Chang'e 7 loses this year's launch window; JWST maps ice on Callisto
China's space agency said Chang'e 7 cannot fly in this year's window; Space.com ties that to Tropical Depression Narra off Hainan. JWST spectra place water ice on Callisto's leading face and carbon dioxide on the trailing side.
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Chang'e 7 cannot fly in this year's window
China's space agency said Chang'e 7 no longer meets launch conditions and cannot fly in this year's planned window, in an announcement Xinhua carried on 23 August. The rocket and the probe had been rolled to the pad at Wenchang on 19 August. Liftoff was first pushed back a single day, to 24 August, before the agency dropped the window altogether. Space.com attributes the decision to Tropical Depression Narra, forming in the Gulf of Tonkin just west of Hainan, and notes that the flight also needs a particular alignment of Earth and the Moon, so it cannot simply resume once the skies clear. No new date has been set, and the Xinhua account points to 2027.[1]
The south pole ice hunt is waiting on the ground
Chang'e 7 pairs an orbiter with a lander that carries a rover and a hopping robot. The stack had been due to lift off from Wenchang on a Long March 5 rocket. The destination is permanently shadowed ground near the lunar south pole, most likely the rim of Shackleton crater, though no landing site has been announced, and the work there is to look for water ice.[1]
JWST puts ice on Callisto's leading face
Near-infrared spectra from the James Webb Space Telescope place water ice in the bright impact basins of Callisto's leading hemisphere and a bullseye pattern of plasma damage on the trailing side, with solid carbon dioxide concentrated opposite the ice. The study, led from Caltech, is accepted at The Planetary Science Journal. The NIRSpec instrument caught the 3.1 micrometre Fresnel peak that marks crystalline ice, strongest around Valhalla and Asgard and around the younger craters Lofn and Heimdall; Valhalla is the largest multi-ring impact structure in the solar system. A 4.25 micrometre band traced frozen carbon dioxide sitting at the centre of the trailing disk. An absorption feature at 4.57 micrometres points to carbon- and nitrogen-bearing compounds, reported as notably stronger on Callisto than on the other Galilean moons, and the telescope also picked up a very faint, patchy carbon dioxide atmosphere strongest near Valhalla. The authors write that the processes moving these volatiles around remain poorly understood; Europe's JUICE mission is scheduled to fly past at much higher resolution.[2]
