What Is NASA’s Mars Sample Return Program?

The Mars Collection

On the rust-colored, dusty plains of Mars, a six-wheeled robotic scientist is meticulously curating a gallery of priceless, irreplaceable artifacts. This robot, NASA’s Perseverance rover, has been exploring the 28-mile-wide Jezero Crater since its dramatic landing in February 2021. The crater itself is a geological marvel, a location specifically chosen because it tells a story of a dramatically different past. More than 3.5 billion years ago, this desolate basin was far from the cold, dry desert it is today. Scientific evidence points to a past where river channels breached the crater wall, spilling water into its expanse and creating a large, standing lake. The remnants of a vast river delta are still visible, a feature on Earth that is unmatched in its ability to trap and preserve sediment – and potentially, signs of life.

Perseverance’s primary job is not just to look, but to collect. It is the first rover in history to carry a sophisticated sample caching system. With a drill at the end of its robotic arm, it has been grinding into carefully selected rocks, extracting finger-sized cores of Martian geology, and hermetically sealing them in 43 gleaming, pencil-sized titanium tubes. These tubes are more than just rocks; they are time capsules. They contain the geologic, chemical, and environmental history of a location on Mars deemed most likely to have been habitable for microbial life. The collection is diverse, ranging from igneous rocks that formed from volcanic magma to fine-grained sedimentary rocks laid down in the ancient lakebed, and even samples of the thin Martian atmosphere itself. This collection represents the culmination of a multi-decade, international strategy, a plan to finally address one of humanity’s most fundamental and persistent questions: are we alone in the universe?.

For more than two decades, the scientific community has spoken with a single, clear voice: these samples must be brought to Earth. This objective, the Mars Sample Return (MSR) campaign, isn’t just one of many priorities; it has been repeatedly identified as the single highest-priority flagship mission for solar system exploration by the U.S. National Academies of Sciences, Engineering, and Medicine in its past three Decadal Surveys. These surveys are the consensus documents that guide NASA’s scientific agenda. The reason for this emphatic endorsement is simple and absolute: the most significant, game-changing questions about Mars cannot be answered by a robot, no matter how sophisticated.

Robots like Perseverance are engineering marvels, but they are fundamentally handicapped. They are car-sized, power-constrained platforms carrying miniaturized instruments. They are remote geologists doing their best with a limited toolkit, millions of miles from home. They can analyze minerals, identify the presence of organic molecules, and see the structure of a rock. But they cannot perform the definitive, high-precision analysis needed to distinguish a potential sign of life (a biosignature) from a non-living mineralogical process that mimics it. They can’t, for example, definitively date a rock or determine the chiral properties of an organic molecule. To answer the big questions – Was there life? When did the water flow? What was the ancient climate really like? – scientists require the full, combined power of state-of-the-art laboratories on Earth.

This grand endeavor, the joint NASA-ESA Mars Sample Return campaign, is an undertaking of almost unimaginable complexity. It involves a “daisy chain” of robotic firsts: the first launch from another planet, the first autonomous rendezvous in another planet’s orbit, and the first return of materials from a (potentially) habitable world. It is, without reservation, one of the most technically difficult robotic missions ever attempted. And as of 2023, the program was in a state of crisis. The original, elaborate multi-mission architecture, painstakingly designed over years of cooperation between NASA and the European Space Agency (ESA), was officially deemed unworkable.

The breaking point came in September 2023, with the release of a scathing report from an Independent Review Board (IRB) commissioned by NASA. This board, chaired by respected aerospace veteran Orlando Figueroa, found that the mission’s design was over-constrained and its management structure flawed. The program’s budget, originally estimated around $5.3 billion, was found to be on a trajectory to balloon to a probable cost of $8 billion to $11 billion. The schedule was equally broken. The IRB concluded that the planned 2027-2028 launches were impossible, and a realistic launch date of 2030 would mean the samples wouldn’t reach Earth until 2040. NASA Administrator Bill Nelson was unequivocal in his response: $11 billion was “way too expensive,” and 2040 was “unacceptably too long”.

Faced with a scientifically vital program on the verge of collapse, NASA made a dramatic and historic pivot. On April 15, 2024, the agency’s leadership held a teleconference to announce their response to the IRB report. They were, in effect, “pulling the plug” on the over-budget, over-schedule architecture. Instead of trying to fix the unfixable, NASA announced it was turning to the commercial space industry for answers. The agency issued a formal request for proposals, soliciting “fresh, exciting, and innovative ideas” from a mix of aerospace giants and nimble newcomers. The directive was clear: design a new mission to get the samples back, and do it “more quickly, with less risk, and at a lower cost”.

This decision has thrust the Mars Sample Return program into a new, uncertain, and fascinating era. The mission is no longer just a scientific quest; it has become a high-stakes test case for an entirely new model of deep-space exploration. This new approach pits NASA’s traditional, in-house, “heritage-based” development model – the one that built the rovers and landers of the past – against the fixed-price, commercial-services model that has fundamentally reshaped access to low-Earth orbit. This commercial approach, exemplified by companies like SpaceX, is now being asked to prove it can work for a complex, flagship-class science mission millions of miles from Earth. The fate of the most valuable scientific collection in history, and with it our best chance to understand the development of life in the solar system, now hangs in the balance of this new “commercial space race” to Mars.

The Scientific Case for Mars Sample Return

The exploration of Mars has been a story of robotic achievement. From the first Sojourner rover to the long-lived Spirit and Opportunity, and now to the advanced mobile laboratories Curiosity and Perseverance, these robots have acted as our remote geologists, eyes, and hands on another world. They have confirmed that liquid water once flowed on the surface, that the ancient environment was habitable, and that the chemical building blocks of life were present. But with each discovery, they have also uncovered new questions that they are fundamentally unequipped to answer.

What Rovers Cannot Do

The limitations of robotic explorers are not a failure of engineering, but a hard constraint of physics and finance. It’s impossible to launch the full scientific capability of a terrestrial laboratory and land it on another planet. The rovers are marvels of miniaturization. Perseverance, for all its prowess, is a car-sized, nuclear-powered platform that must support its own mobility, communication, and robotic arms, all while operating in an extreme environment. The instruments it carries, like the SHERLOC and PIXL on its robotic arm, are designed to give a “cursory analysis”. They can identify the basic mineralogy and chemistry of a rock, but they cannot provide the definitive, unambiguous evidence required for the extraordinary claim of life.

For example, Perseverance’s onboard instruments can detect the presence of organic compounds – carbon-based molecules that are the building blocks of life as we know it. The rover has indeed found these molecules in the rocks of Jezero Crater. However, these same instruments cannot definitively determine the origin of these molecules. Organic compounds can be created by living things (biotic), but they can also be created by non-living geological processes (abiotic), such as water reacting with rock, or they can be delivered to the surface by meteorites. A rover cannot tell the difference. This ambiguity is the central problem of in-situ (on-site) analysis.

A recent finding from the “Cheyava Falls” rock, announced in 2024, perfectly illustrates this limitation. Perseverance’s instruments identified minerals and “leopard spot” markings that, on Earth, are often associated with the byproducts of microbial life. This sample is considered to contain “potential biosignatures”. But “potential” is the key word. The rover’s instruments did not clearly detect the organic compounds they expected to find alongside these minerals. Does this mean organics aren’t there? Or does it mean they are present in concentrations too low for the rover’s sensors to detect, or in a form it can’t identify? The rover can’t answer this. As one scientist involved in the mission stated, “We need to haul its samples home to find out”.

The single most significant scientific gap is geochronology. A rover on Mars cannot tell you, with certainty, how old a rock is. On Earth, scientists determine the absolute age of a rock through radiometric dating. This process involves using incredibly sensitive, room-sized mass spectrometers to measure the precise ratio of radioactive isotopes within a mineral sample (e.g., the decay of potassium to argon, or uranium to lead). This is a delicate, power-intensive, and complex process that is completely impossible to miniaturize and put on a rover.

