Can AI robots replace human astronauts?

On Christmas Eve, an autonomous spacecraft flew past the Sun, closer than any human-made object before it. Descending through the atmosphere, NASA's Parker Solar Probe was on a mission to discover more about the Sun, including how it affects Earth's space weather.

It was a momentous moment for humanity – but without direct human involvement, as the spacecraft performed its pre-programmed tasks on its own as it flew past the sun, without any communication with Earth.

Over the past six decades, robotic probes have been sent across the solar system, reaching destinations impossible for humans. During his 10-day sojournthe Parker solar probe experienced temperatures of 1000C.

But the success of these autonomous spacecraft — combined with the emergence of new advanced artificial intelligence — raises the question of what role humans might play in future space exploration.

Some scientists question whether human astronauts will even be needed.

“Robots are developing rapidly and the case for sending humans is getting weaker all the time,” says Lord Martin Rees, the UK's Astronomer Royal. “I don't think any taxpayer's money should be used to send people into space.

He also points out the risk to humans.

“The only case for sending people (there) is as an adventure, an experience for rich people, and that should be privately funded,” he argued.

Andrew Coates, a physicist at University College London, agrees. “For serious space exploration, I prefer robotics,” he says. “(They) go a lot further and do more things.”

They are also cheaper than humans, he claims. “And as AI advances, robots can get smarter and smarter.”

But what does this mean for future generations of budding astronauts—and surely there are certain functions that humans can perform in space that robots, however advanced, never could?

Robotic spacecraft have visited every planet in the solar system, as well as many asteroids and comets, but humans have only gone to two destinations: Earth orbit and the Moon.

In total, about 700 people have been in space, the earliest since 1961, when Yuri Gagarin of the then Soviet Union became the first space explorer. Most of them have been in orbit (circling the Earth) or in suborbit (short vertical jumps into space lasting minutes, on vehicles such as the New Shepard rocket of the American company Blue Origin).

“Prestige will always be a reason to have people in space,” said Dr. Kelly Weinersmith, a biologist at Rice University in Texas and co-author of “Mars City.” “It seems to have been arranged as a great way to show that your political system is effective and your people are brilliant.

But aside from an innate desire to explore or a sense of prestige, humans also conduct research and experiments in Earth orbit, such as on the International Space Station, and use them to advance science.

Robots can contribute to these scientific studies, with the ability to travel to places inhospitable to humans, where they can use instruments to study and explore the atmosphere and surfaces.

“Humans are more flexible and we do things faster than robots, but it's really hard and expensive to sustain life in space,” says Dr. Weinersmith.

In her 2024 Booker Prize-winning novel Orbital, author Samantha Harvey puts it more lyrically: “A robot needs no hydration, no nutrients, no excretion, no sleep… It does not ask or beg for anything. “

But there are also cons. Many robots are slow and methodical – on Mars, for example, rovers (motorized remote-controlled vehicles) travel at just 0.1 miles per hour.

“AI can beat humans at chess, but does that mean they will be able to beat humans at environmental exploration?” asks Dr Ian Crawford, a planetary scientist at the University of London. “I just don't think we know.”

However, he believes AI algorithms could allow rovers to be “more efficient.”

Technology can play a role in supplementing human space travel by freeing astronauts from certain tasks to allow them to focus on more important research.

“(AI can be used to) automate tedious tasks,” explains Dr Kerry Wagstaff, a computer and planetary scientist in the US who previously worked at NASA's Jet Propulsion Laboratory in California. “On the surface of a planet, people get tired and lose focus, but machines don't.”

The challenge is that huge amounts of power are needed to run systems like large-scale language models (LLMs) that can understand and generate human language by processing huge amounts of textual data. “We are not able to run an LLM on a rover,” says Dr Wagstaff.

“Processors on the rovers run at about one-tenth (of the speed) that your smartphone has” — meaning they are unable to handle the intensive demands of running an LLM.

Complex humanoid machines with robotic arms and limbs are another form of technology that can take over essential tasks and functions in space, especially when they more closely mimic the physical capabilities of humans.

NASA's Valkyrie robot was built by the Johnson Space Center to compete in a robotics challenge in 2013. Weighing in at 300 pounds and standing 6 feet 2 inches tall, he looks nothing like a Star Wars Stormtrooper, but is one of a growing number of humanoid machines with superhuman abilities.

Long before Valkyrie was created, NASA Robonaut is the first humanoid robot designed for use in space, taking over tasks otherwise performed by humans.

Its specially designed hands meant it could use the same tools as astronauts and perform complex, delicate tasks such as grasping objects or pressing switches that were too challenging for other robotic systems.

A later model of Robonaut was sent to the International Space Station aboard the space shuttle Discovery in 2011, where it assisted with maintenance and assembly.

“If we need to change a component or clean a solar panel, we can do it robotically,” said Dr. Sean Azimi, head of the Dexterity Robotics Team at NASA's Johnson Space Center in Texas. “We see robots as a way to secure these habitats when humans aren't around.”

He argues that robots can be useful, not to replace human researchers, but to work alongside them.

Some robots already work on other planets without humans, sometimes even making decisions themselves. NASA's Curiosity rover, for example, is like that study a region called Gale Crater on Mars and autonomously conducts some of its science without human intervention.

“You can direct the rover to take pictures of a scene, look for rocks that might meet the science priorities for the mission, and then autonomously fire your laser at that target,” says Dr Wagstaff.

“He can read a particular stone and send it back to Earth while people are still asleep.”

But the capabilities of rovers like Curiosity are limited by their slow pace. And there's something else they can't compete with. That is, humans have the added bonus of inspiring people back to Earth in a way that machines cannot.

“Inspiration is something intangible,” says Prof. Coates.

Leroy Chiao, a retired NASA astronaut who flew three spaceflights in the 1990s and 2000s on NASA's space shuttle and to the International Space Station, agrees. “People connect when people do something.

“The general public is excited about robotic missions. But I would expect the first man on Mars to be even bigger than the first moon landing.”

Humans have not traveled further than Earth's orbit since December 1972, when the last Apollo mission visited the moon. NASA hopes to return humans there this decade with its Artemis program.

The the next manned mission will see four astronauts fly around the moon in 2026. Another mission planned for 2027 will see NASA astronauts land on the surface of the Moon.

The Chinese space agency, meanwhile, also wants to send astronauts to the moon.

Elsewhere, Elon Musk, CEO of US company SpaceX, has his own space-related plans. He said his long-term plan was to establish a colony on Mars where humans could land.

His idea is to use the Starship, a large new vehicle his company is developing to transport up to 100 people at a time, with the goal of having million people on Mars in 20 years.

“Musk argues that we should move to Mars because it can be a backup for humanity if something catastrophic happens on Earth,” explains Dr. Weinersmith. “If you accept that argument, then sending people into space is necessary.”

However, there are big unknowns about life on Mars, including countless technical challenges that she says remain unresolved.

“Maybe babies can't thrive in that environment,” she says. “There (are) ethical questions (like this) that we don't have an answer to.

“I think we should slow down.”

Lord Rees, however, has his own vision where human and robotic research can merge to such an extent that humans themselves are part of a machine to cope with extreme environments. “I can imagine they would use all the techniques of genetic modification, cyborg augmentation and so on to deal with a very hostile environment,” he says.

“We may have a new species that will be happy living on Mars.”

Until then, however, humans will likely continue their small steps into space along a path long trodden by robotic explorers before them.

Top image credit: NASA

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