NASA’s Curiosity rover uncovered critical new samples, including a series of compounds planetary scientists consider building blocks for the origin of life on Earth
NASA’s Mars Curiosity rover has uncovered never-before-seen organic compounds that could be the most convincing evidence yet that there was life on the red planet.
The nuclear-powered robot uncovered a diverse mix of organic molecules – including chemicals widely considered building blocks for the origin of life on Earth. Scientists say the findings, which came from a chemical experiment performed for the first time on another world, reveal that the Martian surface can preserve the kinds of molecules that could serve as signs of ancient life.
But a bid to gain more of these critical samples has been scuppered as the US space agency suffers from a funding hole Donald Trump is planning to deepen.
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Study leader Professor Amy Williams, from the University of Florida and a scientist on the Curiosity and Perseverance Mars rover missions, explained that definitively identifying signs of past life would require returning rock samples to Earth. NASA was previously planning to do so with its Mars Sample Return (MSR) programme, but this was killed in January.
Congress released a compromise spending bill for the new financial year backing an effort from the Trump administration to kill the programme, leaving planetary scientists’ ambitions for the space agency in jeopardy.
Planetary scientist Victoria Hamilton, from the Southwest Research Institute and chair of NASA’s Mars Exploration Program Analysis Group, said the move was “deeply disappointing” and would knock the US’ space dominance. She said: “When we’ve got memos coming out saying we want to be the dominant power in space, I wonder how we leave something this ambitious behind.”
The funding reduction in January came as the Trump administration attempted to cut NASA’s budget, a move that was rejected but is now being attempted again, with officials requesting to reduce funding by 23 percent.
While the latest experiment can’t distinguish between organic compounds from potential past life on Mars and those formed through geologic processes or delivered by meteorites, it is still a groundbreaking recovery that demonstrates how vital it is that these types of programmes continue to exist, as it demonstrates it is possible to “search for evidence of life”.
Professor Williams, who helped develop this chemical experiment, said: “We think we’re looking at organic matter that’s been preserved on Mars for 3.5 billion years.
“It’s really useful to have evidence that ancient organic matter is preserved, because that is a way to assess the habitability of an environment. And if we want to search for evidence of life in the form of preserved organic carbon, this demonstrates it’s possible.”
Among the 20-plus chemicals identified in the experiment, Curiosity spotted a nitrogen-bearing molecule with a structure similar to DNA precursors – a chemical never before spotted on Mars. The rover also identified benzothiophene, a large, double-ringed, sulphurous chemical often delivered to planets by meteorites.
Professor Williams said: “The same stuff that rained down on Mars from meteorites is what rained down on Earth, and it probably provided the building blocks for life as we know it on our planet.”
Led by NASA’s Jet Propulsion Laboratory, Curiosity Mars landed in Gale crater, in a former lake bed, in August 2012. The rover conducted the experiment in 2020 in the Glen Torridon region of the crater, an area rich in the clay minerals that indicate the area once contained water.
Prof Williams said the clays can hold on to and preserve organic chemicals better than other minerals, making them a prime target for uncovering these compounds.
The experiment was conducted by the instrument suite known as the Sample Analysis at Mars, or SAM, which has been responsible for many of the mission’s most important discoveries about organic chemistry, atmosphere and habitability on Mars. Using a chemical known as TMAH, the experiment broke apart larger organic molecules so they could be analysed by onboard instruments within SAM.
With only two cups of the TMAH chemical onboard Curiosity, success required careful planning and choosing the most favourable location to sample.
The promising results, published in the journal Nature Communications, come as future missions – including the Rosalind Franklin mission to Mars and the Dragonfly expedition to Saturn’s moon Titan – plan to bring the TMAH test onboard to search for organic compounds.
Prof Williams said: “We now know that there are big complex organics preserved in the shallow subsurface of Mars, and that holds a lot of promise for preserving large complex organics that might be diagnostic of life.”
