The orthogrid, a large piece of aluminum-lithium metal, was carved from a single metal plate to be part of the wall of a super-lightweight space shuttle external tank (ET). The waffle pattern in the metal helped keep it strong while also making it light enough to launch. Together, 32 orthogrids made up the liquid hydrogen tank—one of the ET's two propellant tanks. But the orthogrid on display at the Science Center isn't a full piece--the bottom half has been cut off.
Liquid hydrogen used to fuel the space shuttle main engines sloshed against the waffle side of the orthogrid. The back of the orthogrid, which forms part of the tank's smooth outside wall, was coated with insulating foam to keep the hydrogen at an extremely frosty -423°F. During the trip to orbit, temperatures outside the tank could reach 1,200 degrees.
The Science Center's Orthogrid
The Science Center’s orthogrid, manufactured in nearby South El Monte, was made for a super-lightweight tank, which was the most advanced ET developed for the space shuttle. It was donated by AMRO Fabrication Corporation.