Emily LakdawallaAug 25, 2010

A first look at distant hills

Rover fans have been excitedly watching the hills on Opportunity's horizon grow taller and taller as Opportunity rolls toward its destination, Endeavour crater. You can do it, too -- just check the Mars Exploration Rovers raw images website a couple of times a week for new images, or do what I do, use Mike Howard's Midnight Mars Browser software to download all the latest pictures.

But now there's another way to watch the forward view. It's now been more than six months (actually closer to eight) since Opportunity's first clear view of those hills, which was at the end of January, around sol 2140, when Opportunity first pulled up to Concepción crater. Why is six months important? Because six months is how long the rover team has to calibrate and verify their data before sending it all to NASA's Planetary Data System for archiving. Once it's at the PDS, the science data is in the public domain. They archive their data in 90-sol chunks. A few days ago, the rover team sent the PDS the data covering sols 2071 to 2160, which includes the Concepción images. Here's the panoramic view of the distant hills from sol 2140. I've labeled it with the names of visible hills.

Opportunity horizon panorama, sol 2140
Opportunity horizon panorama, sol 2140 On sol 2140 (January 30, 2010), parked at the edge of Concepción crater, Opportunity got her first clear view of the rim of Endeavour crater. She is aiming toward "landfall" at Cape York, a spot to the left of the tall peaks of Cape Tribulation, 13 kilometers away. Cape Tribulation and Cape Dromedary are both on the southwest rim of Endeavour crater, the closest part of the rim to Opportunity. The northwest rim has been eroded away. More distant hills on Endeavour's eastern rim, are much farther away than Cape Tribulation; the spot labeled "Batavia" is 30 kilometers away. Iazu is another crater beyond Endeavour, 36 kilometers away. This panorama was created from archived science data from the Planetary Data System.Image: NASA / JPL / Cornell / color mosaic by Emily Lakdawalla

If the raw images are available right now, why is it work the work and effort to dig into the PDS for the real science data that is at least six months old? Because the science data is better. It turns out to be especially useful for the first, distant views, because the hills are such pale features against Mars' sky. The conversion to JPEG format that is run on the data before it is posted to the raw images website hides some of the little detail that is visible there, and also gunks up the sharp boundary between the red rock and dust of the foreground and the smooth sky. On top of that, Opportunity's glasses are dirty from her many years on Mars' surface, resulting in dark edges to the raw images. But the crafty rover imaging team has ways of processing out these and other camera artifacts, so that mosaics made from the calibrated data are smooth and beautiful.

Just for comparison's sake, here is a grossly contrast-enhanced version of the view of the near-rim features in that panorama. Enhancing the contrast brings out details in the shapes of the peaks.

Opportunity horizon panorama, sol 2140 (contrast-enhanced horizon detail)
Opportunity horizon panorama, sol 2140 (contrast-enhanced horizon detail) A first view of Endeavour's near, southwest rim (13 kilometers way) from Opportunity. The contrast has been greatly enhanced to reveal subtle features on the hills.Image: NASA / JPL-Caltech / Cornell / color mosaic by Emily Lakdawalla

And here's a view of the distant hills captured on Friday, August 20, sol 2337, about 100 sols later. This one is composed of raw images, so it is full of JPEG artifacts, but it does reveal that the hills are growing; during the intervening 100 sols, Opportunity roved about 2 kilometers closer to them.

Near peaks on the horizon, Opportunity sol 2337
Near peaks on the horizon, Opportunity sol 2337 This view of Endeavour's near rim was taken by Opportunity on sol 2337. The composite is made of raw images taken through the right camera eye's infrared and ultraviolet/blue filters, with a green channel synthesized from a mix of the two.Image: NASA / JPL-Caltech / Cornell / color composite by Emily Lakdawalla

I'm looking forward to checking the PDS once a quarter to pull out Opportunity's best views of the distant hills! The next scheduled archive will become available on November 19.

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