The Future of Space Exploration: Robots or Astronauts?

The Future of Space Exploration: Robots or Astronauts?

Do we really need humans to explore space? Or are machines a better alternative to reach into the solar system and beyond? Two physics professors debate the benefits of manned and unmanned space missions.

Humans Are Essential for Space Exploration 

“We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard.” With these words, President John F. Kennedy roused America’s support of space exploration in 1962. He also acknowledged the geopolitical competition with the Soviet Union that provided the impetus to make mankind’s greatest technological achievement a possibility. Absent that Cold War motivation, our manned space program has languished in low Earth orbit for the last 40 years. That drought drives home the point that we must return to the spirit of human exploration of the final frontier exemplified by the Apollo program. The need to see what is over the next horizon — and not to simply see it, but to actually touch it — is a fundamental aspect of human nature. Those horizons beckon on countless asteroids, the moon and Mars.

The manned exploration of space is an expression of one of our finest aspects — curiosity. To truly satisfy that curiosity we need to be participants. My colleague correctly points out that the robotic space program is a far more cost-effective means of advancing our scientific knowledge of the universe, and I could not agree more. While valuable advances have been made because of the manned program, it cannot and should not be justified on the grounds of scientific advancement. It is instead about something equally important as science — the inspiration of our species to pursue lofty goals.

Space scientists frequently make the mistake of assuming that the space exploration budget is a zero-sum game, lamenting the money spent on the manned program that could be used to fund ambitious and scientifically valuable robotic missions. It is naïve to expect that politicians would spend those same billions on purely scientific exploration. If the manned program was canceled today, its budget would disappear, never to be spent on space exploration of any kind. In contrast, the U.S. manned space program enables NASA to maintain a scientific program of space exploration that is by far the largest in the world. We need to move past the debate of manned versus unmanned programs and recognize that they serve different yet complementary roles, and that each endeavor ultimately strengthens the other.


Robots Are Key to Future Space Exploration

On the plus side, humans in space provide operational flexibility, inspiration and native intelligence. On the minus side, that flexibility comes at a steep price. Humans are heavy, fragile, dirty, vulnerable, picky about their environment, and have a low tolerance for the space environment (i.e., high energy radiation, extreme heat and cold, etc.). The fragility of humans, our aversion for risking human life, and the all-too-human need for consumables (food, water and oxygen) require vast amounts of money to pay for the extra engineering and multiple redundant systems we demand to reduce risk to astronauts, as well as for the vastly larger support crews needed to baby-sit every aspect of daily life during a manned space mission.

For crewed spacecraft, Venus and Mercury are impossibly hot, and the asteroid belt and Jupiter are impossibly cold. The longer travel times to these worlds would be a death sentence from radiation exposure, not to mention bone loss and muscle atrophy. Once at an exploration target, humans can be a mixed blessing. Imagine trying to search for life on Mars with human explorers who are shedding pollutants and terrestrial contamination with literally every step and breath.

Fundamentally there is no real choice between robotic and human exploration of space, however. Both are synergistic and mutually dependent. Robotic exploration is necessary to enable human exploration by setting the context, providing critical information, and reducing the risk to humans. Imagine how the Apollo program would have functioned without its robotic precursors — Lunar Orbiter to map the moon’s surface, Ranger to get close-up views of areas that helped perfect NASA’s navigation skills (remember that NASA missed the moon with two of the first three Rangers to get that far), and Surveyor to explore the surface, determine its composition and practice soft landings. Without these robotic precursors it would’ve been impossible to know where to go on the moon, to design the landing hardware, or to have any real idea of what to do once we got there — other than plant the flag.

Is there a choice between human and robotic exploration? Not really. Considering the current limited range of human exploration, robotic exploration is essential to enable manned missions. For the rest of the solar system, robotic exploration is the only realistic game in town.