Shuttle Launch Is Aborted With 11 Seconds Left
NASA computers halted the countdown 11 seconds before today’s launch of space shuttle Discovery, with five astronauts on a mission to study the thinning of the Earth’s protective ozone layer.
The four men and one women aboard Discovery were in no danger as NASA hurriedly turned off shuttle systems.
NASA called off all launch efforts for the night.
Discovery was supposed to lift off at 1:32 a.m. EDT, but NASA held the countdown at nine minutes because of high crosswinds and a last-minute problem with a engine temperature sensor.
Launch officials resumed the countdown after a one-hour wait, and were stunned when the countdown clock halted at 11 seconds to liftoff.
The eight-day flight was to be the second in a series of atmospheric research projects by NASA.
Scientists fear that the upper atmosphere’s layer of ozone gas, a shield against dangerous ultraviolet rays, is being consumed by human-made pollutants and possibly volcanic gases.
The chief culprits are chlorofluorocarbons--chemicals used in air conditioners and refrigerators. CFCs, on the verge of being phased out, release chlorine atoms that wipe out ozone.
Based on measurements from the first research mission, flown by Atlantis last spring, scientists confirmed a 30% buildup of chlorine in the stratosphere since 1985, said William Townsend, deputy associate administrator of the Mission to Planet Earth program. He expected Discovery’s flight to encounter even higher chlorine concentrations.
While a hole in the ozone over the Antarctic is fairly well understood, researchers are perplexed about the increasing loss of ozone over the Northern Hemisphere. No Arctic ozone hole exists--yet.
In February, Canadian scientists reported the lowest ozone levels ever recorded in that country over Edmonton, Alberta--about 25% below pre-1980s levels. And in March, the World Meteorological Organization said ozone levels were 9% to 20% below normal this winter over middle and upper latitudes of the Northern Hemisphere.
If heightened levels of ultraviolet radiation penetrate the atmosphere to Earth’s surface, it could increase skin cancer and cataracts, weaken the human immune system, destroy ocean plankton and stunt plant growth.
A nighttime launch of Discovery was essential for catching sunrises at the northern latitudes, the best time for measuring ozone there. Only seven out of 53 shuttle launches, including Discovery’s today, have been at night.
Many measurements by three ozone instruments in Discovery’s cargo bay were to coincide with observations by satellites.
The cargo bay also held four instruments to measure solar energy. Even small changes in the sun’s energy output can affect Earth’s climate and ozone concentrations.
More than 100 shuttle maneuvers were planned to point the instruments in the right directions.
