So they will land, take a sample, and re-turn to Earth with a spacecraft weighing less than 10kg? Just the engine, propellant and control system weighs a lot. Then they also need a re-entry capsule and parachutes. It would perhaps be possible to do this in several steps: On the first landing you leave the engine and control system. On the second landing you leave the propellant. The third landing brings the sample extract system and recovery system. Step four is to solve the assembly of everything. I would like to see to their calculations, they maybe have it all figured out.