After the discovery of water on the Moon, scientists have picked a new target for the planned October 9 crash of a NASA spacecraft into a crater near the Moon’s south pole, in the hopes of gathering water ice.
Earlier, the Lunar Crater Remote Observation and Sensing Satellite (LCROSS) was going to target Cabeus A, a crater half as wide that sits further from the South Pole.
Now, according to a report in Nature News, LCROSS will now plough into Cabeus, a 100-kilometre-wide crater, in the hopes of kicking up some ice along with the rock and dust of the lunar soil.
Cabeus A presented favourable viewing angles for the many telescopes on Earth that will be trained on the impact site.
But, instruments aboard the Lunar Reconnaissance Orbiter, launched with LCROSS on June 18, have been offering up startling evidence: not only that water could be locked in a deep freeze within permanently shadowed polar craters, but also that there are significant differences between the craters.
In particular, a neutron-counting instrument has shown a significant excess of hydrogen a possible indicator of ice within Cabeus.
“The Cabeus region seems to be one of the places that could be the wettest, so we’d like to go there,” said Jennifer Heldmann, the LCROSS observation campaign coordinator at NASA’s Ames Research Center in Moffett Field, California.
Cabeus is deeper than Cabeus A, so the impact plume will have to rise higher to be seen from Earth.
But, according to Heldmann, this drawback is mitigated by a deep cleft in the rim wall of Cabeus, which will make viewing lower parts of the plume not as difficult as it could be.
The LCROSS team told astronomers of the new target on September 25.
Nancy Chanover, an astronomer at New Mexico State University in Las Cruces, said that the adjustment shouldn’t be too difficult.
“It’s not a big burden,” said Chanover, who is leading an effort to deduce the composition of the plume through an analysis of its ballistics.
Twenty professional observatories, including the Hubble Space Telescope, will be watching the event, and hundreds of amateur astronomers are expected to add their data to the mix.
But LCROSS itself, which has two components, will have the closest view.