Shuttle Studies Earth's Atmosphere With New Lasers

NASA'S NEW SPACE-WALK BACKPACK

SAFER [Simplified Aid for EVA Rescue] - A rocket-powered backpack to help untethered astronauts return to their spacecraft during EVA (Extra-Vehicular Activity).

THE six astronauts now orbiting on board Discovery are setting new bench marks in space.

They are testing the first space-based optical ``radar'' to probe clouds and aerosols in the atmosphere. They are carrying the first automated factory in which a robot, instead of a human astronaut, does the work. And, later this week, they plan to test a new self-rescue rocket-powered backpack that would enable untethered astronauts to get back to their ship or space station if they accidently drift away.

The National Aeronautics and Space Administration (NASA) points out that the propulsion unit will be essential equipment for shuttle astronauts on their visit to the Russian MIR space station, now planned for next spring. Should they have to do any space walking, the self-rescue packs would help ensure safety.

Discovery has another experiment aimed at safety during the MIR rendezvous. Astronaut Susan Helms has been using instruments attached to the shuttle's manipulator arm to measure the effect of Discovery's thruster plumes on nearby objects. This will help engineers determine any danger from thrusters when shuttles dock with MIR. Astronaut Helms said that the 32-foot instrument boom on the end of the 50-foot robot arm is ``an awesome sight,'' as this 82-foot combined structure moves around the shuttle probing the thruster plumes.

The astronauts have been busy with these and other experiments since the space shuttle Discovery began its 8-day, 20-hour, 11-minute mission at 6:23 p.m. last Friday.

The crew has already successfully carried out much of the program planned for the space-based `radar' also known as a lidar probe. NASA considers the probe ``a revolutionary new tool'' that should become a key element in the agency's Mission to Planet Earth program. The program involves extensive environmental monitoring of our planet with a series of satellites beginning in 1998. The constitution and structure of clouds and makeup of aerosol particles in the atmosphere are important environmental factors the program wants to monitor.

Discovery's experimental equipment is called LITE. That's ``spacespeak'' for Lidar-in-space Technology Experiment. It emits pulses of infrared, green, and ultraviolet light ten times a second. By timing the return reflection of these pulses and measuring its strength, scientists can accurately determine droplets and particles composition and estimate their altitude within 50 feet.

NASA also that the laser pulses should be visible from the ground. There should be no danger in seeing them with unaided eyes or small binoculars and telescopes. But NASA warns against trying to see the shuttle with telescopes larger than six inches or with sensitive electronic detectors.

Meanwhile, back in Discovery's cargo bay, a small robot has been methodically taking semiconductor samples out of storage racks and running them through halogen lamp furnaces. Remelting the samples should form more perfect crystals for use in making electronic devices. The object is to begin testing robotic technology that would be used on a space station or in unmanned factories on the moon or Mars.

As the mission continues into its fifth day, the crew plans to release a free-flying satellite to study the solar wind of charged particles and magnetic fields coming from the sun. The astronauts plan to retrieve the satellite later this week. They are due to land at the Kennedy Space Center Sunday. But, if there is enough fuel, NASA may extent the mission one more day.