1.The first spaceflight of Challenger
began on April 4, 1983. Challenger was the second orbiter
built to fly in space after Columbia.
2. Challenger flew 9 successful missions from 1983 to the end of 1985. During that time it flew more than any other orbiter, carried the first woman astronaut in U.S. history, took part in the first-ever repair of a satellite in space, and was the first orbiter launched at night.
3. The year 1986 was to be the biggest year for the Space Shuttle yet. A total of 15 flights were planned: including the launch of the Hubble Space Telescope, the Gailieo and Ulysses space probes, and the first launch from Vandenburg Air Force Base in California. By 1988, NASA was hoping to launch 24 shuttle missions per year. (The most ever achieved was nine. The shuttle cannot fly much more than this in a year.) But the events of a cold day in January would forever alter these plans.
4. Challenger was destroyed on its 10th mission on January 28, 1986 on the 25th space shuttle launch. All seven crew members, including teacher-in-space Christa McAuliffe, were killed in the disaster. During the mission, it was planned that a communication satellite would be deployed and experiments would take place. Christa McAuliffe would also teach some lessons from space that would be transmitted to classrooms on Earth.
5. The accident was caused by a rupture in a joint in the right-hand solid rocket booster. (SRB) . Solid rockets use solid fuel and do not have an actual engine with valves, pipes, and pumps. Like huge firecrackers, they are lit and keep burning until all the fuel is gone. Solid fuel feels much like a rubber eraser when it hardens. Each SRB is 149 feet long and is made up of 4 main sections that are bolted together to form the whole booster. Where these sections come together, there is a weak spot where fire could leak out the side of the rocket when it is burning. To stop this from happening, two rubber O-ring seals (like washers in your water faucet) were placed in the joint. NASA had been having problems (burned seals) with the O-rings for several years, but they believed that the second O-ring would stop any fire from leaking from the joint. A change in the design of the SRB joints was planned for 1988.
6. Rubber becomes stiffer the colder it gets. The launch of mission 25 took place in the coldest weather ever for a launch-36 degrees F. The cold temperature caused the rubber O-rings to fail in the lower joint of Challenger's right SRB. At liftoff, black smoke shot out from the joint, indicating that the O-rings were burning up. The smoke stopped after about 2 seconds into the flight, soot probably clogged the leak-for a while.
7. At T+40 seconds, the shuttle was hit by strong wind shears. Although this was not a danger to the shuttle itself, the winds may have pushed out the soot and caused the joint to leak again. At T+59 seconds, a plume of flame shot out of the rocket joint and burned a hole in the external fuel tank (ET), where liquid oxygen and liquid hydrogen was stored for the shuttle's 3 main engines during launch. It quickly began burning hydrogen in the lower part of the ET. At about T+73 seconds, the plume burned away the lower strut that attached the SRB to the ET. The SRB swung around and the nose slammed into the ET, causing liquid oxygen to spill out. Then the plume caused the dome on the bottom of the external tank to fall off. This released thousands of gallons of liquid hydrogen. Since the ET is pressurized so the fuel will flow into the orbiter's main engines, the fuel acted like a rocket motor, adding nearly 3 million pounds of thrust to the shuttle. This extra thrust was more than the ET could stand, and it broke apart. The fireball that appeared was actually just the fuel from the ET spilling out and burning. There was no explosion. Like the ET, Challenger was not designed to withstand this much thrust in the thick atmosphere at only 46,000 feet. The ET break-up also pushed Challenger off course and out of its slipstream at Mach 2. These forces caused Challenger to break apart into many pieces that fell into the Atlantic Ocean. All seven crew members perished when their crew compartment slammed into the ocean at over 200 MPH. (During the first two minutes of flight, when the SRB's are operating, there is no way for the crew to escape if a major problem occurs with the boosters.)
8. Following the disaster, NASA redesigned the joints of the SRB's, increased the safety in other shuttle systems, and added an escape system for the crew. Discovery made the first flight after the Challenger Accident on September 29, 1988. (32 months after the disaster)
9. To bring the space shuttle fleet back to four after the accident, NASA ordered another orbiter built from Rockwell International. Endeavour joined Columbia, Discovery, and Atlantis in the shuttle fleet in 1992.
10. The disaster was a reminder of the extreme dangers of spaceflight and the courage it takes for people to fly in sapce.
Copyright 2002 B. Holt. No part of the content of this site may be reproduced or retransmitted without the prior written consent of the owner. Any use or sale for profit is strictly prohibited. All rights are reserved. (Some logos and graphics used here are copyrighted by their respective owners.)
Back to Links
Back to Home Page