Space-Based View of the Environment Gets Under Way

SIX astronauts have gone into space to carry out a down-to-earth mission. They are using the most advanced imaging radar ever flown to carry out extensive geological observations. They also are mapping the concentration of carbon monoxide - one of the more important global air pollutants.

After an on-time lift off at 7:05 am EDT Saturday, their space shuttle Endeavour has settled into an orbit 138 miles high and inclined 57 degrees to the equator, allowing detailed geological mapping of most of the northern and southern hemispheres.

Although the spacecraft and crew are American, this is a widely international mission. The United States National Aeronautics and Space Administration (NASA) and the German and Italian space agencies have supplied the mapping radar. Forty-nine scientists plus three associates from thirteen countries are carrying out the radar experiments. It's part of what NASA calls the Mission to Planet Earth, using space-based observations to characterize and monitor the global environment and any human-made changes. Radar is one of the main tools for doing this.

As the Magellan mission that mapped Venus has shown, radar can produce finely detailed surface maps. Moreover, it can ``see'' through clouds and storms and the dark of night as well as seeing in daylight and clear weather. Thus the $366-million instrument Endeavour carries should be able to make observations throughout most of the 10 days currently allotted for this mission. NASA has scheduled Endeavour to carry the equipment back into orbit in August for a comparison study.

The radar instrument is large - measuring 39 feet by over 13 feet. Computers enable the moving radar to produce images with a fineness of detail that only a much larger stationary antenna could provide.

At press time, mission controllers appeared to have worked around a problem with one of the radar amplifiers. It had failed to function automatically. However, it can be used manually. ``Things are looking up,'' Mission Control reported, and the astronauts continued their work collecting some 50 hours worth of radar images covering 18 million square miles of land and sea.

They will survey terrain as varied as the Death Valley desert, the mountainous Alps, and tropical jungles. Wetlands, a key wildlife habitat, are an important feature being surveyed, as well as the waves and flow patterns of the Gulf Stream. Some 2,000 scientists, teachers, and students will be covering the ground at selected sites, making detailed studies to compare with the radar images. Astronauts also plan to take some 14,000 pictures with the 14 cameras they have on board to supplement the radar data.

NASA plans eventually to have imaging radars on unmanned satellites that will be part of a permanent Mission-to-Planet-Earth monitoring system.

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