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Q: What went wrong on Saturday morning?
|[Times photo: Dan McDuffie]
A photo of the Columbia crew and a wreath sits at the Astronauts Memorial at Kennedy Space Center Saturday.
Q: Was the Columbia flying properly before the crash?
Yes. But minutes before losing contact with Columbia Saturday, NASA officials noticed a troubling sign: Heat sensors on the left wing of the shuttle had stopped operating. They also detected a loss of tire pressure on the landing gear.
Q: Were there previous troubles on this mission?
A minute after Columbia lifted off on Jan. 16, a piece of insulating foam on its external fuel tank came off and was believed to have hit the shuttle's left wing. NASA officials said engineers concluded at the time that any damage was minor.
Q: Could this foam incident have led to Saturday's accident?
NASA shuttle project manager Ron Dittemore said that possibility will be studied, but stressed it was too early to conclude that this caused the crash.
Q: Why didn't astronauts conduct a spacewalk to see if tiles on the left wing of the shuttle had been damaged and needed repairs?
Shuttle astronauts do not have the capability to repair tiles in a space flight, Dittemore said.
Q: Was terrorism involved?
"There is no information at this time that this was a terrorist incident," said Gordon Johndroe, spokesman for the Homeland Security Department. "Obviously the investigation is just beginning, but that is the information we have now."
At 39 miles up, the shuttle was beyond the range of surface-to-air missiles.
Q: What are some other possible causes?
An explosion of some of the shuttle's fuels and oxidizers; a collapse of some part of the shuttle's structure; faulty navigation for re-entry; the impact of a speeding rock or space debris.
Q: Was there a black box on the space shuttle?
No. Recorders were on board but officials don't know if they survived. NASA officials say their evaluation of shuttle debris will be one of the keys to determining what happened.
Q: Was weather an issue?
NASA officials say Saturday morning was virtually a perfect day for landing.
Q: What made the Challenger explode 17 years ago? Could the same thing have happened Saturday?
No. Four months after the Challenger crash, an independent commission reported an O-ring seal leaked in the right booster rocket during the shuttle's launch. That allowed hot gases to burn through the bracket securing the booster to the shuttle, rupturing the shuttle tank.
Saturday's accident occurred during the approach to the planned landing in Florida, when a booster rocket is not used.
Q: Does this accident mean months or years of delay as shuttles are analyzed and refitted?
Dittemore said the disaster will put future shuttle flights on hold "until we find the root cause."
Q: What is the status of American astronauts on the international space station? Can they come home without a space shuttle?
Two Americans, Kenneth Bowersox and Dr. Donald Pettit, and Russian Nikolai Budarin are on the international space station. Expedition Six, as the current crew is called, arrived at the station in November, and is supposed to remain at the station until mid March. NASA officials said they could stay in the space station as late as June, if necessary. NASA could retrieve the astronauts using Russian vehicles if need be.
However, if the space agency's remaining shuttles are out of service for an extended period in the wake of today's catastrophe, as seems likely, it will be difficult to maintain the station's operations.
Q: Who will investigate the cause of the crash?
An outside board made up of experts from the Air Force, Navy, the U.S. Department of Transportation and other federal agencies. An internal NASA review also is under way.
Q: What was the last exchange between NASA and the astronauts?
Mission Control: "Columbia, Houston, we see your tire pressure messages and we did not copy your last."
Columbia's commander, Rick Husband, calmly: "Roger...."
Then, for several seconds, the transmission went silent, and after that there was only static.
Q: Where was Columbia at the time of the disaster?
It was 207,135 feet above Texas, traveling at mach 18.3, or more than 18 times the speed of sound.
Q: What was the focus of this mission?
The astronauts looked at such things as ant, bee and spider behavior in weightlessness, and changes in flames and flower scents in orbit. They also took measurements of atmospheric dust and collected blood and urine samples. The crew completed all of more than 80 experiments.
Q: Are these experiments lost?
Data from some experiments were electronically sent to Earth, where scientists can review the information. Other experiments needed to be evaluated on the ground, and these results have been lost.
Q: NASA said debris from the shuttle could contain a mixture of poisonous chemicals that can be dangerous if inhaled or touched. What were they?
Liquid oxygen from the shuttle's fuel system or liquid nitrogen used to inflate the shuttle's tires could severely burn anyone who touches them. Also, liquid nitrogen could combine with oxygen in the atmosphere to form nitrous oxide, a gas that can be fatal. Other dangerous chemicals include monomethyl hydrazine and nitrogen tetroxide, which are used as rocket fuel.
Q: How hot does the space shuttle get while re-entering Earth's atmosphere?
Up to 2,400-degrees Fahrenheit on the tiled underbelly and up to 3,100-degrees on the nose and wings.
Q: What were the previous catastrophic disasters in the U.S. space program?
On Jan. 28, 1986, the Challenger exploded shortly after launch, killing all seven astronauts aboard: Christa McAuliffe, Francis "Dick" Scobee, Michael J. Smith, Ellison S. Onizuka, Judith A. Resnik, Ronald E. McNair and Gregory B. Jarvis. On Jan. 27, 1967, astronauts Gus Grissom, Edward H. White and Roger B. Chaffee died when a fire swept their command module during a ground test at Kennedy Space Center.
-- Compiled by Times staff writer Curtis Krueger and researcher John Martin and includes information from Associated Press, Scripps-Howard and the New York Times.