Alien Pandemics and Interplanetary Contamination

The coronavirus has been wreaking havoc across the world, it's unquestionably a terrifying epidemic that I hope doctors everywhere can contain as soon as possible. But as horrible as our Earthbound terrestrial pathogens already are, it got me thinking: what's the risk of extraterrestrial diseases befalling Earth, and what precautions do we have in place to prevent any alien pandemics?

This is a space finance blog, so of course I gotta compare coronavirus-week to other stock market freefalls! | Source: MarketWatch

Scientists grappled with this problem for the first time during the Apollo Program, as they knew the moon landings would bring the first samples from another world back to our planet. If the moon wasn't as dead as it appeared and lunar lifeforms somehow hitched a ride on the Columbia back to Earth, we needed a way to contain them. So in an abundance of caution, when the astronauts splashed down in the ocean, the first thing the helicopter recovery team did when they opened the spacecraft hatch was throw biological isolation garments (basically hazmat suits) for them to put on before being lifted out of the sea. Then the astronauts were locked away in the Mobile Quarantine Facility (MQF), a modified Airstream trailer that housed them while they were transported to the Lunar Receiving Laboratory in Houston. There they would be extensively examined for weeks in quarantine to ensure they didn't fall ill with any alien diseases that could decimate humanity

The Apollo 11 crew in their isolation garments exiting their spacecraft, and in the MQF speaking to President Nixon

In hindsight we know these quarantine measures were unnecessary - Neil, Buzz, Mike and all other other Apollo astronauts returned from the moon in perfectly good health, and the quarantine was eliminated after Apollo 14. But over lunch with my fellow SpaceX financial analysts a few weeks ago, I posed the question: "what do you think NASA would've done if the Apollo 11 crew came down with horrific symptoms from some mystery moon bug and died right there in quarantine? How in the world would NASA properly dispose of the remains while guaranteeing containment?" Who knows, maybe NASA would've dedicated a rocket launch just to blast the contaminated MQF back into space and away from everyone else! If you have any thoughts, share in the comments because I'm curious to know - I tried researching online but found nothing!

Apollo 12 crew in the MQF - check out Alan Bean (a Texas Longhorn just like me!) giving a Hook 'em Horns after returning from the moon! \m/

Though the moon landings are over (for now!), interplanetary contamination is still an important concern for our robotic probes. There are in fact two types: forward contamination, where we unwittingly transport Earth microbes on our spacecraft that contaminate other celestial bodies, and backward contamination, where hypothetical alien organisms are accidentally brought back to Earth. To prevent contamination, the Committee on Space Research (COSPAR) established by the 1967 Outer Space Treaty sets strict planetary protection guidelines. The stringency of the requirements range from Category I-V as follows, depending on the mission (there are in fact subcategories, click here for more detail):

  • Category I: Destinations highly unlikely to harbor life (i.e. the Sun or Mercury)
  • Category II: Destinations of interest in the evolution and search for life, but unlikely to be compromised by contamination (i.e. the Moon, Venus, comets)
  • Category III: Flyby and orbiter missions to destinations of high interest in the evolution and search for life (i.e. Mars, Europa, Enceladus)
  • Category IV: Landers to the same destinations as Category III
  • Category V: Sample return missions from the same destinations as Category III & IV

Examples of precautions taken to meet these requirements include intense sterilization of spacecraft components prior to launch or contingency plans to safely dispose of the spacecraft, either due to malfunction or end of mission. Thus far no mission has fallen under Category V, but that will hopefully change in the next few decades as both robotic sample return and crewed missions to Mars take shape!

In an example of planetary protection, at the end of its mission the Cassini probe used the last of its fuel to intentionally crash into Saturn so that it wouldn't accidentally collide with Titan or some other potentially life-harboring moon

But to conclude and circle back to our original point about the horrors of an alien coronavirus - while these safeguards against backward contamination are undoubtedly prudent and necessary, the likelihood of an extraterrestrial pandemic exterminating humanity is exceedingly low. Infection occurs when a pathogen successfully binds to a cell's surface; the only reason bacteria and viruses infect humans is because we've coexisted and evolved together for billions of years. And even then, the likelihood of pathogenicity is minuscule - of the gazillions of known bacteria species, only a couple hundred happen to produce the proteins and other toxins capable of binding to our cells and making us sick. Alien organisms simply would not have this intimacy - their contagiousness and our immune systems would never do battle. Lucky for us, they'd simply be two microscopic ships passing in the night
Is this diagram unsettling? Really it should put you at ease - a nice reminder that Earth's pathogens are the only ones you'll ever have to fight!