Could robots really replace human astronauts?

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

This was a landmark moment for humanity, but without direct human participation, as the spacecraft independently carried out its pre-programmed tasks, flying past the Sun, without any communication with the Earth at all.

Robotic probes have been sent around the solar system for the past six decades, reaching places inaccessible to humans. During its 10-day flybyThe Parker solar probe experienced temperatures of 1000°C.

But the success of these autonomous spacecraft – coupled with the emergence of new advanced artificial intelligence – raises questions about what role humans might play in future space exploration.

Some scientists wonder whether human astronauts will be needed at all.

“Robots are advancing rapidly and the case for sending humans is becoming weaker every day,” says Lord Martin Rees, Britain's Astronomer Royal. “I don’t think taxpayer money should be used to send people into space.”

It also indicates danger to humans.

“The only time people were sent [there] it is an adventure, an experience for rich people, and it should be privately funded,” he argues.

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

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

But what does this mean for future generations of budding astronauts – and of course there are certain functions that humans can perform in space that robots, no matter how advanced, will never be able to do?

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

In total, about 700 people have traveled to space since 1961, when Yuri Gagarin of the then Soviet Union became the first space explorer. Most have flown into orbit (circling the Earth) or suborbit (short vertical jumps into space lasting a few minutes on vehicles such as Blue Origin's New Shepard rocket).

“Prestige will always be the reason for the presence of people in space,” says Dr. Kelly Weinersmith, a biologist at Rice University in Texas and co-author of the book “A City on Mars.” “It seemed like it was a great way to show that your political system is effective and your people are brilliant.”

But beyond an innate desire to explore or a sense of prestige, people 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 this scientific research by being able to travel to places inhospitable to humans, where they can use tools to study and explore atmospheres and surfaces.

“Humans are more versatile and we do things faster than robots, but keeping us alive in space is very difficult and expensive,” says Dr Weinersmith.

In her 2024 Man Booker Prize-winning novel Orbital, author Samantha Harvey puts it more lyrically: “The robot needs no hydration, no nutrients, no secretions, no sleep… It doesn’t want or ask for anything.”

But there are also disadvantages. Many robots are slow and methodical—on Mars, for example, rovers (remote-controlled cars) move at only 0.1 mph.

“AI can beat a human at chess, but does that mean it can beat a human 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 that artificial intelligence algorithms could allow rovers to be “more efficient.”

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

“[AI could be used to] automate tedious tasks,” explains Dr Kiri Wagstaff, a US computer scientist and planetary scientist formerly of NASA's Jet Propulsion Laboratory in California. “On the surface of the planet, people get tired and lose concentration, but machines don’t.”

The problem is that systems such as large language models (LLMs), which can understand and generate human language by processing huge amounts of text data, require enormous power. “We're not ready to do an LL.M. on a rover yet,” says Dr. Wagstaff.

“Mars rovers’ processors operate at about a tenth [of the speed] what's in your smartphone” means that they cannot cope with the high demands of the LLM program.

Complex humanoid machines with robotic arms and limbs are another form of technology that can perform basic tasks and functions in space, especially because they more closely mimic human physical capabilities.

NASA's Valkyrie robot was built by the Johnson Space Center to participate in robotics testing in 2013. Weighing 300 pounds and standing 6 feet 2 inches tall, he's not much different from a Star Wars stormtrooper, but he's one of a growing number of humanoid machines with superhuman abilities.

Long before NASA's Valkyrie Robonaut was the first humanoid robot designed for use in space and performing tasks that would otherwise be performed by humans.

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

A later model of Robonaut was flown to the International Space Station on the Space Shuttle Discovery in 2011, where it assisted with maintenance and assembly.

“If we need to replace a component or clean a solar panel, we could do it with a robot,” says Dr. Sean Azimi, leader of a team of dexterous robotics at NASA's Johnson Space Center in Texas. “We see robots as a way to keep these habitats safe when people aren't around.”

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

Some robots are already working on other planets without humans, sometimes even making decisions on their own. For example, NASA's Curiosity rover. study a region called Gale Crater on Mars, where some scientific research is carried out autonomously, without human intervention.

“You could direct the rover to survey the area, look for rocks that might fit the mission's science priorities, and then autonomously fire a laser at that target,” says Dr. Wagstaff.

“It can take readings from a particular rock and send them back to Earth while people are still sleeping.”

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

“Inspiration is something intangible,” says Professor Coates.

Leroy Chiao, a former NASA astronaut who made three space flights in the 1990s and 2000s on NASA spacecraft and the International Space Station, agrees. “People react when people do things.

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

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

next mission with crew In 2026, four astronauts will fly around the Moon. The next mission, planned for 2027, will allow NASA astronauts to land on the surface of the Moon.

Meanwhile, the Chinese space agency 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 is to create a colony on Mars where people could Earth.

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

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

However, there are still many unknowns about life on Mars, including many technical problems that she says remain unresolved.

“Children may not be able to thrive in that environment,” she says. “There [are] ethical issues [like this] to which we have no answers.

“I think we should slow down.”

However, Lord Rees has his own vision in which human and robotic research could merge to such an extent that humans themselves become part machines, capable of coping with extreme conditions. “I can imagine that they will use all the techniques of genetic modification, adding cyborgs and so on to cope with a very hostile environment,” he says.

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

Until then, however, people will most likely continue their small steps into space along the path long ago traversed by robotic explorers.

Top image credit: NASA

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