Mars sample-return mission

Mars meteorites in the Natural History Museum in Vienna

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.[5] Samples may be reanalyzed in the future by instruments that do not yet exist.[6]

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.[7]

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.[8] These meteorites are believed to be from Mars because their elemental and isotopic compositions are similar to rocks and atmospheric gases analyzed on Mars.[9]

Artist concept of a Mars sample-return mission, 1993

For at least three decades, scientists have advocated the return of geological samples from Mars.[10] 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.[11]

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.[12]

In the late 1980's, multiple NASA centers contributed to a proposed Mars Rover Sample Return mission (MRSR).[13][14] 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.[15] 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.[16]

The United States' Mars Exploration Program, formed after Mars Observer's failure in September 1993, supported a Mars sample return.[17] One architecture was proposed by Glenn J. MacPherson in the early 2000s.[18]

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.[19]

As of late 1999, the MSR mission was anticipated to be launched from Earth in 2003 and 2005.[20] 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,[21] was cancelled following a program review.[22]

In the summer of 2001, the Jet Propulsion Laboratory (JPL) requested mission concepts and proposals from industry-led teams (Boeing, Lockheed Martin, and TRW).[23] 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.[24] 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).[25] 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.[26] 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.[27] 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. [28]

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.[29] 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.[7]

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".[30][31] ExoMars's first mission was planned to launch in 2018 [6][32] with unspecified missions to return samples in the 2020–2022 time frame.[33] The cancellation of the caching rover MAX-C in 2011, and later NASA withdrawal from ExoMars, due to budget limitations, ended the mission.[34] The pull-out was described as "traumatic" for the science community.[34]

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.[35] In particular, it endorsed the proposed Mars Astrobiology Explorer-Cacher (MAX-C) mission in a "descoped" (less ambitious) form. This mission plan was officially cancelled in April 2011.

In September 2012, NASA announced its intention to further study several strategies of bringing a sample of Mars to Earth – including a multiple launch scenario, a single-launch scenario, and a multiple-rover scenario – for a mission beginning as early as 2018.[36][37] A "fetch rover" would retrieve the sample caches and deliver them to a Mars ascent vehicle (MAV). In July 2018, NASA contracted Airbus to produce a "fetch rover" concept.[38][39][40]

In April 2018, a letter of intent was signed by NASA and ESA that may provide a basis for a Mars sample-return mission.[41][42] In July 2019, a mission architecture was proposed.[43][44] In April 2020, an updated version of the mission was presented.[45]

A key mission requirement for the Mars 2020 Perseverance rover mission was that it help prepare for MSR.[46][47][37] The rover landed on 18 February 2021 in Jezero Crater to collect samples and store them in 43 cylindrical tubes for later retrieval.

Mars 2020 mission

Mapping Perseverance's samples collected to date

Facsimiles of Perseverance's sample tubes at JPL in Southern California

In support of the Mars sample-return mission, rock, regolith (Martian 'soil'), and atmosphere samples are being cached by Perseverance. Currently, out of 43 sample tubes, rock sample tubes cached: 14,[48] atmosphere sample tubes cached: 1,[49] witness tubes cached: 3,[50] tubes due to be cached: 25. Before launch, 5 of the 43 tubes were designated “witness tubes” and filled with materials that would capture particulates in the ambient environment of Mars.[51]

The Mars 2020 mission landed the Perseverance rover in Jezero crater in February 2021. It collected multiple samples and packed them into cylinders for later return. Jezero appears to be an ancient lakebed, suitable for ground sampling.[52][53][54]

In the beginning of August 2021, Perseverance made its first attempt to collect a ground sample by drilling out a finger-size core of Martian rock.[55] This attempt did not succeed. A drill hole was produced, as indicated by instrument readings, and documented by a photograph of the drill hole. However, the sample container turned out to be empty, indicating that the rock sampled was not robust enough to produce a solid core.[56]

A second target rock judged to have a better chance to yield a sufficiently robust sample was sampled at the end of August and the beginning of September 2021. After abrading the rock, cleaning away dust by puffs of pressurized nitrogen, and inspecting the resulting rock surface, a hole was drilled on September 1. A rock sample appeared to be in the tube, but it was not immediately placed in a container. A new procedure of inspecting the tube optically was performed.[57] On September 6, the process was completed and the first sample placed in a container.[58]

