Inspired by great dreamers like Ray Bradbury, we have all come to expect that someday mankind will explore and settle the Red Planet. Gravitationally and thermally, it is one of only three places in this solar system where a man can productively explore with his own two feet. Geologically, it is more interesting than the Moon, and although far from perfect, it does have many of the natural resources needed to support technologically-advanced human settlements.
Leaders like Robert Zurbin have described how realistic manned missions to Mars are entirely possible and could be within our reach if we are serious and focused upon making them a reality. Crew survival from an Apollo 13 type of failure could be unlikely, but there should be ways to mitigate some of those risks.
Geopolitical considerations suggest that China will want to be the nation to first plant a flag on Mars. The Russians were first to orbit. Americans were first on the Moon. A Chinese taikonaut on Mars could secure them a place in the record books for centuries into the future. They have the required space workforce, program continuity, and technical resources needed to be able to make this happen.
However, the strongest driving force for the exploration of the Red Planet is the question: Is it alive? From thousands of images and measurements we have already ruled out the presence of large surface plants and animals. What we cannot entirely dismiss, however, is the possibility of “invisible” Martians such as microorganisms or anything that could exist below the surface. What makes this question so important is that from a “Yes” we can infer that life is probably prevalent throughout the universe. And there is nothing that an astrobiologist would love more than to be able to analyze the sequence of alien DNA (or other genetic code) to compare with terrestrial organisms.
Given the hostile Martian surface environment, if we are going to detect telltale traces of life, we will need highly sensitive instruments that look for the faintest possible biological signatures such as organic molecules. This is where the story begins to sound more like something out of classic science fiction.
In order for an astronaut to step down onto the surface, he or she will need to step out of an airlock from his spaceship. By necessity, the volume of this airlock will first be exposed to the inside of the spacecraft, and then to the Martian atmosphere. Even clever designs like the lunar electric rover suitport suffer from this inherent limitation.
Living on the surface of each astronaut will be one trillion microorganisms, representing more than 1,000 species of skin flora. Combined with microorganisms from other parts of the body, every single astronaut will bring along to Mars a rich soup of Earth microorganisms that will be released into the atmosphere every time that he climbs out of the hatch. These microorganisms can, under favorable conditions, multiply every 20 minutes, allowing them to rapidly grow, mutate, and adapt to adverse environmental conditions.
One of the adversities on Mars is the high level of UV radiation, which will kill off many of the bacteria that remain exposed on the surface. The organic remnants from these bacteria and viruses could potentially fool ultra-sensitive instruments. Some bacteria will become shielded from the UV, buried just below the surface by footsteps, wheels, and dust devils. And for some, such as a strain that has come to be known as Conan the Bacterium, radiation is not a problem. Through an elaborate collection of repair mechanisms, it is capable of withstanding radiation more than 1,000 times greater than any other known living organism.
Proponents of Mars exploration have attempted to assemble flimsy planetary protection schemes, such as landing dirty spacecraft in mythical “safe” zones where biological contaminants would be less likely to thrive and barring astronauts from entering the genuinely interesting locations where remnants of Martian life could still be viable. Exploration of those regions would be limited to “clean” rovers.
What they conveniently ignore is the capability of the Martian atmosphere to carry microorganisms far and wide, as has frequently been demonstrated by each planetary-scale dust storm.
We have only one Mars, and contamination from careless acts on the part of overenthusiastic trailblazers could easily result in an enormous, unrecoverable setback to astrobiology.
And beyond that, there is the less academic concern of reverse contamination. With each return of an astronaut to the ship, the airlock would introduce Martian biological remnants to the crew, and subsequently, to Earth. We don’t know how serious this might be, but, historically, human exploration has frequently resulted in epidemics.
Over the past decades, space enthusiasts have repeatedly argued over a Mars-first vs. Moon-first strategy for manned space exploration. What has been totally overlooked is the question if we need to initially ban any manned missions to Mars until we can first complete a reasonably exhaustive unmanned exploration campaign to determine if Mars has ever been alive.
If Mars is, or ever was, alive, we might possibly need to restrict future human exploration and settlement. If Mars has always been dead then it will be time to drop the astrobiology pantomimes and open up the Martian Land Rush. As Bradbury once penned, we will be the Martians.