Dawn Engineers Assess Reaction Wheel

August 14, 2012
This artist's concept shows NASA's Dawn spacecraft orbiting the giant asteroid Vesta. The depiction of Vesta is based on images obtained by Dawn's framing cameras. Image credit: NASA/JPL-Caltech

Engineers working on NASA's Dawn spacecraft are assessing the status of a reaction wheel -- part of a system that helps the spacecraft point precisely -- after onboard software powered it off on Aug. 8. Dawn's mission is to study the geology and geochemistry of the giant asteroid Vesta and dwarf planet Ceres, the two most massive objects in the main asteroid belt. Dawn is now using its thrusters to point at Earth for communications. The rest of the spacecraft is otherwise healthy.

During a planned communications pass on Aug. 9, the team learned that the reaction wheel had been powered off. Telemetry data from the spacecraft suggest the wheel developed excessive friction, similar to the experience with another Dawn reaction wheel in June 2010. The Dawn team demonstrated during the cruise to Vesta in 2011 that, if necessary, they could complete the cruise to Ceres without the use of reaction wheels.

The spacecraft has been orbiting Vesta since July 15, 2011. Dawn concluded its primary science observations of Vesta on July 25, 2012, and has been spiraling slowly away from the giant asteroid using its ion propulsion system. Ion thrusting was halted to accommodate the reaction wheel investigation, which may briefly delay the escape from Vesta.

"The Vesta mission has been spectacularly successful, and we are looking forward to the exciting Ceres mission ahead of us," said Robert Mase, Dawn project manager, of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Explore further: Dawn Glides Into New Year

Related Stories

Dawn Glides Into New Year

November 21, 2008

(PhysOrg.com) -- NASA's Dawn spacecraft shut down its ion propulsion system today as scheduled. The spacecraft is now gliding toward a Mars flyby in February of next year.

Engineers Assess Dawn's Reaction Wheel

June 30, 2010

(PhysOrg.com) -- Engineers are studying the reaction wheels on NASA's Dawn spacecraft after automatic sensors detected excess friction building up in one of them and powered it off early on the morning of June 17, 2010. Reaction ...

Dawn beams back asteroid science data

August 12, 2011

(PhysOrg.com) -- The Dawn spacecraft has completed a graceful spiral into the first of four planned science orbits during the spacecraft's yearlong visit to Vesta. The spacecraft started taking detailed observations on Aug. ...

Dawn gets extra time to explore Vesta

April 19, 2012

(Phys.org) -- NASA's Dawn mission has received official confirmation that 40 extra days have been added to its exploration of the giant asteroid Vesta, the second most massive object in the main asteroid belt. The mission ...

Recommended for you

Image: Hubble sees a dying star's final moments

July 31, 2015

A dying star's final moments are captured in this image from the NASA/ESA Hubble Space Telescope. The death throes of this star may only last mere moments on a cosmological timescale, but this star's demise is still quite ...

Exoplanets 20/20: Looking back to the future

July 31, 2015

Geoff Marcy remembers the hair standing up on the back of his neck. Paul Butler remembers being dead tired. The two men had just made history: the first confirmation of a planet orbiting another star.

Earth flyby of 'space peanut' captured in new video

July 31, 2015

NASA scientists have used two giant, Earth-based radio telescopes to bounce radar signals off a passing asteroid and produce images of the peanut-shaped body as it approached close to Earth this past weekend.

Binary star system precisely timed with pulsar's gamma-rays

July 31, 2015

Pulsars are rapidly rotating compact remnants born in the explosions of massive stars. They can be observed through their lighthouse-like beams of radio waves and gamma-rays. Scientists at the Max Planck Institute for Gravitational ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.