Sample return

A sample return mission is a spacecraft mission with the goal of collecting and returning with tangible samples from an extraterrestrial location to Earth for analysis. Sample return missions may bring back merely atoms and molecules or a deposit of complex compounds such as loose material ("soil") and rocks. These samples may be obtained in a number of ways, including a collector array used for capturing particles of solar wind or cometary debris, soil and rock excavation, mining, and any other possible way for retrieving samples in the environment.

Relevance of samples from Solar System bodies

Up to the present, humanity has collected samples of six identified Solar System bodies as well as samples of the solar wind. These samples were acquired through three methods: The collection of samples of Earth itself, the collection of meteoroids that have fallen on Earth, and the collection of samples through sample return missions. Samples of Moon rock from Earth's Moon were collected both from meteorites and through unmanned and manned sample return missions. The comet Wild 2 and the asteroid 25143 Itokawa were visited by unmanned spacecraft which returned samples to Earth. Furthermore samples for three identified Solar System bodies were only collected by means other than sample return missions: These are samples from Earth itself, samples from Vesta in the form of HED meteorites and samples from Mars in the form of Martian meteorites.

Such samples available on Earth can then be analyzed in laboratories and enable us to further our understanding and knowledge as part of the discovery and exploration of the Solar System. Until now many important scientific discoveries about the Solar System were made remotely with telescopes, and some Solar System bodies were visited by orbiting or even landing spacecraft with instruments capable of some forms of remote sensing or even sample analysis. While such an investigation of our Solar System is technically easier than a sample return mission, the scientific tools available here on Earth to study such samples are far more advanced and diverse than what can currently be carried by spacecraft. Analysis of samples on Earth allows to follow up any findings with different tools, or even allows to use tools in the future that have yet to be developed – in contrast a spacecraft can carry only a limited set of analytic tools and these have to be chosen and built long before the spacecraft reaches its target.

The results of such sample analysis on Earth makes it then possible to match findings made be remote sensing and enables us to gain more insight into the processes that formed the Solar System. This was done for example with findings by the Dawn spacecraft which visited the asteroid Vesta from 2011 to 2012 for imaging, and samples from HED meteorites (collected on Earth until then) which were compared to data gathered by Dawn. These meteorites could then be identified as material ejected from the large impact crater Rheasilvia on Vesta. It was then through this that the composition of crust, mantle and core of Vesta was deducted. Similarly some differences in composition of asteroids (and to a lesser extent different compositions of comets) can be discerned by imaging alone. However to get a more precise inventory of the material present on these different bodies more samples will be collected in the future, to match the compositions of the samples returned by spacecraft with the data gathered through telescopes.

One further focus of such investigation – besides the basic composition and geologic history of the various Solar System bodies – is the presence of the building blocks of life on comets, asteroids, Mars or the moons of the gas giants. Several sample return missions to asteroids and comets are currently in the works. More samples from asteroids and comets will help answer the question if some of the building blocks of life formed in space and were carried to Earth in the form of meteorites. Another question under investigation is whether extraterrestrial life formed on other Solar System bodies like Mars or on the moons of the gas giants, and if life might even exist there today. The result of NASA's last "Decadal Survey" was to prioritize a Mars sample return mission, as Mars has a special importance: it is comparatively "nearby", might have harbored life in the past, and might even be able to sustain life today. Jupiter's moon Europa is another important focus in the search for life in our Solar System. However due to the distance and other constraints Europa might not be the target of a sample return mission in the foreseeable future.

Planetary Protection

A sample return from Mars or Europa or other location with possibility to harbour life is a Category V mission under COSPAR. No sample has yet been returned with alien life in it, so we have no past experience to guide us. In the most interesting case then a sample returned from these locations might contain such life. It's not known what the effects of that are likely to be on humans or the environment of the Earth.

It might be that it would have no effect due to the dominance of present life on Earth and because it would not be adapted to infect human or DNA based life. You can also argue the other way however, that in worst case, that we would not be adapted to be able to resist it, and that alien life would not be adapted to have no harmful effects (pathogens are most lethal when they first migrate to a new host).[1] Also some diseases can leap directly to an animal host, such as Legionnaire's disease, jumped straight to humans, previously a disease of amoeba.

For these reasons, Carl Sagan and Joshua Lederberg both argued that we should only do sample return missions classified as Category V missions, with extreme caution, and this has also been confirmed by later studies by the NRC and ESF.[1][2][3][4][5]

For more about this see Planetary protection.

