With solar system exploration progressing at pace, some scientists are considering missions to often overlooked worlds. One of these is Ceres, the smallest known dwarf planet which lies within the asteroid belt. Investigations have shown that it is an excellent target for exploration and may even have astrobiological significance.

Joel Poncy is in charge of interplanetary advanced projects within the Observation and Science Directorate of Thales Alenia Space, a European company that works on satellite systems and other orbital infrastructures.

This organization has been involved in many scientific missions, including the Huygens probe, CoRoT, ExoMars, Mars Express and Venus Express. Poncy and his team, in association with Olivier Grasset and Gabriel Tobie from LPG-Nantes, now have turned their eyes to Ceres.

Preliminary plans for a Ceres Polar Lander are currently being drawn up. The idea is to build a low-cost mission using reliable existing technology to complement other larger missions, while benefiting from NASA's Dawn mission results.

Assuming launch by a Soyuz rocket, the spacecraft would take around four years to reach Ceres. It would then enter orbit before attempting a landing.

Poncy elaborates, "the lander would separate from the carrier, brake, land close to the target site while automatically avoiding boulders and permanent shadows. We would then operate a Phoenix-like analysis of the surrounding soil and release a mini-rover to explore further. Astrobiological experiments similar to ExoMars can be envisaged."

Maximizing existing technology
Landing an automatic vehicle on Ceres will require some impressive technology, but this is already in development as part of other projects. Says Poncy, "techniques are being developed for robotic missions to the South Pole of the Moon, such as ESA's MoonNext, for which Thales Alenia Space has been awarded one of the study contracts."

A Ceres Polar Lander would provide a golden opportunity to transfer at low cost these lunar and martian technologies for lander, rover and instruments to icy moon-like conditions, thanks to comparable orders of magnitude for gravity and temperatures at Ceres' poles.

The Ceres poles were considered as the best landing site because interesting material - perhaps including ice - could be present and easily accessible at the surface. The cold temperature will also more accurately mirror those found on icy moons.

The ultimate design of a Ceres Lander could then be further adapted to suit later missions that explore more distant regions of our solar system, such as the icy moons Enceladus and Europa.

Poncy suggests that a Ceres Polar Lander could prepare in parallel the next step beyond the upcoming Europa Jupiter System Mission and Titan Saturn System Mission.

He explains, "these two missions to Jupiter and Saturn are major achievements to come for mankind and we fully support them. From 2027 to about 2035, they should make fantastic discoveries from orbit and on Titan's surface that will call for landers on Europa, Ganymede or Enceladus to arrive soon afterwards.

We should be ready for that, and not plan on landing in 2060! This is too what motivates us, combined with the opportunity to find something major at Ceres."

Potential for alien life
This "major" discovery could be the Holy Grail for astrobiologists: alien organisms. Poncy explains, "with current knowledge, Ceres should have life's main ingredients: organics and a significant fraction of H2O. The question mark is energy."

Astrobiologists believe that life needs a source of energy, and it is a mystery whether this energy is available on Ceres. One possible way Ceres might provide the necessary energy is through a geological process where rocks oxidize and produce heat. Sunlight reaching the surface and radioactive decay are also options.

Poncy admits, "although the probability of life on Ceres is lower than on Europa and Enceladus, which are favored by their tidal energy, or on Titan, which has huge quantities of organics, it should not be neglected."

If life does exist on Ceres, what would it be like? Poncy muses, "nobody can reasonably expect more than microbial life. A mission there could basically search for water/carbon-based 'life-as-we-know-it'. For more exotic forms, some have floated the idea of clay-based life on Earth as precursor of 'our' life, and there seems to be a lot of clay on Ceres."