Emphasis Is on Science as Challenger Prepares for Afternoon Blastoff
The space shuttle Challenger is scheduled to lift off today on a scientific mission that will explore the nature of the sun and the Earth’s ionosphere, the crucial layer of atmosphere that shields this planet from the sun’s radiation.
If the countdown continues until launch time without serious problems, the Challenger will roar away from the pad at 1:30 p.m PDT packing $72 million of astronomical equipment. Weather forecasters predicted a 40% chance of rain for the liftoff. But, they said, the showers would probably pass quickly and allow the launch to take place.
The flight will be the third in a series of Spacelab missions devoted almost entirely to scientific experiments. The shuttle crew of seven will work 24 hours a day, in two 12-hour shifts, to complete the complex array of projects before its scheduled landing on Friday, July 19, at Edwards Air Force Base in California.
Cosmic Ray Study
In addition to the solar experiments, the crew will attempt to make the first detailed study of cosmic rays, the high-energy particles produced by exploding stars and other violent events in the cosmos. Virtually all cosmic rays are absorbed by the atmosphere before they reach the Earth’s surface and can only be examined in space or the high atmosphere.
To complete these tasks, the National Aeronautics and Space Administration has assembled a flight team with a variety of academic degrees. In addition to the commander and the pilot, the crew includes three astronomers, a geophysicist and a medical researcher.
NASA officials say they have granted the team an unusual degree of freedom in conducting the experiments. The scientists will be free to alter programs should unexpected opportunities appear.
‘Keen Sense of Anticipation’
“They will have the license to capture interesting scientific moments,” said Charles Redmond, a spokesman for NASA. “There is a very keen sense of anticipation about this flight and the scientific rewards it may produce.”
Perhaps the most dramatic event in the weeklong schedule will be an attempt to study the behavior of the ionosphere by using the shuttle’s large maneuvering rockets to “burn” a series of holes in the atmospheric layer.
The ionosphere, so named because it is composed largely of electrically charged ions, extends from about 35 miles above the Earth’s surface to a maximum of 375 miles. It is crucial to man’s survival because of its role in absorbing harmful radiation from the sun. It also reflects radio waves and makes possible worldwide communication via short-wave.
In the experiment, the rocket engines will fire briefly at eight different locations over the Earth. Water, which is a natural by-product of rocket combustion, will temporarily neutralize the ions, giving scientists in space and on Earth an opportunity to penetrate the holes with radio waves and study the reformation of the layer.
Solar Studies
The solar studies will attempt to answer questions about the sun’s surface, particularly the turbulent storms that often dominate its atmosphere. According to Spacelab program manager John Thomas, the solar project has been delayed as NASA waited for the arrival of a redesigned platform on which several telescopes will be mounted.
The platform, manufactured in West Germany, is a sophisticated pointing device that can maintain the position of telescopes with extreme accuracy even during shuttle maneuvers. If the experiments go well, Thomas said, they could provide new information about the relationship between the sun’s activity and weather on the earth.
The cosmic ray project may give scientists their most accurate profile yet of the particles that are born in other galaxies. The experiment will be conducted with a huge, egg-shaped detector made of the plastic Lexan. As cosmic rays strike the plastic, they will produce very brief, blue flashes of light. By taking precise measurements of these strikes, scientists hope to find out more about the origins of cosmic rays.
While these and other experiments are taking place, ham radio operators will be offered their best opportunity yet to communicate with the space vehicle. Two of the astronauts, Anthony England and John-David Bartoe, have volunteered to communicate with earthbound ham radio operators during their free time. In addition, amateur television operators will be able to receive still images from the shuttle’s flight deck on home equipment.
In addition to England and Bartoe, crew members for this all-male flight are Air Force Col. Gordon Fullerton, 48, the commander; Air Force Col. Roy D. Bridges, Jr., 41, the pilot; Karl Henize, 58, an astronomer; F. Story Musgrave, 49, a medical researcher for NASA; and Loren W. Acton, 48, an astronomer for the Lockheed Corp.