Sample return missions

First missions

After two failed Soviet attempts to return lunar soil to Earth through unmanned robotic Luna missions in June and July 1969,[6] the manned US Apollo 11 mission in July 1969 achieved the first successful sample return from another Solar System body. It returned approximately 22 kilograms (49 lb) of Lunar surface material. This was followed by 34 kilograms (75 lb) of material from Apollo 12 and further 326 kilograms (719 lb) material from four more missions from the manned Apollo program.

Perhaps one of the most significant advances in sample return missions occurred in 1970 when the robotic Soviet mission known as Luna 16, successfully returned 101 grams (3.6 oz) of lunar soil. Likewise, Luna 20 returned 55 grams (1.9 oz) in 1974 and Luna 24 returned 170 grams (6.0 oz) in 1976. Although they recovered far less than the Apollo missions, they did this fully automatically.

In 1970, the Soviet Union planned for a 1975 first Martian sample return mission in the Mars 5NM project. This mission was planned to use a N1 superrocket, but as this rocket never flew successfully, the mission got updated to use a double launch with the smaller Proton rocket, and an assembly at a Salyut space station. This Mars 79 mission was planned for 1979, but got cancelled in 1977 and all hardware was ordered destroyed.[7]

New missions after a 20 year hiatus

After the last sample return mission by Luna 24 in 1976, twenty years passed before the Earth-Orbital Debris Collection (ODC) experiment collected extraterrestrial samples. The Experiment was deployed on the Mir space station for 18 months during 1996–1997 and used aerogel to capture particles from low-Earth orbit, consisting of interplanetary dust and man-made particles.

The next mission to return extraterrestrial samples was known as Genesis – it was able to return solar wind samples to Earth from beyond Earth orbit. Unfortunately, the Genesis capsule failed to open its parachute while re-entering the Earth's atmosphere, and it crash-landed in the Utah desert in 2004. There were fears of severe contamination or even total mission loss, but scientists have managed to save quite a bit of the samples—which were the first to be collected from beyond lunar orbit. Genesis used a collector array made of wafers of ultra-pure silicon, gold, sapphire, and diamond. Each different wafer was used to collect a different part of the solar wind.

Genesis was followed by NASA's Stardust spacecraft which returned comet samples to earth January 15, 2006. It safely passed by Comet Wild 2 and collected dust samples from the comet's coma while imaging the comet's nucleus. Stardust used a collector array made of low-density aerogel (99% of which is empty space) which has about 1/1000 of the density of glass. This permits the ability to collect the cometary particles without damaging them due to high impact velocities. Particle collisions with even slightly porous solid collectors would result in destruction of those particles and damage to the collection apparatus.

In June 2010 the Japan Aerospace Exploration Agency (JAXA) Hayabusa probe returned asteroid samples to Earth after a rendezvous with (and a landing on) S-type asteroid 25143 Itokawa. In November 2010 scientists at the agency confirmed that the probe successfully retrieved dust from the asteroid, the first ever brought back to Earth in pristine condition.[8]

The Russian Fobos-Grunt was a failed sample return mission that was supposed to return samples from Phobos, one of the moons of Mars. It was launched on November 8, 2011. However the probe failed to leave Earth orbit and crashed after some weeks into the southern Pacific Ocean.[9][10]

Planned missions

The Japan Aerospace Exploration Agency (JAXA) plans to launch around 2015 the improved Hayabusa 2 space probe and to return asteroid samples by 2020. Current target for the mission is the C-type asteroid (162173) 1999 JU3.

The OSIRIS-REx mission is scheduled to be launched in 2016 on a mission to return samples of from asteroid (101955) 1999 RQ36. The samples are expected to enable scientists to learn more about the time before the birth of our solar system, initial stages of planet formation, and the source of organic compounds which led to the formation of life.[11]

China is planning to conduct a Lunar sample return around 2017. If successful, it would make the first lunar sample return in over 40 years.

