“Mars Sample Return is currently not planned to be continued. It’s a fact.” This was a clear and unambiguous statement of fact made by Daniel Neuenschwander, European Space Agency’s (ESA’s) Director of Human and Robotic Exploration, during a press conference at the agency’s headquarters in Paris on 8 January. With this being the seemingly certain end of the NASA-led MSR mission, what happens to ESA’s primary contribution to the ambitious initiative, the Earth Return Orbiter?
SOURCE: Europe in Space Blog: Andrew Parsonson
The False Start
In 2007, the International Mars Architecture for the Return of Samples (iMARS) task force was established within the International Mars Exploration Working Group (IMEWG), which was formed in 1993 to provide an avenue for international coordination on Mars exploration missions. According to an ESA press release from the time, the working group included participants from more than half a dozen countries in addition to ESA, NASA, the Canadian Space Agency (CSA), and the Japan Aerospace Exploration Agency (JAXA).
This first phase of the iMARS initiative aimed to develop an initial plan that would enable the return of samples from Mars, with a mission potentially occurring between 2018 and 2023. While a second phase of the iMARS initiative was commissioned in 2014, in 2009, ESA and NASA moved to sign a bilateral agreement to create the Mars Exploration Joint Initiative (MEJI) that would include a wide range of missions to the Red Planet, “leading to the return of samples from Mars in the 2020s.“ Interestingly, ESA doesn’t appear to mention the MEJI initiative again following that initial agreement announcement.
In 2010, NASA’s Jet Propulsion Labratory outlined an initial architecture for the mission. This included a European rover with a drilling capability and a NASA rover that would collect the selected samples for “potential future return to Earth.”
In early 2011, NASA published its Vision and Voyages for Planetary Science in the Decade 2013-2022 report. In the report’s executive summary, the agency noted that the “Mars Sample Return campaign is critically dependent on a long-term and enabling collaboration with the European Space Agency.” ESA would, however, not be the cause of the cancellation of this first iteration of the Mars Sample Return mission.
During a March 2012 meeting of the Science Committee of the NASA Advisory Council, NASA effectively acknowledged that its Mars Sample Return ambitions could not be pursued under the agency’s projected budget. Committee discussions highlighted concerns that NASA was spreading itself too thin across too many large flagship missions. Rather than proceeding with a near-term sample return campaign, the agency opted to focus on missions and activities intended to de-risk key technologies and architectures for a possible future Mars Sample Return effort.
Take Two
In April 2018, NASA and ESA restarted efforts to return samples from the Red Planet, signing a statement of intent to explore mission concepts. At the time, then ESA Director of Human and Robotic Exploration David Parker described the goal of retrieving samples from Mars as a “tantalising but achievable vision that lies at the intersection of many good reasons to explore space.”
In July 2018, ESA awarded contracts to Airbus to conduct initial studies for the Sample Fetch Rover and an Earth Return Orbiter. The results of the studies were presented at ESA’s Ministerial Council Meeting towards the end of 2019, with Member States confirming their support for the joint Mars Sample Return Mission.
Under this revised architecture, NASA’s Perseverance rover would collect samples and deposit them in tubes on the Martian surface. The rover was launched in July 2020, rolled onto the Martian surface in February 2021, and dropped its first sample tube in December 2022. A second rover, the Sample Fetch Rover, was supposed to retrieve the samples and deliver them to the Sample Retrieval Lander, where they would be launched into space aboard the Mars Ascent Vehicle. The samples would then be retrieved by the Earth Return Orbiter, which would carry them back to Earth, releasing a return capsule for delivery to the planet’s surface.
In October 2020, ESA awarded Airbus a €491 million contract to develop and deliver the Earth Return Orbiter. At the time, Airbus announced that the spacecraft was expected to be launched aboard an Ariane 6 rocket in 2026. This was followed by NASA finally approving the mission for Phase A development in December 2020, with the agency announcing that it expected the samples to be returned to Earth in the early 2030s.
“Returning samples of Mars to Earth has been a goal of planetary scientists since the early days of the space age, and the successful completion of this MSR key decision point is an important next step in transforming this goal into reality,” said Thomas Zurbuchen, associate administrator for science at NASA.
The incredible success of the Ingenuity helicopter, which was transported to Mars with the Perseverance rover, prompted the only significant change to the mission architecture. The helicopter completed 72 flights over 3 years, totaling 2 hours, 8 minutes, and 48 seconds of flight time. While its last flight would only be in early 2024, its early success appeared to prompt NASA to remove the Sample Fetch Rover from the mission architecture in July 2022, replacing it with two sample recovery helicopters.
In September 2023, the lofty ambitions of the Mars Sample Return mission all came crashing down. A NASA independent review board report found that the Mars Sample Return mission’s budget and schedule expectations were “unrealistic.” The initial cost estimate was around $4 billion. However, the subsequent review found that, at best, the mission would cost roughly twice that amount and could rise to as much as $11 billion. For context, NASA’s James Webb Space Telescope, which was notoriously delayed and over budget, ultimately cost around $10 billion. With that in mind, the question became whether a sample return mission could deliver a comparable level of scientific return, and whether NASA could realistically shoulder another flagship project with similarly uncontrolled budgetary risks.
For ESA, the report triggered a broader strategic reassessment. Just after its publication, an ESA spokesperson told European Spaceflight that the agency was evaluating how to realign the direction of its contribution with its overarching strategic objectives for Mars.
“We are conducting preliminary studies to assess all options given the various scenarios and will inform Member States and coordinate with NASA on the outcome as soon as possible,” explained the spokesperson. “The way forward will then be decided with Member States and NASA.”
Earlier this year, the US Senate passed a “minibus” spending bill that included $24.4 billion for NASA’s 2026 budget. While the budget rejected many of the cuts proposed by President Trump, the Mars Sample Return mission was not spared the chopping block, effectively killing it in its current form.
