Mars sample return mission

A Mars sample-return (MSR) mission is a proposed mission to collect rock and dust samples on Mars and return them to Earth. Such a mission would allow more extensive analysis than that allowed by onboard sensors.

The three most recent concepts are a NASA–ESA proposal, a CNSA proposal, Tianwen-3, and a Roscosmos proposal, Mars-Grunt. Although NASA and ESA's plans to return the samples to Earth are still in the design stage as of 2022, samples have been gathered on Mars by the ''Perseverance'' rover.

Risks of cross-contamination of the Earth biosphere from returned Martian samples have been raised, though the risk of this occurring is considered to be extremely low.

Scientific value

Once returned to Earth, stored samples can be studied with the most sophisticated science instruments available. Thomas Zurbuchen, associate administrator for science at NASA Headquarters in Washington, expect such studies to allow several new discoveries at many fields. Samples may be reanalyzed in the future by instruments that do not yet exist.Mars Sample-Return
NASA Accessed 2008-05-26

In 2006, the Mars Exploration Program Analysis Group identified 55 important investigations related to Mars exploration. In 2008, they concluded that about half of the investigations "could be addressed to one degree or another by MSR", making MSR "the single mission that would make the most progress towards the entire list" of investigations. Moreover, it was reported that a significant fraction of the investigations could not be meaningfully advanced without returned samples.

One source of Mars samples is what are thought to be Martian meteorites, which are rocks ejected from Mars that made their way to Earth. As of April 2019, 266 meteorites had been identified as Martian, out of over 61,000 known meteorites. These meteorites are believed to be from Mars because their elemental and isotopic compositions are similar to rocks and atmospheric gases analyzed on Mars.

History

For at least three decades, scientists have advocated the return of geological samples from Mars. One early concept was the Sample Collection for Investigation of Mars (SCIM) proposal, which involved sending a spacecraft in a grazing pass through Mars's upper atmosphere to collect dust and air samples without landing or orbiting.

The Soviet Union considered a Mars sample-return mission, Mars 5NM, in 1975 but it was cancelled due to the repeated failures of the N1 rocket that would have launched it. Another sample-return mission, Mars 5M (Mars-79), planned for 1979, was cancelled due to complexity and technical problems.

In the late 1980s, multiple NASA centers contributed to a proposed Mars Rover Sample Return mission (MRSR). As described by JPL authors, one option for MRSR relied on a single launch of a 12-ton package including a Mars orbiter and Earth return vehicle, a 700-kg rover, and a 2.7-ton Mars ascent vehicle which would use pump-fed liquid propulsion for a significant mass saving. A 20-kg sample package on the MAV was to contain 5 kg of Mars soil. A Johnson Space Center author subsequently referred to a launch from Earth in 1998 with a MAV mass in the range 1400 to 1500 kg including a pump-fed first stage and a pressure-fed second stage.

The United States' Mars Exploration Program, formed after ''Mars Observer'' failure in September 1993, supported a Mars sample return. One architecture was proposed by Glenn J. MacPherson in the early 2000s.

In 1996, the possibility of life on Mars was raised when apparent microfossils were thought to have been found in Mars meteorite, ALH84001. This hypothesis was eventually rejected, but led to a renewed interest in a Mars sample return.

As of late 1999, the MSR mission was anticipated to be launched from Earth in 2003 and 2005. Each was to deliver a rover and a Mars ascent vehicle, and a French supplied Mars orbiter with Earth return capability was to be included in 2005. Sample containers orbited by both MAVs were to reach Earth in 2008. This mission concept, considered by NASA's Mars Exploration Program to return samples by 2008, was cancelled following a program review.

In the summer of 2001, the Jet Propulsion Laboratory (JPL) requested mission concepts and proposals from industry-led teams (Boeing, Lockheed Martin, and TRW). The science requirements included at least 500 grams of samples, rover mobility to obtain samples at least 1 kilometer from the landing spot, and drilling to obtain one sample from a depth of 2 meters. That following winter, JPL made similar requests of certain university aerospace engineering departments (MIT and the University of Michigan).

Also in 2001, a separate set of industry studies was done for the Mars ascent vehicle (MAV) due to the uniqueness and key role of the MAV for MSR. Figure 11 in this reference summarized the need for MAV flight testing at a high altitude over Earth, based on Lockheed Martin's analysis that the risk of mission failure is "extremely high" if launch vehicle components are only tested separately.

