Orbital space debris ‘poses main threat to shuttle crew’

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    The US government urgently needs to develop an interagency surveillance strategy involving both the Department of Defense (DoD) and the National Aeronautics and Space Administration (NASA) to combat the growing problem of space debris, according to the General Accounting Office (GAO), the investigative arm of Congress.

    The recommendation, made in a report published by the GAO last month, coincides with a separate report from the National Research Council (NRC) urging the space agency to boost its efforts to protect the space shuttle from meteoroids and orbital space debris. The council says these now represent "the single greatest threat to the shuttle and its crew" — even higher than the hazards encountered during launch and ascent.

    The United States already has a sophisticated Space Surveillance Network, operated by the US Space Command, on which both the DoD and NASA rely for information on objects orbiting the Earth. But the GAO says that this is not capable of providing the information the space agency needs — in terms of both locating and identifying the size of such objects — adequately to predict possible collisions with multibillion-dollar space programmes, such as the international space station.

    Although the defence department has plans to modernize its surveillance network radar system and to develop three new ballistic missile warning systems, the GAO says that these plans "do not adequately consider DoD's or NASA's surveillance requirements". Nor does the National Space Policy, published in 1996, make provision for an interagency mechanism to ensure that NASA's requirements are met.

    The NRC report was drawn up by a panel set up by its Aeronautics and Space Engineering Board committee to address the potential threat to space shuttle missions posed by orbital debris such as spent rocket bodies, satellite fragments and even paint chips. It points out that NASA's four operating shuttles, which were designed in the 1970s, were not built to repel bombardment by such debris, as it was not recognised at the time to be a substantial threat.

    But the growing amount of debris over the past decades, says the committee, has almost doubled the likelihood that the crew might be harmed or that the spacecraft might incur major damage. The committee also points out that more than 95 per cent of the debris that could critically damage the shuttle is too small to be picked up by current ground-based sensors operated by the DoD.

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