Challenger Memo

TO: Engineering and Managerial Services Distribution

National Air and Space Administration (NASA)

Marshall Space Flight Center

Morton Thiokol, Inc. (MTI)

FROM: Krystal Miarecki

DATE: July 16, 2009

RE: URGENT: SRM O-Ring Design Problem / Failure

ISSUE

After several evaluations of the Space Shuttle's Solid Rocket Boosters (SRB), engineers at MTI have discovered an issue with the O-Rings that if not addressed, could have fatal effects on the next space shuttle launch mission.

Facts:

• Primary "O" ring erosion (nozzle to case) has occurred in twelve (12) flights

• Primary "O" ring erosion (case to case) has occurred in five (5) flights; pressure build up on primary "O" ring causes secondary "O" ring to unseat

• Primary "O" ring sealing: FAILED

• During motor pressurization, field joint secondary seal lifted off metal surface (e.g. seal maintained contact at 100° F, lost contact for 2.4 seconds at 75° F and lost without re-establishing contact at 50° F)

• Secondary "O" ring sealing; FAILED at 50° F

Result of "O" ring failure:

Due to the joint erosion, the primary "O" ring fails during ignition. As a result, the secondary "O" ring may fail to serve its purpose as the redundant seal. Upon failure of a primary ring, the secondary ring may not pressurize and respond to the clevis opening rate, which means, there is no guarantee that the secondary seal would hold.

**FAILURE OF THE SRM "O" RINGS COULD RESULT IN A FATAL ACCIDENT AND LOSS OF HUMAN LIVES.**

RECOMMENDATION

Taking into consideration the time of the year and low temperatures, I feel we should not risk using the current "O" ring seals on the shuttle. It is my recommendation that the space shuttle mission scheduled for January 27, 1986 be delayed until further noticed.

In the meantime, I feel we should develop a special project team consisting of engineers and managers from NASA, MTI and Marshall dedicated to the "O" ring issue and meet weekly via conference call to discuss the project status. Furthermore, any interim correspondence should be sent via email and include all project team members.

Thank you for your attention to this matter.