[meteorite-list] Dawn Nears Historic Dwarf Planet Arrival

[Ron Baalke]

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