„Robotic missions are much cheaper and may provide more scientific information, but they don’t catch the public imagination in the same way, and they don’t spread the human race into space, which I’m arguing should be our long-term strategy. If the human race is to continue for another million years, we will have to boldly go where no one has gone before.“
Stephen Hawking, Cambridge University
Will unmanned robotic missions be able to detect weird microscopic life-forms they are not programmed to recognize that might be lurking below the surface of Saturn’s Titan, or beneath the murky seas of Jupiter’s jumbo moon, Europa?
The answer to this question is at the core of one of the greatest of the ongoing debates in space exploration: the question of man vs. unmanned robotic missions.NASA currently operates more than 50 robotic spacecraft that are studying Earth and reaching throughout the solar system, from Mercury to Pluto and beyond. Another 40 unmanned NASA missions are in development, and space agencies in Europe, Russia, Japan, India and China are running or building their own robotic craft.
What is not commonly known however is that many of NASA’s leading scientists also champion human exploration as a worthy goal in its own right and as a critically important part of space science in the 21st century. The Obama administration’s new NASA strategy that strongly favors robotic exploration, has opened the debate anew.
Recently, the President announced that he plans to cancel the Constellation program which was designed as our next step in the human flight area, focusing on a return to the moon. His goal is to move NASA away from its current role as a space transportation provider and allow it to again become a research and development organization. This will leave NASA without the capability to send humans to orbit.
„Tomorrow’s NASA space program will be different,“ says Wallace Fowler of the University of Texas, a renowned expert in modeling and design of spacecraft, and planetary exploration systems. „Human space flight beyond Low Earth Orbit (LEO), beyond Earth’s natural radiation shields (the Van Allen belts), is dangerous. Currently, a human being outside the Van Allen belts could receive the NASA defined “lifetime dose” of galactic cosmic radiation within 200 days. If the Sun spews out a coronal jet of radiation in a solar storm in the direction of the spacecraft, a lethal dose can be received in a few hours. Mars does not have the equivalent of the shielding Van Allen belts, so a Mars base would also need shielding. Until we develop appropriate shielding, probably an intense magnetic field around the spacecraft, human travel, even to the moon, will likely be limited.“
„Robotic missions, in the short term, will be limited to the inner solar system,“ continues Fowler aruing the hard realities of manned space travel. „In the inner solar system (within the orbit of Mars), the solar cells can be used to power spacecraft. Beyond Mars, spacecraft power systems rely on radioactive means to create electricity, and we do not currently have a supply source for the needed material. There is a very short supply of Plutonium 238, the radioactive element used to provide electricity for spacecraft going to Jupiter and beyond. We have exhausted the U.S. supply and have been buying it from the Russians. Now they are in short supply and other sources are not currently available.“
In a past issue of Scientific American Jim Bell, an astronomer and planetary scientist at Cornell University, and author of “Postcards from Mars,” notes that “…you might think that researchers like me who are involved in robotic space exploration would dismiss astronaut missions as costly and unnecessary.”
But he then he goes on, “Although astronaut missions are much more expensive and risky than robotic craft, they are absolutely critical to the success of our exploration program.“
The heart of the debate is this: robotic machines will only do what they are programmed to do; they are not programmed to detect weirdness: the unimaginable, the unknown, the strange non-carbon life that we may have encountered on Mars, for example with the two Viking vehicles, in 1976. Each carried equipment for sampling the Martian soil and miniature chemistry laboratories to test the samples for signs of life.The results these automated labs radioed back to Earth were enigmatic: the chemical reactions from the Martian soil were strange, unlike anything seen on Earth. But they were also unlike any reactions that living organisms would produce.
Ben Bova, the science-fiction author of Titan and The Aftermath, his most recent novels in is his ongoing series about the expansion of the human race throughout the Solar System, points out in an interview that most scientists examining the Viking results, reluctantly concluded that was lifeless: „But the fact is that the landers were equipped only to detect signs of Earth-type life. The chemical reactions observed could have been the results of Martian life. They certainly were not ordinary inorganic chemistry.“