Another Major Milestone For The Space Shuttle Endeavour’s 'Go For Stack' Mission Is Here

The California Science Center started moving a large external space shuttle tank into the Endeavour’s permanent “Go For Stack” position Wednesday morning.

The 65,000-pound bright orange tank, known as ET-94, will be slowly and steadily transported through Exposition Park to the construction site for the Endeavour’s new home — the soon-to-be Samuel Oschin Air and Space Center.

About ET-94

Jeff Rudolph, the president and CEO of the California Science Center, told LAist this is the last flight-ready external tank left in the world.

ET-94 worked like your car’s gas tank, but for the space shuttle orbiter that's about 30 times heavier.

It carried all the propellants, such as liquid oxygen and liquid hydrogen, that flowed into the main engines to help push the space shuttle into orbit, according to the California Science Center.

The tank also worked as a structural support for the entire stack and is the only piece that was not reusable.

Each time a shuttle was sent out into space on a mission, its empty external tank would detach about 70 miles above the surface of the Earth. It would then fall back toward the ground on a planned path over the Pacific Ocean or the Indian Ocean, almost completely disintegrating on its way through the atmosphere.

Three types of tanks were used for the Space Shuttle Program: standard-weight tanks, lightweight tanks, and super lightweight tanks. They all look the same on the outside, but their internal construction and materials vary.

Larry Clark is a retired space shuttle engineer who worked on all 135 missions at the Kennedy Space Center in Florida.

He told LAist this tank is “very special” because it was built to fly to the International Space Station on the Columbia space shuttle, but it didn’t end up being used because those missions started requiring the newer super lightweight tanks. 

However, Columbia ended up being destroyed in 2003 on its return to Earth for its 28th and final flight. ET-94’s sister tank, ET-93, was involved with that mission.

Seven astronauts were killed, and ET-94 was studied extensively to try and figure out if it contributed to the disaster in any way, according to the California Science Center.

Many pieces ended up being removed from the tank, and the museum has had specialists doing restoration work so the tank will be ready for display at the Samuel Oschin Air and Space Center once construction is complete.

For example, most of the tank had been covered with a 1-inch thick layer of spray-on foam to protect it from the extreme heat of launch, but a lot of that foam was removed after the Columbia disaster.

California Science Center mold makers have been using silicone impressions to cast new pieces of foam that have been added to the areas that have a lot missing. Restoration specialists have also been painstakingly hand-sculpting the new pieces so they match the texture of the rest of ET-94.

Alyson Goodall, the chief advancement officer for the California Science Center, told LAist they weren’t sure if they’d be able to get this tank because NASA had other plans for the part. 

ET-94 did eventually make it to Exposition Park in 2017. Goodall said it made the journey by barge through the Panama Canal from a NASA facility in Louisiana.

California Science Center crews spraying foam on the external tank so it'll be ready for public display once construction is complete.

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The California Science Center

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What’s next

Now that ET-94 is put in place, the California Science Center will lift the enormous tank vertically with an even bigger crane late Thursday night.

Clark noted it’s going to be a slow and steady process because it fits directly between both of the solid rocket boosters. 

“It’s like choreographing and performing a difficult ballet,” he said. “Body position is just like the crane position.”

It's expected to take several hours into early Friday morning, weather, and wind permitting. Goodall said the safety of the people and the artifacts involved is their top priority, and just like a space shuttle launch, the lift could get scrubbed.

The 154-foot-tall tank is the largest piece of the space shuttle stack. Once this major milestone is complete and the external tank is set-up in the construction zone, crews will turn their focus towards the Endeavour.

The last piece of the “Go For Stack” puzzle will be moving the roughly 176,000 pound orbiter from its temporary home at the Samuel Oschin Pavilion, where it’s been on public display for more than a decade.

Toward the end of January, crews will carefully move the Endeavour east through the California Science Center’s property. The orbiter will then be lifted hundreds of feet into the air and installed with the rest of the stack.

Once complete, the Endeavour will be in its 20-story vertical “ready-to-launch” position in what will be the world’s only authentic space shuttle stack.

Lynda Oschin is chairperson of the Mr. and Mrs. Samuel Oschin Family Foundation. She told LAist it's a dream come true to watch these milestones for the space shuttle stack that will be housed in a building named after her late husband, Samuel Oschin. 

“It’s all about the things that my husband loved,” she said. “It’s inside that shuttle, everything that he loved and thought about and dreamed about.”

Oschin credits Clark and the Kennedy Space Center team for making the “Go For Stack” dream a reality. She said she wouldn’t have done it without them, and she means it.

In her contract with the California Science Center, Oschin said she included a stipulation that this specific team had to do the work, or else she wouldn’t be a part of it. She said it was very important for her that they would be able to bring their decades of knowledge, expertise, and passion to this project.

However, you’ll have to wait a while to see it again. The California Science Center still needs to finish building the rest of the Samuel Oschin Air and Space Center, which is expected to take at least another two years or so.

“Everyone from the foam restorers, to the engineers that figure out how to put the stack together, to the people operating the crane — everyone is committed to this absolutely one of a kind project,” Goodall said. “It will be a worldwide attraction right here in South L.A.” 

The California Science Center will livestream the tank's lift with commentary here from 10 p.m. on Thursday until the lift is complete.