Space 1990: Launching a New Decade of Exploration

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Space 1990 Launching a new decade of exploration

NASA enters a new era of scientific exploration with a year of missions that span the agency's capabilities. Some projects use the shuttle as a delivery van and even as a multipurpose laboratory. Others use one-shot, unmanned rockets known as expendable launch vehicles (ELVs). And several feats will not involve new launchings at all, being instead the work of craft already in space.

One such venture comes first on NASA's 1990 science calendar. When the Galileo spacecraft--launched last Oct. 18 on a circuitous route to reach Jupiter in 1995--flies around Venus on Feb. 9, it will take pictures of the planet's clouds, measure charged particles in the interplanetary magnetic field and monitor the activity of the sun in what has already proved a record-setting solar cycle.

But apart from demonstrating whether Galileo still works, the Venus flyby will give 1990 a frustratingly taciturn beginning. Instead of opening the year with a data-rich radio "downlink" of new Venus measurements, Galileo will have to keep its discoveries to itself for more than eight months. Scientists must wait until the craft gets close enough to Earth to transmit the results using the less efficient of its two antennas, since the other will remain furled until later in the mission to protect it from the heat of the sun (SN: 9/30/89, p.218).

Galileo's work for 1990 will not end with its Venus data-dump, however. On Dec. 8, it will pass even closer to Earth and its moon, photographing both of them by visible, ultraviolet and infrared light. Among the crafths tools is the most sophisticated camera NASA has yet sent off for planetary observations.

Beyond February's Venus encounter awaits a diverse series of space endeavors:

* Scheduled for a March 26 launch by the shuttle is what the space agency hopes will prove its hit of the year: the long-awaited Hubble Space Telescope. Astronauts should release the satellite from Discovery's cargo bay on March 27, for a run hoped to last 15 years or more (SN: 1/6/90, p.8). NASA officials describe the $2 billion device as the most expensive single scientific instrument ever built, although other projects, such as the Superconducting Super Collider, may capture that title in coming years.

* On April 26, NASA plans to orbit another telescopic payload, but this time the instruments will stay fixed in the shuttle's cargo bay. Called Astro, it is designed to work as part of the European Space Agency's crew-carrying Spacelab module. This means it will operate only for the 10 days or less that the shuttle can remain in space. Plans call for a second Astro mission in 1992.

Astro will carry three ultraviolet telescopes aimed by a single pointing system. Together, the telescopes will study extreme ultraviolet sources, such as quasars and galaxies, while making wideangle observations of various objects whose emissions represent a wide band of ultraviolet wavelengths. Project officials expect the ultraviolet trio to conduct as many as 200 to 300 independent observations during each of its two missions.

The first Astro flight will also carry an X-ray telescope originally planned for a mission called the Shuttle High-Energy Astrophysics Laboratory, which fell victim to a launch shortage created by the 1986 loss of the shuttle Challenger. NASA eliminated the laboratory as a separate program but retained the telescope by assigning it to the Astro flight. The instrument measures the amount of energy of each X-ray wavelength detected. The resulting spectrum enables astronomers to determine the composition, temperature and degree of ionization of each X-ray source.

* Scheduled for launch no sooner than May, the Roentgen Satellite, or ROSAT, was originally designed to be carried aboard the shuttle. But when post-Challenger flight delays left NASA short of available shuttle space, project scientists redesigned the satellite so that it could ride a Delta 2 rocket into orbit. …