in space for extended periods. The weight of water and the large equipment required to recycle it, however, proved too much of a burden, says NASA spokesman Jay Bolden, leaving today's space dwellers resorting to "basic squirts of water and soap on washcloths for sponge baths."

Space Medicine

Gagarin's mission lasted 108 minutes, so he didn't have to eat. But the cosmonaut who followed him into space, German Titov, went up for more than a day. People wondered: Would he be able to swallow food?

Today's big questions about space travel and the human body involve bone loss and radiation exposure, but fundamental questions existed even then, notes NASA's chief historian Bill Barry. "People asked if you could swallow without gravity. One of Titov's experiments was to eat something in space," he says.

Another mystery was "space sickness," involving severe nausea. Titov suffered a bad case of it, which worried the Soviets greatly, says Barry. Now it's known to be common among space travelers and even bears a medical name: space adaptation syndrome.

Modern studies focus on the effects of long-term space travel, as eyes turn to Mars and people spend months—even longer than a year in the case of cosmonaut Valeri Polyakov—working in space. "In less than a week we see signs of degradation in the human body," says Launius of the Smithsonian. "I would contend that the real challenge for space travel is biomedical, not technological."

Commercialization

Perhaps the most remarkable change in space travel since Gagarin's historic flight is how routine it's become—and possible for the right price.

Millions of dollars have landed private citizens a seat on Russian spacecraft, though Russia halted its space-tourism role in 2010. (It cited the need to devote its Soyuz capsules to ferrying ISS crew members after NASA ended its space-shuttle program.) Still, so-called space tourism remains on the map as companies like Virgin Galactic race to launch suborbital flights that skirt the edge of space and offer a taste of weightlessness. Virgin's ticket price: $200,000.

"Not all commercial space activities are about tourism," notes Launius. "Many are about communication, remote sensing, or other activities in which a profit may be made."

One thing that hasn't changed is the view from above. People may no longer stop to take in the video feed from spacecraft floating above Earth, but just listen to Gagarin's conversation with his ground control and you can feel the suspense and awe of seeing the planet from space.

No wonder a great window counts as a major creature comfort for the ISS crew. "The astronauts love to hang out in the station's cupola ," with its panoramic views of Earth, says Barry. "I hear they moved an exercise bike there, and one guy likes to hang out and play his guitar."

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Astro for kids: Why does time change when traveling close to the speed of light?

Why does time change when traveling close to the speed of light?

Timothy, age 11 Shoreview, Minnesota

Imagine you’re in a car driving across the country watching the landscape. A tree in the distance gets closer to your car, passes right by you, then moves off again in the distance behind you.

Of course, you know that tree isn’t actually getting up and walking toward or away from you. It’s you in the car who’s moving toward the tree. The tree is moving only in comparison, or relative, to you — that’s what  we physicists  call  relativity . If you had a friend standing by the tree, they would see you moving toward them at the same speed that you see them moving toward you.

In his 1632 book “ Dialogue Concerning the Two Chief World Systems ,” the astronomer Galileo Galilei first described the  principle of relativity  – the idea that the universe should behave the same way at all times, even if two people experience an event differently because one is moving in respect to the other.

If you are in a car and toss a ball up in the air, the physical laws acting on it, such as the force of gravity, should be the same as the ones acting on an observer watching from the side of the road. However, while you see the ball as moving up and back down, someone on the side of the road will see it moving toward or away from them as well as up and down.

Special relativity and the speed of light

Albert Einstein much later proposed the idea of what’s now known as  special relativity  to explain some confusing observations that didn’t have an intuitive explanation at the time. Einstein used the work of many physicists and astronomers in the late 1800s to put together his theory in 1905, starting with two key ingredients: the principle of relativity and the strange observation that the speed of light is the same for every observer and nothing can move faster. Everyone measuring the speed of light will get the same result, no matter where they are or how fast they are moving.

Let’s say you’re in the car driving at 60 miles per hour and your friend is standing by the tree. When they throw a ball toward you at a speed of what they perceive to be 60 miles per hour, you might logically think that you would observe your friend and the tree moving toward you at 60 miles per hour and the ball moving toward you at 120 miles per hour. While that’s really close to the correct value, it’s actually slightly wrong.

The experience of time is dependent on motion.

This discrepancy between what you might expect by adding the two numbers and the true answer grows as one or both of you move closer to the speed of light. If you were traveling in a rocket moving at 75% of the speed of light and your friend throws the ball at the same speed, you would not see the ball moving toward you at 150% of the speed of light. This is because nothing can move faster than light – the ball would still appear to be moving toward you at less than the speed of light. While this all may seem very strange, there is  lots of experimental evidence  to back up these observations.

Time dilation and the twin paradox

Speed is not the only factor that changes relative to who is making the observation. Another consequence of relativity is the concept of  time dilation , whereby people measure different amounts of time passing depending on how fast they move relative to one another.

Each person experiences time normally relative to themselves. But the person moving faster experiences less time passing for them than the person moving slower. It’s only when they reconnect and compare their watches that they realize that one watch says less time has passed while the other says more.

This leads to one of the strangest results of relativity – the  twin paradox , which says that if one of a pair of twins makes a trip into space on a high-speed rocket, they will return to Earth to find their twin has aged faster than they have. It’s important to note that time behaves “normally” as perceived by each twin (exactly as you are experiencing time now), even if their measurements disagree.

