Astronomy Picture of the Day Index - Space Technology: Orbiting Observatories

APOD: 1995 August 10 - The Orbiting Hubble Space Telescope
Explanation: The Hubble Space Telescope (HST) is the largest orbiting public optical telescope in history. Its 2.4 meter diameter reflecting mirror and its perch above Earth's atmosphere allow it to create exceptionally sharp images. Originally launched in 1990, HST optics were repaired to their intended accuracy in 1993 by the first of several regular servicing missions. Astronomers using HST continue to make numerous monumental scientific discoveries, including new estimates of the age of our universe, previously unknown galaxies, evidence of massive black holes in the centers of galaxies, previously unknown moons, and a better understanding of physical processes in our universe.

APOD: 2000 January 16 - The Compton Gamma Ray Observatory
Explanation: The Compton Gamma Ray Observatory (CGRO) was the most massive instrument ever launched by a NASA Space Shuttle in 1991 and continues to revolutionize gamma-ray astronomy. Before Compton loses more stabilizing gyroscopes, NASA is considering firing onboard rockets to bring it on a controlled reentry into the ocean. This orbiting observatory sees the sky in gamma-ray photons - light so blue humans can't see it. These photons are blocked by the Earth's atmosphere from reaching the Earth's surface. Results from CGRO, pictured above, have shown the entire universe to be a violent and rapidly changing place - when viewed in gamma-rays. Astronomers using CGRO data continue to make monumental discoveries, including identifying mysterious gamma-ray bursts that uniquely illuminate the early universe, discovery of a whole new class of QSOs, and discovery of objects so strange that astronomers can't yet figure out what they are.

APOD: 1999 July 27 - Chandra X-ray Telescope
Explanation: Wrapped in protective blankets and mounted atop an Inertial Upper Stage (IUS) rocket, the Chandra X-ray Telescope is seen in this wide-angle view before launch snuggled into the space shuttle Columbia's payload bay. Columbia's crew released the telescope, named in honor of the late Nobel Laureate Subrahmanyan Chandrasekhar, into orbit on Friday, July 23rd, where it is now undergoing check out and activation of its scientific instruments. To help realize its enormous potential for exploration of the distant Universe at X-ray energies, controllers will perform a series of firings in the coming days which will eventually boost the 10,000 pound telescope into a highly ecentric orbit. In fact, the final working orbit for Chandra will range from a close point of about 6,200 miles out to 87,000 miles or one third of the distance to the Moon. The elongated orbit will carry Chandra's sensitive X-ray detectors beyond interference caused by the Earth's radiation belts allowing Chandra to make about 55 hours of continuous observations per orbit. The shuttle Colombia, commanded by Eileen Collins is scheduled to land this evening at 11:20 pm EDT at Kennedy Space Center.