NASA Engineering Department
NASA Headquarters
Suite 5R30
Washington, DC 20546
(202) 358-0001 (Office)
(202) 358-4338 (Fax) nasa.gov January 20, 1986

Mr. Cummings
Director of Investigations
Federal Government Investigative Agency
1600 Pennsylvania Avenue
Washington D.C, 02210
Dear Mr. Cummings:
RE: Challenger shuttle; solid-propellant booster O-ring failure
I am writing to inform you about my concerns regarding the launch of space shuttle Challenger which is scheduled to launch on January, 28 1986. I have already attempted to voice my concerns to my engineering supervisor through an interoffice memorandum, but my concerns were promptly dismissed in a manner that failed to resolve my concerns. For this reason, I am writing to ask for your help in averting what could potentially be a fatal accident if these concerns are not addressed.
I am an engineer working the space shuttle Challenger project. My job is to observe every part of the shuttle before and after it has been launched. I make detailed documentations of every part of the shuttle and ensure they are functioning according to its manual.
The space shuttle is designed to be a reusable launch vehicle with two solid-propellant boosters, and a single liquid-propellant booster. My main concern is with regards to the solid-propellant booster. Unlike its liquid counterpart, a solid-propellant booster has the disadvantage that once it is ignited, there is no immediate method to shut it off or to control the amount of thrust coming from it. For this reason, O-rings had to be installed inside the boosters in order to prevent hot gases from the combustion from escaping. Unfortunately, the rings are not particularly heat resistant and tend to be damaged by the heat emitted from the combustion. To prevent damage to the rings, a heat-resistant putty is placed inside the booster.
My concern with the boosters is in the joints where the rings and putty are located. The internal pressures from the propellant causes the joint to open slightly, allowing the hot gases to escape through that small opening. Since the joints must be fully sealed in order for the putty to protect the rings effectively, the hot gases escaping the joints cause the rings to erode significantly. If the rings completely burn through before the solid-boosters run out of fuel and are jettisoned, there is a high risk of heat combustion igniting the liquid-propellant, which would lead to the explosion of the liquid-booster itself.
I became aware of this problem on January 24, 1985, which is the date of the first documented joint failure after the launch of one of the space shuttles. It seemed that the rings lost some of its resiliency at reduced temperatures; the temperature that day was 53 degrees Fahrenheit. Although this problem was first noticed on January 24, 1985, redesigning and reconstructing the rings in order to resist more heat would take much more than a year to complete. After speaking with the director of the Solid Rocket Booster Project, Alan McDonald, we both came to the conclusion that the shuttle should launch when the outside temperature is at least 53 degrees in order to avert complete erosion of the rings before the fuel runs out. The weather forecast for the launch of Challenger showed that the temperature on January 28, 1986 will be 28 degrees. I immediately voiced my concerns to my supervisor, recommending to postpone the launch until the weather conditions were more favorable or the erosion problem is addressed. My supervisor, after looking at the forecast and speaking Mr. McDonald, promptly dismissed my concerns. The reasons my concerns were dismissed was because the data from my memorandum was inconclusive with the fact that the boosters were originally specified to work at temperatures as low as 31 degrees. I attempted to voice my concern again by mentioning the fact that a temperature of 28 degrees would still be unsatisfactory with the original specification. Once again, my concerns were dismissed on the basis that my data was inconclusive and that the postponement of the launch would cause NASA to potentially lose its funding.
Majority of the engineers who read over my memorandum agreed that there is a potential problem with the O-rings at decreased temperatures and that the launch should be postponed until the problem is properly addressed. They also mentioned that postponing the launch would make Congress increasingly unhappy with the shuttle project and shuttle performance. In my professional opinion, launching the shuttle on this date would lead to a potentially fatal malfunction of the O-rings that can lead to the explosion of the liquid-fuel booster. This alone would make the situation worse for NASA since we are putting the lives of astronauts at a greater risk due to a fatal flaw in the design of the solid-propellant boosters.
As an engineer, it is my duty to use my professional judgment to decide whether there is a fatal flaw in the design of any part of the shuttle, which includes the boosters themselves. The most important right I have as an engineer is the right of professional conscience, which involves the right to exercise professional judgment in fulfilling my duties and to exercise this judgment in an ethical manner. This clear and important harm puts the lives of astronauts at a greater risk. I have first-hand knowledge of the flaw in the engines since I checked the blue prints and documentations myself. My co-workers and I believe there is a reasonable chance of success in postponing this launch with your help. This is my last resort to solve this problem since I have already attempted to contact the head of NASA, who has also dismissed my concerns for the launch for the same reasons. Although I do fear that I might lose my job and that I am also putting the jobs of my co-workers at stake, I do believe that I am doing what is ethically correct. It is not my intention to make NASA lose its funding, although it might not. It is not my intention to risk the jobs of my co-workers and it is not my intention to do any wrongdoing to my employer nor the company I work for. My only intention is to avert disaster and to proceed with the launching in a more safe and productive manner. Putting the lives of these astronauts at a greater risk gives no benefit to anyone and jeopardizes our true mission, which is to expand our knowledge of the universe. I only ask that you investigate this case and postpone this launch. Grounding the whole institution should be done only as a last resort. I hope that you side with the evidence that is included in this envelope and that you see the dangers that I see as a professional engineer.

Sincerely,
Joe
NASA engineer
guallpav@NASA.gov