NASA’s Perseverance rover has found complex carbon compounds in a Martian crater that had previously shown tantalising possible signs of ancient life. On Earth, these compounds are typically associated with dead organisms, but scientists say it is too early to draw the same conclusion here as these compounds are also found in lifeless environments, like on meteorites.

In 2024, Perseverance entered a rocky outcrop, called Bright Angel, near what appeared to be an ancient riverbed that once fed a lake inside Jezero crater. Several rocks photographed by the rover displayed unusual spotted patterns, which NASA scientists called “leopard spots” and “poppy seeds”. These markings, which are largely or entirely formed of dark, circular blots of up to a millimetre in size, look very similar to the patterns left behind by ancient microbial activity on Earth.

Although non-biological sources couldn’t be ruled out, the markings are some of the best candidates we have for potential ancient life on Mars. But scientists lacked comprehensive information on the chemical make-up of these patterns or how widely distributed they were in the Bright Angel formation.

However, Perseverance carries measurement tools that can provide more chemical context about the rocks it encounters, such as the SHERLOC instrument, which uses the reflected light from an ultraviolet laser to identify elements and compounds in a rock sample.

Now, at the Planetary Science Institute in Tucson, Arizona, and her colleagues have used SHERLOC to identify large, complex carbon-containing molecules, called macromolecular carbon, on the surface of the marked rocks in the Bright Angel formation, as well as in a separate rock in the same formation around 100 metres away.

“On Earth, macromolecular carbon is often found in extremely old rocks and, in some cases, it is the only organic evidence of past microbial life,” says Murphy. “Finding these organic macromolecules on Mars and other planetary bodies helps us determine whether the necessary chemical ingredients and environmental conditions to support life have ever existed there.”

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The existence of these carbon compounds can’t imply a biological origin by themselves, as they are also found in places like meteorites, says at the University of Westminster in London. However, Murphy and her colleagues also discovered that the compounds were associated with carbonate and sulphate minerals, which tend to form in water-rich environments, another key ingredient for life. “It’s giving us information about the geological context of where those organics are being found,” says Dartnell.

Jezero crater was already suspected to have been water-rich at some point, so the fact that these carbon compounds existed here is unsurprising by itself, says team member at NASA’s Jet Propulsion Laboratory in California. However, macromolecular carbon has never been seen on the surface of a rock like this, says Uckert, which might imply that it is unusually resistant and different from other carbon-bearing compounds that have been found on Mars.

“Its ubiquitous presence within mudstones at Bright Angel compared with observations elsewhere in the crater was surprising,” says Uckert. Although it is currently unclear why that should be the case, this is a good sign for the possibility of finding other signs of past life, says Dartnell. “This detection confirms that complex organics, like these macromolecular deposits, can stick around for long periods of time.”

While the SHERLOC instrument can identify macromolecular carbon, it can’t give detailed information on the actual make-up of the compounds beyond saying that they are carbon-rich, says at the University of Edinburgh, UK. “We would need to get the samples back to Earth to figure out if the carbon in these rocks was of biological origin,” he says.

The New Scientist Book Club  has been reading Kim Stanley Robinson’s classic sci-fi novel Red Mars, about the first 100 astronauts to settle on the Red Planet. Robinson chatted to New Scientist head of books Alison Flood about the novel, casting his mind back to when he wrote it, more than 30 years ago, as well as revealing his hopes that stories can help shift the dial on climate change – and what he really thinks about current plans to colonise Mars.

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I’m happy to think of people reading Red Mars in 2026. Its story begins around this year, but I wrote the book between 1989 and 1991, so naturally one aspect of reading it now is to note all the discrepancies between what the book thought this decade would be like and what it’s really like.

That always happens to science fiction novels: as time passes, the story shifts from being about the future to being about a past set of ideas about the future. This is a valuable window onto what that past felt like to those alive in that time, something not easy to recapture.

When we read old science fiction, we catch glimpses of what people back then thought might come to pass, which was an important part of their reality. The old text then becomes not so much a matter of inaccurate prediction as it is quite accurate portrayals of that moment’s sense of potentiality, expressing its hopes and fears about what seems to be coming.

