The race to commercial space flight has well and truly started, with more than 85 companies and organizations seeking a future in interplanetary tourism. Yet some researchers worry we might be getting ahead of ourselves.

Before travel outside of Earth becomes a regular event, the world needs to implement some basic biosecurity measures, they warn. Otherwise, we could start receiving unwelcome alien visitors.

If a foreign organism manages to hitch a ride back to our planet on one of our spacecrafts, it could wreak havoc on Earth's equilibrium.

The chance of that actually happening is improbable, especially since we haven't yet found life outside of Earth. But given how bad it could get, it's a reality some think we should prepare for.

A more likely scenario would be a human tourist carrying an Earthly organism to space, and that's also a significant risk.

In space-like conditions, studies have shown some microbes can undergo rapid genetic mutations. After growing a thousand generations of Escherichia coli in micro-gravity conditions, for instance, researchers found the harmful bacteria grew even more competitive, acquiring antibiotic resistance.

If that resistant strain is then carried back to Earth, it could seriously threaten human life.

"Risks that have low probability of occurrence, but have the potential for extreme consequences, are at the heart of biosecurity management," says invasion biologist Phill Cassey from the University of Adelaide in Australia.

"Because when things go wrong, they go really wrong."

The international Committee on Space Research (COSPAR) has put together a Panel on Planetary Protection, but no current member has expertise in invasion science.

Invasion biologists in Australia think that's a serious oversight. They say we need more sophisticated protocols to prevent biological contamination from extraterrestrial environments to Earth and vice versa.

"Given the enormous foundation of research in the science and management of invasive species," the biologists write, "we contend that greater collaboration between invasion biologists and astrobiologists would enhance existing international protocols for planetary biosecurity—both for Earth and for extraterrestrial bodies that could contain life."

Because right now, it seems our biosecurity protocols are failing us.

When an Israeli spacecraft crashed into the Moon in 2019, for instance, it dumped dehydrated tardigrades onto the surface, which could possibly still be alive.

Even more worrisome, bacterial strains with signs of extreme resistance have also been isolated in NASA "clean rooms" where employees assemble spacecraft. If these dangerous microbes hitchhike into space, there's a chance they could grow even more virulent in microgravity.

Stopping that from happening in the first place is much easier than trying to tackle mutating organisms once they make it to, say, Mars.

Even then, however, some experts think it might be nearly impossible keeping Earthly microbes here on Earth. Everywhere else humans have gone, we've inevitably taken organisms with us.

Space, invasion scientists warn, is merely "the next frontier of biosecurity risk".

The study was published in BioScience.