Maybe you’ve noticed that in older pictures of the , the Shuttle’s giant external tank appears brilliant white instead of the rusty orange color we have become so accustomed to over the years. So what caused the tank’s change in color palette?

Originally the Shuttle’s external tank was painted with white latex paint not just to match its fellow Orbiter and Solid Rocket Boosters components, but to reflect UV rays, keeping the tanks’ liquid oxygen and liquid hydrogen fuel cool after being filled prior to launch.

After the first two Shuttle flights, STS-1 and STS-2, NASA and Lockheed Martin, who built the tanks, decided that this extra bit of thermal protection was not really needed and that 600 pounds could be saved by not including it. The weight saved by omitting the white paint could be used for extra payload or performance. As a result, future missions reverted to the tank’s insulating foam’s natural tone, which was rust orange in color.

Today these photos of shining white Shuttle Stacks from the early 1980s stand as a sobering testament to a time in America’s history where so much seemed possible. Sadly, the Shuttle Program would turn out to be more of a very expensive anchor that would keep mankind stuck in orbit for decades than a economical space plane that could facilitate exploration beyond earth’s orbit.

The Shuttle’s external tank would further hamper the program after the tragic loss of Columbia in 2003. Still, perhaps the Shuttle’s retirement was premature as it came once we finally learned how to confidently operate the complex system in a safe manner.

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Photos via NASA.