Choosing the place to collect the first samples of Mars that we will study on Earth

NASA's Mars 2020 rover promises to be a key mission for the study of Mars. Not only because this Curiosity twin will look for traces of the possible presence of life in the red planet's past, but also because it will collect surface samples that must be collected and brought to Earth by a later mission. That is why choosing the Mars 2020 landing site is so crucial, since the samples of this mission will be analyzed exhaustively during the next decades. The scientific community has selected three landing places. The favorite is the Jezero crater, followed by the northeast area of Syrtis Major and, ultimately, the Columbia Hills. The Columbia Hills were explored by the Spirit rover and have been selected for the presence of ancient hydrothermal vents, while Jezero and Syrtis Major present evidence that water ran down their surface for eons. But the interesting thing is that these last two areas are relatively close. So, already put to bring samples of an interesting place, why not bring them from several places?

Rover Mars 2020 (NASA).

Unfortunately, the landing areas of Jezero and Syrtis Major are 37 kilometers away from each other, a distance that is too great when it comes to designing a robust and safe exploration plan. But earlier this year NASA researchers and engineers identified a landing ellipse located halfway between Jezero and Syrtis Major that has been dubbed Midway for obvious reasons. The terrain of Midway is easy to cross by a rover and includes geological structures similar to those of Syrtis Major, an interesting area because it has very old sedimentary rocks. In addition, Midway is only 27 kilometers from the Jezero landing ellipse, which means that it is now feasible to plan a mission to explore the two zones.

Rover Mars 2020 and its instruments (NASA).

The problem is that the rover Mars 2020 has been designed for a primary mission of 15 kilometers and, although obviously it can last longer, there is no guarantee that it will succeed. To make matters worse, the region between Jezero and Midway is full of dune fields that will not be easy to cross. At the moment it has not been decided if the rover will descend in Jezero - the favorite place of the scientific community for its fossil river delta - and will go afterwards to Midway - a safer area to land - or it will be the other way around. In any case, if you choose the option of visiting Midway and Jezero, you should carefully plan the strategy to drop the samples. The current plan is for the rover to deposit them on the surface in a single zone at the end of its primary mission, which will last a little less than two and a half years (836 soles or Martian days). Samples collected throughout the extended mission are supposed to be deposited in the same area, which means that the rover has to return to the same place repeatedly.

The three candidate places and landing ellipses of the rover Mars 2020 (NASA).

Possible Jezero exploration route and on the way to Midway. On the right the landing ellipse (NASA).

This option is valid if the rover is limited to exploring the same area as Jezero, but if it visits the two stops is not possible. Not in vain, it is estimated that the rover will take 401 soles to travel the distance between Jezero and Midway. The further away or scattered the samples are, the more distance the future rover will have to travel from the sample collection mission, so simplifying the work of the Mars 2020 rover can result in complicating the work of the future rover. The rover Mars 2020 carries 42 tubes to store the samples, although five of them will be reserved in case it can not use the robot arm and will not be used for this purpose. The tubes, which will be filled with material excavated by the robot arm and will be hermetically sealed, have a length of 5 centimeters and a diameter of 1 centimeter, with a mass of 15 grams. Those in charge of the mission expected to use twenty tubes in the primary mission. One possibility is that he rover a few samples in Jezero and take the rest to Midway, where he would leave all the others. This way if something goes wrong on the way to Midway, the reserve samples of Jezero would become the priority (or vice versa if it finally lands in Midway and then moves to Jezero).

Plan to deposit the samples in one place (NASA).

Robot arm of the Mars 2020 rover and sample collection system (NASA).

Pipes for samples (NASA).

The decision on the landing site will be taken next year directly by NASA headquarters after the last scientific conference on the subject took place last week. The Mars 2020 rover, 1,050 kg, should take off in July 2020 and will carry the first helicopter that will fly through the skies of another planet. This small experimental vehicle will have a mass of 1.8 kg and dimensions of 1.1 x 0.25 x 0.02 meters. It will have two counterrotator helices with a diameter of 1.21 meters. The rover will "drop" the helicopter in a flat area and is expected to make about five flights of up to two minutes in an interval of one month.

The rover Mars 2020 will carry a small helicopter under the chassis (NASA).

The rover Mars 2020 carries multiple cameras to film the landing (NASA).

Sequence of EDL of Mars 2020 (NASA).

Stage sky crane of the rover Mars 2020 (NASA).

The mission of return of samples (MSR) has not been approved yet, but NASA and the European space agency (ESA) agreed on April 26 to carry it out jointly. According to the preliminary plan, in 2026 the first element of the MSR mission, the SRL probe (Sample Retrieval Lander). This NASA probe would be formed by a lander that would carry to the surface the European rover SFR (Sample Fetch Rover), responsible for collecting the samples left behind by the Mars 2020 rover. The SFR would pass the samples to a capsule (OS) located at the MAV rocket end (Mars Ascent Vehicle) of hybrid propulsion, built by NASA, using the robot arm STA (Sample Transfer Arm) of European manufacture. The MAV, of one stage, would be responsible for leaving the capsule with the samples in a stable orbit around Mars.

Schematic of the return mission of samples from NASA and ESA with the SRL and ERO probes (NASA).

MAV rocket hybrid propulsion to put the Martian samples in orbit (NASA).

European ERO Orbiter to bring Martian samples to Earth (Airbus / ESA).

The European rover SFR (ESA).

Thanks to European participation it would also be possible to launch in 2026 the second MSR mission probe, called ERO (Earth Return Orbiter). ERO, which would take off using an Ariane 6 launcher, would be a European probe that would capture the capsule with the samples in Martian orbit and bring them to Earth in 2029. Hopefully, before the Chinese mission of returning Martian samples achieves the same objective. With so much at stake, the associate administrator of NASA's Directorate of Scientific Missions, Thomas Zurbuchen, faces a complicated decision. Jezero, Midway or both?

References:

https://www.nature.com/articles/d41586-018-07064-y

The entrance Choosing the place to collect the first samples of Mars that we will study on Earth It was written in Eureka.

LINK OF THE ORIGINAL SOURCE NAUKAS DANIEL MARIN

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