Space 5 November 2026 4 MIN READ
Why Mars Sample Return Stalled and Then Ended
Why NASA's plan to bring Mars rocks to Earth stalled and ended: the 2023 review, the 2040 redesign, the January 2026 budget and what stays on Mars.
THE SHORT ANSWER
Mars Sample Return would have brought Perseverance's rock tubes to Earth, but a 2023 independent review judged its budget and schedule unrealistic, with a probable cost of $8–11 billion. NASA's redesign pushed return to 2040, and Congress declined to fund the programme in January 2026.
On this page
A relay with many handoffs
Since 2021 the Perseverance rover has been sealing rock and sediment cores in tubes. NASA’s sample page says it carried 43 tubes to Mars: 38 for samples and five “witness” tubes that record how clean its sampling system stayed. The plan, run with the European Space Agency (ESA), was to bring the sample tubes to Earth for study in laboratories that no rover can carry.
That meant a relay. A Sample Retrieval Lander would land near Perseverance in Jezero Crater. Its Mars Ascent Vehicle would launch a container of samples into Mars orbit. An ESA Earth Return Orbiter, carrying a capture and containment system, would catch the container and fly it home. NASA’s own review documents describe this chain by its pieces, and the review board warned about the places where one piece hands over to the next.
Why it was hard
NASA set up an independent review board in May 2023. Its report, released in September 2023, has 20 findings and 59 recommendations, and it is blunt. It says the programme “was established with unrealistic budget and schedule expectations from the beginning” and had “no credible, congruent technical, nor properly margined schedule, cost, and technical baseline that can be accomplished with the likely available funding.”
The numbers followed from that. The board found a near-zero probability that the Earth Return Orbiter or the lander and ascent vehicle could meet their 2027 and 2028 launch dates. The earliest likely launch was 2030, at a cost of about $8.0 to $9.6 billion, with more than $1 billion a year needed for three or more years. Across alternative designs it put the probable lifetime cost at $8 to $11 billion. Ars Technica reported that the plan had assumed a total budget of $4.4 billion.
The board named the structural problems: ageing communications relays around Mars, multiple handoffs between systems on the way from Mars to Earth, and expertise spread across many organisations and cultures.
Two years of redesign
NASA answered in April 2024. Its response team agreed that the budget was likely $8 to $11 billion and said that any revised design “will delay the return of samples to 2040”. It called the ascent vehicle “the primary driver of architecture complexity, cost and risk” and opened a competition for very different, cheaper designs.
In January 2025 NASA announced it would study two ways to land the payload, one reusing the sky crane method flown with Curiosity and Perseverance and one using new commercial landers, both with a smaller ascent vehicle. It planned to confirm one design in the second half of 2026. Science later reported that the final proposal would have brought the cost down to about $7 billion.
How it ended
The decision came from the budget, not from a technical verdict. The White House proposed ending the programme in its 2026 request. In January 2026 Congress agreed. The explanatory text of the spending bill says the agreement “does not support the existing Mars Sample Return” effort, while moving $110 million into a Mars Future Missions account for radar, spectroscopy, entry, descent and landing systems and related technologies.
The House passed the bill 397 to 28 on 8 January and the Senate 82 to 15 shortly after. The Planetary Society reports that the President signed it on 23 January. NASA’s own Mars Sample Return page now speaks of it in the past tense: it “was” a plan.
What stays on Mars
The samples are still there. NASA lists each tube’s location as either the rover or a sample depot on the surface. No mission is funded to fetch them. Congress did not forbid a later return, and the $110 million keeps some of the technology alive, but there is no plan to point to.
Researchers quoted by Science called the outcome a loss. The magazine adds that in 2024 the rover found what many researchers believe could be the best potential evidence for past life on Mars, and it quotes a planetary scientist who notes that China is building its own Mars sample-return programme.
Our take: this was a failure of fit, not a proof of impossibility. The review board said a 2030 launch was achievable with adequate funding. What did not hold up was the match between a mission of $8 to $11 billion and a budget set on the assumption of about $4.4 billion. Anyone who wants to bring Mars samples home will have to start by pricing the real mission.
Questions and answers
What was Mars Sample Return?
A NASA and ESA plan to bring the sample tubes Perseverance collected on Mars to Earth. A lander would pick them up, an ascent vehicle would launch them into orbit and a European orbiter would carry them home.
Why did Mars Sample Return cost so much?
An independent review in 2023 found it had started with unrealistic budget and schedule assumptions. It put the probable cost at $8 to $11 billion, against the earlier plan of about $4.4 billion reported by Ars Technica.
Who cancelled Mars Sample Return?
The White House proposed ending it in its 2026 budget request, and Congress agreed in the spending bill signed on 23 January 2026. It said it did not support the existing programme.
What happens to the samples on Mars?
They stay in the rover and in a depot on the surface. No mission is funded to return them, though Congress did not forbid a future one and set aside $110 million for related technology.
Do you agree?
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Sources
- Mars Sample Return (MSR) Independent Review Board-2 Final Report (1 September 2023) · NASA · Accessed
- NASA Releases Independent Review’s Mars Sample Return Report · NASA · Accessed
- Independent reviewers find NASA Mars Sample Return plans are seriously flawed · Ars Technica · Accessed
- NASA’s response to the second Mars Sample Return Independent Review Board recommendations (15 April 2024) · NASA Science Mission Directorate · Accessed
- NASA to Explore Two Landing Options for Returning Samples from Mars (7 January 2025) · NASA · Accessed
- NASA’s Mars Sample Return mission is dead (6 January 2026) · Science (AAAS) · Accessed
- Congress passes minibus spending bill that rejects proposed NASA cuts · SpaceNews · Accessed
- NASA is funded. Now what? · The Planetary Society · Accessed
- Mars Sample Return · NASA Science · Accessed
- Mars Rock Samples · NASA Science · Accessed
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