Good Acta Astronautica for March (vol. 228):
Ge, D. Shen, X. Liang, Z. et al. Efficient selection of asteroid landing sites using composite guidance vectors Page 121 .11.055
Yang, Y. Zhou, S. Yuan, S. et al. Optimization design and mechanism study of ion thruster performance based on C02/xenon multi-propellant Page 149 .12.008
Pallotta, N. A. Bazzocchi, M. C. F. Optimization of tethered artificial gravity assists for capture about binary asteroids in the circular restricted three-body problem Page 285 .11.009
Lopez, F. Conte, D. Interplanetary pit stops: Harnessing asteroids as solar filling stations for Earth-to-Mars missions Page 515 .12.009
Jakubczak, M. Riazantsev, A. Cichorek, O. et al. Design and performance of a 1 J ablative pulsed plasma thruster fed with non-volatile liquid propellant Page 813 .12.039
Landing site selection is a balancing act, between science pull and engineering push (away). Some of the more interesting sites are the more dangerous ones for a spacecraft. Here’s some engineering: more favorable landing sites, via GNC (Guidance, Navigation, and Control) per Ge et al.
Yang et al. and Jakubczak et al. take us through two candidates for efficient, robust mission ΔV (propulsion capability). We have had asteroid probes with ion thrusters; in fact, two are flying now. But they’re far from perfected and nominal; the experience with Hayabusa 1 showed that. Haya1 also had a rather complex system for its attitude (secondary) thrusters. PPTs (Pulsed Plasma Thrusters) are, in some implementations, the simplest thrusters one might guess. But they’re still at a rather early stage in their development; of the multiple propellant options, a ‘winner’ has not yet emerged.
One propellant of note is… no propellant at all. The tether people will have you believe tethers are the cure for all ills. Not literally, but for the special case of binary asteroids, there’s promise.
There’s promise to be had in more cases. Just like D. Adamo briefed us back at SBAG, asteroids hold promise for multiple reasons on the path to Mars. Adamo only quickly touched upon asteroids as resource reserves, no specifics. Here, Lopez et al. fill the gap: asteroids to fill one’s tanks.