Without this capability, our understanding of Mars’s timeline is built on a model, not on direct evidence. Scientists estimate the age of a surface by counting the number of impact craters on it – the more craters, the older the surface. But this entire model is calibrated against a single data point: the ages of the lunar rocks returned by the Apollo missions. We are, in effect, guessing Mars’s history based on the Moon’s. This uncertainty is a massive barrier to understanding the planet’s evolution. We don’t know with precision whenMars was wet, when its volcanoes erupted, or how long its habitable window may have lasted. Only returned samples can provide this “ground truth.”

The Power of Earth-Based Laboratories

The scientific revolution of Mars Sample Return will not happen on Mars. It will happen in laboratories in Houston, London, Berlin, Tokyo, and around the world. The decision to bring the samples back is a decision to replace the limited capabilities of one robot with the full, collective, and ever-advancing power of Earth’s entire scientific community.

The advantages of this approach are significant. First, it enables unlimited analytical power. Instead of the miniaturized tools on a rover, scientists can use instruments of any size, power, or complexity. They can use scanning electron microscopes to see features at the nanometer scale. They can use Synchrotron light sources – football-stadium-sized particle accelerators – to map the chemical composition of a sample without destroying it. And, most importantly, they can use the high-precision mass spectrometers needed for definitive geochronology and life-detection. The relatively small and few scientific instruments that Perseverance carries “offer only very limited possibilities” compared to what is available on Earth.

Second, it enables collaboration and verification. A discovery as monumental as extra-terrestrial life would require extraordinary evidence. It would not, and should not, be accepted based on the reading of a single instrument on a single rover. In terrestrial labs, a sample could be analyzed by dozens of independent teams using multiple, cross-checking methods. One lab could search for morphological fossils while another analyzes isotopic ratios, and a third looks for the chemical signatures of metabolism. This level of certainty, reproducibility, and peer review is the bedrock of the scientific method, and it is only possible with returned samples.

Third, returned samples provide a direct anchor for planetary evolution. The MSR campaign has several key science objectives. A primary one is geology: to reconstruct the formation and alteration history of Mars. By taking the igneous (volcanic) rock samples collected from the floor of Jezero Crater and precisely dating them, scientists will, for the first time, establish a firm, absolute date for a specific location on Mars. This single anchor point will allow scientists to recalibrate and update the entire crater-counting model for the whole planet. This will, in turn, revolutionize our understanding of the timeline of all planetary processes in the inner solar system, from the formation of atmospheres to the history of water and climate.

Fourth, the samples are the key to astrobiology. A core objective is to determine the “potential astrobiological significance” of the samples and determine if they “contain evidence of past life on Mars”. The sedimentary rocks from the Jezero delta, which were deposited in a lakebed, are the prime targets. In Earth-based labs, scientists can search for definitive biosignatures – clues that life, not geology, was at work. This could include:

• Microfossils: The preserved, mineralized remains of microbial cells.
• Isotopic Ratios: Life preferentially uses lighter isotopes of elements like carbon. A sample enriched in Carbon-12, for example, would be a very strong indicator of biological processes.
• Molecular Evidence: Analyzing the specific structures of organic molecules. On Earth, life builds molecules with a specific “handedness” (chirality). Finding such a preference in a Martian sample would be a smoking gun.A rover can’t do any of this.

Fifth, the samples are an investment in future human exploration. A key MSR objective is to “identify and characterize potential risks and opportunities for future human missions”. The returned regolith (dust) samples are especially important. Martian dust is thought to be fine, abrasive, and potentially toxic, containing high levels of perchlorates. Understanding its properties is essential for designing space suits, habitats, and life support systems that won’t fail and for protecting astronaut health. The samples will also be analyzed for “in-situ resources,” such as minerals that may contain trapped water, which could one day be harvested by astronauts.

Finally, the MSR collection, like the Apollo lunar samples, represents an archive for the future. The Apollo samples, collected in the 1970s, are still studied today, yielding new discoveries with instruments and techniques that were unimaginable at the time. The same will be true for the Mars samples. The plan is to analyze only a small portion of the returned material initially. The vast majority will be carefully curated and preserved, held in trust for future generations of scientists to study with instruments not yet invented, to answer questions we haven’t yet thought to ask. This ensures the mission’s scientific value will continue to grow for decades, if not centuries, to come.

The Archive in Jezero Crater

The old adage of “location, location, location” is as true in planetary science as it is in real estate. The scientific value of a returned sample is entirely dependent on its context – where it came from and what story it can tell. A random rock from a random plain on Mars would be interesting, but a carefully selected rock from one of the most astrobiologically promising locations on the planet is a potential Rosetta Stone.

This is why NASA and the international science community spent years in a rigorous, community-driven process to select the landing site for the Mars 2020 mission. The choice, Jezero Crater, was a bold one. It’s a 28-mile-wide (45-kilometer) impact basin, but what makes it special is its past. High-resolution images from orbit, particularly from the Mars Reconnaissance Orbiter, show the unmistakable, fossilized remnants of an ancient river delta on its western edge. This is a fan-shaped deposit of sediment that formed when a river channel breached the crater wall and flowed into a standing body of water, creating a large lake.

This delta-lake system was active more than 3.5 billion years ago (during Mars’s Noachian period), at a time when Earth’s own microbial life was just getting started. On our planet, river deltas are biological hotspots. As the river slows, it deposits fine-grained mud and silt, which are exceptionally good at trapping and preserving organic matter and the physical remains of microbes. The hypothesis is simple: if microbial life ever existed on Mars, a place like the Jezero crater lake is one of the most likely places it could have thrived. And the sedimentary rocks of its delta are the most likely place its remains would be preserved. The crater tells a story of an on-again, off-again wet past, with evidence that water carried clay minerals – which are also good at preserving organics – into the lake.

The First Sample-Caching Mission

The Perseverance rover was designed from the ground up to exploit this location. It is the first mission to bring a sophisticated “sample caching system” to another world. This system is a complex assembly of drills, robotic arms, and hermetic sealing stations.

The process is meticulous. The rover uses a rotary-percussive drill at the end of its 7-foot robotic arm to cut a cylindrical core, roughly the size of a piece of chalk, from a target rock. The drill bit then retracts, and the sample tube (which was already inside the bit) is transferred into the rover’s chassis. Inside, a robotic mechanism photographs, measures, and hermetically seals the tube with a cap. These sealed tubes are then stored in a “belly” rack aboard the rover.

Perseverance also carries “witness tubes”. These are five tubes that were pre-filled on Earth with special materials designed to capture the Martian environment around the rover. When the rover drills a rock, it opens a witness tube to capture any airborne dust or particulates kicked up by the process. These tubes act as a “control” sample. They will allow scientists back on Earth to distinguish between the pristine material inside the rock core and any contamination from the modern-day Martian surface or the rover’s own landing system. Three of these witness tubes are planned for return.

A Curated Geologic “Campaign”

The rover’s path through Jezero Crater was not a random wander. It has been a series of deliberate, multi-year “campaigns,” with each campaign targeting a different, fundamental geologic unit of the crater. The goal is to collect a diverse suite of samples that, together, tell the complete story of Jezero’s formation, its watery past, and its subsequent evolution. As of 2024-2025, the rover has filled 33 of its 43 tubes and has completed several major campaigns.

Crater Floor Campaign: The rover’s first set of samples was collected from the crater floor itself. Scientists were surprised to find that these rocks were not the sedimentary lakebed they expected, but rather igneous (volcanic) rocks. This was a discovery of immense importance. These rocks formed from cooling magma, meaning they contain minerals that are perfect for high-precision radiometric dating. These samples (with names like “Melyn” and “Otis Peak”) are the key to the geology objective. They will allow scientists to establish the absolute “clock” for the Jezero system – pinpointing when the crater formed, when the lake was present, and when the delta was built.