In 2003, JPL reported that the mission concepts from 2001 had been deemed too costly, which led to the study of a more affordable plan accepted by two groups of scientists, a new MSR Science Steering Group and the Mars Exploration Program Analysis Group (MEPAG). Instead of a rover and deep drilling, a scoop on the lander would dig 20 centimeters deep and place multiple samples together into one container. After five years of technology development, the MAV would be flight-tested twice above Earth before the mission PDR (Preliminary Design Review) in 2009.

In 2004, JPL published an update on the 2003 plan. MSR would use the new large skycrane landing system in development for the Mars Science Laboratory mission (later named Curiosity). A MSR Technology Board was formed, and it was noted that the use of a rover might return to the MSR plan, in light of success with the Spirit and Opportunity rovers that arrived early in 2004. A 285-kg ascent rocket would carry 0.5 kg of samples inside a 5-kg payload, the Orbiting Sample (OS). The MAV would transmit enough telemetry to reconstruct events in case of failure on the way up to Mars orbit.

As of 2005, a rover had returned to the MSR plan, with a rock core drill in light of results from the Mars Exploration Rover discoveries. Focused technology development would start before the end of 2005 for mission PDR in 2009, followed by launch from Earth in 2013. Related technologies in development included potential advances for Mars arrival (navigation and descent propulsion) and implementing pump-fed liquid launch vehicle technology on a scale small enough for a MAV.

In late 2005, a peer-reviewed analysis showed that ascent trajectories to Mars orbit would differ depending on liquid versus solid propulsion, largely because small solid rocket motors burn faster, requiring a steeper ascent path to avoid excess atmospheric drag, while slower burning liquid propulsion might take advantage of more efficient paths to orbit.

Early in 2006, the Marshall Space Flight Center noted the possibility that a science rover would cache the samples on Mars, then subsequently a mini-rover would be sent along with the MAV on a sample return lander, in which case either the mini-rover or the science rover would deliver the samples to the lander for loading onto the MAV. A two-stage 250-kg solid propellant MAV would be gas ejected from a launch tube with its 5-kg payload, a 16-cm diameter spherical package containing the samples. The second stage would send telemetry and its steering thrusters would use hydrazine fuel with additives. The authors expected the MAV to need multiple flight tests at a high altitude over Earth.

In mid-2006, the International Mars Architecture for the Return of Samples (iMARS) Working Group was chartered by the International Mars Exploration Working Group (IMEWG) to outline the scientific and engineering requirements of an internationally sponsored and executed Mars sample-return mission in the 2018–2023 time frame.

In 2007 Alan Stern, then NASA's Associate Administrator for Science, was strongly in favor of completing MSR sooner, and he asked JPL to include sample caching on the Mars Science Laboratory mission (later named Curiosity). A team at the Ames Research Center was designing a hockey puck-sized sample-caching device to be installed as an extra payload on MSL.

Early in 2009, the In-Space Propulsion Technology project office at the NASA Glenn Research Center (GRC) presented a ranking of six MAV options, concluding that a 285-kg two-stage solid rocket with continuous telemetry would be best for delivering a 5-kg sample package to Mars orbit. A single-stage pump-fed bipropellant MAV was noted to be less heavy and was ranked second.

Later in 2009, the Chief Technologist of the Mars Exploration Directorate at JPL referred to a 2008 workshop on MSR technologies at the Lunar and Planetary Institute, and wrote that particularly difficult technology challenges included the MAV, sample acquisition and handling, and back planetary protection, then further commented that "The MAV, in particular, stands out as the system with highest development risk, pointing to the need for an early start" leading to flight testing before preliminary design review (PDR) of the lander that would deliver the MAV.

In October 2009, NASA and ESA established the Mars Exploration Joint Initiative to proceed with the ExoMars program, whose ultimate aim is "the return of samples from Mars in the 2020s". ExoMars's first mission was planned to launch in 2018 with unspecified missions to return samples in the 2020–2022 time frame. The cancellation of the caching rover MAX-C in 2011, and later NASA withdrawal from ExoMars, due to budget limitations, ended the mission. The pull-out was described as "traumatic" for the science community.

In early 2011, the US National Research Council's Planetary Science Decadal Survey, which laid out mission planning priorities for the period 2013–2022, declared an MSR campaign its highest priority Flagship Mission for that period. In particular, it endorsed the proposed Mars Astrobiology Explorer-Cacher

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