. 24/7 Space News .
Gravity Probe B Rollout Continues

Overall, at two and a half weeks after launch, it appears that all of the spacecraft's subsystems are continuing to meet or exceed mission requirements, in preparation for beginning the science experiment.
Stanford - May 10, 2004
As of Mission Day #17, the Gravity Probe B spacecraft continues to perform well, and we are expecting a smooth and successful transition into the science phase of the mission.

The spacecraft remains in a science mission orbit, within the plane of the Guide Star, I'm Pegasi. The gyro readout system performance continues to exceed expectations, and all four SQUIDs (Super-conducting Quantum Interference Devices) are functional and calibrated, with very low noise levels. Power and thermal systems meet all of our mission requirements. All spacecraft subsystems continue to perform nominally.

All four gyros have been electrically suspended in analog mode, and gyros #1, #2 and #4 are now digitally suspended; we expect gyro #3 to transition from analog to digital suspension shortly.

Last weekend, the spacecraft was hit by radiation while passing over the Earth's south magnetic pole. This radiation caused data errors in the spacecraft's primary (A-side) computer, which exceeded its capacity for self-correction. Thus, by design, the spacecraft automatically switched over the backup (B-side) computer, placed the spacecraft in a "safe" mode, and put the planned timeline of events on hold.

The automatic switch over from primary to backup computer worked flawlessly. The GP-B mission operations team has since re-booted the primary computer, restored its data parameters, and then commanded the spacecraft to switch back to the primary computer, which is once again in control. During this incident, the GP-B science instrument continued to function perfectly--as expected--with all four gyros remaining suspended in their assigned modes.

The spacecraft's Attitude Control System (ATC) is continuing to maintain a stable attitude (relative position in orbit-pitch, yaw and roll). However, the process of locking onto the Guide Star, I'm Pegasi, has been delayed a few days by the South Pole radiation incident.

Overall, at two and a half weeks after launch, it appears that all of the spacecraft's subsystems are continuing to meet or exceed mission requirements, in preparation for beginning the science experiment.

The spacecraft is being controlled from the Gravity Probe B Mission Operations Center, located at Stanford University. Mission operations have demonstrated that the hardware developed for the GP-B mission is functioning as planned, and the Stanford-NASA-Lockheed Martin operations team is continuing to perform superbly.

The Initialization & Orbit Checkout (IOC) phase of the Gravity Probe B mission is planned to last within 60 days, after which the 13-month science data collection will begin. This will be followed by a two-month final calibration of the science instrument assembly.

NASA's Gravity Probe B mission, also known as GP-B, will use four ultra-precise gyroscopes to test Einstein's theory that space and time are distorted by the presence of massive objects. To accomplish this, the mission will measure two factors -- how space and time are warped by the presence of the Earth, and how the Earth's rotation drags space-time around with it.

Related Links
Gravity Probe B at Stanford
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express

Gravity Probe B In Mission Orbit
Huntsville (SPX) Apr 29, 2004
In its first week on orbit, Gravity Probe B has achieved many successes that will ensure a smooth transition into the science phase of the mission and the best possible experimental accuracy. The spacecraft has already achieved a science mission orbit, within the plane of the Guide Star, I'm Pegasi, and its inclination error is six times better than expected.



Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only














The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.