[meteorite-list] NASA's Dawn Spirals Down to Lowest Orbit Around Vesta

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 12 Dec 2011 15:39:53 -0800 (PST)
Message-ID: <201112122339.pBCNdrm1002048_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2011-384

NASA's Dawn Spirals Down to Lowest Orbit
Jet Propulsion Laboratory
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.

"Dawn has performed some complicated and beautiful choreography in order
to reach this lowest orbit," said Marc Rayman, Dawn chief engineer and
mission manager based at NASA's Jet Propulsion Laboratory, Pasadena,
Calif. "We are in an excellent position to learn much more about the
secrets of Vesta's surface and interior."

Launched in 2007, Dawn has been in orbit around Vesta, the second most
massive object in the asteroid belt between Mars and Jupiter, since July
15. The team plans to acquire data in the low orbit for at least 10 weeks.

Dawn's framing camera and visible and infrared mapping spectrometer
instruments will image portions of the surface at greater resolution
than obtained at higher altitudes. But the primary goal of the low orbit
is to collect data for the gamma ray and neutron detector (GRaND) and
the gravity experiment. GRaND will be looking for the by-products of
cosmic rays reflected off Vesta to reveal the identities of many kinds
of atoms in the surface of Vesta. The instrument is most effective at
this low altitude.

Close proximity to Vesta also enables ultrasensitive measurements of its
gravitational field. These measurements will tell scientists about the
way masses are arranged in the giant asteroid's interior.

"Dawn's visit to Vesta has been eye-opening so far, showing us troughs
and peaks that telescopes only hinted at," said Christopher Russell,
Dawn's principal investigator, based at UCLA. "It whets the appetite for
a day when human explorers can see the wonders of asteroids for themselves."

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's mission to Vesta and Ceres is managed by JPL for NASA's Science
Mission Directorate in Washington. JPL is a division of the California
Institute of Technology in Pasadena. Dawn is a project of the
directorate's Discovery Program, managed by NASA's Marshall Space Flight
Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission
science. Orbital Sciences Corp. in Dulles, Va., designed and built the
spacecraft. The German Aerospace Center, the Max Planck Institute for
Solar System Research, the Italian Space Agency and the Italian National
Astrophysical Institute are international partners on the mission team.

More information about the Dawn mission is online at:
http://www.nasa.gov/dawn .

To follow the mission on Twitter, visit: http://www.twitter.com/NASA_Dawn .

Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook at jpl.nasa.gov

2011-384
Received on Mon 12 Dec 2011 06:39:53 PM PST