From Newsgroup: sci.space.news


http://www.jpl.nasa.gov/news/news.php?feature=6608

Dawn Sets Course for Higher Orbit
Jet Propulsion Laboratory
August 31, 2016

After studying Ceres for more than eight months from its low-altitude
science orbit, NASA's Dawn spacecraft will move higher up for different
views of the dwarf planet.

Dawn has delivered a wealth of images and other data from its current
perch at 240 miles (385 kilometers) above Ceres' surface, which is closer
to the dwarf planet than the International Space Station is to Earth.
Now, the mission team is pivoting to consider science questions that can
be examined from higher up.

After Dawn completed its prime mission on June 30, having surpassed all
of its scientific objectives at Vesta and at Ceres, NASA extended the
mission to perform new studies of Ceres. One of the factors limiting Dawn's lifetime is the amount of hydrazine, the propellant needed to orient the spacecraft to observe Ceres and communicate with Earth. By going to a
higher orbit at Ceres, Dawn will use the remaining hydrazine more sparingly, because it won't have to work as hard to counter Ceres' gravitational
pull.

"Most spacecraft wouldn't be able to change their orbital altitude so
easily. But thanks to Dawn's uniquely capable ion propulsion system, we
can maneuver the ship to get the greatest scientific return from the mission," said Marc Rayman, chief engineer and mission director, based at NASA's
Jet Propulsion Laboratory, Pasadena, California.

On Sept. 2, Dawn will begin spiraling upward to about 910 miles (1,460 kilometers) from Ceres. The altitude will be close to where Dawn was a
year ago, but the orientation of the spacecraft's orbit -- specifically,
the angle between the orbit plane and the sun -- will be different this
time, so the spacecraft will have a different view of the surface.

The mission team is continuing to develop the extended mission itinerary
and will submit a full plan to NASA next month.

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

More information about Dawn is available at the following sites:

http://dawn.jpl.nasa.gov

News Media Contact
Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425
elizabeth.landau@jpl.nasa.gov

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