Space Operations:

NASA's Communications Support for Earth Orbiting Spacecraft

IMTEC-89-41: Published: Apr 7, 1989. Publicly Released: May 12, 1989.

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Pursuant to a congressional request, GAO reviewed the National Aeronautics and Space Administration's (NASA) plans for providing emergency backup communications support for earth-orbiting spacecraft.

GAO found that NASA: (1) before implementation of its space-based Tracking and Data Relay Satellite System (TDRSS), primarily relied on its worldwide network of ground stations to provide communications support; (2) phased out 13 ground network stations between 1980 and 1985 as it deployed TDRSS, and planned to phase out 4 more, pending successful on-orbit testing; and (3) originally believed that three special substations and three remaining ground stations could provide adequate backup communications support for spacecraft emergencies, but later requested Goddard Space Flight Center to review the four planned closings, citing concerns about how the closures could endanger future missions, the ground stations' other activities, and transmission of scientific data. GAO also found that: (1) Goddard did not perform a risk assessment, but affirmed its belief that the closings posed an extremely low risk of spacecraft loss or damage; (2) Goddard maintained that TDRSS was intended solely for emergency backup support for spacecraft safety and functioning, and not for transmission of scientific data; (3) spacecraft averaged 2.2 malfunctions annually, with most malfunctions resulting in little or no permanent damage to the spacecraft; and (4) NASA planned to construct a replacement for its ground terminal which was most critical to the operational reliability of earth orbiting spacecraft, based on concerns about the reliability of the original terminal.

Recommendation for Executive Action

  1. Status: Closed - Implemented

    Comments: A risk analysis for current missions was completed, a French company took over operations of Ascension Island, and plans are not needed for new small explorer missions because no requirements have been developed.

    Recommendation: The Administrator, NASA, should ensure that: (1) appropriate risk analyses are performed and documented for present and future earth-orbiting spacecraft missions before the four ground stations located at Guam, Hawaii, Santiago, and Ascension Island are closed; (2) plans for support for launches of expendable vehicles are finalized before the Ascension Island station is closed; and (3) a plan is developed to provide support for Small Explorer Missions in equatorial orbits.

    Agency Affected: National Aeronautics and Space Administration


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