Changes in the heavens, or new craters on the planet Mars

In recent years the planet Mars has been saturated with visiting spacecraft and a consequence of all this attention is that change in the martian landscape is becoming easier to spot. Mars Global Surveyor (MGS) was one of those machines; MGS was a NASA spacecraft operating in orbit about Mars from September 1997 to November 2006.

During early 2006 members of the MGS science team decided to look for signs of change:

"A year ago [2004/2005], it had not occurred to us, the MGS MOC science operations team, that we could find places on Mars where meteorites had impacted the surface during the course of the MGS mission. Such craters, if they were forming at all, would be a few meters to a few tens of meters across; much to small to notice (or so we thought) in our MOC wide angle camera coverage. But, on 9 January 2006, we began to realize that not only could we find such craters, we might also be able to characterize the present-day impact cratering rate on Mars. Surveying for fresh craters formed during the MGS mission would provide the first direct observation—for any body in the Solar System, including Earth and its Moon—of the present-day cratering rate, which in turn can help test models used all the time by members of the scientific community to estimate the age of features on planetary surfaces." (How we found the first of the fresh impact sites that formed during the Mars Global Surveyor Mission, MGS MOC Release No. MOC2-1611, 6 December 2006)

For me, aside from the excitement I feel about the science done and the thril of discovery, it shows that change occurs on places other than the Earth at time scales much less than the millions and billions of years we routinely hear of. In this case in a matter of months.

The image above (MOC2-1614-a) is of another fresh crater found by the MOC team on the slopes of the volcano Ulysses Patera in northern hemisphere of Mars, investigations determined that the impact occurred between 18 April 2003 and 7 February 2004. For further details follow this link.

A note on the sources used in this post: the image and information came from two sources, the database of Mars Orbiter Camera images at Malin Space Science Systems (the American corporation that built the camera that flew on the MGS) and from NASA's Planetary Photojournal. For convenience I given here a link to a number of pages at the Malin Space Sciences Systems web site, Present-Day Impact Cratering and Gully Activity on Mars MGS MOC Releases MOC2-1611 through MOC2-1622, 6 December 2006.

For those who want to read the actual science done here is the citation to the article from the journal Science (unfortunately the Science website only provides the abstract, i.e. summary, so check with your favourite library):

Present-day impact cratering rate and contemporary gully activity on Mars Michael C. Malin, Kenneth S. Edgett, Liliya V. Posiolova, Shawn M. McColley, Eldar Z. Noe Dobrea, Science 8 December, 2006, 314 (5085), p. 1573-1577.

Astronomical friends of mine will remember a less detailed version of this discussion and the image from an email of mine in December 2006, so this is old news for them.

Images: © NASA/JPL/Malin Space Science Systems, 2006