Thursday, August 16, 2012

Mars Rover Curiosity On Familar Ground


With its seven minutes of terror and a spectacular rocket-assisted landing behind it, the SUV-sized Mars rover Curiosity now finds itself just where scientists wanted it: at the northern edge and rim of Gale Crater. What’s remarkable is how familiar the landscape looks. 

“You would really be forgiven for thinking that NASA was trying to pull a fast one on you, and we actually put a rover out in the Mojave Desert and took a picture,” said project scientist John Grotzinger during a press conference.

Curiosity has begun its expedition near a fan-shaped apron of sediment called an alluvial fan, which likely formed when liquid water spilled down the side of Gale Crater, through a network of valleys, and onto the crater floor. Adjacent to the alluvial fan and quite near the rover, there is also an intriguing, light-colored “high thermal inertia” deposit with rocks that retain heat well. (Click here for a map that shows the locations of the rover and the deposit, and click here for one that shows the alluvial fan. Many of the latest images related to Curiosity's mission are here.)

Visitors to Badwater Basin area in California’s Death Valley National Park might see similarities in the images Curiosity has been sending home. The Badwater Basin is dense with alluvial fans like the one in Gale Crater. The alluvial fans in Death Valley are produced by occasional, intense storms that send storm water rushing down canyons in the otherwise arid slopes of the Panamint and Amargosa mountain ranges.

In the image above, captured in 2002 by the Advanced Land Imager on NASA’s Earth Observing-1 (EO-1) satellite, numerous alluvial fans are visible. Water has transported tan sediment from the mountains (far right), depositing it in the series of fan-shaped patterns near the center of the image.

This part of Death Valley shares other characteristics with Martian landscapes, and the area has long been a favorite for scientists planning for Mars landing sites. Wind, volcanism, and alternating wet and dry conditions have left similar marks on the rocks of both Mars and the Mojave Desert. The dark patch north of the largest alluvial fan has even been called Mars Hill for decades due to similarities to the rocks observed at the Viking 1 landing site from the 1970s. Mars Hill is the toe of an old alluvial fan, comprised of basaltic cobbles and gravels that stick out of the overlying, younger sediments.

The salt pan on the left is another feature that makes this part of Death Valley interesting to Mars researchers. Badwater Basin and Gale Crater are both enclosed basins with no outflows, so the water flowing into them would form temporary lakes and eventually salt flats after the water evaporates.


Of course, there are also major differences between the geology of Death Valley and Gale Crater. “Death Valley is a much younger and more dynamic place than Gale Crater, ” explained Aaron Zent, a planetary scientist at NASA’s Ames Research Center. “The valley floor is still sinking relative to the surrounding ranges, and more and more sediment is brought in, producing a sedimentary sequence that is mostly buried, with just a bit of salt on top. At Gale, the sediments, of whatever origin, are on top of the original crater floor and extensive salts, if present, are on the bottom and buried. If young, they may have been eroded and redistributed by the wind.”


Close-up view of a zone where the soil at Curiosity's landing site was blown away by the thrusters on the rover's descent stage.
This color full-resolution image showing the heat shield of NASA's Curiosity rover was obtained during descent to the surface of Mars on Aug. 5 PDT (Aug. 6 EDT). The image was obtained by the Mars Descent Imager instrument known as MARDI and shows the 15-foot (4.5-meter) diameter heat shield when it was about 50 feet (16 meters) from the spacecraft.
These are the first two full-resolution images of the Martian surface from the Navigation cameras on NASA's Curiosity rover, which are located on the rover's "head" or mast. The rim of Gale Crater can be seen in the distance beyond the pebbly ground.

The topography of the rim is very mountainous due to erosion. The ground seen in the middle shows low-relief scarps and plains. The foreground shows two distinct zones of excavation likely carved out by blasts from the rover's descent stage thrusters.
These images from NASA's Mars Reconnaissance Orbiter (MRO) show a before-and-after comparison of the area where NASA's Curiosity rover landed on Aug. 5 PDT (Aug. 6 EDT). The images were taken by the Context Camera on MRO on Aug. 1 and Aug. 7.
This full-resolution color image from NASA's Curiosity Rover shows the gravel-covered surface of Mars. It was taken by the Mars Descent Imager (MARDI) several minutes after Curiosity touched down on Mars.
This is the first image taken by the Navigation cameras on NASA's Curiosity rover. It shows the shadow of the rover's now-upright mast in the center, and the arm's shadow at left. The arm itself can be seen in the foreground.

The navigation camera is used to help find the sun -- information that is needed for locating, and communicating, with Earth. After the camera pointed at the sun, it turned in the opposite direction and took this picture. The position of the shadow helps confirm the sun's location.
This is the first 360-degree panoramic view from NASA's Curiosity rover, taken with the Navigation cameras. Most of the tiles are thumbnails, or small copies of the full-resolution images that have not been sent back to Earth yet. Two of the tiles near the center are full-resolution.

Mount Sharp is to the right, and the north Gale Crater rim can be seen at center. The rover's body is in the foreground, with the shadow of its head, or mast, poking up to the right.
This Picasso-like self portrait of NASA's Curiosity rover was taken by its Navigation cameras, located on the now-upright mast. The camera snapped pictures 360-degrees around the rover, while pointing down at the rover deck, up and straight ahead. Those images are shown here in a polar projection. Most of the tiles are thumbnails, or small copies of the full-resolution images that have not been sent back to Earth yet. Two of the tiles are full-resolution.
This image shows the location (green) where scientists estimate NASA's Curiosity rover landed on Mars within Gale Crater, based on images from the Mars Descent Imager (MARDI). The landing estimates derived from navigation and landing data agree to within 660 feet (200 meters) of this MARDI estimate.

The red line shows the northern edge of the targeted landing region, a probability distribution defined by an ellipse.
NASA Earth Observatory image by Jesse Allen and Robert Simmon, using EO-1 ALI data provided courtesy of the NASA EO-1 team. Caption by Adam Voiland, with information from Joy Crisp, Tom Farr, and Aaron Zent. Instrument: EO-1 - ALI