Space probes provide planetary images
Once a source of major embarrassment for NASA, the Hubble space telescope was in the news again last monththis time with a positive spinafter astronauts from the space shuttle Columbia successfully installed a new central power unit in the telescope.
Once a source of major embarrassment for NASA, the Hubble space telescope was in the news again last month—this time with a positive spin—after astronauts from the space shuttle Columbia successfully installed a new central power unit in the telescope. The achievement is notable because the unit was never designed to be replaced—it took two astronauts and a seven-hour spacewalk to complete the job. In the days following the power unit replacement a new Advanced Camera for Surveys was installed—which is supposed to improve the telescope's imaging ability by a factor of ten—and the astronauts attempted to revive the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) by installing a replacement cooling system. The overall mission represents an impressive accomplishment that could give Hubble a completely new lease on life.
Of course Hubble is not the only imaging spacecraft launched by NASA. The thermal imaging system on board its Mars Odyssey will provide infrared images 30 times sharper than those previously available. A composite of early photos is on our cover.
Before the days of space observatories, astronomers had to be satisfied with images from Earth-bound instrumentation. As the sophistication of ground-based telescopes increases so too must that of the supporting instrumentation. Ambitious interferometry programs at the Very Large Telescope on Paranal Mountain in Chile, for instance, require a laser metrology system capable of monitoring instrumentational disturbances to an accuracy of 5 nm.
Elsewhere this month we include an Optoelectronics World supplement with two closely related articles intended to serve as a "designer's guide" to the most common types of detectors used in analytical instrumentation (see supplement following p. 80); an article about the use of indium phosphide modulators for 10-Gbit/s metro networks (see p. 61); and a discussion of the importance of optical regeneration for future 40-Gbit/s networks.
Meanwhile, NASA also reported last month that its Pioneer 10 space probe launched March 2, 1972, is now about 7.5 billion miles away from Earth and is still "phoning home" after 30 years.
Stephen G. Anderson
Associate Publisher/Editor in Chief