Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.stsci.edu/hst/hst/proposing/documents/primer/primer_appendixB2.html
Дата изменения: Unknown Дата индексирования: Tue Apr 12 03:28:29 2016 Кодировка: Поисковые слова: п п п п п р п р п р п |
![]() |
HST Call for Proposals and HST Primer for Cycle 24 |
help@stsci.edu |
The Hubble Space Telescope (HST) is a cooperative project of the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) to operate a long-lived space-based observatory for the benefit of the international astronomical community. HST was first conceptualized in the 1940s, designed and built in the 1970s and 80s. In April 1990, the Space Shuttle Discovery deployed HST in low Earth orbit (~600 kilometers). The initial complement of Scientific Instruments (SIs) was:Soon after deployment, it was discovered that the primary mirror suffers from spherical aberration, which limited the quality of HST data obtained in the first few years of operation.During servicing mission 1 (SM1) in December 1993, Space Shuttle astronauts successfully refurbished HST. They replaced the HSP with COSTAR, a corrective optics package. COSTAR’s reflecting optics were deployed into the optical paths of the FOC, FOS, and GHRS, which removed the effects of the primary mirror’s spherical aberration. The performance of the FGSs was unaffected by COSTAR. The WF/PC was replaced by a new instrument: the Wide Field and Planetary Camera 2 (WFPC2). It contained its own internal optics to correct the spherical aberration of the primary mirror.HST has six rate-sensing gyroscopes on board. In the years after SM2, gyroscopes failed at a higher than expected rate, ultimately leading to a halt of HST observing in November 1999. In anticipation of this event, servicing mission SM3, which had been in planning for several years, was split into two separate missions: SM3A and SM3B.In December 1999, Space Shuttle astronauts lifted off for servicing mission SM3A. Six new gyroscopes were successfully installed, which allowed HST to resume normal operations.Along with the gyro replacements, the HST Project used this “unplanned” mission to make other planned upgrades and refurbishments:3. FGS2 was replaced by a refurbished fine guidance sensor, FGS2R, to enhance the performance of the pointing and control system (see Appendix B.1.2). However, FGS1R remains the best choice for science observations due to its superior angular resolution.B.1.5 Loss of STISB.1.7 SM4HST is expected to continue to operate in three-gyro mode for the foreseeable future.