Fan Front and Upper Fan Campaigns: After exploring the floor, Perseverance drove to the base of the ancient river delta and began to climb it. Here, it collected its prime astrobiology samples: sedimentary rocks. These rocks, formed by particles settling in the ancient lake, are the ones most likely to contain the chemical or physical evidence of past microbial life. Geochronological analysis of carbonate cements within these rocks can also be used to determine when the deltaic sediments became solid rock.

Margin Campaign: The rover also explored the “Margin Unit,” the ring of rocks along the inner edge of the crater. This campaign, which included the promising “Cheyava Falls” sample (formally “Sapphire Canyon”), is helping scientists understand the relationship between the crater floor and the lake’s ancient shoreline. The “Cheyava Falls” sample, collected in 2024, is particularly exciting. Its mineralogy, rich in water-deposited minerals like silica and carbonates, indicates it was awash in water for an extended period, “perhaps as part of an ancient Martian beach”. On Earth, these minerals are known to be “good at trapping and preserving ancient organic material and biosignatures”. This single sample embodies why the rover was sent to Jezero and why these samples must be returned for study.

Regolith and Atmosphere Samples: The collection is not just solid rock. Perseverance has drilled two cores of “regolith” (the broken rock and dust on the surface). It has also used its sampling system to capture a sample composed purely of the modern Martian atmosphere. This atmospheric sample is a boon for atmospheric scientists. By analyzing the noble gases and isotopes in this pristine sample, they can understand the origin and evolution of Mars’s atmosphere, helping to explain how and why the planet lost its thick, warm atmosphere and became the cold desert it is today. Scientists are also excited to study the “headspace,” or the small puff of air trapped in the top of every rock-core tube, which provides many more tiny glimpses of the atmosphere’s composition.

The “Three Forks” Backup Plan

This entire collection, currently valued at billions of dollars and decades of scientific effort, is stored in two separate locations. The primary set of samples remains inside the Perseverance rover, ready for a direct hand-off to a future lander. But what if Perseverance, a complex robot operating in a harsh environment, were to fail before that hand-off?

To mitigate this risk, NASA executed a backup plan. In late 2022 and early 2023, Perseverance drove to a carefully selected, flat, and featureless piece of terrain nicknamed “Three Forks”. There, over several weeks, it meticulously dropped 10 of its sample tubes – a duplicate “greatest hits” collection representing the diversity of the crater floor and delta campaigns – onto the surface in a precise zigzag pattern.

This is the “Three Forks Depot”. It is a passive, static backup. The tubes will lie there on the surface, weathering the Martian environment, for years or even a decade. The original mission plan (which is now in flux) included a method to retrieve these backup tubes, either with a dedicated ESA-built “fetch rover” or with small, specialized helicopters. This depot ensures that even in a worst-case scenario where Perseverance fails, the core of the MSR scientific collection is not lost.

The Original Grand Architecture

The challenge of Mars Sample Return is not just one mission; it’s a campaign, a “daisy chain” of missions that must work in perfect, robotic sequence. The original plan, formalized by NASA and ESA in 2022, was a marvel of engineering ambition, a three-part relay race that would span two planets and more than a decade. The plan’s goal, as one engineer put it, was to “break up the mission into affordable, technically achievable, cleanly-defined segments”. This segmentation created a web of interdependencies that would prove to be its downfall.

Mission 1: The Collector (In Progress)

The first leg of this interplanetary relay is the only one that has flown. NASA’s Mars 2020 mission successfully landed the Perseverance rover in Jezero Crater on February 18, 2021. Its mission, which is still ongoing, is to act as the first “leg” of the relay – the field geologist collecting and caching the samples. As detailed previously, Perseverance has been collecting these samples and holds the primary set in its chassis, while having deposited a backup set at the Three Forks depot. This part of the plan has been a resounding success.

Mission 2: The Retrieval (The Canceled Behemoth)

The second leg was the most complex and, ultimately, the component that broke the program’s budget and schedule. This part of the plan centered on the Sample Retrieval Lander (SRL), a massive, stationary spacecraft that NASA would build and launch.

The SRL was an absolute behemoth. At a planned mass of over 3,375 kg (7,440 pounds) and the size of a two-car garage, it would have been the largest and heaviest spacecraft ever sent to the Martian surface. Its mass was nearly double that of the Perseverance rover itself. Landing such a large object required pushing NASA’s “sky crane” landing system to its absolute limits, or developing a new system entirely.

This lander was not a rover; it was a stationary “launch pad” and “transfer station”. Its mission was to land with pinpoint precision near the Three Forks depot and await the samples. To accomplish its task, it carried a payload of other sophisticated robots.

The Sample Retrieval Method (Original Plan): Initially, the SRL was to carry a small, fast “fetch rover” built by ESA, named the Sample Fetch Rover (SFR). This small rover’s job was to deploy from the lander, drive out to the Three Forks depot, and one-by-one, grab the 10 tubes lying on the surface. It would then ferry them back to the lander and hand them off.

The Sample Retrieval Method (Revised Plan): This plan was later updated. Citing the “recently updated analysis of Perseverance’s expected longevity,” NASA and ESA changed the architecture in 2022. The new plan designated the Perseverance rover itself as the primary means of sample delivery. Perseverance, having proven to be a durable and healthy rover, would drive its own internal cache of 30 samples over to the SRL.

The ESA fetch rover was canceled. In its place, the SRL would carry two small, Sample Recovery Helicopters as a backup. These helicopters, based on the wildly successful design of the Ingenuity helicopter, would be slightly heavier and more capable, featuring wheels for mobility on the ground and a small gripper. If Perseverance failed, these helicopters would be deployed to fly out to the Three Forks depot, pick up the cached tubes, and fly them back to the lander one at a time.

The Sample Transfer Arm (STA): Once the samples arrived at the lander (either via Perseverance or the helicopters), the next key component would take over: ESA’s Sample Transfer Arm. This was a 2.5-meter-long, highly autonomous robotic arm with seven degrees of freedom, designed to “see,” “feel,” and make its own decisions. This arm’s delicate job was to pick up each of the 30 pencil-sized tubes, precisely orient them, and load them one by one into the nose cone of a small rocket.

The Mars Ascent Vehicle (MAV): The primary payload, and the entire reason for the lander’s massive size, was NASA’s Mars Ascent Vehicle (MAV). The MAV was a 10-foot-tall, 992-pound (450 kg) rocket designed to be the first-ever vehicle to launch from the surface of another planet. It was a two-stage, solid-propellant rocket. The SRL’s entire structure was, in effect, a launch platform for the MAV. After the STA arm finished loading the sample container and sealing the MAV’s nose cone, the lander’s job was done. The MAV would then ignite, blast off from the lander’s deck, and fly for about 10 minutes to reach a speed of 2.5 miles per second, inserting its precious payload – the Orbiting Sample (OS) container – into a stable, low-Mars orbit.

Mission 3: The Return (The Interplanetary Catcher)

The third and final leg of this grand relay was the responsibility of the European Space Agency. ESA was contracted to build and operate the Earth Return Orbiter (ERO), a spacecraft of equally ambitious proportions.

ERO Design: The ERO, with Airbus as the prime contractor, was set to be the largest spacecraft to ever orbit Mars. Weighing seven metric tons, the 7-meter-tall spacecraft was dominated by a gigantic pair of solar arrays. Spanning nearly 40 meters (144 square meters), these were the largest solar arrays ever designed for an interplanetary mission. They were necessary to power the spacecraft’s high-efficiency, hybrid propulsion system, which combined conventional chemical thrusters for Mars orbit insertion with a set of powerful solar-electric ion engines for the long, slow, multi-year cruise between Earth and Mars and back.