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Just as with all other fiction, science fiction is therefore always mostly about the present, even though it’s set in the future, and, as it ages, becomes a window onto the past. In its form and its content, it serves as kind of time travel, both forwards into the future and backwards into the past.

That said, if you were to look at Red Mars as 1990 trying to imagine the 2020s, even though that isn’t what it was trying to do, I still think it holds up pretty well. The US and Russia as failing empires, teaming up in a desperate attempt to hold off new emerging powers? Check. China and India on the rise? Double check.

And there’s more that feels right, like the danger Earth is in ecologically and economically, hammered by climate change and geopolitical conflict even to the point of war. Or an emerging social order manifesting as a gigantic ongoing argument over what it should become. None of this took any special vision to call out; our situation has been a mess for a long time and something new is going to emerge, because things can’t go on as they are, just in the physical sense. What can’t happen won’t happen, and what will happen is something that can happen. Reality bites, it won’t go away.

I like noting the technological details in the book that I foretold pretty well, also the details that I missed entirely. Sometimes these two are mixed together, for instance when they are still using video tapes, but making something like YouTube out of them. Or when John Boone’s Dick Tracy-style wristwatch includes a talking AI, Pauline – a modest precursor to the many Paulines scattered through my subsequent work (see my novel 2312 in particular). That’s what happens when you speak about the future: you are always wrong but sometimes right, in an interesting mix.

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As for Mars itself, when I wrote my trilogy we were still in the immediate aftermath of the huge amount of new information about Mars that had been given to us by the Mariner satellite fly-bys in 1969 and the Viking orbiters and landers in 1976. Those machines gave us Mars in a way that no previous generation had: a new world, real but empty, handed to us on a plate.

It’s not a coincidence that our new knowledge of Mars was soon joined by a new speculative science called terraforming. Could humanity engineer an alien planet to make it a place where humans could “walk around in their shirtsleeves”? This question got asked in part because an excellent candidate for such a transformation had just been found, right next door.

Terraforming ideas got applied hypothetically to almost every rocky planet and moon in the solar system, but the best candidate by far remained Mars. It has water, pretty significant gravity, a little atmosphere and all the various elements life needs – although not as much nitrogen as one might like – so perhaps the nitrogen currently wrapping Saturn’s moon Titan could be transferred down to it? This was the kind of big-screen thinking that the terraforming community deployed in those days. It was as much science fiction as it was science, a game planetologists played after hours. For me, given my project, these discussions were immensely valuable. What sense of plausibility my book has is due to these scientists.

Now, 35 years later, it has to be said that we have learned more about Mars, and about human biology, such that the whole project of humans inhabiting Mars looks much more difficult than it did back then. The rovers of the early 2000s, for instance, discovered there are perchlorates mixed into the sand of Mars in the parts-per-hundred range, and these perchlorates are poisonous to humans in the parts-per-million range. It turns out the surface of Mars is extremely poisonous to us!

Also, we’ve learned more about the bad effects of lighter-than-Earthly gravity on human bodies, and of unblocked cosmic radiation on mammal brains. So the bold claims made by certain billionaires about how we will soon colonise Mars are simply fantasies. They express a wish that the Mars we know now would revert to that earlier, more survivable version. But no. In 1990, I was writing science fiction; now that same story has become a fantasy.

Oh no! Like a lot of people, I wish it would work. I hold on to the dream, and indeed I still say we could go to Mars, but in a different way. It would resemble the way we go to Antarctica now. We could set up scientific stations on Mars somewhat like McMurdo Station in Antarctica, and people could go live there for a year or two, then return to Earth.

In effect, they would be living much like my characters did in Underhill in the third and fourth chapters of my book, but that lifestyle would not change. The visiting scientists would suffer some damage to their health, but would perhaps regard that as being worth it for the sake of their adventure. We would learn a lot from their efforts, and people would be interested in their project to the same degree they’re interested in the work going on in Antarctica now – in other words, not very much. Humans on Mars will be just one more aspect of the Anthropocene.

That’s the science fiction story that looks most realistic right now. Possibly, if you extend the timeline out several thousand years and include in it the creation of a healthy relationship between humans and Earth, the terraforming and full inhabitation of Mars could eventually happen. I hope so.

