Saturday, May 26, 2012
Dawn Rising Over Vesta
The above images are of Aquilia crater and the surrounding surface. The left image shows the apparent brightness of the surface. The right image is a color-coded representation of the topography. Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
Let's check in on NASA's Dawn mission to Vesta and Ceres in the asteroid belt. At the moment, Dawn and Vesta are orbiting the sun at a point that is roughly opposite the sun as seen from Earth. Only a few Earth probes have ever operated so far from home.
Beginning December 1, the Dawn spacecraft performed a low-altitude study of Vesta, orbiting at an average altitude of 210 kilometers (130 miles). At this point in the mission, the Dawn team could not be happier, and for two very good reasons. First, because the mission got 40-day extension to their stay at Vesta. And second, because that extension allow them to spend another month in their low orbit, and collect even more great data.
On May 1, the team began navigating the Dawn spacecraft through a six-week ascent to high orbit. And thanks to the earlier extension, the team will have more time up there to study Vesta before departing on August 26, 2012 (my birthday) for the long journey to Ceres.
As of May 22nd, the Dawn spacecraft was at an average altitude of about 450 kilometers (280 miles), over twice its altitude during its low-orbit phase. But the planned ascent has another three weeks to go and the ion propulsion system continues to run just fine. Dawn's destination is an altitude of about 680 kilometers (420 miles), where it will conduct a series of mapping orbits.
While Dawn is rising (pun intended), we have some time to learn a bit about how Dawn gather's it surface data. The above images of Aquilia crater and the surrounding surface can provide an example of the process. The left-hand image is a Dawn FC (framing camera) image, which shows the apparent brightness of Vesta's surface. The right-hand image is based on this apparent brightness image, which has had a color-coded height representation of the topography overlain onto it. The topography is calculated from a set of images that were observed from different viewing directions, which allows stereo reconstruction. The various colors correspond to the height of the area. The white and red areas in the topography image are the highest areas and the blue areas are the lowest areas. Aquilia crater is the large crater that dominates the top part of both images. The three-dimensional structure of Aquilia is clearer in the topography image: the deepest part of the crater (colored blue) is offset from the crater's center, the smaller crater on Aquila's rim is also relatively deep and the top side of Aquila is steeper than the opposite side.
These images are located in Vesta's Pinaria quadrangle, in Vesta's southern hemisphere. NASA's Dawn spacecraft obtained the apparent brightness image with its framing camera on Oct. 16, 2011. This image was taken through the camera's clear filter. The distance to the surface of Vesta is 700 kilometers (435 miles) and the image has a resolution of about 70 meters (230 feet) per pixel. This image was acquired during the HAMO (high-altitude mapping orbit) phase of the mission. These images are lambert-azimuthal map projected.
And now, the mission particulars...
The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA's Science Mission Directorate, Washington D.C. UCLA is responsible for overall Dawn mission science. The Dawn framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.
For more information about the Dawn mission, visit: www.nasa.gov/dawn and dawn.jpl.nasa.gov .