![\"A](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/01\/d41586-026-00060-7_51921872.jpg\"\/)
<\/p>\n <\/p>\n
NASA\u2019s Mars Perseverance rover poses for a selfie after drilling a sample from Cheyava Falls, the arrowhead-shaped rock in the centre of this picture. Credit: NASA\/JPL-Caltech\/MSSS<\/p>\n
Far away on desolate Mars, a set of dust and rock samples<\/a> awaits a ride that might never come.<\/p>\n After years in limbo, NASA\u2019s groundbreaking Mars Sample Return (MSR) programme, which was supposed to ferry Martian material collected by the Perseverance rover<\/a> to Earth, looks set to be cancelled. Earlier this week, a bipartisan group of US lawmakers passed a spending bill that axes the MSR programme<\/a>, which would have been the first mission to bring Martian samples to Earth. <\/p>\n Mars rocks await a ride to Earth \u2014 can NASA deliver?<\/p>\n <\/a><\/p>\n The mission\u2019s demise did not come out of the blue. The ambitious project\u2019s estimated cost has ballooned, reaching US$11 billion in 2023<\/a> \u2014 similar to the amount it cost to build the James Webb Space Telescope<\/a>. And early last year, NASA conceded that it still had no concrete plan to return the Martian samples to Earth<\/a>. The administration of US President Donald Trump sought to cancel the MSR project and many other NASA science missions<\/a>.<\/p>\n Happily for many scientists, the bill restores funding for the vast majority of NASA space science missions that the administration\u2019s budget proposal had placed on the chopping block, such as the Habitable Worlds Observatory space telescope, which would search for signs of life on planets outside the Solar System. As a result, the bill, which still requires Senate approval, \u201cis ultimately a good bill for NASA science\u201d, says Casey Dreier, chief of space policy at the Planetary Society, a non-profit organization in Pasadena, California.<\/p>\n But many scientists were disappointed by MSR\u2019s fate. \u201cI was certainly disheartened to hear the news,\u201d says Ryan Ogliore, a planetary scientist at the University of Central Florida in Orlando. \u201cBut I wasn\u2019t surprised because of what we\u2019d been hearing these last couple years.\u201d<\/p>\n Asked for comment, NASA did not respond before publication. <\/p>\n Here Nature looks at the scientific opportunities that will be lost because of the programme\u2019s cancellation and the prospects for a mission revival.<\/p>\n Biosignature bargain<\/p>\n Among the most tantalizing samples collected by Perseverance is number 25, taken from a rock called Cheyava Falls. In September last year, NASA announced that the rover had discovered spots on the surface of the rock that contained two chemical compounds, which are found on Earth around decaying matter and are produced by certain microbial life1<\/a>. These compounds, researchers suggested, could be a fingerprint of ancient microbial life<\/a>.<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/01\/d41586-026-00060-7_25804596.jpg\"\/)
<\/p>\n
![\"\"](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/01\/d41586-026-00060-7_50429946.jpg\"\/)
<\/p>\n