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Gravity Probe A Collection

Identifier: MC-15
Scientific documents, project definition materials, project implementation materials, spacecraft flight materials, flight data analyses, Atomic H Dissociator documents, personal documents, spacecraft data and trajectory tabulations, spacecraft payload drawings, Gravity Probe A data tapes.


  • 1968 - 1984


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.


11 Linear Feet (5 boxes, 1 oversize, and 22 film reels.)

Biographical / Historical

Gravity Probe A (GP-A) was a NASA project conducted by the Marshall Space Flight Center (MSFC) and by the project Principal Investigator at the Astrophysical Observatory of the Smithsonian Institution (SAO). MSFC was responsible for overall management of the project and for provision of the launch vehicle and required logistics, and SAO was responsible for the hydrogen maser payload. The probe was launched successfully on June 18, 1976 into a nearly vertical trajectory to an apex of about 10,000 kilometers (or about 6,214 miles).

At the time of the project execution, and arguably until Gravity Probe B in 2004, GP-A was the most fundamental experiment undertaken by NASA. It was a measurement of the gravitational red shift of an electromagnetic signal as dictated by the equivalence principle, a fundamental premise of Einstein's theories of relativity; thus, GP-A was an investigation at the very foundation of physical theory. The final scientific results of this historic project were published in the “Physical Review Letters,” Vol. 45, pp 2081-2084, 29 Dec. 1980 (Item GA1014 in this collection).

The GP-A project was also a remarkable demonstration of a complex and demanding collaboration between diverse personnel in several NASA organizations and the scientists, engineers, and administrators at the Smithsonian Astrophysical Observatory. The detailed project documentation that has been archived, abstracted, and cataloged captures this interplay between organizations and personnel. Although GP-A was a relatively small project compared to many NASA projects, GP-A was managed in a standard NASA manner; this archive collection can be considered as a detailed illustration of NASA project management practice at the time of its performance.

Immediate Source of Acquisition

Gift of Robert Vessot and 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.
Anne Coleman, Charles Lundquist
Description rules

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