ERO’s Role: The ERO would launch from Earth (on an Ariane 6 rocket) and take about two years to cruise to Mars and spiral down into its operational orbit. Once there, its first job was to act as a critical communications relay for the surface missions, providing the high-bandwidth link needed for the SRL’s landing and the MAV’s launch.

Its second, and most difficult, job was autonomous rendezvous and capture. The ERO would have to detect, track, and intercept the basketball-sized Orbiting Sample (OS) container that the MAV had launched. This had to be done completely autonomously, from 50 million miles away, with European and NASA navigation teams orchestrating the “catch”. This would be the first-ever robotic rendezvous and capture of an object in orbit around another planet.

The Journey Home: Once the ERO captured the OS, it would use a NASA-built payload, the Capture, Containment,and Return System (CCRS), to robotically draw the sample container inside. As will be detailed later, this system would seal the OS within a multi-layered biocontainment vessel to ensure planetary protection. With the sample secured, the ERO would spend another two years firing its ion engines to slowly spiral away from Mars and begin its journey back to Earth.

Three days before arriving at Earth, the ERO would perform its final act: it would release the sealed sample capsule, known as the Earth Entry Vehicle (EEV), placing it on a precise trajectory to land in the Utah desert. The ERO itself would never return, performing a maneuver to fly past Earth and enter a stable orbit around the Sun.

This was the plan. It was an intricate, multi-billion-dollar dance of at least nine distinct robotic systems (Perseverance, SRL, Helicopters, STA, MAV, OS, ERO, CCRS, EEV), all of which had to work perfectly, in sequence, for the mission to succeed. The sheer number of “first-ever” feats involved made it a technological masterpiece on paper, and a programmatic nightmare in reality.

An Untenable Program

The magnificent, complex “Grand Architecture” was, from its inception, built on a shaky foundation. It was sold as a lean, fast, and focused program, with initial estimates pegging its cost around $5.3 billion and a target launch date of 2026. This optimism quickly collided with the harsh realities of engineering, budget cycles, and the sheer, unprecedented complexity of the task.

The program was, in NASA’s own internal language, “over-constrained”. This meant it was given unrealistic expectations for its budget, schedule, and required workforce from the very beginning. The mission’s success depended on multiple, parallel developments – the lander, the rocket, the arm, the orbiter – all progressing perfectly, on time and on budget, without any of the technical setbacks that are normal for such advanced work. External events, such as the war in Ukraine, also contributed to design complexities and supply chain issues.

By early 2023, it was clear the program was in deep trouble. NASA’s FY2024 budget request for MSR was a massive $949 million, and even that wasn’t enough. In April 2023, NASA Administrator Bill Nelson informed the Senate that he had “just learned” the mission needed another $250 million on top of that just to stay on its already-delayed schedule. The Senate Appropriations Committee was “not impressed”. Their response was a clear signal of lost confidence: in their version of the budget, they slashed NASA’s $949 million request, providing only $300 million. This was a body blow, effectively starving the program of the funds it needed to move forward.

The 2023 Independent Review Board (IRB)

In response to these mounting challenges, NASA did what it does to assess its largest, most troubled “Flagship” missions: it commissioned a high-level Independent Review Board (IRB). This was the second IRB to look at MSR; the first, in 2020, had already recommended substantial changes. This new board, established in May 2023 and chaired by Orlando Figueroa, was given a simple, urgent task: evaluate the technical, cost, and schedule plans and tell NASA if the program, as designed, was realistic.

After a two-month, deep-dive evaluation, the IRB delivered its report to NASA in September 2023. The findings were devastating.

Cost: The IRB’s independent analysis concluded that the program’s true probable Life Cycle Cost (LCC) was not $5.3 billion, or even the $7 billion NASA was then projecting. The board placed the probable cost in a range of $8 billion to $11 billion. This figure was considered untenable, as it would “cannibalize” NASA’s entire Planetary Science budget, forcing the cancellation of other high-priority missions.

Schedule: The board found that the planned 2027/2028 launch dates for the Sample Retrieval Lander (SRL) and Earth Return Orbiter (ERO) were “not feasible”. The earliest probable launch readiness date for both components, assuming no major setbacks, was 2030. This delay, coupled with the multi-year flight times, meant the Martian samples would not arrive back on Earth until 2040.

Complexity and Management: The report was not just about money and time. It was a sharp critique of the mission’s “unrealistic” design and management. The board stated that MSR was “a very complex program and campaign with multiple parallel developments, interfaces, and complexities” that were “beyond the experience base” of NASA’s Science Mission Directorate. It criticized the “hybrid” and “unclear” organizational structure, which it said “impeded effective management” and diluted accountability. In short, the program was too big, too complex, and not being managed in a way that could lead to success.

The board’s conclusion was a clear, unambiguous “no confidence” vote: “The program is not ready to be baselined, technically or programmatically“.

The Fallout: A Program on Ice

The IRB-2 report sent shockwaves through NASA, Congress, and the entire planetary science community. Administrator Bill Nelson immediately accepted the findings, stating in no uncertain terms that the $11 billion price tag was “too expensive” and the 2040 return date was “unacceptably too long”. The 2040 date was a particular sticking point; Nelson noted that NASA wanted to have astronauts on Mars by the 2040s, and a key reason for MSR was to analyze the samples before sending crews. A 2040 return would make the mission partially moot.

In response, NASA officially “paused” the Mars Sample Return program in November 2023. This was not a cancellation, but a hard stop on development while NASA’s leadership, led by Deputy Associate Administrator Sandra Connelly, formed a team to review the IRB’s findings and formulate a new path forward.

This programmatic “pause” had immediate, painful, and real-world consequences. NASA, anticipating a severe budget cut from Congress, instructed its centers working on MSR – JPL, Goddard, and Marshall – to “begin ‘ramping back’ on activities” to conserve money. The uncertainty was crippling.

The “worst-case scenario” arrived in early 2024. With MSR’s funding for the year in limbo, NASA’s Jet Propulsion Laboratory (JPL), the lead center for the mission and the intellectual heart of Mars exploration, was forced to act. On February 12, 2024, JPL announced it was laying off 530 employees, or 8% of its total workforce, along with 40 contractors. The layoffs, which took effect immediately, were a direct and painful consequence of the MSR program’s untenable budget and schedule.

The message was clear: the “Grand Architecture” was not just flawed; it was broken. A complete and total rethinking of the entire mission was no longer an option. It was an imperative.

NASA’s Commercial “Hail Mary”

Faced with a flagship program in disarray, a demoralized workforce, and a skeptical Congress, NASA’s leadership opted for a “Hail Mary” pass. On April 15, 2024, Administrator Bill Nelson and Science Associate Administrator Nicola Fox held a media teleconference to announce their official response to the IRB-2 report. The message was a seismic shift in NASA’s approach to deep-space exploration.

Nelson stated bluntly that he had “pulled the plug” on the $11 billion, 2040 architecture. The old plan was dead. In its place, NASA was “moving forward” with a new, competitive approach to find a “more affordable and faster” method to bring the Mars samples home.

The new strategy was to formally solicit “out-of-the-box” architectures and innovative ideas from the private sector. “Mars Sample Return will be one of the most complex missions NASA has undertaken,” Nelson said, “and it is… [necessary] that we carry it out more quickly, with less risk, and at a lower cost”. He was explicitly looking for “fresh, exciting, and innovative ideas” to find cosmic secrets from the Red Planet.

This was a public admission that NASA’s traditional, in-house, cost-plus contracting model had failed to produce a viable plan for this specific challenge. The agency was now turning to the commercial space industry – the same industry that had taken over astronaut and cargo transport to low-Earth orbit – and asking it to solve a flagship-class, deep-space problem.

