MIflyer
1st Lieutenant
A cold front is approaching Central Florida right now. Tonight it will get down into the upper 30's. Tomorrow the high will be around 51F and tomorrow night it is forecast to hit freezing. Conditions are similar but less severe to those of 28 Jan 1986 when the S[ace Shuttle Challenger was lost.
Most people probably think that NASA blew past the allowable temperature limits to launch the Challenger. The reality is There Were No Temperature Limits. There were no launch temperature limits on any of our other launch vehicles, either.
Our launch vehicles were based on modification or even conversion of ballistic missiles. The standard military specification lower temperature limits established in the 1950's was Minus 65 degrees F. The reason for this as simple. At 35,000 ft the standard temperature is -65F; at 50,000 ft it is -69.7 F. So if you are going to fly even that high your equipment had to be able to handle it. This was carried over to missiles and the launch vehicles derived from them.
At Cape Canaveral and Vandenberg AFB it never gets anywhere near even 0 F; at the Cape temperatures below freezing are pretty rare and at Vandenberg pretty much unheard of. Now, vehicles did have limits on temperature for components, both high and low. Gyroscopes could not be too cold, LOX ducts could not be too warm, and propellants could not be too cool, that kind of thing, but overall Outside Air Temperature limits on the ground were unheard of; it was an alien concept. Aloft, there were limits on low temperatures in clouds to avoid triboelectric charging that can cause "St Elmos Fire" and damage flight hardware, but on thee ground or in clear air, nothing.
No launch weather lower temperature limit was ever specified for the Space Shuttle. NASA developed a policy of equipment working at 32F but that was never applied to the Shuttle. The solid rocket boosters were supposed to be tested down to plus 40F but that was never done; it is too hard to get the weather to cooperate for tests that have to done outside.
So, under pressure to make the "Shuttle Is the Only Allowed US Launch Vehicle" policy work, they launched STS-28. It broke up and exploded at T+66 sec.
Most people probably think that NASA blew past the allowable temperature limits to launch the Challenger. The reality is There Were No Temperature Limits. There were no launch temperature limits on any of our other launch vehicles, either.
Our launch vehicles were based on modification or even conversion of ballistic missiles. The standard military specification lower temperature limits established in the 1950's was Minus 65 degrees F. The reason for this as simple. At 35,000 ft the standard temperature is -65F; at 50,000 ft it is -69.7 F. So if you are going to fly even that high your equipment had to be able to handle it. This was carried over to missiles and the launch vehicles derived from them.
At Cape Canaveral and Vandenberg AFB it never gets anywhere near even 0 F; at the Cape temperatures below freezing are pretty rare and at Vandenberg pretty much unheard of. Now, vehicles did have limits on temperature for components, both high and low. Gyroscopes could not be too cold, LOX ducts could not be too warm, and propellants could not be too cool, that kind of thing, but overall Outside Air Temperature limits on the ground were unheard of; it was an alien concept. Aloft, there were limits on low temperatures in clouds to avoid triboelectric charging that can cause "St Elmos Fire" and damage flight hardware, but on thee ground or in clear air, nothing.
No launch weather lower temperature limit was ever specified for the Space Shuttle. NASA developed a policy of equipment working at 32F but that was never applied to the Shuttle. The solid rocket boosters were supposed to be tested down to plus 40F but that was never done; it is too hard to get the weather to cooperate for tests that have to done outside.
So, under pressure to make the "Shuttle Is the Only Allowed US Launch Vehicle" policy work, they launched STS-28. It broke up and exploded at T+66 sec.
