LONDON, Ontario, March 12 (UPI) -- The danger of a high-speed meteoroid striking the space shuttle Columbia during its tragic last mission was no higher than predicted before the flight, Canadian researchers, armed with new meteor radar tracking data, have reported.
The data practically rule out the possibility an unexpected increase in the number of meteoroids might have played a role in the shuttle's destruction Feb. 1, astronomer Peter Brown of the University of Western Ontario in London, told United Press International.
NASA estimates there is normally a 1-in-370 chance a collision with a meteoroid or a piece of debris from previous missions will end a shuttle flight -- either by forcing an early return to Earth or catastrophically, as in the case of Columbia, Brown said.
The estimate is based on a mathematical model of how many meteoroids and other objects are in a position to slam into a shuttle on a given mission, Brown said. However, it is possible the model could have underestimated the danger for Columbia or there was a sudden increase in the number of meteoroids in the shuttle's path during its 16-day mission.
Data from the Canadian Meteor Orbit Radar -- a collection of tracking stations located on a farm about 40 miles from the university -- show "there were no surprises -- the initial estimates held up," Brown said.
CMOR has been tracking the so-called "meteoroid flux" -- the variation in the numbers of small natural particles passing through the Earth's upper atmosphere -- since last January, Brown said. The meteoroid flux includes "tens of thousands" of particles, most of them less than four-hundredths of an inch in diameter.
"The flux was not significantly different from other times the shuttle flew," Brown said.
Despite their small size, such particles can cause damage, Brown said, because they are moving at speeds between 27,000 and 158,000 miles per hour. The average speed of the particles is about 45,000 miles per hour.
There is always a small possibility a meteoroid strike created enough damage to cause Columbia's spectacular demise, in which the shuttle's seven crew members were killed, according to former astronaut Frederick Hauck, who chaired a 1997 committee that studied the danger of orbiting debris to the shuttle.
"You certainly can't rule anything out," he told UPI.
Hauck was commanding a shuttle mission in 1993, when a tiny paint fleck struck his craft with enough force to leave a crater "one-sixteenth of an inch deep in a one-inch (thick) window," he said. The extent of the damage "certainly surprised me at the time," he said.
NASA spokesman Catherine Watson said the agency cannot comment yet on how Brown's data fit into the investigation into the shuttle disaster. "We're at the very beginning of the investigation," she told UPI. "Everything is a possibility still."
CMOR scans a swath of sky about 190 miles wide above southern Ontario, between 50 and 75 miles up. The results are then extended to the rest of the sky, much in the way rainfall measured in one place can be used to say how much rain falls over a much wider area.
Because the meteoroids are so tiny, Brown said, the system does not detect them directly. Instead, it detects the electrical trail left as they streak through the atmosphere.
(Reported by Michael Smith, UPI Science News, in Toronto)
