NASA | JPL-Caltech | MRO | 2016 May 25
[img3="Signs of a Martian Ice Age - Credit: NASA/JPL-Caltech/Sapienza Univ of RomeScientists using radar data from NASA's Mars Reconnaissance Orbiter (MRO) have found a record of the most recent Martian ice age recorded in the planet's north polar ice cap.
By analyzing radar images like the one at top, scientists discovered evidence for a past ice age in the northern polar ice cap of Mars. A blue line across the Viking map indicates the ground track of the radar cross section. "]http://photojournal.jpl.nasa.gov/jpeg/PIA20029.jpg[/img3][hr][/hr]
The new results agree with previous models that indicate a glacial period ended about 400,000 years ago, as well as predictions about how much ice would have been accumulated at the poles since then.
The results, published in the May 27 issue of the journal Science, help refine models of the Red Planet's past and future climate by allowing scientists to determine how ice moves between the poles and mid-latitudes, and in what volumes.
Mars has bright polar caps of ice that are easily visible from telescopes on Earth. A seasonal cover of carbon-dioxide ice and snow is observed to advance and retreat over the poles during the Martian year. During summertime in the planet's north, the remaining northern polar cap is all water ice; the southern cap is water ice as well, but remains covered by a relatively thin layer of carbon dioxide ice even in southern summertime.
But Mars also undergoes variations in its tilt and the shape of its orbit over hundreds of thousands of years. These changes cause substantial shifts in the planet's climate, including ice ages. Earth has similar, but less variable, phases called Milankovitch cycles.
Scientists use data from MRO's Shallow Subsurface Radar (SHARAD) to produce images called radargrams that are like vertical slices though the layers of ice and dust that comprise the Martian polar ice deposits. For the new study, researchers analyzed hundreds of such images to look for variations in the layer properties.
The researchers identified a boundary in the ice that extends across the entire north polar cap. Above the boundary, the layers accumulated very quickly and uniformly, compared with the layers below them. ...
SwRI Scientists Discover Evidence of Ice Age at Martian North Pole
Southwest Research Institute | 2016 May 25
An Ice Age Recorded in the Polar Deposits of Mars - Isaac Smith et al
- Science 352(6289):1075 (27 May 2016) DOI: 10.1126/science.aad6968