The Call for Proposals

The agency immediately issued a “Request for Proposals” (RFP) to industry, as well as tasking its own NASA centers (including JPL and the Johns Hopkins Applied Physics Laboratory) to go back to the drawing board. The goal was to create a “bake-off,” a competition of ideas.

NASA would award firm-fixed-price contracts of up to $1.5 million each for accelerated, 90-day architectural studies. The companies were asked to investigate either entirely new, end-to-end mission architectures or, more narrowly, innovative designs for specific mission elements, like a smaller, lighter Mars Ascent Vehicle (MAV). The rationale was clear: a smaller MAV was the “key to a smaller, lighter, less complex, and lower cost and risk Sample Retrieval Lander”.

The response from industry was robust. In June 2024 (with updates in October), NASA announced it had selected 11 studies to move forward: eight from industry and three from its internal or affiliated centers.

The list of selected companies represented a new paradigm for deep-space exploration:

• Lockheed Martin: An aerospace giant with a long, successful history of building NASA’s Mars orbiters and landers (including the InSight lander).
• SpaceX: The new-space titan, whose Starship rocket is explicitly designed for Mars.
• Blue Origin: The other heavy-lift competitor, whose proposal was titled “Leveraging Artemis for Mars Sample Return,” suggesting a link to its Blue Moon lander.
• Northrop Grumman: A major defense and aerospace contractor with deep experience in solid-rocket motors, a key MAV technology.
• Aerojet Rocketdyne: A leading propulsion company, proposing a high-performance liquid-fueled MAV.
• Rocket Lab: A “new space” company known for its small, fast, and cheap “Electron” rocket, now scaling up to larger vehicles and interplanetary missions.
• Whittinghill Aerospace: A smaller company focused on a single-stage MAV.
• Quantum Space: A company focused on orbital logistics and tugs.

This was a fundamental shift. NASA wasn’t just asking companies to bid on building a pre-designed component. It was asking them to design the entire mission or its most difficult parts, and to do so with a focus on commercial speed and cost-efficiency. Administrator Nelson summed up the new philosophy: “by involving industry, and not NASA centers like [JPL],… they’re coming out with much more practical (proposals), where they can speed up the time and considerably lower the cost”. The competition was on.

The New Contenders: Competing Visions for Mars

The 90-day studies, which were assessed by NASA in late 2024, represented a clash of three fundamentally different philosophies for solving the Mars Sample Return problem. These philosophies reflected the unique corporate identities and technical strengths of the companies involved, offering NASA a clear menu of options: leverage heritage, bet on revolution, or build on synergy.

Lockheed Martin: The “Heritage and Fixed-Price” Bid

Lockheed Martin’s proposal, announced in June 2025, was arguably the most disruptive, not for its technology, but for its business model. As an aerospace giant with 50 years of Mars experience – having built 11 of NASA’s 22 Mars spacecraft and currently operating all three active NASA orbiters – their proposal came from a place of deep heritage.

Their pitch: they offered to execute the core sample return mission for a firm-fixed price of under $3 billion. This was a direct shot at the $11 billion IRB estimate and even NASA’s internal $7 billion figure. A firm-fixed price contract means the company agrees to deliver the final product for a set price, assuming the cost and risk of overruns themselves. This is the opposite of the traditional “cost-plus” model, where NASA pays for the development costs plus a fee, and which is often blamed for budget-behemoth missions.

Lockheed’s philosophy was not revolutionary; it was evolutionary. They argued that NASA’s original plan was bloated and that the mission could be done far more cheaply and quickly by “reducing complexity by leveraging heritage, flight-proven elements”. Their proposed architecture featured:

• A Smaller, Simpler Lander: Instead of a bespoke, $4 billion lander, Lockheed proposed using their previously flight-proven InSight spacecraft design. This lander design is smaller, lighter, and – most importantly – already built and flown, dramatically reducing design and testing costs.
• A Smaller MAV and EES: The smaller lander necessitates a smaller, lighter Mars Ascent Vehicle (MAV). Their proposal also included a compact Earth Entry System (EES) based on their successful heritage from the OSIRIS-REx asteroid sample return mission, which returned its capsule in 2023.
• A Simplified Surface Mission: Their plan assumed the healthy Perseverance rover would drive its samples to this new, smaller lander. This would eliminate the need for the complex and risky backup helicopters or a fetch rover, further streamlining the mission and cutting costs.

Lockheed’s proposal was a “back to basics” approach. It represented a direct commercial challenge: that a private company, using its own proven designs and efficient management, could deliver a flagship science mission for less than half the price and in half the time (targeting a return in the early 2030s).

SpaceX: The “Starship” Option

SpaceX’s proposal, titled “Enabling Mars Sample Return With Starship,” offered a radically different philosophy: “mass changes everything”.

While the specifics of their 90-day study are not public, the proposal centers on their Starship vehicle, a fully reusable, 120-meter-tall rocket and spacecraft system. Starship is explicitly designed to carry over 100 metric tons of cargo and, eventually, crew to the surface of Mars.

The SpaceX philosophy is not to play by the rules of mass-constrained, complex “daisy-chain” missions. It is to change the rules of the game entirely. Instead of NASA’s intricate, multi-launch relay race, the Starship option could fundamentally simplify the problem by using “brute force” lift capacity.

There are two likely “levels” to this proposal:

1. The Simple Version: Use Starship as a “dumb truck.” A single Starship could launch all the elements of a traditional MSR mission (a lander, a MAV, and an orbiter) in one go, potentially saving billions in launch costs and mission integration complexity.
2. The Revolutionary Version: Use Starship as the mission. In this scenario, a Starship vehicle would land itself on Mars, just as it is designed to do. It could then use its own robotic systems (perhaps the “Optimus” robots Musk has discussed) to go out, collect the sample tubes from both Perseverance and the Three Forks depot, and load them into its cargo bay. Then, the entire Starship would re-launch from the Martian surface, fly back to Earth, and land.

This revolutionary version would eliminate the need for a separate Sample Retrieval Lander, Mars Ascent Vehicle, and Earth Return Orbiter, collapsing the entire $11 billion architecture into a single, reusable vehicle.

The massive, glaring hurdle for this approach is that Starship is not yet a proven vehicle. As of 2025, it has completed several atmospheric flight tests but has not yet achieved a fully successful, operational mission to orbit, let alone a landing on another planet. Its complex “flip and burn” landing maneuver has not been tested on Mars, and its ability to be refueled in orbit – a requirement for a Mars trip – is still in development. SpaceX is planning to send its first uncrewed Starships to Mars as early as 2026 or 2029 to gather landing data. The SpaceX proposal is a bet on a revolutionary future that is not yet here.

Blue Origin: The “Artemis Leverage” Plan

Blue Origin’s proposal, “Leveraging Artemis for Mars Sample Return,” presented a third, synergistic philosophy: “reuse development”. Their concept argued that NASA is already spending billions of dollars developing and funding a human-rated landing system for the Artemis Moon program, and that this massive investment should be leveraged for other missions.

Blue Origin is one of the prime contractors for the Artemis Human Landing System (HLS), developing its “Blue Moon” lander. Their MSR proposal was to adapt this hardware for Mars. The concept, revealed in internal NASA documents, includes:

• A “Blue Mars Lander”: A Mars lander based directly on their Blue Moon HLS design.
• All-Propulsive Landing: A key innovation. This lander would use its powerful engines (like the BE-7) to decelerate all the way from orbit to the surface. This all-propulsive “soft landing” would eliminate the need for the complex, high-risk “seven minutes of terror” hardware: the heat shield, parachute, and sky crane. This “lower degree of complexity” would, in theory, increase reliability and reduce cost.
• Orbital Transportation: Their “Blue Ring” orbital tug, a versatile spacecraft also in development, could be used as the transportation stage to ferry the lander from Earth to Mars orbit.

