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    • The SHADOW Project

    Paper number

    IAC-07-A3.4.08

    Author

    Mr. Jean-Yves Prado, Centre National d'Etudes Spatiales (CNES), France

    Coauthor

    Mr. Alain Perret, Union pour la Promotion de la Propulsion Photonique, France

    Coauthor

    Mr. Olivier Boisard, U3P (Union pour la Promotion de la Propulsion Photonique), France

    Coauthor

    Dr. Regis Bertrand, Centre National d'Etudes Spatiales (CNES), France

    Year

    2007

    Abstract
    The orbit of asteroids like Apophis is difficult to extrapolate on the long term mainly due to the uncertainties upon the effect of non gravitational forces. The Yarkovsky effect, which is the main unknown, is the consequence of the time needed for the asteroid surface to warm up and cool down. This thermal phenomenon produces a very small but permanent thrust, of which intensity and direction are directly related to the nature of the soil, the characteristics of the rotation and the physical properties of the asteroid.

By transposing to Apophis what has been observed on 6489 Golevka, we conclude that this effect can modify the Apophis orbit by about 7000 kilometers in less than 20 years.

The SHADOW mission we propose would be phased in the following way:
\\- as soon as possible, send a SEP (Solar Electric Propulsion) probe to rendez-vous with Apophis and provide the requested information to assess the Yarkovsky effect (visible and thermal imagers, high precision accelerometers, laser altimeter). The probe itself being tracked from the ground with meter level accuracy, the characterization of the Yarkovsky thrust can be achieved after a few month flyby.
\\- after assessing the risks of Earth impacts for the coming decades, a decision can be made about the possible mitigation techniques. 
\\- if the Yarkovsky effect is found to be important, cancelling it will be sufficient to avoid a collision with the Earth. This can be achieved by shadowing and cooling the asteroid with a wide solar shield. This solar sail would be equipped with a SEP system in order to balance the photonic pressure exerted on the sail. Preliminary evaluations show that a 300m diameter 5 metric tons sail could be kept in station a few hundred meters above the asteroid during several years.
    Abstract document

    IAC-07-A3.4.08.pdf

    Manuscript document

    IAC-07-A3.4.08.pdf (🔒 authorized access only).

    To get the manuscript, please contact IAF Secretariat.