Using its framing camera, Dawn obtained this image of Vesta on 24 July 2011, from a distance of about 5,200 km. The three vertically-aligned craters on the left have been nicknamed 'the snowman' by camera team members.
Credit: ASA/JPL-Caltech/UCLA/MPS/DLR/IDA
n this image a set of three craters, informally nicknamed 'Snowman' by the camera's team members, is located in the northern hemisphere of Vesta.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
PASADENA: The first spacecraft ever to orbit an object in the main asteroid belt is spiraling towards its first of four intensive science orbits.
The Dawn spacecraft's initial orbit of the rocky world Vesta begins on August 11, at an altitude of nearly 2,700 km and will provide in-depth analysis of the asteroid. Vesta is the brightest object in the asteroid belt as seen from Earth and is thought to be the source of a large number of meteorites that fall to Earth.
Images from Dawn's framing camera, taken for navigation purposes and as preparation for scientific observations, are revealing the first surface details of the giant asteroid. These images go all the way around Vesta, since the giant asteroid turns on its axis once every five hours and 20 minutes.
"Now that we are in orbit around one of the last unexplored worlds in the inner Solar System, we can see that it's a unique and fascinating place," said Marc Rayman, Dawn's chief engineer and mission manager at NASA's Jet Propulsion Laboratory in Pasadena.
2.8 billion km journey
After travelling nearly four years and 2.8 billion km, Dawn has been captured by Vesta's gravity, and there currently are 2,900 km between the asteroid and the spacecraft. The giant asteroid and its new neighbor are approximately 184 million km away from Earth.
"We have been calling Vesta the smallest terrestrial planet," said Chris Russell, Dawn's principal investigator at University of California, Los Angeles (UCLA). "The latest imagery provides much justification for our expectations. They show that a variety of processes were once at work on the surface of Vesta and provide extensive evidence for Vesta's planetary aspirations."
Engineers still are working to determine the exact time that Dawn entered Vesta's orbit, but the team has reported an approximate orbit insertion time of 12:47 am EDT on July 16.
Determining interior structure
In addition to the framing camera, Dawn's instruments include the gamma ray and neutron detector and the visible and infrared mapping spectrometer. The gamma ray and neutron detector uses 21 sensors with a very wide field of view to measure the energy of subatomic particles emitted by the elements in the upper metre of the asteroid's surface.
The visible and infrared mapping spectrometer will measure the surface mineralogy of both Vesta and Dawn's next target, the dwarf planet Ceres. The spectrometer is a modification of a similar one flying on the European Space Agency's Rosetta and Venus Express missions.
Dawn also will make another set of scientific measurements at Vesta and Ceres using the spacecraft's radio transmitter in tandem with sensitive antennas on Earth. Scientists will monitor signals from Dawn and later Ceres to detect subtle variations in the objects' gravity fields. These variations will provide clues about the interior structure of these bodies by studying the mass distributed in each gravity field.
"The new observations of Vesta are an inspirational reminder of the wonders unveiled through ongoing exploration of our solar system," said Jim Green, planetary division director at NASA Headquarters in Washington.
Vesta must be remarkable.
"Vesta is the brightest object in the asteroid belt as seen from Earth and is thought to be the source of a large number of meteorites that fall to Earth. " Hmmm....how does Vesta produce meteorites?
On another note, does anyome know how much light falls on Vesta? My question relates to the exposure time needed for such a photograph - assuming its a visible light image. Of course, I imagine the camera(s) has amazing light enhancing technology.
D.
Strike a light on Vesta?
These wonderful photographs show detailed striations that seem to be parallel to the direction of rotation.
I wonder if Vesta has had numerous contacts with other smaller space rocks that have tumbled and glanced around the asteroid as it has rotated?
This sort of contact may then have transferred rotational motion to the smaller body and it may have eventually gone off in a dizzy tizzy??
If Dawn observes smaller rocks in the vicinity with such contra rotation
this mechanism might be confirmed?
The positive test might be to manipulate a handy small orbiting rock into a glancing collision and watch what happens?
If the surface texture was soft , say like pumice,perhaps even the "snowman"might be the result of a series of slow bouncing impacts before the"merger proposal" was rejected?
The potential disturbance in the orbits of the smaller objects would I guess be the reason to think of Vesta as a source of Earth bound travellers?
It's great that us terrestial apes can be looking at such things just a few hundred years after wooden ships were the latest invention.
Best Wishes Ron Horgan