NASA wants to hire a new 鈥� but if you are dreaming of joining the Men in Black to defend Earth from alien attack, it鈥檚 probably not the job for you.
That鈥檚 because it鈥檚 not really Earth that needs protection, but everywhere else in the solar system. 鈥淧lanetary protection is concerned with the avoidance of organic-constituent and biological contamination in human and robotic space exploration,鈥� reads the . In plain English, it鈥檚 about microbes.
Any time NASA sends a spacecraft to another word, it runs the risk of contaminating it with microbes from Earth. If that happens, researchers looking for extraterrestrial life could think they鈥檝e found it, when all they actually see is relocated bacteria from our own probes.
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Once the microbes are there, it will be nearly impossible to tell whether they are natives or have just hitched a ride over. Even worse, there鈥檚 a chance that Earth microorganisms could overrun the locals, destroying our chance of making one of the greatest discoveries in history.
Alien flu
Ok, there is a bit of Earth defence involved. If samples from other worlds are brought back, there鈥檚 a risk that any alien microbes they carry might be dangerous for humans or other Earth organisms, so we need proper quarantine procedures in place. No one wants extraterrestrial flu, after all.
Handling all those risks is the job of the planetary protection officer, a role NASA has had for decades and just happens to be hiring for now. Their number one goal is to make sure all the microbes stay on the worlds where they belong.
Unfortunately, it鈥檚 impossible to get any spacecraft perfectly clean: even the most pristine landers that we鈥檝e sent to Mars were covered in thousands to millions of microbes. So the planetary protection officer determines how many microbes represent an acceptable risk.
What qualifies as an acceptable risk depends on where the mission is headed. An orbiter can have lots of microbes on it, because they鈥檒l probably all die before it crash-lands at the end of its mission. Mars landers are allowed to have 1000 microbes per square metre of surface area.
Risk avoidance
Certain areas on Mars and other worlds, generally the areas with water, are designated as 鈥渟pecial regions鈥� because they are the areas where extraterrestrial microbes are most likely to live and thus the spots most dangerous to contaminate. No rovers are allowed to visit special regions.
At some point, though, we鈥檒l reach a crossroads: either we leave the most interesting areas on other worlds alone forever, or we dive in and probably contaminate them.
A conservative view of planetary protection would prescribe that before we send spacecraft anywhere, we should be absolutely sure that there鈥檚 no alien life there to contaminate. But no matter how thoroughly we look, we can never be 100 per cent sure that there aren鈥檛 any signs of life that we just missed.
As NASA sends more rovers to Mars, plans a trip to Jupiter鈥檚 icy moon Europa, and starts to ramp up work on human space flight, the new planetary protection officer will have to help decide how much exploration is allowed. But being too protective and requiring too much certainty could mean barring ourselves from finding anything at all. Sure, it鈥檚 not Men in Black levels of exciting, but maybe the new officer needs to take a few risks.
