Yearly Archives: 2009

Mars, Mars Express

Welcome to a Martian Landscape

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Mars Express Images a Valley on Mars

A Mars Express image of a region near Maadim vallis, one of the largest canyons on Mars. Courtesy European Space Agency. (Click to embiggen.)
A Mars Express 3D "ortho-image" of a region near Ma'adim vallis, one of the largest canyons on Mars. Courtesy European Space Agency. (Click to embiggen.)

It’s a great day in the solar system — there are telescopes aimed at Jupiter to follow the aftermath of the recent collision into the southern polar region; instruments are monitoring solar activity, Cassini continues to show us the wonders of the Saturn system, Mercury is still being mapped, the Moon is under heavy study, and the news and images from landers and mappers at Mars continues to flow our way.  Now, if we just had PEOPLE on Mars!  Well, when the first Marsnauts DO get there, they’ll have great images like this one from Mars Express to study.

Where is this place? It’s near one of the largest canyons on Mars — a giant rift called Ma’adim Vallis. This area lies between the Tharsis volcanic region of Tharsis (and its four large volcanoes) and the Hellas Planitia impact basin.

There’s quite a lot of interesting terrain here and a little planetary science interpretation tells an interesting story. The canyon itself is 20 kilometers wide and 2 kilometers deep. It begins in the southern highlands close to the a region called the “dichotomy boundary” that divides the cratered highlands on Mars and the nearby lowland plains. The canyon ends in Gusev crater, where the Spirit Rover is currently exploring.

The region near Maadim Vallis, as seen by Mars Express. (Click to embiggen.)
The region near Ma'adim Vallis, as seen by Mars Express. (Click to embiggen.)

The image you see here covers a region of Mars about the size of the island of Cyprus on Earth.  There’s a sharp boundary is visible that divides dark material to the west and light material to the east. This probably the edge of a basaltic lava flow. Wrinkle ridges are clearly visible on the surface of the lava flow and they probably formed as the rock was compressed by tectonic action after the lava was laid down.

The crater in the north part of the image is about 20 kilometers across and seems to be partly filled with lava deposits that flowed in after the crater formed.  The smaller crater at the southern edge of the larger crater must have formed later because it has an ejecta blanket that may have formed from material rich in water ice that was blasted out during the impact.

A 200-kilometer-long linear feature divides the image almost in half. This is probably a trough that formed when the Tharsis volcanic region was active. That activity caused the whole area to “lift up” — and that had to have created a lot of stress in the crust.  The typical way that surface crusts deal with stress is to break into pieces. Hence, you get fracture zones, and the creation of troughs and other broken terrain like you see here.

Images like these are fascinating for a lot of reasons. First, they’re another world — one that we’re learning a LOT about as our robot explorers send back more images and data. Second, they’re from a world that we hope humans will visit very soon. Third, those regions look so very familiar because we see places like them on Earth — and we know how they formed on Earth, so that helps us understand how they work on Mars. Finally, they’re just darned cool!  Not a very scientific-sounding reason, but hey — science IS cool.  And so is studying other planets!

Gemini Observatory, impacts, planetary science

Jupiter’s Southern “Bruise”

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As Seen by Gemini Observatory

The impact site of Jupiter, as seen by Gemini Observatory. It looks similar to the Shoemaker-Levy 9 crash sites that appeared in 1994 after the impact of that comet with Jupiters cloud tops.
The impact site of Jupiter, as seen by Gemini Observatory. It looks similar to the Shoemaker-Levy 9 crash sites that appeared in 1994 after the impact of that comet with Jupiter's cloud tops. (Click to embiggen.)

As more observatories turn their attention to the bruise at Jupiter’s southern polar region, the images just keep getting better.  Today’s release from Gemini Observatory on Mauna Kea in Hawai’i shows a composite mid-infrared view of the impact site (the bright yellow pair of blobs at the bottom center of the image at left).

This is looking more and more like the SL-9 crash effects from 1994, a point that SL-9 veteran Heidi Hammel pointed out as she described what they see in the images. “The morphology is suggestive of an arc-like structure in the feature’s debris field,” she added.

The mid-infrared wavelength image is showing the effect of scattered material as a result of this most recent impact.  It’s likely that the impactor was a small (hundreds of meters across) comet or asteroid — not something that could have been seen from Earth even with powerful telescopes.

The Gemini images that  made up the composite were obtained with the MICHELLE spectrograph/imager. This gave a series of images at seven different mid-infrared wavelengths. Two of the images (8.7 and 9.7 microns) were combined into a color composite image by Travis Rector at the University of Alaska, Anchorage to create this final false-color image. By using the full set of Gemini images taken over a range of wavelengths from 8 to 18 microns, the team will be able to disentangle the effects of temperature, ammonia abundance, and upper atmospheric aerosol content so that they can understand just what it was that plowed into Jupiter and what chemical elements it contained. Comparing these Gemini observations with past and future images will permit the team to study the evolution of features as Jupiter’s strong winds disperse them.

This image is one of those “target of opportunity” sets that observatories plan for when they allocate time each year. Essentially, the planning committees put aside time “just in case” something happens — just like it did with this impactor at Jupiter. As scientist Imke de Pater noted, “the Gemini support staff made a heroic effort to get these data.”  The Gemini team (Tom Geballe, Chad Trujillo, Rachel Mason and Paul Hirst, aided by Glenn Orton and Leigh Fletcher (of JPL)) swung into action immediately, making the telescope available within 24 hours of the request for observing time. It’s important to get data as soon as possible during these types of events, which are “transient” — meaning that they and their effects don’t last long, and the evidence for whatever the impactor was gets dissipated pretty quickly.  For more details on this Gemini image, swing your attention to the impact’s image page at Gemini’s website.

Update:  I heard that HST has also looked at this site as a target of opportunity. Not sure exactly when in the next day or so the image(s) will be available, but whatever shows up should be spectacular!