At the last meeting of the MEPAG, an international working group charged with defining the Mars Exploration Strategy, NASA and ESA reaffirmed their support for this necessary mission and confirmed the timetable decided a few years ago which foresees a return to Earth of Martian samples in 2031. In order to meet this objective, NASA and ESA need an official go-ahead by the end of 2019 in order to start the initial phases of the development of the various elements of the mission.
Although neither NASA nor the European Space Agency has officially approved a Mars Return Mission (MSR), both time-constrained space agencies are taking steps to start their projects.
The main reason is that NASA’s March 2020 rover will be on time. The second is that because before sending humans to Mars (as NASA plans to do by 2033) it will be necessary to have a fairly precise idea of the toxicity of Martian dust – we know it would be an irritant and a mechanical oxidizer but also a chemical poison. But there is also a third constraint.
Due to the orbits of Mars and Earth, launch opportunities only open every 24 to 26 months. Opportunities that materialize by shooting windows making the trip to Mars shorter and easier than in another period. But since the orbits of the two planets are not perfectly circular or situated in the same plane, these windows are not identical, so that the durations of the journey differ. There is a compromise to be found with the quantities of propellants to take away, which influences the mass of the probe, therefore the power of the launcher to use, and therefore the cost of the mission.
In the case of the MSR mission, the firing windows of 2026 and 2028 are much more favorable than the following ones which do not allow an MSR mission at an acceptable cost. In the summer of 2026, NASA will launch the lander on which the MAV and fetch rover will be installed. The fall of 2026 will see the launch of ESA ‘s satellite capture and return satellite. If the ESA orbiter joins Mars in one year, the NASA lander will take two years to reach the Red Planet.