Will Dawn Visit a Third Object in the Asteroid Belt?

Dawn spacecraft asteroid missions
(Image credit: NASA/JPL-Caltech)

NASA is considering sending the Dawn spacecraft to a third asteroid after it finishes its mission at the dwarf planet Ceres.

Dawn, which visited the asteroid Vesta before putting itself into orbit around Ceres, was expected to run out of fuel for its novel ion propulsion system by the end of this year.

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The spacecraft had used extra propellant for thruster burns to orientate itself in space after problems with its reaction wheels prompted flight controllers to shut down the system. The wheels' spin naturally generates momentum to point the spacecraft without using fuel.

Upon arrival at Ceres in March 2015, flight controllers turned Dawn's reaction wheels back on and found the system operational.

"They worked great. There's been no other anomalies in that particular area for Dawn," NASA planetary science chief Jim Green told a science advisory committee during a webcast meeting this week.

"It turns out it is actually pretty significant," Green said.

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"They have had a variety of things they've discussed, and because it's a proposal I'm not at liberty to talk about it. But once again, an exciting mission," Green said.

In an email, Dawn lead scientist Christopher Russell told DNews, "Discussion of this topic is premature. We have only one approved continued operation plan and that is to remain in our present orbit."

"An extended mission review is underway," Green told the advisory group. "The panels have met and final deliberations are not quite done yet. We'll announce what NASA's decision is on that in the August-September time frame."

Originally published on Discovery News.

Irene Klotz
Contributing Writer

Irene Klotz is a founding member and long-time contributor to Space.com. She concurrently spent 25 years as a wire service reporter and freelance writer, specializing in space exploration, planetary science, astronomy and the search for life beyond Earth. A graduate of Northwestern University, Irene currently serves as Space Editor for Aviation Week & Space Technology.