What Caught the Editor’s Eye

[Richard Harrison, Space Research Today General Editor]

One research paper that really caught my eye in the last six months was that of Wynne et al. on “Planetary caves: A Solar System view of processes and products” (Journal of Geophysical Research Planets, 127, doi: 10.1029/2022JE0007303). In many ways it feeds a basic human desire to explore, and, as a non-planetary scientist, I read with interest, bordering on excitement, that the authors were providing the first Solar System-wide compendium of speliogenic processes and products. The statement that 3,545 ‘subsurface access points’ (SAPs), i.e. caves to most of us, have been identified on 11 planetary bodies was a striking result, and that does not include the Earth. In addition, they discuss the potential for such features on four other bodies. They report on an impressive 1,062 SAPs for Mars, 2,147 for Titan, 221 for the Moon, with others on Ceres, Enceladus, Europa, Triton, Pluto and Charon. They show maps of the Moon and Mars, with the Moon showing a fairly even spread of SAPs and Mars showing a major cluster of SAPs in the western hemisphere. As the authors note, with future missions, we will certainly find many more SAPs, and we can look forward to the robotic, even human exploration of caves, particularly on the Moon and Mars.

Nature Astronomy (2022, doi: 10.1038/s41550-022-01841-6) published a paper by Noguchi et al. entitled ‘A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu’. As with the previous paragraph, I have to say that as a solar physicist, these topics are way out of my area of expertise, but, as a lifelong back-garden astronomer, they fascinate me. Ryugu is a near-Earth asteroid (number 162173). It is a C-type asteroid, which means that it is composed of materials largely unchanged since the formation of the Solar System. As Noguchi et al. report, the JAXA Hayabusa2 spacecraft brought back samples for Ryugu for analysis in the laboratory. As they point out, with no protective atmosphere, exposed surfaces in space gradually undergo an alteration in composition, structure and optical properties through space weathering. Here was a chance to investigate this. They report on processes that the surface grains from Ryugu experienced, in particular, surface dehydration, but stress that this is not a bulk loss of water from the asteroid.

‘‘with no protective atmosphere, exposed surfaces in space gradually undergo an alteration in composition, structure and optical properties through space weathering’’

On a completely different topic, as someone from the UK, of course I was interested in the planned first launch of a spacecraft from British soil, in January of this year. The launch was due to take place from the new horizontal launch facility at the airport near Newquay in Cornwall, on the southwest coast of England. The payload of a number of cubesats was to be carried aboard a rocket carried under a Virgin Orbit Boeing 747; the rocket, called LauncherOne, was to be dropped by the carrier 747, subsequently igniting and travelling to orbit. The carrier aircraft flight and the first stage flight of LaucherOne were perfect, but problems late in the rocket flight meant that the spacecraft failed to reach orbit. So, whilst it was in fact the first launch into space from European soil, orbit was not achieved. The Virgin Orbit press release can be seen here.