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.

SpaceX launched its secretive Starfall delivery today, which saw a demo capsule blast off to low Earth orbit. There are few details about the launch or a future service, but SpaceX has previously said Starfall will enable cargo delivery from space, such as for manufactured materials in low Earth orbit like pharmaceutical compounds or semiconductor alloys.

The Starfall capsule took off from Cape Canaveral in Florida at around 6.50am local time (1152 BST) this morning, riding on a Falcon 9 rocket, which later landed on a floating platform in the Atlantic Ocean.

What will Starfall do?

SpaceX hasn’t revealed much publicly about Starfall, but an assessment published by the US Federal Aviation Administration (FAA) showed that the project’s purpose was for the “transport and delivery of goods through space”. SpaceX has said that the mission will allow for “routine access to the microgravity environment for scientific research and in-space manufacturing”. The FAA assessment also showed that two associated re-entry vehicle landings were approved for this demonstration mission.

Unlike SpaceX’s spacecraft that ferry human passengers to the International Space Station, the vehicle for Starfall is designed for cargo only. It is a windowless, black, stumpy cylinder, measuring around 3 metres across and less than a metre tall, and has capacity for a 1-tonne payload. The capsule is split into two parts that are designed to separate after re-entry into Earth’s atmosphere: an upper dish where the payload is stored, and a heat shield made from carbon fibre beneath it, which also has compressed gas that can be used to manoeuvre the cargo safely to Earth.

What happened during the launch?

After the Falcon 9 rocket took off, the booster successfully landed on a floating platform in the Atlantic Ocean. However, SpaceX has provided no further updates about the Starfall capsule in space, such as how long it will remain in orbit before it aims to splash down in the Pacific Ocean 1300 kilometres from the Californian coast.

Is SpaceX the only company doing this?

There are much smaller companies that are seeking to manufacture materials in low Earth orbit, such as the US firm Varda Space Industries (VSI), which aims to make pharmaceuticals in orbit before flying them back to Earth, or the Welsh company Space Forge, which hopes to make semiconductors and alloys in low Earth orbit. Both firms hope that producing materials in low-gravity environments will free them from the defects and structural deformities that can form as a result of Earth’s gravity, such as when heavier particles sink to the bottom of a liquid rather than distributing uniformly.

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These companies, however, operate at a much smaller scale than Starfall. VSI has flown six containers to orbit, but these are only around a metre wide and have a total weight of 300 kilograms, whereas Starfall is three times larger.

SpaceX has contracts with the US military, of which Starfall could play a part. The Pentagon has announced a project called Rocket Cargo, which would use SpaceX’s larger Starship rocket to deliver supplies to remote locations in under an hour, but Starfall could plug the gap for smaller deliveries. The US military has also signed contracts with other companies, such as Jeff Bezos’s Blue Origin and New Zealand-based Rocket Lab, to study the possibility of cargo delivery from space.