Video: Out Of Options | The Space Shuttle That Lost An Engine | STS 51 F

Footage: https://www.youtube.com/NASA Marianne Dyson: https://www.mariannedyson.com Images: https://commons.m.wikimedia.org/wiki/File:Pressure_fed_rocket_cycle.svg https://upload.wikimedia.org/wikipedia/commons/7/71/Gas_generator_rocket_cycle.svg Scott’s Video: https://youtu.be/4QXZ2RzN_Oo This is the story of challengers 8th mission or STS-51-F, the story of STS 51 F starts on the 12th of July 1985, the space shuttle was on the pad and ready to go. The space shuttle was carrying space lab 2, it was a reusable lab that was developed by the ESA, A helium cooled IR telescope and I kid you not pepsi and coke in specially designed cans so that astronauts could drink pepsi and coke in space. Actually coke had their can ready to go on an earlier mission and pepsi asked the reagan administration to not let coke be the first cola in space.

Anyway the countdown on the 12th was scrubbed when a coolant valve on engine number 2 of the space shuttle's main RS-25 engines malfunctioned at T-3 seconds. The coolant valve had to partially close for the engine startup; it had to go from 100% open to 70% open but this didn't happen. They had to abandon their launch attempt and their next window of opportunity was on the 29th of july 1985, and on the 29th all the readings from the vehicles were healthy, they were a go for launch, at 5 pm edt after a delay of about and hour and a half challenger was on her way to space, the engines ramped up to full power to clear the shuttle of the tower and as she executed the roll program, they throttled the engines down to 65%. The engines are throttled back at max-q or maximum aerodynamic pressure to reduce the loads on the vehicle. Challenger made it through max-q, and when it was a little over two NM from the launch pad huston came on the frequency and said “Challenger huston youre go with throttle up” giving them the all clear to push the engines back up to 104%. So far so good the APUs and the fuel cells were all in the green. One minute and 30 seconds into the flight all looked good, the shuttle zoomed upward at 2000 feet per second. A while later the solid rocket boosters fell away as they had done all that they could to get challenger into orbit. 5 minutes and 5 seconds had gone by still, everything was going according to plan. Suddenly a voice comes over the radio and says “standby for press to ATO”, Which was quickly followed up by “challenger huston press to ATO”. Challengers engine number 1 had failed and they were told to ATO or reject to orbit. Now i am using the word reject instead of another word. Just bear with me ok? ATO was a way to safely reject the launch, in this case due to the engine failure they wouldn't be able to reach their intended orbit and the ATO allowed them to reach a safe albeit lower orbit than the targeted orbit.
This reject call was made based off of a flurry of activity at Houston. At the flight dynamics console two people by the name of brian perry and bruce hilty had been pouring over the ARD or the reject region determinator. It was a computer that gave them their reject options in the current phase of flight. A person by the name of Jenny Howard monitored the main engine parameters that were being beamed down from challenger. As her data told her the bad news jenny howard called “center engine down” on the flight director loop. Focus was now on perry and bruce, they now had to make the all important decision of what to do.

Challenger at this point was at an altitude of 58 nm and the downrange distance was 275 nm. Challenger was too far away to attempt a return to Kennedy space center. Challenger could make it to a lower orbit with two engines but before they could make that call brian perry his flight dynamics team had to run some calculations about how the external fuel tank which was still attached to the shuttle would impact things. The math checked out they would be able to reject this launch and reach the safe lower orbit , and thats how huston made the ATO call. Once the shuttle crew got the ATO command from houston shuttle commander Gordon fullerton turned a rotary dial in the cockpit to the ATO setting