A Summary of the Mars Sample Return (MSR) Concept
The analysis in Earth laboratories of samples that could be returned from Mars is of extremely high interest to the international Mars exploration community. IMEWG (the International Mars Exploration Working Group) has been evaluating options, by means of a working group referred to as iMOST, to refine the scientific objectives of MSR. The Mars 2020 sample-caching rover mission is the first component of the Mars Sample Return campaign, so its existence constitutes a critical opportunity. Finally, on April 26, 2018, NASA and ESA signed a Statement of Intent to work together to formulate, by the end of 2019, a joint plan for the retrieval missions that are essential to the completion of the MSR Campaign. All of these converged April 25-27, 2018 in Berlin, Germany, at the 2nd International Mars Sample Return Conference.
In April 2018, a letter of intent was signed by NASA and ESA that may provide a basis for a Mars sample-return mission.. In July 2019, a mission architecture was proposed to return samples to Earth by 2031.
[view large image]. See "Exploring Mars with Returned Samples".
In April 2020, an updated version of the mission was presented  (as described briefly in the followings) :
- Mars 2020 Perseverance Rover -
[view large image]
The Mars 2020 Perseverance rover launched on 30 July 2020 and landed on 18 February 2021 in Jezero Crater will collect samples and store them in 43 cylindrical tubes and leave them behind on the surface for later retrieval.
- Retrieval Lander -
Mars Sample Return lander, rover and ascent rocket, [view large image].
After a launch in July 2026, NASA's sample retrieval lander with a 3-meter long, two-stage, solid-fueled Mars ascent rocket developed by NASA and a sample collection fetch rover (developed by ESA). It will land near the Mars 2020 rover Octavia E. Butler Landing site in August 2028. The new rover collects the samples left behind by Mars 2020 by robotic arm and delivers them to the lander. If Mars 2020 is still operational, it could also deliver sample tubes to the landing site.
- Retrieval Operation -
Design of The Mars Sample Return Ascent Vehicle, [view large image].
Then the lander will use its robotic arm to take the sample tubes from the rover and load them into the sample Return Capsule which is inside the rocket's payload fairing by its own systems. Once loaded with the samples, the Mars ascent rocket will launch with the sample return canister in spring 2029, reaches a low Mars orbit.
- Earth-return Hardware -
Orbiter with sample return capsule, and EEV [view large image].
The Earth-return orbiter will be launched on an Ariane 6 rocket in October 2026 and arrives at Mars in 2027, using ion propulsion and a separate propulsion element to gradually lower its orbit to the proper low Martian orbit by July 2028. The orbiter will retrieve and seal the canister with the samples in orbit and use a NASA built orbiter robotic arm to place the sealed container into an Earth-entry capsule, raise its orbit, release the propulsion element and return it to Earth during the 2031 Mars-to-Earth transfer window.
Samples gathered by Perseverence -
Successful sampling attempts (10 September 2021), [view large image].
In February 2021 the 2020 Mars rover Perseverance was landed in the crater Jezero, which seemed to be an ancient lakebed, suitable for ground sampling which hopefully would reveal whether or not Mars in ancient times harbored life.
- In the beginning of August 2021, the 2020 Mars rover Perseverance made the first attempt to collect a ground sample by drilling out a finger-size core of Martian rock for return to Earth. This attempt did not succeed. A drill hole was produced, as indicated by instrument readings, and proven by a clear photograph of the drill hole. However, the sample container turned out to be empty. This was interpreted that the rock sampled was not robust enough to produce an intact core.
- A new attempt with a target rock judged to have better chances to yield a sufficiently robust sample was made at the end of August and the beginning of September 2021. After abrasing the target rock, cleaning away the dust thus produced by means of puffs of high pressurized nitrogen, and inspecting the resulting rock surface, a hole was drilled on September 1. The result seemed to be a rock sample in the tube; but it was not immediately placed in a sample container. A new procedure of inspecting the tube optically was performed. This procedure was introduced in order to avoid setbacks as with the earlier attempt. On September 6, the process was completed and the first sample placed in a closed titanium container.
- In support of the Mars sample-return mission, soil samples are being cached by Perseverance. Currently, out of 43 sample tubes, soil sample tubes cached: 2, gas sample tubes cached: 1, witness tubes cached: 1, tubes due to be cached: 39. 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.
Returned Samples Containment : MSR Mission (2021-2031), [view large image].
The absolute prohibition of destructive impact upon return, the need for containment throughout the return phase of all returned hardware which directly contacted the target body or unsterilized material from the body, and the need for containment of any unsterilized sample collected and returned to Earth. Post-mission, there is a need to conduct timely analyses of any unsterilized sample collected and returned to Earth, under strict containment, and using the most sensitive techniques. If any sign of the existence of a non-terrestrial replicating entity is found, the returned sample must remain contained unless treated by an effective sterilizing procedure.
See COSPAR by Kminek et al. 2017, COSPAR Planetary Protection Policy and a general idea of "Planetary Protection".
"The Relationship of Mars Sample Return Science and Containment"
Returned Samples Science :
"Planning for Mars Returned Sample Science : Final Report of the MSR End-to-End International Science Analysis Group (E2E-iSAG)".
Here's a tentative scale (proposed in 2021) to categorize the level of evidence for life beyond Earth.
See "Call for a framework for reporting evidence for life beyond Earth", and "The Peril".