List of samples cached

Sample Details
Sampling Attempt	Date	Tube No.	Seal No.	Ferrule Prefix[note 1]	Ferrule No.	Contents	Sample Name and Image	Rock Name	Core Length[note 2]	Estimated Martian Atmosphere Headspace Gas[note 3]	Location	Notes
1	22 June 2021 (Sol 121)	SN061	SN147	10464848-7	SN090[59]	Witness Tube (Empty)	N/A	N/A	N/A	2.2 x 10−6 mol	North Séítah Unit[60]	This was taken as a dry-run in preparation for later sampling attempts, and did not aim to sample a rock. During final pre-launch activities, this witness tube was activated (the inner seal was punctured to begin accumulation) and placed in the Bit Carousel. This tube will therefore have accumulated contaminants for the entire duration of exposure from a few months before launch through cruise and EDL until it was sealed on the surface of Mars. Given its long exposure, it is likely that the inner surfaces of WB1 will be saturated with organic contaminants, i.e., they will be in adsorption equilibrium with theirimmediate surroundings in the rover (and or the entire spacecraft prior to landing). WB1 is therefore expected to have higher concentrations of contaminants, and potentially different contaminants, than the sample tubes.
2	6 August 2021 (Sol 165)	SN233	SN025	10464848-7	SN062	Atmospheric Gas	Roubion (failed attempt of caching rock sample)	Roubion 18.42767°N 77.45167°E / 18.42767; 77.45167	N/A	4.9x10−6 mol	Polygon Valley, Cratered Floor Fractured Rough Unit[61]	Attempted to sample the rock but did not succeed, as they didn't reach the bit carousel and the caching system stored and sealed an empty tube. However, in this process, it collected atmospheric samples.
3	6 September 2021 (Sol 195)	SN266	SN170	10464848-6	SN099[62]	Basalt (or possibly basaltic sandstone) Rock Sample	Montdenier	Rochette 18.43074°N 77.44433°E / 18.43074; 77.44433	5.98 cm (2.35 in)	1.2x10−6 mol	Arturby Ridge, Citadelle, South Séítah Unit	Successful sample.[63][64][65]
4	8 September 2021 (Sol 197)	SN267	SN170	10464848-6	SN074[66]		Montagnac		6.14 cm (2.42 in)	1.3x10−6 mol		Sampled from same rock as previous sample.
5	15 November 2021 (Sol 263)	SN246	SN194	10464848-5	SN107[67]	Olivine cumulate Rock Sample	Salette	Brac 18.43398°N 77.44305°E / 18.43398; 77.44305	6.28 cm (2.47 in)	1.1 x10−6 mol	Brac Outcrop, South Séítah Unit
6	24 November 2021 (Sol 272)	SN284	SN219	10464848-6	SN189[67]		Coulettes		3.30 cm (1.30 in)	2.5 x10−6 mol
7	22 December 2021 (Sol 299)	SN206	SN184	10464848-7	SN064		Robine	Issole 18.43264°N 77.44134°E / 18.43264; 77.44134	6.08 cm (2.39 in)	1.0 x10−6 mol	Issole, South Séítah Unit
8	29 December 2021 (Sol 307)	SN261	SN053	10464848-6	SN062		Pauls (Abandoned sample from this site due to Core Bit Dropoff.)		N/A	N/A		Pebble-sized debris from the first sample fell into the bit carousel during transfer of the coring bit, which blocked the successful caching of the sample.[68] It was decided to abandon this sample and do a second sampling attempt again. Subsequent tests and measures cleared remaining samples in tube and debris in caching system[69][70] The tube was reused for second sample attempt, which was successful.
9	31 January 2022 (Sol 338)						Malay		3.07 cm (1.21 in)	2.7 x10−6 mol
10	7 March 2022 (Sol 372)	SN262	SN172	10464848-6	SN129	Basaltic Andesite Rock Sample	Ha'ahóni (aka "Hahonih")	Sid 18.45242°N 77.44386°E / 18.45242; 77.44386	6.50 cm (2.56 in)	0.98 x10−6mol	Ch’ał outcrop(100 m (330 ft) east of Octavia E. Butler Landing), Séítah Unit
11	13 March 2022 (Sol 378)	SN202	SN168	no Cachecam images	SN074		Atsá (aka "Atsah")		6.00 cm (2.36 in)	1.3 x10−6 mol
12	7 July 2022 (Sol 491)		SN188	10464848-4	SN101	Sedimentary Rock Sample	Swift Run	Skinner Ridge 18.40617°N 77.45893°E / 18.40617; 77.45893	6.69 cm (2.63 in)		Skinner Ridge, Delta Front	First Deltaic and First sedimentary sample cached by Perseverance.
13	12 July 2022 (Sol 496)		SN192	10464848-6	SN068		Skyland		5.85 cm (2.30 in)
14	16 July 2022 (Sol 500)	SN205	SN110	10464848-6	SN170	Witness Tube (Empty)	N/A	N/A	N/A		Hogwallow Flats,[71] Delta Front	This maybe done to clean out any leftover debris during the previous sampling attempts.
15	27 July 2022 (Sol 510)	SN172		10464848-7	SN099	Sedimentary Rock Sample	Hazeltop	Wildcat Ridge 18.40589°N 77.45863°E / 18.40589; 77.45863	5.97 cm (2.35 in)		Wildcat Ridge, Delta Front
16	3 August 2022 (Sol 517)	SN259	SN177	10464848-5	SN110		Bearwallow		6.24 cm (2.46 in)
17	2 October 2022 (Sol 575)	SN264		10464848-5	SN085		Shuyak	Amalik outcrop 77.40144°N 18.45073°E / 77.40144; 18.45073	5.55 cm (2.19 in)		Amalik outcrop, Delta Front
18	6 October 2022 (Sol 579)	SN184					Mageik					There was some undisclosed problem in processing, sealing which was done again on 23 October 2022 (Sol 596) successfully.
19	14 October 2022 (Sol 586)	SN188	SN153	10464848-5	SN073	Witness Tube (Empty)	N/A		N/A	N/A
Sample Overview							Cached Samples
Samples Tubes Cached  (44%) 43 19												All Drilled Holes On Mars By Perseverance (except Atsá sample) (Scrollable image)
Sources:[72][73][74][75]

