New year in space; NASA zeros in on planet earth - National Aeronautics and Space Administration 1994 mission schedule

Science News, Jan 15, 1994 by Ron Cowen

One of the telescopes, the Ultraviolet Coronal Spectrometer, will detect ultraviolet light emitted by atomic hydrogen and ions in the corona, The emissions may help determine which of two theories about coronal heating may be correct.

Some astronomers propose that the coronas heat sterns from intermittent but powerful microflares, created when magnetic loops in the corona suddenly snap like a rubber band and release vast amounts of stored energy. Others suggest that sound waves produced in the turbulent region beneath the sun's visible surface create shock waves that heat the corona.

While the spectrometer aboard Spartan 201 lacks the resolution to observe either the microflares or the shocks directly. the satellite should discern their differing effects on the corona and solar wind flow.

The craft's other telescope, the WhiteLight Coronagraph, detects visible light to determine the density of electrons in different parts of the corona, both in closed magnetic-field loops and in open magnetic-field structures. These observations may help track the bulk flow of the corona and pinpoint regions where material in the corona expands and becomes part of the solar wind.

On the same September shuttle flight, scientists will test a laser system designed to investigate atmospheric chemistry, Known as LITE, for LIDAR In-Space Technology Experiment, this pilot study will examine the composition of aerosols in the stratosphere and troposphere, gauge the altitudes of clouds, and measure the temperature and density of the upper atmosphere in the range of 10 to 40 kilometers.

A transmitter on the LITE payload generates 10 laser pulses per second at three wavelengths, directing the pulses into Earth's atmosphere. Aerosols and clouds in the atmosphere scatter some of the laser light back toward LITE, and a telescope collects the backscattered signals and directs them to an optical receiver.

October: For the third time, a suite of instruments dedicated to studying the chemistry of ozone creation and destruction will ride aboard a shuttle orbiter. The third flight of the Atmospheric Laboratory for Applications and Science (ATLAS-3) will examine Earth's atmosphere and the energy output of the sun to better understand ozone processes.

Because scientists will precisely calibrate the ATLAS instruments just before launch and after its return, engineers can use these detectors to verify the accuracy of data from several similar or identical devices aboard NASA and NOAA satellites.

The same shuttle flight will also carry a new set of cooled infrared spectrometers and telescopes to observe the atmosphere. The assembly, known as the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), will be released from the shuttie and float freely in space to make its observations. The shuttle crew will then retrieve CRISTA for its return to Earth.

November:. Astro-2, NASA's final mission of the year, features a trio of telescopes that will image the heavens and take the spectra of faint astronomical objects in the far ultraviolet. One of the telescopes will study the polarization of ultraviolet light emitted by hot stars and galaxies to investigate such phenomena as their magnetic fields. All of the instruments, which will make observations during a 10-day flight aboard the space shuttle, are holdovers from the first Astro mission (SN: 1/5/91, p. 10), which also included an X-ray detector.