Blue Origin’s pitch was one of programmatic synergy and long-term vision. By using a common set of hardware for both the Moon (Artemis) and Mars (MSR), NASA would get a better return on its lunar investment, reduce redundant development, and build a sustainable, reusable architecture for the entire “Moon to Mars” exploration strategy.

The Path Forward: NASA’s 2025 Dual-Track Plan

On January 7, 2025, NASA leadership held a media teleconference to announce the results of its program-wide review and the new, official path forward for Mars Sample Return. After assessing the 11 “out-of-the-box” studies from industry and its own centers, the agency, in a savvy programmatic and political move, chose not to pick a single winner.

Instead of betting the entire program on one company or one unproven idea, NASA established a “dual-track” strategy. This new plan will fund two competing landing architectures simultaneously during the formulation phase, creating a “bake-off” between NASA’s most trusted internal systems and the new, lower-cost commercial concepts.

This dual-path approach is designed to maximize the chances of success while encouraging the competition and innovation that NASA leadership was seeking. The agency plans to pursue both paths forward, with a final “down-select” to a single winning architecture expected in the second half of 2026.

The two competing tracks for landing the MSR payload on Mars are:

1. Option 1: The “Heritage” Path (NASA/JPL-led): This track will leverage NASA’s own, highly successful, and flight-proven entry, descent, and landing (EDL) system: the Sky Crane. This is the “flying jetpack” system that defied skeptics and successfully landed the one-ton Curiosity rover in 2012 and the even heavier Perseverance rover in 2021. This path represents the low-risk, “we know how to do this” option, relying on NASA’s unparalleled heritage.
2. Option 2: The “Commercial” Path: This track will “capitalize on using new commercial capabilities” to deliver the lander to the surface. This path keeps the innovative proposals from companies like Lockheed Martin (with its InSight-based lander) and Blue Origin (with its all-propulsive lander) in the game. It allows these companies to continue to mature their lower-cost designs, backed by NASA funding, and compete directly against the in-house JPL model.

A New, Streamlined Architecture

While the landing method is now a two-way competition, NASA’s 2025 announcement also revealed a new, streamlined architecture for the lander itself, adopting key lessons from the commercial studies and the IRB report. These changes apply to both the heritage and commercial tracks, and immediately reduce the complexity and risk of the original, failed plan.

• A Smaller MAV: The new plan officially adopts the central recommendation of the commercial studies. Both lander options will be designed to carry a smaller, lighter version of the Mars Ascent Vehicle (MAV). This is a fundamental change that makes a smaller, cheaper lander possible.
• Nuclear Power: The massive, complex, and vulnerable solar panels from the original SRL design are gone. Both lander options will now be powered by a radioisotope power system (RPS). This is a type of nuclear battery (like the one that powers the Perseverance rover) that provides a constant, reliable source of electricity and heat. This single change solves two massive problems:
  1. It allows the lander to operate and survive through the dark, cold Martian winters and dust storm seasons, which would have been mission-ending for a solar-powered lander.
  2. It provides the electricity needed to keep the MAV’s solid-rocket motors warm. This was a major engineering hurdle for the MAV, as cold propellant can crack and explode. The RPS provides a simple and reliable solution.
• A Simpler, Cleaner Transfer: The new plan calls for a redesign of the sample loading system, simplifying the “break the chain” process. The new design will “eliminate the accumulation of dust on the outside of the sample container,” making the planetary protection protocol (which will be detailed later) easier to implement.
• Capacity: The new architecture is being designed to retrieve 30 sample tubes – the full set currently held aboard the Perseverance rover.
• ESA’s Role: The partnership with the European Space Agency remains a cornerstone of the new plan. Both of NASA’s landing options still rely on ESA’s Earth Return Orbiter (ERO) to perform the orbital rendezvous, capture the 30-tube sample container, and safely bring it home. While NASA’s part of the mission was paused and radically restructured, ESA’s work on the ERO has continued, with its robust design passing a critical design review.

This new 2025 dual-track strategy is a direct, logical, and objective response to the 2023 IRB report. It acknowledges the failures of the past by embracing a smaller, simpler, and more robust design (RPS-powered, smaller MAV). And it hedges its bets on the future by fostering a head-to-head competition between its most reliable internal team and the promise of a faster, cheaper commercial industry.

The shift to a commercial-competitive model addresses the programmatic and financial crises of MSR. It does not change the fundamental, laws-of-physics-based engineering challenges. Regardless of who builds the hardware – JPL, Lockheed Martin, or SpaceX – the mission still requires a chain of “first-ever” feats of robotics and rocketry, any one of which is arguably the most difficult thing ever attempted in space exploration.

What makes MSR uniquely hard is its “system of systems” nature. A typical flagship mission might have one or two primary elements, like an orbiter and a lander. MSR has up to nine, depending on how you define them. And they all must work, in sequence, with no human intervention, millions of miles from home.

Challenge 1: The First Launch From Another World

The single most daunting hurdle is launching the Mars Ascent Vehicle (MAV). This will be the first rocket ever fired from the surface of another planet. The only analogue in history is the ascent stage of the Apollo Lunar Module, but that comparison is misleading and dangerous.

• Gravity: The Apollo astronauts launched from the Moon, which has only 1/6th of Earth’s gravity. Mars has 38% of Earth’s gravity. This significantly higher gravity well means the MAV needs much more power and propellant; it must be a real rocket, not just a simple ascent module.
• Atmosphere: The Moon has no atmosphere. Mars has a thin but important atmosphere. This means the MAV must be designed to be aerodynamic, fighting against drag and experiencing “dynamic pressure” and shock waves as it accelerates to its 2.5 mile-per-second (4 km/s) orbital velocity. NASA has conducted extensive wind tunnel testing at Marshall Space Flight Center – using the same facility that tested the Apollo Saturn rockets – to understand the “aeroacoustic” environment and ensure the rocket doesn’t shake itself apart.
• The Long, Cold Wait: This is the MAV’s greatest challenge. The rocket can’t just “launch.” First, it must survive the bone-jarring violence of a launch from Earth. Then, it must endure a 6-to-9 month journey through the deep-space radiation environment. Then, it must survive a “fiery entry” and “not-so-soft landing” on the surface of Mars. And then, it must sit, dormant and exposed, on the Martian surface for as long as an Earth year, waiting for Perseverance to arrive.
• The Temperature Problem: This “long, cold wait” exposes the MAV to the extreme Martian temperature swings, with nights plunging to -40 degrees Fahrenheit or colder. For a solid-propellant rocket (NASA’s original MAV design), this is a critical threat. At these low temperatures, the solid fuel propellant can become brittle and develop micro-cracks. Upon ignition, the flame can penetrate these cracks, causing the entire motor to catastrophically explode instead of burning in a controlled way. This is why the new 2025 plan’s shift to a nuclear (RPS) power source is so important – it provides the “housekeeping” heat to keep the MAV’s solid motors warm and safe for launch.
• Total Autonomy: When it’s time to launch, there is no “3-2-1” from a human in Houston. The light-time delay between Earth and Mars can be up to 22 minutes one-way. “You can’t joystick it”. The MAV must, on its own, determine its exact position and pointing direction, ignite its engines, and fly a perfect, closed-loop trajectory to a precise point in orbit.

Challenge 2: Robots Finding Robots in Orbit

Once the MAV has successfully delivered the basketball-sized Orbiting Sample (OS) container into orbit, the second “miracle” must occur. ESA’s Earth Return Orbiter (ERO) must find it and catch it.

This is the first autonomous rendezvous and capture mission ever attempted at another planet. While NASA and other agencies have perfected autonomous rendezvous in Earth orbit (think SpaceX’s Dragon docking with the ISS), doing it at Mars is an entirely new level of difficulty.

