In a previous post, I discussed the Mars Global Surveyor (MGS). It has returned vast amounts of data over the several years it has been orbiting Mars, but unfortunately seems to have finally stopped functioning. In that post, I mentioned that MGS had taken photographs of gullies that were thought to have been created by liquid water flowing on the surface—in some cases, the gullies seemed to have formed rather recently, but it was uncertain how recently the water may have flowed. The MGS team looked for evidence of change from previous photographs. In a press release today, they write
In June 2000, we reported the discovery, using the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC), of very youthful-appearing gullies found on slopes at middle and high latitudes on Mars. Many examples were presented in our captioned web releases and in a paper published in the journal, Science. Since that time, tens of thousands of gullies have been imaged by all of the Mars orbiting spacecraft: Mars Global Surveyor, Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter.