Mushrooms to Mars: how fungi research could help long-duration space travel

I've often noted that fungi are the forgotten heroes of the ecosystem, beavering away largely out of sight and therefore out of mind. Whether it's the ability to break down plastic waste or their use as meat substitutes and pharmaceuticals, this uncharismatic but vital life form no doubt hold many more surprises in store for future research to discover. It's estimated that less than ten percent of all fungi species have so far been scientifically described; it's small wonder then that a recent study suggests an entirely new use for several types of these under-researched organisms.

Investigation of the Chernobyl nuclear power station in 1991 found that Cladosporium sphaerospermum, a fungus first described in the late nineteenth century, was thriving in the reactor cooling tanks. In other words, despite the high levels of radiation, the species was able to not only repair its cells but maintain a good rate of growth in this extreme environment. This led to research onboard the International Space Station at the end of 2018, when samples of the fungus were exposed to a month of cosmic radiation. The results were promising: a two millimetre thick layer of the fungus absorbed nearly two percent of the radiation compared to a fungus-free control.

This then suggests that long-duration crewed space missions, including to Mars, might be able to take advantage of this material to create a self-repairing radiation shield, both for spacecraft and within the walls of surface habitats. A twenty-one centimetre thick layer was deemed effective against cosmic rays, although this could potentially be reduced to just nine centimetres if the fungal mycelia were mixed with similar amounts of Martian soil. In addition, there is even the possibility of extracting the fungus' radiation-proof melanin pigment for use in items that require much thinner layers, such as spacesuit fabric.

If this sounds too good to be true, there are still plenty of technological hurdles to be overcome. Science fiction has frequently described the incorporation of biological elements into man-made technology, but it's early days as far as practical astronautics is concerned. After all, there is the potential for unique dangers, such as synthetic biology growing unstoppably (akin to scenarios of runaway nanobot replication). However, NASA's Innovative Advanced Concepts program (NIAC) shows that they are taking the idea of fungi-based shielding seriously, the current research considering how to take dormant fungal spores to Mars and then add water to grow what can only be described as myco-architecture elements - even interior fittings and furniture. In addition to the radiation shielding, using organic material also has the advantage of not having to haul everything with you across such vast distances.

Even more ideas are being suggested for the use of similarly hardy species of fungi on a Mars base, from bioluminescent lighting to water filtration. Of course, this doesn't take into account any existing Martian biology: the seasonal methane fluctuations that have been reported are thought by some to be too large to have a geochemical cause; this suggests that somewhere in the sink holes or canyon walls of Mars there are colonies of methane-producing microbes, cosily shielded from the worst of the ultraviolet. If this proves to be the case, you would hope that any fungi taken to the red planet would be genetically modified to guarantee that it couldn't survive outside of the explorer's habitats and so damage Martian biota. Humanity's track record when it comes to preserving the ecosystems of previously isolated environments is obviously not something we can be proud of!

What fungi can do alone, they also do in symbiosis with algae, i.e. as lichens. Various experiments, including the LIchens and Fungi Experiment (LIFE) on the International Space Station (incidentally, doesn't NASA love its project acronyms?) have tested extremophile lichens such as Xanthoria elegans and Rhizocarpon geographicum in simulated Martian environments for up to eighteen months. The researchers found that the organisms could remain active as long as they were partially protected, as if they were growing in sink holes beneath the Martian surface. Of course, this success also enhances the possibility of similar lifeforms already existing on the red planet, where it would have had eons in which to adapt to the gradually degraded conditions that succeeded Mars' early, clement, phase.

The CRISPR-Cas9 system and its successors may well develop synthetic fungi and lichens that can be used both on and especially off the Earth, but we shouldn't forget that Mother Nature got there first. Spacecraft shielding and myco-architecture based on natural or genetically modified organisms may prove to be an extremely efficient way to safeguard explorers beyond our world: the days of transporting metal, plastic and ceramic objects into space may be numbered; the era of the interplanetary mushroom may be on the horizon. Now there's a phrase you don't hear every day!

Resurrecting megafauna: the various problems of de-extinction

The record-breaking success of Jurassic World proves that if there's anything a lot of people want to see in the animal kingdom it is species that are both large and fierce. Unfortunately, in these post-glacial times that type of fauna has been much reduced and will no doubt wane even further - not that I particularly wish to encounter an apex predator at close quarters, you understand.

Hollywood, of course, has much to answer for. There was plenty of poor science in the original Jurassic Park movie - the use of gap-filling frog DNA being a far worse crime in my book than the over-sized velociraptors (think Achillobator and similar species) but the most recent film in the franchise has pointedly ignored the advances in dinosaur knowledge made in the intervening period. Perhaps a CGI test of a feathered T-Rex looked just to comical?

In contrast, the amount of publically-available material discussing de-extinction has increased exponentially in the two decades since Jurassic Park was released, with the line between fact and fiction well and truly blurred. That's not to say that an enormous amount hasn't been learned about the DNA of extinct species during this period. I recently watched a rather good documentary on the National Geographic channel (yes, it does occasionally happen) about the one-month old baby mammoth Lyuba, recovered in Siberia almost forty-two thousand years after she died. The amount of genetic information that has been recovered from mammoths is now extremely comprehensive, but then they were alive until almost yesterday at geological timescales. Needless to say the further back in time a creature existed, the more problematic it is to retrieve any genetic material.