The ERO will be “on its own,” operating 50 million miles from its ground controllers. It must use its own onboard sensors – cameras and “lidar” (laser-ranging) – to find a tiny, cold, non-communicating object in the vastness of Mars orbit. The OS is a passive target; it’s just a “dumb” container. The ERO is the smart “catcher.”

The orbital mechanics are unforgiving. The ERO must precisely match the OS’s orbit and velocity, then slowly close in for the capture. The risk is immense. A small miscalculation could mean the ERO misses the container entirely, ending the entire multi-billion dollar mission. Or it could collide with the container, destroying it. This single, high-stakes maneuver is a critical point of failure upon which the entire campaign rests.

Challenge 3: The Surface Relay

Even before the launch, the autonomous operations on the surface are a choreographer’s nightmare, fraught with difficulty. In the new, streamlined 2025 plan, the mission’s success relies on the health of a rover that, by the time the lander arrives, will be many years past its original “warranty.”

The plan requires the Perseverance rover, which landed in 2021, to be healthy, mobile, and functional well into the 2030s. It will have to drive, potentially for many miles, from its exploration site to the lander’s location. If Perseverance fails before it can make this drive, the 30 samples in its belly are lost. This is why the original plan had the backup helicopters – to retrieve the “Three Forks” depot as insurance. It’s unclear if the new, lower-cost 2025 plan retains this helicopter backup, or if it is “all-in” on Perseverance’s longevity.

Assuming Perseverance does arrive, the next challenge begins: the robotic hand-off. The lander’s robotic arm (originally ESA’s 7-jointed STA) must perform an intricate, autonomous transfer. It must be able to “see” the sample tubes presented by Perseverance, grasp them, and then precisely load them, one by one, into the tiny opening of the OS container, which is itself sitting atop the MAV. This requires a level of autonomy, dexterity, and sensor-driven “feel” that is at the cutting edge of robotics. If the arm drops a tube, or can’t align one properly, or if its gripper fails in the -100°F cold, the chain is broken.

This “system of systems” is what makes MSR so uniquely hard. It is not one challenge, but a chain of unprecedented, co-dependent challenges. If any single link in that chain breaks – the old rover, the new arm, the novel rocket, or the orbital catcher – the entire multi-billion-dollar campaign fails.

“Break the Chain”: Protecting Two Planets

Beyond the immense robotics and rocketry challenges lies an even more fundamental, non-negotiable requirement: planetary protection. This discipline, governed by international treaty (Article IX of the 1967 Outer Space Treaty), is a primary driver of the MSR mission’s cost, complexity, and design.

Planetary protection is a two-way street, concerned with two distinct types of biological contamination.

Forward Contamination: Protecting Mars

First, there is forward contamination: the transfer of life from Earth to another celestial body. NASA has a stringent requirement to protect the scientific integrity of its missions. If we are searching for signs of life on Mars, we must be absolutely certain that any “life” we find is not just a hardy Earth-bacterium that hitched a ride on the rover.

For this reason, spacecraft like the Perseverance rover are assembled in sterile, “cleanroom” environments, and their components are baked, irradiated, or chemically cleaned to kill as many terrestrial microbes as possible. This is done to ensure we don’t contaminate the Martian environment and compromise the very science we are trying to conduct.

Back Contamination: Protecting Earth

The second, and for MSR, the paramount concern, is back contamination: the potential introduction of extraterrestrial organisms into Earth’s biosphere.

The samples are being collected from Jezero Crater, a location specifically chosen because it was once a habitable environment. The scientific consensus is that Mars as a whole is of significant interest to the process of chemical evolution and the origin of life. While the probability of bringing back a living, extant Martian organism – a “pathogen” that could harm Earth’s environment or its inhabitants – is considered to be exceptionally low, it is not zero.

The history of life on Earth has shown that host-pathogen relationships are evolutionary; a Martian microbe would have no evolutionary history with Earth life. At the same time, Mars material has been landing on Earth for billions of years in the form of meteorites, with no apparent harm. But because the risk is not zero, and the consequences of being wrong are unthinkable, MSR is treated with the utmost caution.

The mission is classified as “Category V: Restricted Earth Return”. This is the most stringent classification in planetary protection, reserved for missions returning from worlds that may harbor life. This classification mandates that the mission must, with extreme reliability, “avoid… adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter”. This requirement adds “well-warranted complexity to every step of the process”.

The “Break the Chain of Contact” Strategy

The entire MSR architecture is built around a “safety first” engineering philosophy. The core of this philosophy is a multi-layered, redundant strategy called “Break the Chain of Contact”.

The rule is simple and absolute: No uncontained hardware that has contacted Mars, directly or indirectly, may be returned to Earth’s biosphere unless it is sterilized.

This is the “chain of infection” model, but on a planetary scale. The mission’s job is to break this chain at every possible link. This is not a single action, but a sequence of carefully engineered steps from Mars to Earth.

1. On Mars: The process begins on the Martian surface. The sample tubes are sealed by Perseverance. The MAV’s Orbiting Sample (OS) container is designed to be protected from Martian dust. The 2025 redesigned plan explicitly calls for a system that “eliminates the accumulation of dust on the outside of the sample container,” a simplification that makes the next steps easier.
2. In Mars Orbit (The “Seal and Sterilize”): This is the most important “break” in the chain. After ESA’s Earth Return Orbiter (ERO) captures the OS in orbit, it pulls it inside the NASA-built Capture, Containment, and Return System (CCRS).
3. The OS is sealed inside the primary containment vessel.
4. The system then performs a “robust” heat sterilization of the seam of this primary vessel. This “weld” heats the seal to a temperature high enough to destroy any protein structures and inactivate any biological material (i.e., kill any “bugs”) that might be clinging to the outside.
5. Passing the “Clean” Sample: This primary container, now sterile on its exterior, is robotically passed from the “dirty” section of the CCRS into a separate, “clean” chamber.
6. “Container within a Container”: In this clean chamber, the primary container is sealed inside a secondary containment vessel.
7. This entire “container within a container” assembly is then finally placed inside the tertiary and final container – the robust Earth Entry Vehicle (EEV).

This multi-step, redundant process ensures that the exterior of the EEV – the only piece of hardware that will actually enter Earth’s atmosphere – has never been exposed to the Martian environment. The “chain of contact” is definitively broken in deep space.

As an additional precaution, the “dirty” parts of the ERO and CCRS hardware (the parts that did touch the OS before sterilization) are ejected and left behind in Mars orbit, never to return to Earth. The EEV is also protected by a micrometeoroid shield during its journey home to ensure its containment is not breached.

The “Fort Knox” on Earth: The Sample Receiving Facility

The “break the chain” strategy doesn’t end in space. The planetary protection protocols continue, out of an abundance of caution, all the way to the landing site and beyond.

After its fiery, 27,000-mph entry into the atmosphere, the parachute-less EEV is designed to land (or “impact,” in a controlled way) at the secure, remote Utah Test and Training Range. Even though the EEV is certified “clean” on its exterior, recovery teams will treat it “as if it were hazardous biological material”. The capsule will be immediately secured, placed in additional containment, and transported to a “first-of-its-kind” dedicated laboratory.

This laboratory is the Sample Receiving Facility (SRF). As of late 2025, this facility does not exist. It is still in the planning and assessment phase. NASA has been conducting assessment studies (like the Mars SRF Assessment Study, or MSAS) and has issued a Request for Information (RFI) for a potential site location in the contiguous United States.

