SMALL SATELLITE MISSIONS TO LONG-PERIOD COMETS - THE HALE-BOPP OPPORTUNITY

Long-Period Comets are possibly the best preserved primitive bodies of the Solar System because of the limited number, if not any, of passag es close to the Sun, thus minimizing the consequences following the on set of cometary activity. The unpredictability of their appearance and the short time spent inside the inner planetary region impose heavy c onstraints (e.g. limited time from comet discovery to launch) when try ing to plan a space mission toward a long-period comet. The reduced co st and overall complexity introduced by studying small satellite missi ons allowed to draw realistic scenarios. The appearance of comet Hale- Bopp in July 1995 is therefore used to investigate in a real case the feasibility of the proposed LOGO (Long Period Comet Observer) mission. It is found that if all preliminary studies are already carried out a t the time of comet appearance, a sufficient timespan is left to prepa re and launch a small spacecraft to encounter Hale-Bopp at the descend ing node of its orbit. A preliminary spacecraft design is presented, s ome general considerations on the problem of having to wait for a long -period comet to appear are discussed and alternative scenarios are pr oposed. Copyright (C) 1997 Elsevier Science Ltd.