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Gravity Probe B Collection

Identifier: MC-16


  • Creation: 2004 - 2010


Conditions Governing Access

This collection is open for research in the Archives & Special Collections reading room. Handling guidelines and use restrictions will be communicated and enforced by archives staff members.

Conditions Governing Use

This material may be protected under U. S. Copyright Law (Title 17, U.S. Code) which governs the making of photocopies or reproductions of copyrighted materials. You may use the digitized material for private study, scholarship, or research. Though the University of Alabama in Huntsville Archives and Special Collections has physical ownership of the material in its collections, in some cases we may not own the copyright to the material. It is the patron's obligation to determine and satisfy copyright restrictions when publishing or otherwise distributing materials found in our collections.

Biographical / Historical

The immediate follow-up to Gravity Probe A, Gravity Probe B was a satellite developed by the Marshall Space Flight Center and Stanford University and launched by NASA in 2004. The satellite’s purpose was to test the geodetic effect, spacetime being curved by Earth’s mass, and the frame-dragging effect, how a rotating mass drags spacetime along with it, two major elements of Albert Einstein’s theory of relativity.

Gravity Probe B’s reference telescope and the spin axes of its four gyroscopes were aligned on the binary star IM Pegasi. For the duration of the 17½ month mission, the satellite’s telescope was to remain aligned on IM Pegasi while scientists measured how the alignment of each gyroscope’s spin axis changed in the plane of orbit and in the plane of Earth’s rotation.

The satellite measured a geodetic effect to an accuracy of 1%, later calculations determining the accuracy to be to an accuracy of 0.5%; the frame-dragging rate measured to an accuracy of 15%.


19 Linear feet (19 boxes.)

Language of Materials


Immediate Source of Acquisition

Gift of Rudolf Decher, 2004.

Processing Information

Collections are processed to a variety of levels, depending on the work necessary to make them usable, their perceived research value, the availability of staff, and competing priorities. The library attempts to provide a basic level of preservation and access for all collections as they are acquired and does more extensive processing of higher priority collections as time and resources permit.

Megan Sullivan
Description rules
Describing Archives: A Content Standard
Language of description
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Repository Details

Part of the The University of Alabama in Huntsville Archives & Special Collections Repository

M. Louis Salmon Library
301 Sparkman Drive
Huntsville, AL 35899 Alabama 35899 United States of America