TO: Distribution - Engineering and Managerial Services, National Air and Space Administration, Marshall Space Flight Center, Morton Thiokol, Inc.
FROM: Krystal Miarecki, Heidi Pak
RE: URGENT: Avoiding Disaster on STS 51-L (Challenger Shuttle) Mission
In regards to STS 51-L (Challenger Shuttle), we have identified a design problem with the SRM O-rings that, if not addressed, could result in a fatal mission.
Solid Rocket Boosters (SRBs) are relatively new technology to us, as opposed to liquid-fueled systems. As the Challenger will be the first astronaut-manned mission using SRBs, we cannot take any risks.
The problem we have run across lies in the O-rings. At launch, the O-rings will lose their original shape due to motor pressurization. While it is in the nature of the O-rings to return to its original shape, we have found that there are milliseconds in between the transformation of the O-rings that determine system failure or success.
Furthermore, we have discovered that temperature affects the rate at which O-rings return to their original shape. After numerous tests, we found that field joint secondary seals lifted off metal surface under the following conditions: 1) at 75° F lost contact for 2.4 seconds; and 2) at 50° F lost contact without re-establishing. With our launch deadline set for January 27th, the temperatures have very little chance of being above 50 degrees.
When dealing with extremely sensitive materials that determine success or failure in milliseconds, it is unethical to gamble with the seven astronauts' lives and the reputations of our three organizations. Therefore, I urge the managers to consider postponing the launch date until further research is conducted and safe launching temperature has been reached.
As funding is tight and deadlines are crucial, a public statement must be released regarding the crucial need for more research into the technology behind the O-rings, as well as supporting statements as to why we are relying on SRB versus liquid-fueled systems.
Thank you for your attention and consideration.
Heidi and I approached our memos a little differently. Her memo provided an overview of facts and felt personal in nature. My memo was more technical in regards to details of the shuttle problem. Both memos were of an urgent nature. We combined the two memos, providing a good balance of technical details and personal touch; while keeping an urgent tone. I feel this was a good combination for our mixed audience of managers and engineers.
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