Mars Sample return mission logo

The NASA-ESA plan is to return samples using three missions: a sample collection mission (Perseverance), a sample retrieval mission (Sample Retrieval Lander + Mars ascent vehicle + Sample Transfer arm + 2 Ingenuity class helicopters), and a return mission (Earth Return Orbiter).[76][77][78] The mission hopes to resolve the question of whether Mars once harbored life.

Sample collection

The Mars 2020 mission landed the Perseverance rover, which is storing samples to be returned to Earth later. After consideration, it was decided that given Perseverance's expected longevity, it will be the primary means of transporting samples to Sample Retrieval Lander (SRL).

Mars 2020 Perseverance Rover

Sample retrieval

Mars Sample Return Program[79]
(Artwork; 27 July 2022)

The sample retrieval mission involves launching a sample return lander in 2028 with the Mars Ascent Vehicle and two Ingenuity class sample recovery helicopters, both of which will be collecting the samples with a tiny robotic arm as a backup for Perseverance. The rover and helicopters will transport the samples to the SRL lander. SRL's robotic arm will be used to extract the samples and load them into the Sample Return Capsule in the Ascent Vehicle.[76] It is planned to land near the Octavia E. Butler Landing site in 2029.

Mars Ascent Vehicle (MAV)

A mock-up of Mars Ascent Vehicle on display stand

VECTOR release sequence

MAV is a 3-meter long, two-stage, solid-fueled rocket that will deliver the collected samples from the surface of Mars to the Earth Return Orbiter. Early in 2022, Lockheed Martin was awarded a contract to partner with NASA's Marshall Space Flight Center in developing the MAV.[80] It is planned to be catapulted into the air just before it ignites, at a rate of 16 feet (5 meters) per second, to remove the odds of wrong liftoff like slipping or tilting of SRL under rocket's shear weight and exhaust at liftoff. This Vertically Ejected Controlled Tip-off Release (VECTOR) system adds a slight rotation during launch, pitching the rocket up and away from the surface.[81] MAV would enter a 380 km orbit.[82] It will remain stowed inside a cylinder on the SRL and will have a thermal protective coating. The rocket's first stage would be run by a single updated STAR-20 engine burning for 70 seconds, while the second stage would have a single updated STAR-15 engine burning for another 27 seconds. They would be separated by a coast phase, after which the sample container would be released in orbit. As of early 2022, the second stage is planned to be spin-stabilized to save weight in lieu of active guidance, while the Mars samples will result in an unknown payload mass distribution.[82]

