Solwind

The satellite's Orbiting Solar Observatory (OSO) platform included a solar-oriented sail and a rotating wheel section. Ball Aerospace was the primary contractor for design and construction, and provided the attitude control and determination computer programs. The P78-1 carried a gamma-ray spectrometer, a white-light coronagraph, an extreme-ultraviolet imager, an X-ray spectrometer, a high-latitude particle spectrometer, an aerosol monitor, and an X-ray monitor. The X-ray monitor, designated NRL-608 or XMON, was a collaboration between the Naval Research Laboratory and Los Alamos National Laboratory. The white-light coronagraph and the ultraviolet imager were combined in a single package, designated NRL-401 or SOLWIND, which was built by the Naval Research Laboratory. The coronagraph was the flight spare of the white-light coronagraph on the OSO-7 satellite. The ultraviolet imager used a CCD imager, one of the first uses of a CCD in space. == Discovery of comets ==

P78-1 was the first satellite in space to discover a comet in general and a sungrazing comet in particular. In total, 9 sungrazing comets, all belonging to the Kreutz group, were discovered on images taken by the Solwind coronagraph: Apart from these yet another comet C/1984 R1 (Solwind) was found by Rainer Kracht, a German amateur astronomer, on 23 July 2005 in Solwind's images of 17 Sep 1984. Its perihelion distance of 0.1051 AU was at least ten times larger than that of the previously found true sungrazers. == Destruction ==

By 1985, the satellite's batteries were degrading. This caused more and more frequent "under-voltage cutoffs", a condition where the satellite detected a low main bus voltage and automatically shut down all non-vital systems. In addition, the last of the three tape recorders failed in the spring of 1985, so data collection could only occur while the spacecraft was in contact with a ground station. but had deorbited by 2008. The last piece of debris, COSPAR 1979-017GX, SATCAT 16564, deorbited 9 May 2004 according to SATCAT. The test outraged some scientists because although five of P78-1's instruments had failed at the time of the test, two instruments remained in operation, and the satellite was what one solar physicist called "the backbone of coronal research through the last seven years". == See also ==