In Acta Astronautica for July (vol. 232):
Kuppa, K. McMahon, J. W. Dietrich, A. B. Autonomous shape modeling of small bodies using infrared image silhouettes P. 215 .2025.03.005
Iwakawa, A. Mizojiri, S. Hall-effect thruster system of fully water propellant with microwave discharge cathode P. 307 .2025.03.023
Pai, A. Kawase, M. Nishida, M. et al. 3D numerical and experimental investigation of hypervelocity impacts on dual bumper plate Whipple shields for spacecraft protection P. 374 .2025.03.012
Gondol, N. Shirasu, K. Yoshida, H. et al. Design, performance, and preliminary erosion evaluation of a 50W-200W water-fueled Hall thruster with permanent magnets P. 693 .2025.03.042
Asteroids are (generally) nonspherical. This is a relic of their formation and history; in turn, shape knowledge is necessary for serious orbiters, and landers. Kuppa et al. try extending our grasp of asteroid morphologies, turning to the infrared. Resolution is worse, but it’s still complementary to the visible.
And how would those orbiters/landers get to an asteroid or other small body? Work on electric propulsion continues. EP is transformative, since specific impulse (Isp) is not merely incrementally higher than chemical propulsion, but a leap forward. For the top categories of EP, the Isp can rise by an order of magnitude… which has a similar effect on overall acceleration capability, or similar reduction in propellant requirement (which largely sets launch cost). Many electric ‘fuels’ are also nontoxic, with benign handling properties, which may further enable cost and risk reductions. Iwaka et al. and Gondol et al. are working the wide (and growing) variety of EP technologies.
“Other small body” refers to comets, as well as astero-comets (transition objects). In Bennu’s case, the activity was not really threatening to orbiter spacecraft, since ejection speeds were mild. For fast flyby spacecraft, such as all comet missions except Rosetta, the spacecraft itself is traveling at risky speeds relative to the comet. Spacecraft shielding becomes a mission requirement, as Pai et al. write.