Nov 4 1985
From The Space Library
A team of Jet Propulsion Laboratory (JPL) researchers launched on November 4, as part of the Balloon-borne Laser In-situ Sensor (BLISS) experiment, a 10.2-million-cubic-foot balloon carrying a microprocessor-controlled payload that produced vertical profile measurements of nitrogen dioxide, water vapor, and nitric oxide concentrations at 115,000 and then 90,000 feet in altitude, the JPL Universe reported. When researchers left JPL for Palestine, Texas, to conduct the research, they expected to return home in three weeks. But two hurricanes, a cancelled insurance policy, and a balloon failure-which caused JPL's instrument-laden gondola to be dumped in the mud in a prison camp-extended the trip to 11 weeks.
The researchers used two balloons, each large enough to enclose an entire football field, to lift scientific payloads into the atmosphere. At launch, the balloons stood about 600 feet high and were about 70 feet across; at cruising altitude they expanded to about 420 feet.
A balloon's 3000-lb. payload included two types of lasers, a TV camera, and a retroreflector suspended by a steel cable one-third mile below the gondola after the balloon reached cruising altitude. The optically tracked retroreflector-swinging like a pendulum-bounced infrared laser beams through the atmosphere and back to the payload's receiving optics. "We use liquid helium to cool the lasers and our supply only lasts a day," said Dr. Christopher Webster, principal investigator for the experiment. "So over the 11 weeks we had to fill the cryostats 220 times." Balloon failures in scientific research occurred frequently, mainly due to defects in the thin plastic balloon material or because seams ripped out, Webster noted. "This is a serious problem and scientific research is definitely suffering because of it," he said. "However, the payload recovery is excellent, so JPL does not lose its instruments." "The greatest advantage of a balloon-borne laser instrument;' he added, "is that we can obtain continuous spectroscopic analysis of the upper atmosphere in situ with high sensitivity." (JPL Universe, Nov 29/85, 3)
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