This facility must be an engineering marvel, as it has two conflicting design requirements:

1. Biosafety: It must be a Biosafety Level 4 (BSL-4) equivalent facility. BSL-4 is the highest level of biocontainment, used for labs that handle the world’s most dangerous and exotic pathogens (like Ebola). This “high-containment” is necessary to “isolate the samples from Earth’s biosphere” and protect the public.
2. Scientific Purity: At the same time, it must be an ultra-pristine cleanroom. This is to protect the samples from Earth. The entire scientific purpose of the mission is to study pristine Martian material. If the samples are contaminated by Earth’s air, microbes, or organic molecules upon opening, their scientific value is destroyed.

The SRF will be a “cleanroom inside a BSL-4 fortress,” a place where scientists will work in bulky, positive-pressure suits, handling the samples inside sealed, sterilized isolation cabinets. It is here, inside this high-containment “Fort Knox,” that the sample tubes would be opened for the very first time, and the final phase of the mission would begin.

The Payoff: Curating a New World

The arrival of the Earth Entry Vehicle in the Utah desert is not the end of the mission; it is the beginning of the next, multi-decade phase of discovery. Once the sealed capsule is transported to and secured within the high-containment walls of the Sample Receiving Facility (SRF), the real scientific payoff begins.

The Sample Safety Assessment Protocol (SSAP)

Before a single grain of Martian sand can be sent to a university lab, the samples must be certified as safe. The first and most important task within the SRF is to conduct the Sample Safety Assessment Protocol (SSAP).

This is not a “check-the-box” formality. The SSAP is a rigorous, pre-defined sequence of biological and chemical tests, designed by an international team of experts spanning public health, sample analysis, and regulatory policy. The protocol is designed to answer one question: does this material from Mars show anyevidence of being a biological hazard to Earth’s biosphere?.

The samples will be treated as “guilty until proven innocent.” They will be subjected to a battery of tests to look for signs of life or bio-activity. This is a “life detection” experiment in itself. Only after this rigorous testing protocol is complete, and the samples are “determined by rigorous testing to be safe for release,” will they be eligible to leave high containment. This entire process – from designing the protocol to its execution – will be subject to multiple, independent peer reviews by outside experts before it is approved.

If any sample fails the SSAP – or if scientists want to study material before the lengthy protocol is complete – there is another path: sterilization. A portion of the sample can be “rendered non-hazardous” through a proven sterilization process (like heat or intense radiation) and then safely distributed to laboratories outside the SRF.

The “Menu”: Cataloging and Curation

The SRF is not intended to be a long-term research lab; it’s a processing and distribution center. Its other main job is curation: the “clean storage, processing, and allocation” of the samples.

As the samples are being tested for safety, a dedicated curation team will perform an “initial sample characterization”. This is not the primary scientific investigation, but rather the process of creating a “sample catalog”. Using a suite of approved, non-destructive instruments inside the SRF (like X-ray computed tomography (XCT) scanners and magnetometers), the team will scan, weigh, and describe each sample.

This catalog will be the “menu” for the global scientific community. It will be populated with data from every stage of the mission – from Perseverance’s initial analysis on Mars to the new scans inside the SRF. This catalog will allow a geologist in Germany or an astrobiologist in Japan to see the composition and texture of “Sapphire Canyon” and write a research proposal asking for a 10-milligram sub-sample.

Global Science: Allocation

The core principle of MSR, as a joint NASA-ESA campaign, is that the scientific investigation will be global. Once the catalog is published, the allocation process begins.

Sample requests for scientific research will be openly competed and jointly selected by NASA and ESA. An international “sample allocation committee” (similar to the one that governs the Apollo lunar samples) will be formed. This committee will review the proposals submitted by the world’s research community and make the difficult decisions about who gets what. The goal is to maximize the scientific return and ensure the samples are studied by the best instruments and brightest minds on the planet.

An MSR Campaign Science Group (MCSG), already active, comprises 20 internationally competed scientists from eight countries, providing input on all science-related activities. This international structure is already in place, demonstrating the global nature of the project.

An Archive for Humanity

The SRF itself is not a permanent home. It’s a temporary, high-containment facility, with a nominal utilization period of only 2-5 years.

Once the samples are certified as safe, they will be transferred out of the BSL-4 fortress and moved to one or more long-term curation facilities. This is the model humanity has used for over 50 years with the Apollo lunar samples, which are primarily stored and curated at NASA’s Johnson Space Center.

These long-term facilities will be pristine cleanrooms, but without the extreme biocontainment, making them much easier and cheaper to operate. Here, the vast majority of the Mars collection will be carefully preserved, protected from Earth’s environment.

This is the ultimate payoff of Mars Sample Return. It is not a single, immediate answer, but the creation of a new, invaluable scientific resource. Like the Apollo rocks, the Mars samples will be studied for decades, if not centuries, to come. They will be held in trust, an archive of another world, allowing future generations of scientists, using instruments and techniques we cannot yet imagine, to continue to unlock the secrets of Mars and our place in the solar system.

Summary

The Mars Sample Return campaign stands at a pivotal, high-stakes juncture. It is a mission motivated by a scientific prize of unmatched value: a meticulously curated collection of pristine samples from another world, samples that hold the potential to reveal the history of a second genesis… or confirm its significant absence. NASA’s Perseverance rover, acting as a robotic field geologist, has already secured this prize. It has successfully drilled, collected, and cached an archive of rock, regolith, and atmosphere from the ancient lakebed of Jezero Crater, a location deemed most likely to have preserved the signs of past life.

But the plan to retrieve that priceless archive, a “Grand Architecture” of unprecedented complexity designed in partnership with the European Space Agency, collapsed under its own programmatic and financial weight. The original multi-mission, multi-launch “relay race” was a masterpiece of technological ambition, involving a chain of “first-ever” feats: a massive lander, robotic transfer arms, backup helicopters, a rocket launch from Mars, and an autonomous orbital rendezvous. A 2023 Independent Review Board exposed this plan as untenable, projecting a new cost of up to $11 billion and a return date delayed to 2040 – a price and timeline NASA’s own leadership declared “too expensive” and “unacceptably too long”.

This programmatic failure, which led to a painful pause and significant layoffs at NASA’s Jet Propulsion Laboratory, has forced a radical and historic pivot. In 2024, NASA turned to the commercial space industry, soliciting “fresh, exciting, and innovative ideas” to find a faster, cheaper, and more reliable path home. This “commercial pivot” has thrown open the doors to a new model of deep-space exploration, pitting aerospace giants like Lockheed Martin against new titans like SpaceX and Blue Origin. These companies have returned with competing philosophies: Lockheed Martin’s $3 billion firm-fixed-price offer leveraging flight-proven “heritage” hardware; SpaceX’s revolutionary (but unproven) concept of using a single Starship to do it all; and Blue Origin’s synergistic plan to leverage NASA’s own Artemis Moon program hardware.

The result of this review is NASA’s new 2025 “dual-track” strategy. It is a savvy “bake-off,” a head-to-head competition pitting NASA’s most reliable internal team, using the heritage Sky Crane lander, against the lower-cost, innovative designs of its new commercial partners. This new, streamlined plan has already adopted key commercial-driven lessons: a smaller, lighter Mars Ascent Vehicle and a shift from solar power to a more robust, nuclear-based Radioisotope Power System for the lander.

Immense, “first-ever” challenges remain. Any successful mission must still autonomously launch a rocket from the cold, thin atmosphere of Mars, flawlessly capture a small canister in deep-space orbit, and adhere to the iron-clad, non-negotiable rules of planetary protection. The “Break the Chain of Contact” strategy, a multi-layered biocontainment process from Mars orbit to a BSL-4 facility on Earth, remains the mission’s inflexible backbone, driving much of its design and complexity.

For the first time since the program’s inception, there is a competitive, commercially-infused, and more realistic path forward. If this new model succeeds, it will not only bring home the long-awaited secrets of Mars – a priceless archive to be studied by generations of scientists – it will fundamentally redefine how humanity reaches for, and returns from, other worlds.