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New Vesta Mapping Orbit

September 30, 2011 - PASADENA, Calif. -- NASA's Dawn spacecraft has completed a gentle spiral into its new science orbit for an even closer view of the giant asteroid Vesta. Dawn began sending science data on Sept. 29 from this new orbit, known as the high altitude mapping orbit (HAMO).

In this orbit, the average distance from the spacecraft to the Vesta surface is 420 miles (680 kilometers), which is four times closer than the previous survey orbit. The spacecraft will operate in the same basic manner as it did in the survey orbit. When Dawn is over Vesta’s dayside, it will point its science instruments to the giant asteroid and acquire data, and when the spacecraft flies over the nightside, it will beam that data back to Earth.

Perhaps the most notable difference in the new orbit is the frequency with which Dawn circles Vesta. In survey orbit, it took Dawn three days to make its way around the asteroid. Now in HAMO, the spacecraft completes the same task in a little over 12 hours. HAMO is scheduled to last about 30 Earth days, during which Dawn will circle Vesta more than 60 times. For about 10 of those 30 days, Dawn will peer straight down at the exotic landscape below it during the dayside passages. For about 20 days, the spacecraft will view the surface at multiple angles.

HAMO, the most complex and intensive science campaign at Vesta, has three primary goals: to map Vesta’s illuminated surface in color, provide stereo data, and acquire visible and infrared mapping spectrometer data. In addition, it will allow improved measurements of Vesta’s gravity.

Image of the Day: October 12-14

(1) Boulders on Vesta (October 12, 2011) This detail of a Dawn FC (framing camera) image shows a fresh scarp rimmed crater with many boulders on the crater floor.

(2) Ejecta blanket on Vesta (October 13, 2011) This detail of a Dawn Framing Camera image shows an ejecta blanket mantling (e.g. covering) the surface and obscuring older caters.

(3) Dark areas in cratered terrain on Vesta (October 14, 2011) In this Dawn FC (framing camera) image, a number of small dark areas, mostly clustered in the center and left of the image, are visible in Vesta’s cratered landscape.

Image Credits: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Image of the Day: Oct. 15 - 17

(1) Fresh dark ray crater: This Dawn FC (framing camera) image shows a fresh dark rayed crater in the center of the image. This crater is 1.7 km in diameter. Commonly rays from impact craters are brighter than the surrounding surface so further study on this, and other, dark rayed craters will be important. This crater was emplaced onto the ejecta blanket of two large twin craters. The bright, uneven rim of one of the twin craters is seen to the right of the dark rayed crater. This ejecta blanket covers most of the Vestan surface visible in this image and is identified by its smooth texture compared to the rest of Vesta. Some craters which are older than the ejecta blanket can be partially seen below it as shallow, roughly circular depressions.

(2) Equatorial troughs and dark material I: This Dawn FC (framing camera) image shows the equatorial troughs of Vesta running obliquely across the image. These troughs occur around most of Vesta’s equatorial region and are one of its most striking features. They both overlie and are overlain by impact craters. A large linear structure seems to cut across these troughs in the bottom left side of the image. Also distinctive is the dark material which is associated with the troughs, impact craters (right side of image) and the dark hill (center of image). This dark hill remains dark from many different viewing angles in a selection of images, so its dark appearance is not just due to shadowing effects. Many possible formation mechanisms for this dark hill are currently under investigation.

(3) Equatorial troughs and dark material II: This Dawn FC (framing camera) image is a close up, nearly 4 times higher resolution view of Vesta’s equatorial troughs and dark material than yesterday’s Image of the Day. Smaller scale features become visible in this image, for example the grabens (linear depressions) which run parallel to and inside the troughs. These troughs run obliquely across the top of the image. Also visible are craters which are only a few pixels across. This corresponds to a diameter of roughly 100-200km. The shape and structure of the dark hill (offset from center of image) can also be more precisely defined in this image. The dark material surrounding this hill is roughly lobate in shape and the boundary between this material and Vesta’s surface is rather irregular.