Future missions

There were plans to launch a Mars Sample Return (MSR) mission in 2004, but following the twin-failures of the Mars Climate Orbiter and Mars Polar Lander, MSR was cancelled. NASA has long planned a Martian sample return mission, but has yet to secure the budget to successfully design, build, launch, and land a probe that would do just that. There have been mission proposals in the past, but most have not made it far beyond the drawing boards. The mission remained on NASA's roadmap for planetary science as of the 2013 Planetary Science Decadal Survey.[12] A Mars sample return mission in collaboration with Europe (as part of the Aurora programme) was proposed launch around 2018. Due to budget cuts at NASA the future of this mission is uncertain. The ESA may attempt this mission alone, but no earlier than the mid-2020s.

Furthermore Russia has plans for Luna-Grunt mission to return samples from the Moon by 2021 and Mars-Grunt to return samples from Mars five to ten years later.

In addition OpenLuna is planning a first open source Boomerang-class lunar sample return mission.

In September 2012, NASA announced plans to further study several strategies of returning a sample of Mars to Earth - including a multiple launch scenario, a single launch scenario and a multiple rovers scenario - for a mission beginning as early as 2018.[13]

China has plans for a Mars sample return mission by 2030.[14][15]

Methods of sample return

Sample return methods include, but are not restricted to the following:

Collector array

A collector array may be used to collect millions or billions of atoms, molecules, and fine particulates by using a number of wafers made of different elements. The molecular structure of these wafers allows for the collection of various sizes of particles. Collector arrays, such as those flown on Genesis are ultra-pure in order to ensure maximum collection efficiency, durability, and analytical distinguishability.

Collector arrays are useful for collecting tiny, fast-moving atoms such as those expelled by the Sun through solar wind, but can also be used for collection of larger particles such as those found in the coma of a comet. The NASA spacecraft known as Stardust implemented this technique. However, due to the high speeds and size of the particles that make up the coma and the area nearby, a dense solid-state collector array was not viable. As a result, another means for collecting samples had to be designed as to preserve the safety of the spacecraft and the samples themselves.


Main article: Aerogel

Aerogel is a silicon-based, porous, solid with a sponge-like structure in which 99.8% of its volume is composed of empty space. Aerogel has about 1/1000 of the density of glass. An aerogel was implemented for use with the Stardust spacecraft because the collision of a particle smaller than the size of a grain of sand would have an impact velocity of about six times the speed of a rifle bullet, and hence a collision with a dense solid could alter its chemical composition, and perhaps vaporize it completely.

Since the aerogel is mostly transparent, it is extraordinarily easy for the scientists to find and retrieve the particles since they leave a carrot-shaped path once they penetrate the surface. Since its pores are on the nanometer scale, the particles do not merely pass through the aerogel completely. Instead, they slow to a stop and then are embedded within it.

The Stardust spacecraft has a tennis racket shaped collector with aerogel fitted to it. The collector is retracted into its capsule for safe-storage and delivery back to Earth. One thing that makes aerogel a good choice for missions such as Stardust is that it is quite strong and easily survives both launching and outer space environments.

Excavation and rocket return

Some of the most risky and difficult types of sample return missions are those that require landing on an extraterrestrial body such as an asteroid, moon, or planet. It takes a great deal of time, money, and technical ability in order to even initiate such plans. It is a difficult feat that requires that everything from launch to landing to retrieval and launch back to Earth be planned out with high precision and accuracy.

This type of sample return, although having the most risks, is the most rewarding for planetary science. Furthermore, such missions carry a great deal of public outreach potential, which is an important attribute for space exploration when it comes to publicity.

NASA is considering launching an international sample return mission of this type to Mars around the year 2018, depending on its budget. Previous attempts to launch this type of sample return mission have been scrubbed due to technical difficulty, budget constraints, and other factors such as recent mission failures (e.g.: Mars Climate Orbiter and Mars Polar Lander). The only successful robotic sample return missions of this type have been the former U.S.S.R. Luna landers.

List of sample return missions

Manned missions

Launch date Operator Name Sample origin Samples returned Return date Mission result
July 16, 1969 United States Apollo 11 The Moon 22 kilograms (49 lb) July 24, 1969 Success
November 14, 1969 United States Apollo 12 The Moon 34 kilograms (75 lb) November 24, 1969 Success
April 11, 1970 United States Apollo 13 The Moon None April 17, 1970 Failure
Did not land on the Moon
Astronauts returned safely
January 31, 1971 United States Apollo 14 The Moon 43 kilograms (95 lb) February 9, 1971 Success
July 26, 1971 United States Apollo 15 The Moon 77 kilograms (170 lb) August 7, 1971 Success
April 16, 1972 United States Apollo 16 The Moon 95 kilograms (209 lb) April 27, 1972 Success
December 7, 1972 United States Apollo 17 The Moon 111 kilograms (245 lb) December 19, 1972 Success
March 22, 1996 United States
Earth-Orbital Debris Collection (ODC)
(Onboard Mir)
Particles in
low-Earth orbit (LEO)
Natural and man-made
particles from LEO
October 6, 1997 Success[16]

