The MASCOT lander on Hayabusa 2 seems to be powered by batteries only, I couldn't find any reference to solar panels or an RTG. What is its expected lifetime on the asteroid?
The expected lifetime of MASCOT is sufficient to operate during two asteroid days, mainly limited by the energy stored in the battery and to some degree dependent on the actual thermal conditions met at the landing sites.
Ryugu's rotational period is around ~7.5 hours, giving MASCOT only ~15 hours operational life.
A total of ~128 Wh of energy is supplied by a battery:
The recommended solution then is a primary battery pack with ~160 Wh for 0.8 kg consisting of 6 cells SAFT LSH20. A degradation of 15% during 5 years (one year before launch until MASCOT operations) has been considered.
This 160 Wh energy budget accounts for:
- ~85 Wh for surface operations
- ~5 Wh for descent
- 20% margin for converter losses
- further 20% overall safety margin
- 15% degradation margin