Do we still need astronauts when robots can explore for less?

There is no settled answer, and the argument is better than it sounds. People who favour robots point to cost and risk: many missions are more suited to telerobotic than crewed operation, and some destinations, such as Venus or the vicinity of Jupiter, are too hostile for human survival with current technology. Saturn, Uranus and Neptune are too distant for crewed spaceflight, so robots are the only way to explore them. Spacecraft can also be sterilised to protect regions vulnerable to contamination by Earth micro-organisms; humans cannot.

The reasons given for exploring space at all make a different list. Common rationales include advancing scientific research, national prestige, uniting different countries and ensuring the future survival of humanity. Stephen Hawking said he did not think the human race would survive the next thousand years unless it spread into space, and Arthur C. Clarke argued that humanity's choice was between expansion into space and cultural, and eventually biological, stagnation and death.

Neither side has a perfect record. Robots fail: roughly two-thirds of all spacecraft destined for Mars failed before completing their missions. And people have been the repair crew: Hubble is the only telescope designed to be maintained in space by astronauts, while Webb cannot be repaired by a crewed mission.

Artemis puts the debate in dollars. Its goal is to return humans to the Moon for the first time since Apollo, and as of 2026 its second mission, Artemis II, has flown four astronauts around the Moon. A 2021 NASA Inspector General audit put the true cost of the programme at about $93 billion until 2025, and in 2025 the White House called its SLS rocket "grossly expensive" and proposed ending it after Artemis III, while Congress then funded SLS rockets for two more missions.