The twin paradox isn’t actually a paradox.

You might be wondering: If each twin sees themselves as stationary and the other as moving toward them, wouldn’t they each measure the other as aging faster? The answer is no, because they can’t both be older relative to the other twin.

The twin on the spaceship is not only moving at a particular speed where the frame of references stay the same but also accelerating compared with the twin on Earth. Unlike speeds that are relative to the observer, accelerations are absolute. If you step on a scale, the weight you are measuring is actually your acceleration due to gravity. This measurement stays the same regardless of the speed at which the Earth is moving through the solar system, or the solar system is moving through the galaxy or the galaxy through the universe.

Neither twin experiences any strangeness with their watches as one moves closer to the speed of light — they both experience time as normally as you or I do. It’s only when they meet up and compare their observations that they will see a difference – one that is perfectly defined by the mathematics of relativity.

Michael Lam , Assistant Professor of Physics and Astronomy,  Rochester Institute of Technology

This article is republished from  The Conversation  under a Creative Commons license. Read the  original article .

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to  [email protected] . Please tell us your name, age and the city where you live.

And since curiosity has no age limit — adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

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History of Space Travel

Learn about the history of humans traveling into space.

The first earthling to orbit our planet was just two years old, plucked from the streets of Moscow barely more than a week before her historic launch. Her name was Laika. She was a terrier mutt and by all accounts a good dog. Her 1957 flight paved the way for space exploration back when scientists didn’t know if spaceflight was lethal for living things.

Humans are explorers. Since before the dawn of civilization, we’ve been lured over the horizon to find food or more space, to make a profit, or just to see what’s beyond those trees or mountains or oceans. Our ability to explore reached new heights—literally—in the last hundred years. Airplanes shortened distances, simplified travel, and showed us Earth from a new perspective. By the middle of the last century, we aimed even higher.

Our first steps into space began as a race between the United States and the former Soviet Union, rivals in a global struggle for power. Laika was followed into orbit four years later by the first human, Soviet Cosmonaut Yuri A. Gagarin. With Earth orbit achieved, we turned our sights on the moon. The United States landed two astronauts on its stark surface in 1969, and five more manned missions followed. The U.S.’s National Aeronautics and Space Administration (NASA) launched probes to study the solar system. Manned space stations began glittering in the sky. NASA developed reusable spacecraft—space shuttle orbiters—to ferry astronauts and satellites to orbit. Space-travel technology had advanced light-years in just three decades. Gagarin had to parachute from his spaceship after reentry from orbit. The space shuttle leaves orbit at 16,465 miles an hour (26,498 kilometers an hour) and glides to a stop on a runway without using an engine.

Space travel is nothing like in the movies. Getting from A to B requires complex calculations involving inertia and gravity—literally, rocket science—to "slingshot" from planet to planet (or moon) across the solar system. The Voyager mission of the 1970s took advantage of a rare alignment of Jupiter, Saturn, Uranus, and Neptune to shave off nearly 20 years of travel time. Space is also dangerous. More than 20 astronauts have died doing their job.

That hasn’t stopped people from signing up and blasting off. NASA’s shuttle program has ended, but private companies are readying their own space programs. A company called Planetary Resources plans to send robot astronauts to the Asteroid Belt to mine for precious metals. Another company named SpaceX is hoping to land civilian astronauts on Mars—the next human step into the solar system—in 20 years. NASA and other civilian companies are planning their own Mars missions. Maybe you’ll be a member of one? Don’t forget to bring your dog.

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Does space travel make people age more slowly?

• 2 min. read ▪ Published February 22, 2021
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Scientists have recently observed for the first time that, on an epigenetic level, astronauts age more slowly during long-term simulated space travel than they would have if their feet had been planted on Planet Earth.

“Many of us assume that being exposed to radiation or other harm in space would be reflected by increased aging. But there’s also been a lot of research that has shown the opposite,” said Jamaji C. Nawanaji-Enwerem, Berkeley Public Health postdoctoral fellow and first author of a study published in Cell Reports in November 2020. The study reviewed data from the six participants of the Mars-500 mission, a simulated space travel and residence experiment launched by the European Space Agency in 2010.

In space, people usually experience environmental stressors like microgravity, cosmic radiation, and social isolation, which can all impact aging. Studies on long-term space travel often measure aging biomarkers such as telomere length and heartbeat rates, not epigenetic aging. To fill in the gap, Nawanaji-Enwerem and his team members took the novel step to look at epigenetic biomarkers such as DNAmPhenoAge, a robust marker of disease risk, and DNAmGrimAGE, a predictor of mortality risk.

The findings show that space mission duration will lead to a slower aging process, which looks like a good thing. “But if the mission goes on for longer, it can actually be a bad thing for you,” said Nawanaji-Enwerem.

“It also informs future research in terms of what biomarkers of aging are important to measure,” said Andres Cardenas, study co-author and assistant professor of Environmental Health Sciences at Berkeley Public Health.

During the Mars-500 experiment, six astronaut crews stayed in an isolated space and lived as if they were on Mars for 520 days. Cosmic radiation and microgravity were not replicated in the experiment, so the slower aging process found by scientists is caused by social isolation and other relative effects.

Although it’s not clear why space travel would lead to slower epigenetic aging, the findings will be valuable for understanding the health implications for future space travel.

“It’s not if, but when, we’re going to transition to space living,” said Cardenas.

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