A lot has been written about the methods that have been, or could in the near future, be used to resurrect ancient animals. Some procedures involve the use of contemporary species as surrogate parents, such as elephants standing in for mother mammoths. But it seems fair to say that all such projects are finding difficulties rather greater than originally planned. One common misconception is that any resurrected animal would be a pure example of its kind. Even the numerous frozen mammoth carcasses have failed to supply anywhere near a complete genome and of course it isn't just a case of filling in gaps as per a jigsaw puzzle: one primary issue is how to know where each fragment fits into the whole. Our knowledge of genetics may have advanced enormously since Watson and Crick's landmark 1953 paper, but genetic engineering is still incredibly difficult even with species that are alive today. After all, Dolly the sheep wasn't a pure clone, but had nuclear DNA from one donor and mitochondrial DNA from another.

Therefore instead of resurrecting extinct species we would be engineering hybrid genomes. Jurassic World took this process to the extreme with Indominus rex, a giant hybrid of many species including cuttlefish! Some research suggests that the most of the original genes of any species over a million years old – and therefore including all dinosaurs – might never be recovered. Something  terrible lizard-ish may be built one day, but it would be closer to say, a chicken, with added teeth, a long bony tail and a serious attitude problem. In fact, George Lucas has been a key funder of the chickenosaurus project with aims along these lines. Let's hope he doesn't start building an army of them, totally obedient clones, ready for world domination…oh no, that was fiction, wasn't it?

But if – or more likely, when – creating variants of extinct species becomes possible, should we even attempt it? Apart from the formidable technical challenges, a lot of the drive behind it seems to be for populating glorified wildlife parks, or even worse, game reserves. The mock TV documentary series Prehistoric Park for example only contained large animals from various periods, frequently fierce carnivores, with no attention given to less conspicuous creatures or indeed flora. This gee-whiz mentality seems to follow a lot of the material written about de-extinction, masking some very serious long-term issues in favour of something akin to old-style menageries. Jurassic Park, in fact.

A big question that would be near impossible to answer in advance is whether such a species would be able to thrive or even survive in a climate far removed from the original, unless there was major genetic engineering just for such adaptive purposes. Again, the further back the animal lived, the less likely it is that there is a contemporary habitat close to the original. It may be possible to recreate glacial steppes suitable for some mammoth species, but what about the Earth of ten million or one hundred million years ago? Prehistoric Park got around the issue for its Carboniferous megafauna by housing them in a high oxygen enclosure, which is certainly a solution, if something of a fire hazard!

Any newly-created animal will lack the symbiotic microbial fauna and flora of the original era, but I've not seen much that tackles this issue. I suppose there could be a multi-stage process, starting with deliberate injections of material in vitro (or via the host /mother). But once the animal is born it will have to exist with whatever the local environment/habitat has to offer. The chimerical nature of the organism may help provide a solution, but again this takes the creature even further from the original.

Then there is the rather important issue of food. To his credit, Michael Crichton suggested in Jurassic Park that herbivorous dinosaurs swallowing gizzard stones might accidentally eat berries that their metabolism couldn't handle. It would be extremely expensive to maintain compounds large enough for megafauna that are constantly kept free of wind-blown, bird-dropped and otherwise invasive material dangerous to the animals.

If the hybrids were allowed free reign, what if they escaped or were able to breed naturally? Given a breeding population (as opposed to say, sterilised clones) evolution via natural selection may lead them in a new direction. It would be wise to consider them as an integral part of the ecosystem into which they are placed, remembering Darwin's metaphor of ten thousand sharp wedges. Is there a possibility that they could out-compete modern species or in some other way exacerbate the contemporary high rate of extinction?

I've previously discussed the dangers of deliberate introduction of foreign species for biological control purposes: surely introducing engineered hybrids of extinct species is the ultimate example of this process? Or would there be a complete ban on natural reproduction for resurrected species, with each generation hand-reared from a bank of genetic material? At this point it should be clear that it isn't just the nomenclature that is confusing.

Some research has been undertaken to investigate the de-extinction of species whose demise during the past few centuries can clearly be blamed on humans, obvious examples being the Tasmanian tiger and the nine species of New Zealand moa. It could be claimed that this has more to do with alleviating guilt than serving a useful purpose (assuaging crimes against the ecosystem, as it were) but even in these cases the funds might be better turned towards more pressing issues. After all, two-thirds of amphibian species are currently endangered, largely due to direct human action. That's not to say that such money would then be available, since for example, a wealthy business tycoon who wants to sponsor mammoth resurrection - and they do exist - wouldn't necessarily transfer their funding to engineering hardier crops or revitalising declining pollinating insect species such as bees.

As it happens, even species that existed until a few hundred years ago have left little useable fragments of DNA, the dodo being a prime example. That's not to say that it won't one day be retrievable, as shown by the quagga, which was the first extinct species to have its DNA recovered, via a Nineteenth Century pelt.

As Jeff Goldman's chaos mathematician says in Jurassic Park, "scientists were so preoccupied with whether or not they could that they didn't stop to think if they should". Isn't that a useful consideration for any endeavour into the unknown? If there's one thing that biological control has shown, it is to expect the unexpected. The Romans may have enjoyed animal circuses, but we need to think carefully before we create a high-tech living spectacle without rather more consideration to the wider picture than appears to currently be the case.