Certainly a big obstacle to the Mars project now, even more important than its poisonousness, is the way we are poisoning Earth. We have to solve the problems we’ve created here before going anywhere off planet will become even slightly relevant. If and when we manage to create that healthy relationship, Mars will be there still, as a kind of reward for our success, a new project to try.

Remember this, please, when you see clickbait and pronunciamentos about humans very soon migrating to Mars. I, author of the Mars trilogy, call bullshit on that fatuous fantasy.

I want to finish by saying that all these aspects surrounding Red Mars are not what I feel are most important about it. Because it’s not a blueprint or a prophecy or a technical evaluation, it’s a novel. So what I like most about it are its characters and its plot. These are the elements that drive any novel, and are crucial to how a reader feels about it.

It’s been so long since I wrote Red Mars that, a couple of years ago, I was able to read it without feeling I had it semi-memorised, and without trying helplessly in my mind to revise it one more time. I just took it in. What a pleasure that was.

Nadia and Maya, John and Frank, Sax and Ann, Michel and Hiroko and Arkady, Phyllis and Vlad and Ursula and Spencer and all the other secondary characters, they all stepped off the page and into my head. None of them are anything like me, and I don’t know where they came from. They just showed up and told me their stories. What a gift! And what a story – not just their interpersonal relationships, but also their political interactions with Earth and their terraforming work, and their lives through the many decades, all weaving together to become history, or, as my beloved teacher Fredric Jameson once put it, to History.

I’m very happy that this book flew through me and stuck to the page, and is still there for readers to read. I hope you enjoy it.

The New Scientist Book Club is currently reading Kim Stanley Robinson’s . Sign up and read along with us here.

Mars was empty before we came. That’s not to say that nothing had ever happened. The planet had accreted, melted, roiled and cooled, leaving a surface scarred by enormous geological features: craters, canyons, volcanoes. But all of that happened in mineral unconsciousness, and unobserved. There were no witnesses – except for us, looking from the planet next door, and that only in the last moment of its long history. We are all the consciousness that Mars has ever had.

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Now everybody knows the history of Mars in the human mind: how for all the generations of prehistory it was one of the chief lights in the sky, because of its redness and fluctuating intensity, and the way it stalled in its wandering course through the stars, and sometimes even reversed direction. It seemed to be saying something with all that. So perhaps it is not surprising that all the oldest names for Mars have a peculiar weight on the tongue – Nirgal, Mangala, Auqakuh, Harmakhis – they sound as if they were even older than the ancient languages we find them in, as if they were fossil words from the Ice Age or before. Yes, for thousands of years Mars was a sacred power in human affairs; and its color made it a dangerous power, representing blood, anger, war and the heart.

Then the first telescopes gave us a closer look, and we saw the little orange disk, with its white poles and dark patches spreading and shrinking as the long seasons passed. No improvement in the technology of the telescope ever gave us much more than that; but the best Earthbound images gave Lowell enough blurs to inspire a story, the story we all know, of a dying world and a heroic people, desperately building canals to hold off the final deadly encroachment of the desert.

It was a great story. But then Mariner and Viking sent back their photos, and everything changed. Our knowledge of Mars expanded by magnitudes, we literally knew millions of times more about this planet than we had before. And there before us flew a new world, a world unsuspected.

It seemed, however, to be a world without life. People searched for signs of past or present Martian life, anything from microbes to the doomed canal-builders, or even alien visitors. As you know, no evidence for any of these has ever been found. And so stories have naturally blossomed to fill the gap, just as in Lowell’s time, or in Homer’s, or in the caves or on the savannah – stories of microfossils wrecked by our bio-organisms, of ruins found in dust storms and then lost forever, of Big Man and all his adventures, of the elusive little red people, always glimpsed out of the corner of the eye. And all of these tales are told in an attempt to give Mars life, or to bring it to life. Because we are still those animals who survived the Ice Age, and looked up at the night sky in wonder, and told stories. And Mars has never ceased to be what it was to us from our very beginning – a great sign, a great symbol, a great power.

And so we came here. It had been a power; now it became a place.

This is an extract from Kim Stanley Robinson’s , the latest pick for the New Scientist Book Club. Sign up and read along with us here.