Three years after Space Shuttle Endeavour threaded its way across the streets of Los Angeles to its final home at the California Science Center, another gargantuan vessel could be making the same epic journey, the museum said Thursday.

The science center has acquired one of the giant orange external fuel tanks the shuttles once rode piggy-back into space. The donation from NASA will bring the museum one step closer to its mission of creating a “full stack” for Endeavour’s final display at the future Samuel Oschin Air and Space Center. The plan is to present the shuttle in its launch position.

"I think NASA really shared our belief that the vision of building a full stack and having it in one place, the whole space shuttle system, was really valuable," President and CEO of the California Science Center Jeff Rudolph told KPCC. "They knew that we'd been planning from the beginning to display Endeavour in launch position."

The tank, dubbed ET-94, is currently housed at NASA’s Michoud Assembly Facility in New Orleans and is expected to begin its journey to L.A. sometime at the end of 2015 or in early 2016, depending on weather conditions and the progress of its own restoration, according to the museum. NASA's external tanks were not designed for reuse, so this one has never been used, and the museum said ET-94 is the only "flight-qualified" tank in existence.

ET-94 is the sister tank to ET-93 which was involved in the space shuttle Columbia accident. Columbia accident investigators spent a lot of time examining ET-94 and, in doing so, cut away some pieces of the foam, Rudolph said. These have to be restored before it goes on display.

"We are thrilled that NASA has gifted the California Science Center and the city of Los Angeles with the last surviving flight-qualified space shuttle external tank (ET) in the world. The city plans to work with the Science Center to make this a great welcome and celebration as it did with Endeavour two and a half years ago," Los Angeles Mayor Eric Garcetti said in a written statement.

Many Southern California residents will recall the shuttle’s own carefully orchestrated final journey, with splashy flyovers of key landmarks, a final trek over city streets, and the removal of dozens of trees and traffic signals to make way for its cumbersome, five-story frame.

ET-94 is a much bigger beast than the shuttle, but it is not expected to have quite the same impact on the local infrastructure.

"It's going to be a lot easier to move because it's larger in volume, but it doesn't have wings so it's nowhere near as wide as Endeavour was," Rudolph said. "We're looking at about 32 feet vs. 78 feet wide."

Because it's narrower and lower to the ground, fewer utilities will be impacted and no trees will be removed along its route to the science center, though some may get a trim, the museum said in its statement.

Rudolph said the move might only take a day.

"We're still working on all the logistics planning so we don't have a final route yet, but we're coordinating a meeting with the cities involved and others to make sure that we come up with a route," he said.

For the trivia fans, the museum released the following fact sheets about the ET-94, which it dubbed the "last of the flight external tanks."

External tanks general fact sheet

Functioned as the “gas tank” for the Orbiter; it contained the propellants used by the Space Shuttle Main Engines

Three main components of the External Tank: oxygen tank, located in the forward position, hydrogen tank located in an aft-position, and a collar-like intertank, which connected the two propellant tanks, housed instrumentation and processing equipment and provided the attachment structure for the forward end of the solid rocket boosters

the hydrogen tank was 2.5 times larger than the oxygen tank but weighed only one-fifth as much when filled to capacity

the difference in weight is that liquid oxygen is 16 times heavier than liquid hydrogen

Functioned as the “backbone” of the Shuttle during the launch, providing structural support for attachment with the solid rocket boosters and orbiter

At liftoff, the External Tank absorbed the total (7.4 million pounds) thrust loads of the three main engines and the two solid rocket motors

Most of the ET’s skin was covered with a thermal protection system that is a 2.5 centimeter (1-inch) thick coating of spray-on polyisocyanurate foam. The thermal protection systems acts to maintain the propellants at an acceptable temperature, to protect the skin surface from aerodynamic heat, and to minimize ice formation

ET was the only component of the Space Shuttle that was not reused. Approximately 8.5 minutes into the flight, with its propellant used, the tank was jettisoned

When the Solid Rocket Boosters separated at an altitude of approximately 45 kilometers (28 miles), the orbiter, with the main engines still burning, carried the External Tank piggyback to near orbital velocity, approximately 113 kilometers (70 miles) above the Earth

The empty tank separated and fell in a preplanned trajectory with the majority of it disintegrating in the atmosphere and the rest falling into the ocean

External Tank Stats: Weight: Empty: 65,000 pounds Propellant: 1,629,577 pounds Total: 1,694,577 pounds Propellant Weight: Liquid oxygen: 1,391,936 Liquid hydrogen: 237,641 pounds Total: 1,629,577pounds Propellant Volume: Liquid oxygen tank: 143,351 gallons Liquid hydrogen tank: 385,265 gallons Total: 528,616 gallons



ET-94 fact sheet

Three types of External Tanks or ET’s were manufactured for the Space Shuttle program: Original ET’s used during the first six missions were standard weight tanks (SWTs); improved tanks used throughout the 1990’s were lightweight tanks (LWTs); and super lightweight tanks (SWLTs).

ET-94 was one of three LWT tanks NASA ordered specifically to support science missions for the Space Shuttle Columbia.

Referred to as a “deferred-build” tank since production of SLWT’s had already begun.

ET-94 was delivered to NASA In January 2001 but stored at the Michoud Assembly Facility.

The first of the “deferred-build” tanks, ET-93, was involved in the Space Shuttle Columbia accident.

The Columbia Accident Investigation Board (CAIB) and NASA were interested in finding out if there was anything unique to the deferred-build tanks that contributed to the accident. Investigators spent a lot of time examining ET-94.

The investigation team dissected foam from various parts of the tank and generally inspected every aspect of the tank looking for answers.

This explains why there are significant pieces of foam missing from ET-94 and the need for cosmetic restoration before it is assembled with the Orbiter.

After Columbia was lost, NASA did not fly any dedicated low-earth orbit science missions, eliminating the need for the remaining deferred-build tanks.

Since the external tank was discarded on every mission, ET-94 is the only flight external tank remaining.

Three of the original test tanks also remain – one in a museum in Florida, one in Alabama (Huntsville), and one disassembled at Michoud Assembly Facility.

The last of the deferred-build tanks, ET-95, was never assembled.

This story has been updated.