Mars, Mercury and NEOs

1 Oct 2011

The Messenger spacecraft orbiting Mercury has provided a raft of information - see www.physorg.com/print236595592.html - from flood volcanism,  crater like depressions, measurements of chemical composition, and lastly, observations of its magnetic field. A series of papers based on Messenger data have been published in Science, Sept 30th 2011.

Meanwhile, NASAs WISE mission is said to have found fewer than expected asteroids on a Near Earth orbit - in the mid-size range (see www.physorg.com/print236525341.html and www.jpl.nasa.gov/news/news.cfm?release=2011-304&cid=release_2011-304 ). Pausing for a moment, this is not fewer smaller NEOs or fewer very large asteroids but is referring to objects over 100m in size (but less than 1km). However, it is an estimate and most of them remain to be actually discovered. Objects larger than 1km are mostly known about - it is thought. In addition, there are a million smaller NEOs (smaller than a 100m across) and these are apparently invisible as yet - in the main (see also www.nasa.gov/wise ).

Moving to Mars and the discovery of new information - see www.physorg.com/print236529838.html - by the European ESA Mars Express spacecraft. The data comes from an onboard spectrometer and provided evidence that Mars atmosphere is saturated with water vapour. Previous models or computer simulations of the atmosphere of Mars are therefore redundant - just like that. A rethink is in progress.