Unmanned missions

Launch date Operator Name Sample origin Samples returned Recovery date Mission result
June 14, 1969 Soviet Union Luna E-8-5 No.402 The Moon None - Failure
Launch failure
July 13, 1969 Soviet Union Luna 15 The Moon None - Failure
Crash-landed on the Moon
23 September 1969 Soviet Union Cosmos 300 The Moon None - Failure
Failed to leave Earth orbit
22 October 1969 Soviet Union Cosmos 305 The Moon None - Failure
Failed to leave Earth orbit
6 February 1970[6] Soviet Union Luna E-8-5 No.405 The Moon None - Failure
Launch failure
September 12, 1970 Soviet Union Luna 16 The Moon 101 grams (3.6 oz)
of lunar rock
September 24, 1970 Success
September 2, 1971 Soviet Union Luna 18 The Moon None - Failure
Crash-landed on the Moon
February 14, 1972 Soviet Union Luna 20 The Moon 55 grams (1.9 oz)
of lunar rock
February 25, 1972 Success
November 2, 1974 Soviet Union Luna 23 The Moon None - Failure
Drilling device damaged on Moon landing
Mission abandoned
October 16, 1975 Soviet Union Luna E-8-5M No.412 The Moon None - Failure
Launch failure
August 9, 1976 Soviet Union Luna 24 The Moon 170 grams (6.0 oz)
of lunar rock
August 22, 1976 Success
1979 (planned)
(canceled 1977)
Soviet Union Mars 79 ("Mars 5M") Mars - - Canceled in 1977[17]
Planned to return 500 grams (18 oz)
February 7, 1999 United States Stardust 81P/Wild
(Comet coma)
Over 1 million
comet particles
January 15, 2006 Success
August 8, 2001 United States Genesis Solar wind Solar wind particles September 8, 2004 Partial success
Return capsule damaged after failed parachute deployment
Some usable samples recovered
May 9, 2003 Japan Hayabusa 25143 Itokawa
(Asteroid surface)
1,500 grains
of asteroid particles
June 13, 2010 Partial success
Planned to return several hundred milligrams
November 8, 2011 Russia Fobos-Grunt Phobos
(Mars satellite soil)
None - Failure
Failed to leave Earth orbit
Crashed into the southern Pacific Ocean
Returned none of the 200 grams (7.1 oz) planned
July 2014
(planned, earliest)
Japan Hayabusa 2 Planned for
(162173) 1999 JU3
(Asteroid surface)
- 2020 (planned)
United States OSIRIS-REx Planned for
1999 RQ36
(Asteroid regolith)
- 2023 (planned) Planned to return between 60 g to 2 kg (2.1 oz to 4.4 lb)
China Chang'e 5 The Moon - 2017 (planned) Planned to return at least 2 kilograms (4.4 lb)
Not the esa flag.png MarcoPolo-R Near-Earth object
(Asteroid surface)
- To be determined To return samples from a yet to be determined near-Earth object
Russia Luna-Grunt The Moon - 2021 (planned) Planned to return up to 1 kilogram (2.2 lb)
Not the esa flag.png
United States
Mars - To be determined To be determined
Russia Mars-Grunt Mars - To be determined Intended to return about 200 grams (7.1 oz)
By 2030 China Chinese Mars sample return mission Mars - To be determined To be determined
To be determined United States
OpenLuna The Moon - To be determined Intended to return about 200 kilograms (440 lb)

See also


External links

  • Jet Propulsion Laboratory Mars Exploration Program on sample return missions.
  • Jet Propulsion Laboratory Stardust mission website.
  • Jet Propulsion Laboratory Genesis mission website.
  • Stardust website on aerogel technology.
  • JAXA Hayabusa project update.
  • on Mars Sample Return missions.
  • A list of missions to the Moon from 1958 to 1998.
  • Evaluating the Biological Potential in Samples Returned from Planetary Satellites and Small Solar System Bodies The National Academies, Space Science Board 1998
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