[meteorite-list] Dawn Nears Historic Dwarf Planet Arrival

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon, 2 Mar 2015 16:44:43 -0800 (PST)
Message-ID: <201503030044.t230ihkJ003332_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4496

NASA Spacecraft Nears Historic Dwarf Planet Arrival
Jet Propulsion Laboratory
March 2, 2015

NASA's Dawn spacecraft has returned new images captured on approach to
its historic orbit insertion at the dwarf planet Ceres. Dawn will be the
first mission to successfully visit a dwarf planet when it enters orbit
around Ceres on Friday, March 6.

"Dawn is about to make history," said Robert Mase, project manager for
the Dawn mission at NASA's Jet Propulsion Laboratory in Pasadena, California.
"Our team is ready and eager to find out what Ceres has in store for us."

Recent images show numerous craters and unusual bright spots that scientists
believe tell how Ceres, the first object discovered in our solar system's
asteroid belt, formed and whether its surface is changing. As the spacecraft
spirals into closer and closer orbits around the dwarf planet, researchers
will be looking for signs that these strange features are changing, which
would suggest current geological activity.

"Studying Ceres allows us to do historical research in space, opening
a window into the earliest chapter in the history of our solar system,"
said Jim Green, director of NASA's Planetary Science Division at the agency's
Headquarters in Washington. "Data returned from Dawn could contribute
significant breakthroughs in our understanding of how the solar system
formed."

Dawn began its final approach phase toward Ceres in December. The spacecraft
has taken several optical navigation images and made two rotation characterizations,
allowing Ceres to be observed through its full nine-hour rotation. Since
Jan. 25, Dawn has been delivering the highest-resolution images of Ceres
ever captured, and they will continue to improve in quality as the spacecraft
approaches.

Sicilian astronomer Father Giuseppe Piazzi spotted Ceres in 1801. As more
such objects were found in the same region, they became known as asteroids,
or minor planets. Ceres was initially classified as a planet and later
called an asteroid. In recognition of its planet-like qualities, Ceres
was designated a dwarf planet in 2006, along with Pluto and Eris.

Ceres is named for the Roman goddess of agriculture and harvests. Craters
on Ceres will similarly be named for gods and goddesses of agriculture
and vegetation from world mythology. Other features will be named for
agricultural festivals.

Launched in September 2007, Dawn explored the giant asteroid Vesta for
14 months in 2011 and 2012, capturing detailed images and data about that
body. Both Vesta and Ceres orbit the sun between Mars and Jupiter, in
the main asteroid belt. This two-stop tour of our solar system is made
possible by Dawn's ion propulsion system, its three ion engines being
much more efficient than chemical propulsion.

"Both Vesta and Ceres were on their way to becoming planets, but their
development was interrupted by the gravity of Jupiter," said Carol Raymond,
deputy project scientist at JPL. "These two bodies are like fossils from
the dawn of the solar system, and they shed light on its origins."

Ceres and Vesta have several important differences. Ceres is the most
massive body in the asteroid belt, with an average diameter of 590 miles
(950 kilometers). Ceres' surface covers about 38 percent of the area of
the continental United States. Vesta has an average diameter of 326 miles
(525 kilometers), and is the second most massive body in the belt. The
asteroid formed earlier than Ceres and is a very dry body. Ceres, in contrast,
is estimated to be 25 percent water by mass.

"By studying Vesta and Ceres, we will gain a better understanding of the
formation of our solar system, especially the terrestrial planets and
most importantly the Earth," said Raymond. "These bodies are samples of
the building blocks that have formed Venus, Earth and Mars. Vesta-like
bodies are believed to have contributed heavily to the core of our planet,
and Ceres-like bodies may have provided our water."

"We would not be able to orbit and explore these two worlds without ion
propulsion," Mase said. "Dawn capitalizes on this innovative technology
to deliver big science on a small budget."

In addition to the Dawn mission, NASA will launch in 2016 its Origins-Spectral
Interpretation-Resource Identification-Security-Regolith Explorer (OSIRIS-REx)
spacecraft. This mission will study a large asteroid in unprecedented
detail and return samples to Earth.

NASA also places a high priority on tracking and protecting Earth from
asteroids. NASA's Near-Earth Object (NEO) Program at the agency's headquarters
manages and funds the search, study and monitoring of asteroids and comets
whose orbits periodically bring them close to Earth. NASA is pursuing
an Asteroid Redirect Mission (ARM), which will identify, redirect and
send astronauts to explore an asteroid. Among its many exploration goals,
the mission could demonstrate basic planetary defense techniques for asteroid
deflection.

Dawn's mission is managed by JPL for NASA's Science Mission Directorate
in Washington. Dawn is a project of the directorate's Discovery Program,
managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
UCLA is responsible for overall Dawn mission science. Orbital ATK Inc.,
in Dulles, Virginia, designed and built the spacecraft.

The German Aerospace Center, Max Planck Institute for Solar System Research,
Italian Space Agency and Italian National Astrophysical Institute are
international partners on the mission team. For a complete list of mission
participants, visit:

http://dawn.jpl.nasa.gov/mission

For more information about Dawn, visit:

http://dawn.jpl.nasa.gov

For more information on OSIRIS-REx and ARM visit:

http://www.nasa.gov


Media Contact

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
elizabeth.landau at jpl.nasa.gov

Dwayne Brown
NASA Headquarters, Washington
202-358-1726
dwayne.c.brown at nasa.gov

2015-073
Received on Mon 02 Mar 2015 07:44:43 PM PST