Robots in Space: Will They Replace Human Astronauts?

Could robots take over the job of astronauts in space? On 24 December 2024, a spacecraft flew closer to the Sun than any human-made object before. NASA's Parker Solar Probe moved through the Sun's atmosphere. Its goal was to learn more about the Sun and space weather.

This was a major event. Yet, no human was controlling it live from Earth. The spacecraft did its pre-set tasks all by itself.

For sixty years, robotic probes have been sent across the solar system. They go to places that are impossible for humans. The Parker Solar Probe faced temperatures of 1,000°C. The success of such self-operating spacecraft, plus advanced artificial intelligence (AI), raises a big question. What part will humans play in the future of space exploration?

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

"Robots are improving fast. The reason for sending humans is getting weaker," says Lord Martin Rees, the UK's Astronomer Royal. "I don't think tax money should be used to send humans into space." He points to the dangers. He says the only reason to send people is for adventure, which should be paid for privately.

Andrew Coates, a physicist, agrees. "For serious space exploration, I much prefer robotics," he says. "They go much further and do more things." He adds that robots are cheaper. As AI gets better, they can become smarter.

But what does this mean for people who want to be astronauts? Can humans do things in space that even advanced robots cannot?

Robotic spacecraft have visited every planet in the solar system, plus many asteroids and comets. Humans, however, have only been to two places: Earth's orbit and the Moon.

Since 1961, about 700 people have gone to space. Most have only gone into orbit around Earth. Dr. Kelly Weinersmith, a scientist and author, says showing power is a big reason for sending humans. "It is a great way to show that your political system works and your people are brilliant," she explains.

Besides showing power, humans do important research in Earth's orbit. On the International Space Station, they run experiments that help science. Robots help with research too. They can travel to dangerous places and study other worlds.

"Humans are more flexible and we finish work faster than a robot. But we are really hard and expensive to keep alive in space," says Dr. Weinersmith. In contrast, a robot needs no food, water, or sleep. But robots have problems. Many are very slow. The rovers on Mars move at barely 0.1 miles per hour.

"AI can beat humans at chess, but does that mean they will be better at exploring new places?" asks Dr. Ian Crawford, a space scientist. "I just don't think we know." He does believe AI might help rovers work better.

Technology can also work with human space travel. It can free astronauts from boring jobs so they can focus on important research.

"[AI could be used to] handle dull tasks," explains Dr. Kiri Wagstaff, a former NASA scientist. "On a planet's surface, humans get tired, but machines won't."

The challenge is that advanced AI systems need a lot of power. These systems can understand human language. "We cannot run this kind of AI on a Mars rover right now," says Dr. Wagstaff. "The rovers' computer chips are about ten times slower than your smartphone."

Humanoid robots with arms and legs are another technology. They could do simple tasks in space because they copy human physical abilities.

NASA's Valkyrie robot was built in 2013. It is tall and heavy, and it is one of many human-like machines with special abilities. Before Valkyrie, NASA's Robonaut was the first humanoid robot designed for space. Its special hands could use the same tools as astronauts. It could hold objects or turn switches, tasks that are hard for other robots.

A later model of Robonaut was sent to the International Space Station in 2011. It helped with repairs and assembly work.

"If we need to change a part or clean a solar panel, we could do that with a robot," says Dr. Shaun Azimi, who leads a robotics team at NASA. "We see robots as a way to protect space stations when humans are not there." He argues robots could be useful not to replace human explorers, but to work with them.

Some robots already work on other planets without humans. Sometimes, they make their own choices. NASA's Curiosity rover explores Mars's Gale Crater. It does some science on its own, without waiting for commands from Earth.

"You can tell the rover to take pictures of an area, find rocks that fit science goals, and then fire its laser at that target by itself," says Dr. Wagstaff. "It can study a rock and send the data to Earth while the humans are asleep."

But the abilities of rovers are limited by their slow speed. Humans have another benefit: they inspire people on Earth in a way machines cannot.

"Inspiration is something you cannot touch," argues Professor Coates. Leroy Chiao, a retired NASA astronaut, agrees. "Humans connect when other humans are doing something," he says. "People are excited about robotic missions. But I think the first human on Mars will be an even bigger event than the first Moon landing."

Humans have not traveled past Earth's orbit since December 1972, when the last Apollo mission went to the Moon. NASA hopes to return humans to the Moon this decade with its Artemis program. A mission in 2026 will send four astronauts to fly around the Moon. Another, planned for 2027, aims to land astronauts on the Moon. China also wants to send astronauts to the Moon.

In another effort, Elon Musk, head of SpaceX, has his own plans. His long-term goal is to create a colony on Mars where humans could live. He wants to use a huge new vehicle called Starship to carry up to 100 people at a time. His aim is for a million people to live on Mars within 20 years.

"Musk argues we need to move to Mars as a backup plan for humanity if something terrible happens on Earth," explains Dr. Weinersmith. "If you agree with that, then sending humans into space is necessary."

However, there are many unknowns about living on Mars. Many technical problems are not yet solved. "Maybe babies cannot grow in that environment," she says. "There are big ethical questions we do not have answers for. I think we should slow down."

Lord Rees imagines a different future. He thinks human and robotic exploration might combine. Humans might become part-machine to survive in extreme places. "I can imagine they will use genetic changes and machine add-ons to handle very harsh environments," he says. "We may have a new kind of species that will be happy to live on Mars."

For now, however, humans will likely keep taking small steps into space. They will follow a path that has long been traveled by robotic explorers before them.