MAV is scheduled to be launched in 2028 on board the SRL lander.[76]

Earth Entry Vehicle (EEV)

The Capture/Containment and Return System (CCRS) would stow the sample in the EEV. EEV would return to Earth and land passively, without a parachute. The desert sand at the Utah Test and Training Range and shock absorbing materials in the vehicle were planned to protect the samples from impact forces.[85][47][37] EEV is scheduled to land on Earth in 2033.[86]

Components of the Sample Return Landers

Interior design of MAV, First Extraterrestrial Staging Rocket

MAV exterior design

MAV flight plan

Mars Sample Return 2020-2033 Timeline

Artist's concept of Mars sample return orbiter

cross section of the Earth return orbiter

Earth Return Orbiter

capture and containment system

Whether life forms exist on Mars is unresolved. Thus, MSR could potentially transfer viable organisms to Earth, resulting in back contamination — the introduction of extraterrestrial organisms into Earth's biosphere. The scientific consensus is that the potential for large-scale effects, either through pathogenesis or ecological disruption, is small.[105][106][107][108][109] Returned samples would be treated as potentially biohazardous until scientists decide the samples are safe. The goal is that the probability of release of a Mars particle is less than one in a million.[106]

The proposed NASA Mars sample-return mission will not be approved by NASA until the National Environmental Policy Act (NEPA) process has been completed.[110] Furthermore, under the terms of Article VII of the Outer Space Treaty and other legal frameworks, were a release of organisms to occur, the releasing nation(s) would be liable for any resultant damages.[111]

The sample-return mission would be tasked with preventing contact between the Martian environment and the exterior of the sample containers.[106][110]

In order to eliminate the risk of parachute failure, the current plan is to use the thermal protection system to cushion the capsule upon impact (at terminal velocity). The sample container would be designed to withstand the force of impact.[110] To receive the returned samples, NASA proposed a custom Biosafety Level 4 containment facility, the Mars Sample-Return Receiving facility (MSRRF).[112][113]

Other scientists and engineers, notably Robert Zubrin of the Mars Society, argued in the Journal of Cosmology that contamination risk is functionally zero leaving little need to worry. They cite, among other things, lack of any known incident although trillions of kilograms of material have been exchanged between Mars and Earth via meteorite impacts.[114]

The International Committee Against Mars Sample Return (ICAMSR) is an advocacy group led by Barry DiGregorio, that campaigns against a Mars sample-return mission. While ICAMSR acknowledges a low probability for biohazards, it considers the proposed containment measures to be unsafe. ICAMSR advocates more in situ studies on Mars, and preliminary biohazard testing at the International Space Station before the samples are brought to Earth.[115][116] DiGregorio accepts the conspiracy theory of a NASA coverup regarding the discovery of microbial life by the 1976 Viking landers.[117][118] DiGregorio also supports a view that several pathogens – such as common viruses – originate in space and probably caused some mass extinctions and pandemics.[119][120] These claims connecting terrestrial disease and extraterrestrial pathogens have been rejected by the scientific community.[119]

• Potential sample-return landing site (14 April 2022)
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• 

Mars sample-return mission - Sampling Process

Context

MidView

CloseUp

Sample in drill

Sampling drill

Sample Tube 233

Mars sample-return mission – Sample Tubes

Exterior

Interior

CT Scan (animation)

Witness Sample Tube

Mars sample-return mission

Perseverance rover – Sample collection and storage
(animated video; 02:22; 6 February 2020)

Orbiting sample container (concept; 2020)

Inserting sample tubes into the rover

Cleaning sample tubes

Mars sample-return mission (2020; artist's impression)[121][122]

01. Perseverance rover obtaining samples

02. Perseverance rover storing samples

03. SRL 1 landing pattern

04. SRL unfolded

05. Mars Samples return helicopters deployed by SRL and fetching samples as a backup

06. SRL picking up samples and loading them on MAV for launch

07. Launching from Mars to low Martian Orbit

08. MAV in powered flight after release from vector

09. MAV in coast phase in Low Mars orbit after Main engine cutoff awaiting stage separation and second engine startup

10. Payload Separation thereby Releasing samples for later pickup by the Earth Return Orbiter

• Timeline of Solar System exploration

• Mars Sample return media reel produced by NASA and JPL (video)