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 91av Book Club has been reading Adrian Tchaikovsky’s Alien Clay, a science fiction epic in which a political prisoner must unlock the secrets of a strange and dangerous planet. Best known for his series Shadows of the Apt and for his Hugo Award-winning Children of Time series, Tchaikovsky has arguably cemented himself as a master of science fiction. This week, our fiction reviewer Emily H. Wilson caught up with Tchaikovsky to delve into his disciplined writing process, the inevitable interweaving of politics and science, and the true definition of “science fiction”.

Read more: Adrian Tchaikovsky: “Could life have gone any other way?”

Humanoid mosquitoes, alien contact on deadly moons, implants that let you know everything your partner is thinking… the science fiction novels on offer in February feel especially interesting, and I’m looking forward to transporting myself to during this cold, dark time of the year. Whether you’re after classic science fiction from the likes of Gareth L. Powell and Adrian Tchaikovsky, high-concept thrillers or flooded future Earths, you’ll find it here. Enjoy!

After reading Tchaikovsky’s excellent sci-fi novel Alien Clay for the 91av Book Club – we’re in the middle of it right now, so please do sign up and join us; it’s free and we’ll be talking to Adrian next month! – I’m definitely in the mood for more from this brilliant writer. This latest is a tale of survival and first contact on a deadly pitch-black moon, buzzing with radio activity. When two humans are forced to make a landing on the hostile moon, they start to learn more about the strange species that lives there. Our sci-fi columnist Emily H. Wilson really enjoyed this – watch out for her review next week.

Adrian Tchaikovsky: “Could life have gone any other way?”

The author of the latest read for the 91av Book Club on the science that lies behind his novel Alien Clay, set on a prison planet where the biology is very different to that on Earth

Elijah convinces Anna to go to OneMind to celebrate their 10th anniversary; this high-tech company will give them implants that will enable them to hear each other’s thoughts. But Anna may have something to hide from her partner… I love a good high-concept thriller, and this is a fun (and terrifying) idea.

Powell is the British Science Fiction Award-winning author of Stars and Bones and Embers of War, and his latest novel sounds like another great slice of hard science fiction. It follows the story of archaeologist Ursula Morrow, who becomes infected with an alien parasite. Her worries about jeopardising her career come to nothing, however, as Earth is subsequently destroyed, and no one really needs archaeologists anymore. Two years on, she’s in a refugee camp on a backwater world when she’s tasked with finding the alien artefact that infected her, in the hopes that it might help humanity to survive.

I absolutely love how wonderfully weird this novel sounds. In 2272, New York and Buenos Aires have been underwater for years, and the Patagonian archipelagos are Earth’s only habitable lands. Our protagonist is a humanoid mosquito whose horrendous appearance repulses everyone. As the world collapses around him, Dengue Boy searches for the truth about his origins – and the meaning of his life. This is translated from Spanish by Rahul Bery, and I think it sounds amazing!

I like the sound of this blend of archaeology and science fiction, in which a mountain unexpectedly arrives in the Marlborough Downs, looming over the city of Swindon. Clare Holworth is part of an archaeological investigation into its origins, in an attempt to manage the site before public pressure to get to the summit grows out of control.

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This blend of sci-fi and thriller follows Nate Cartwright, lonely and jobless, as he returns to his family’s summer cabin in Oregon to start again. In the cabin, he discovers a man named Alex and a 10-year-old girl, Artemis Darth Vader, who is a lot more than she seems – and who is in danger from forces who want to control her.

I can’t promise that this is science fiction, because I haven’t read it yet, but it’s being compared to works by speculative fiction authors like Margaret Atwood, David Mitchell and Kaliane Bradley (The Ministry of Time author), and it sounds very intriguing. It centres on a woman who never ages or dies, but through the centuries and across the continents, those around her do – in terrifying and similar ways. Can she be stopped? It could be that this shades more into horror than sci-fi; I’ll report back either way.

Our writers pick their favourite science fiction books of all time

We asked 91av staff to pick their favourite science fiction books. Here are the results, ranging from 19th-century classics to modern day offerings, and from Octavia E. Butler to Iain M. Banks

More speculative horror here, this time compared to the films of Jordan Peele and Stranger Things – a comparison I’m very much here for. Calla is 25, and a reluctant guardian to her 16-year-old brother Jamie. All the while she’s haunted by “The Nightmare”, in which Jamie and their middle brother Dre keep dying. When Jamie’s actions spiral out of control, the siblings go on the run, finding themselves facing a threat in which their lives, and reality, hang in the balance.

This is for my fellow Octavia E. Butler fans, and you completists out there: the book looks at little-known manuscripts in Butler’s collection and at her childhood influences and writings, and explores “animals, science fiction, Black girlhood, and racial and environmental justice”, says its publisher.

I mentioned this one last month, but the hardback is actually out in February, so I’m reminding you of it as it does sound great. As I said before, it’s been tipped by our sci-fi columnist Emily H. Wilson as one to watch for, and follows sci-fi author Zelu as she decides to write a novel about androids and AI after the extinction of humanity. But as she writes, the lines between what she’s writing and reality begin to blur…