Inevitably, I’ve seen a couple of conspiracy theorists spout that COVID-19 came from space (it didn’t).
But should we worry about viruses from space? In the earliest days of space travel, we really didn’t know. During the Apollo missions, we quarantined astronauts after landing because of concerns about “moon bugs.” Needless to say, the moon is confirmed lifeless. Astronauts still quarantine before their flights for two weeks because nobody, nobody wants to get a cold in space.
The Apollo astronauts spent 21 days in a modified Airstream trailer.
So, should we worry about space viruses. A recent article claimed that we should be careful with Martian sample return (Pro tip: We will, but it will be to keep Earth life from contaminating the samples).
Could We Catch a Space Virus?
Viruses, not being truly alive, are very hard to “kill” or inactivate. In fact, some astronauts have experienced subclinical reactivation of a virus they recently caught (meaning no symptoms), because zero G isn’t great for your immue system.
A virus from another planet, though? Let’s remind ourselves how viruses work.
A virus is essentially biological code. It is a strand of either RNA (COVID-19 is an RNA virus) or DNA encased within a protein coat. When a virus enters a cell, it drops the protein coat and hijacks the cell’s own replication machinery to copy itself. Needless to say, this isn’t great for the host, with cells hijacked their function isn’t carried out properly.
Viruses can also be used to hack cells; domesticated viruses called “viral vectors” are used in gene therapy. In fact, genetic material transferred by viruses assists with bacterial evolution.
But for a virus to work, it has to have DNA or RNA. The coding has to match.
Will this be true for space viruses?
The ultimate answer is, of course: We don’t know.
Any kind of life has to have a controlling biological code. On Earth that is DNA and RNA. The base proteins and components of DNA have been potentially found on meteorites, meaning that those components exist across the universe.
For a space virus to infect a human being, though, those components would have to be arranged in a similar, if not identical fashion. We have already synthesized at least one biological coding system that is not DNA. So, it’s possible, and indeed quite likely, that an alien virus would not use the same coding system. This would make it a lot harder for the virus to hijack our cells.
What Would Happen if it Tried?
The other basic question is this:
A space virus based on another code gets into your system. What happens? First of all, we’re going to assume this virus has the ability to enter cells (or it’s not a virus). It evolved, perhaps, to infect and hijack microbial life on Mars and may have remained dormant for a very long time.
It gets into our cells, then it looks around. There are a few possibilites:
- The virus finds nothing it recognizes and is unable to hijack the cell. In this case, the virus would probably end up inactivated.
- The virus chops up the cell’s DNA but is unable to hijack it. This would result in some destruction of cells, but as the virus could not replicate you probably wouldn’t get sick.
- The virus still manages to hijack the cell, resulting in the production of alien DNA in your system. This is not likely to be good for you (at a science fiction level it gives some rather intriguing, if unlikely, story ideas).
Our immune systems might also have issues recognizing alien viruses as a threat. Or not. Antibodies attack not the cellular code in a virus, but its protein sheath. Which means we should develop antibodies against an alien virus absolutely fine.
(I’m not responsible for any nightmares fueled by the idea of alien viruses reprogramming our genes and turning us into tentacle monsters or something).
In general, space viruses may in fact be a concern (there’s a lot of assumption that situation 1. would be the most common, whilst I’m leaning towards 2. in most cases), but not nearly as much of one as other pathogens. Anything analogous to a fungus, for example…
But it’s a moot point for now; any samples that come back from Mars are going to be handled very carefully so we don’t find “Martian” life that turns out to be a researcher’s gut bacteria.
If we ever make contact with aliens…well. That could prove interesting.