The objective of this study was to help define how to maintain and further develop European access to the surface of Mars, the major destination for European exploration, following the most recent approved and developed (or currently in development) missions (ExoMars 2016, ExoMars RSP).

The focus of this study was the system-level assessment of potential small mission architectures that could operate at Mars in the 2030s, after or potentially in parallel with MSR mission.

In particular two cases were evaluated:

• Mission 1: Mars Communications Constellation (MCC), for supporting assets on the surface and providing science
• Mission 2: Mars Science Orbiter (MSO), a science-driven mission, remote sensing

A recent activity with GSTP Element 2 and Italy, has taken their most up-to-date and lowest cost solar cell and qualified it for use in space missions.

Achievements and status:

Iodine as a propellant is considered a valid alternative to xenon for electric propulsion application, in particular on Hall effect thrusters. Several advantages when using iodine as opposed to xenon can be enumerated. Iodine and xenon atomic mass and first ionization energy are very close and thruster performances, in terms of thrust density, thrust efficiency and specific impulse, have proved to be almost the same. Iodine is solid at ambient temperature and pressure, with a density about four times the density of xenon stored at 200 bar of pressure and ambient temperature.

Current single-frequency Satellite Based Augmentation Systems (SBAS) and planned dual-frequency multi-constellation (DFMC) SBAS systems enable approach operations with vertical guidance with time to alarm (TTA) of 6 seconds, but do not support auto land operations with decision height (DH) much less than 200 feet, and time to alarm down to 1-2 seconds . These critical TTA requirements cannot be met by having all integrity monitors centralized at the Ground Segment. Therefore, there is a need to distribute the integrity monitors amongst different Ground, Space and User Segments.

Predictive capability of thermo-elastic analyses for distortion (stability) and strength is not satisfactory, as shown by the recent examples of GAIA, Pleiades, Herschel, Planck, but also with the ongoing work for Bepi Colombo and Solar Orbiter, while the requirements for stability keep getting more challenging. The analytical models are usually not correlated by tests on ground wrt to thermo-elastic predictive capability, hence the performance verification is limited to analyses and unacceptable/unquantified levels of uncertainty remain.

Background and justification: