|
|
The Planetary Society Blog
By Emily Lakdawalla
Newly released archive of Mars Express HRSC data
May. 3, 2006 | 17:48 EDT | 21:48 UTC
Last month, a big chunk of data from the Mars Express mission was released to ESA's Planetary Science Archive -- this is the ESA equivalent of NASA's Planetary Data System, the public repository of archived data from planetary missions, free for the investigation by the curious. I haven't had the time to figure out how best to use the Planetary Science Archive, but fortunately I have friends who can show me how to do it! Doug Ellison obligingly provided me with a couple of delightful examples of images from this latest release.
Apparently this crop of data is notable because it is "map projected." This is particularly important for Mars Express because the spacecraft has quite an elliptical orbit; as a result, as it captures a long, skinny image strip, its distance from the planet changes, which introduces geometric distortions.
So without further ado, this is a strip acquired by Mars Express across Mars' permanent north polar cap. The actual spot of the north pole is just a tad off the left edge of the image; the arcuate depressions in the north polar cap do a nice job of arcing around the approximate location of the north pole, so it's pretty easy to figure out roughly where the pole is. This image rewards close investigation, so I encourage you to download the whole thing; however, if your data rate won't allow it, I've clipped out a bunch of interesting detail spots below. Mars' north polar capThis strip across the north pole of Mars was captured by Mars Express on December 14, 2004. It covers a region about 1,140 kilometers (710 miles) long and is shown here at a resolution of about 200 meters per pixel; the area shown is roughly the same as the land area of France or Greenland. It is a false color image composed by Doug Ellison from infrared, green, and blue filtered images from data released to ESA's Planetary Science Archive in April, 2006. White areas are the polar cap itself; reddish areas are dusty; and darker brown areas are windblown sand dunes. Credit: ESA / DLR / FU Berlin (G. Neukum) / Doug Ellison |
For comparison, here is a Mars Global Surveyor MOC wide-angle view of the same region (it's rotated roughly 90 degrees with respect to the Mars Express view above; the strip crosses roughly the middle of this view):Mars' north polar cap in summerMars Global Surveyor captured this wide-angle view of the north pole of Mars early in the northern summer season on March 13, 1999. The entire cap is approximately 1,100 kilometers (680 miles) across. Credit: NASA / JPL / Malin Space Science Systems |
OK, so here are the spots where I picked out detailed views that tickled my fancy:The detailed images follow. All are shown at their full resolution as available from the Planetary Science Archive -- about 100 meters per pixel, so each is about 25 kilometers square. The first two, at the top, show dark crescent-shaped dunes; the right-hand one shows you that the dunes can march right across the icy material of the cap. I like how their shapes shange as they follow topography. On the second row, on the left side, is what looks to me like a buried crater. On the right, I don't know what this is; it looks like a bottle opener to me!On the third row are two examples of what happens when you get a trough cut somehow into layered materal -- gorgeous parallel lines of more ice-rich and more dust-rich layers. The one on the right has something of a plateau cut across the layered material, making psychedelic concentric shapes. The last image is a little dark, but I liked the sharpness of the edge of the cap here. I can't tell from the image whether those are very parallel sets of dunes, or maybe scarps from some kind of landslide procss. But the shapes are very pretty!
|
|
[ what is this? ]