New from Space Science Reviews (vol. 221):
Prettyman, T. H. Mittlefehldt, D. W. Asphaug, E. I. et al. The Psyche Light Elements Investigation art. 110 s11214-025-01240-z
A little into the weeds if you’re into instrument hardware. While many Space Sci Rev papers cover instruments (including Psyche instruments), this one’s more hard science, giving the rationale and requirements for those instruments.
We know of Earth’s core… indirectly. There is a lump of iron(-alloy) in the planet’s center; we know this from cosmochemical logic, seismic deduction and modeling, and magnetospheric observations. We also have iron meteorites in hand, and lesser observations of e. g., Mars. Unfortunately, logic and deduction and modeling do not close the causal loop, and the magnetospherics are indirect observations. Meteorites are diverse, not defining, and the Mars story is a ‘cliffhanger’ so far.
(16) Psyche, as a planet-scale metal ball, may be the missing piece- or will this story have a twist ending? Iron is kept fluid (“eutectic”) by solutes; what elements actually keep cores (partly or wholly) molten, and to what degree? Multiple Psyche instruments can contribute multiple lines of evidence, because of course they can- they were chosen to do so. This paper gives that choice.