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Image of the Day: Oct. 20 - 21

Unusual Craters

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Image of the Day - Oct. 24

Rillen auf Vesta: This Dawn FC (framing camera) image shows small scars (known as rilles) on Vesta’s surface, which are mostly concentrated in the right half of the image. They are presumably due to impacts throwing out boulders, which then crash across the surface scouring the rilles as they go. Such boulders are visible as tiny black dots, due to their shadows, in the top right of the image. They are just underneath a bright patch, which is the edge of an impact crater. This impact crater could be where these boulders originated. In the top left of the image short rilles cut across partially infilled impact craters.

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Endlich gibt es wieder ansehliche Bilder von Vesta ...

Image of the Day - Nov. 10 - 12

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Image of the Day - Nov. 14 - 16

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Nicht mehr ganz neu, aber damit ihr auf dem laufenden bleibt:

NASA'S Dawn Spirals Down to Lowest Orbit

December 12, 2011 - PASADENA, Calif. -- NASA’s Dawn spacecraft successfully maneuvered into its closest orbit around the giant asteroid Vesta today, beginning a new phase of science observations. The spacecraft is now circling Vesta at an altitude averaging about 130 miles (210 kilometers) in the phase of the mission known as low altitude mapping orbit.

After the science collection is complete at the low altitude mapping orbit, Dawn will spiral out and conduct another science campaign at the high altitude mapping orbit altitude (420 miles, or 680 kilometers), when the sun will have risen higher in the northern regions. Dawn plans to leave Vesta in July 2012 and arrive at its second destination, the dwarf planet Ceres, in February 2015.

Dawn Obtains First Low Altitude Images of Vesta

December 21, 2011 - PASADENA, Calif. -- NASA’s Dawn spacecraft has sent back the first images of the giant asteroid Vesta from its low-altitude mapping orbit. The surface shows abundant small craters, and textures such as small grooves and lineaments that are reminiscent of the structures seen in low-resolution data from the higher-altitude orbits. Also, this fine scale highlights small outcrops of bright and dark material.

Dawn scientists plan to acquire data in the low-altitude mapping orbit for at least 10 weeks. The primary science objectives in this orbit are to learn about the elemental composition of Vesta’s surface with the gamma ray and neutron detector and to probe the interior structure of the asteroid by measuring the gravity field.

A gallery of images can be found online at: dawn/multimedia/gallery

Vesta Likely Cold and Dark Enough for Ice

January 25, 2012 - PASADENA, Calif. -- Though generally thought to be quite dry, roughly half of the giant asteroid Vesta is expected to be so cold and to receive so little sunlight that water ice could have survived there for billions of years, according to the first published models of Vesta's average global temperatures and illumination by the sun.

Image of the Day

February 9, 2012 - Chains and clusters of secondary craters

February 10, 2012 - Markings of ejected material on Vesta’s surface

February 13, 2012 - Vesta’s surface at high resolution: dominated by impact craters

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Image of the Day

February 15, 2012 - Mass wasting on steep slopes

February 16, 2012 - Successive formation of impact craters

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Image of the day

(1) February 28, 2012 - Light and shadow in northern hemisphere

(2) February 29, 2012 - Dust-covered surface with fresh small craters

The distance to the surface of Vesta is 272 kilometers and the resolution is about 25 meters per pixel. These images were acquired during the LAMO (low-altitude mapping orbit) phase of the mission.

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Weitere Bilder aus dem LAMO (Low Altitude Mapping Orbit)

Dawn Image of the Day - March 2012

March 1 - Impact crater with smoothed rim

March 2 - Sharp crater rim with dark material and boulders

March 22 - Blocks of ejected material and small craters near a crater rim

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Weitere Bilder aus dem LAMO (Low Altitude Mapping Orbit)

Dawn Image of the Day - March 2012

March 26 - Lines of craters

March 28 - Dark and bright material in a crater wall

March 29 - Linear and curvilinear grooves

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Weitere Bilder aus dem LAMO (Low Altitude Mapping Orbit)

Dawn Image of the Day - April 2012

April 3 - Curved chain of small craters

April 4 - Sharp crater rim

April 5 - Dark material in the ejecta of a small crater

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA

Dawn Image of the Day - April 2012

April 9 - An old crater almost completely filled with regolith

April 10 - Surface covered by regolith and fresh young impacts

April 11 - Chain of secondary craters

Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA