SLS Fuel Tank Nears Completion

Image Credit: NASA/Michoud/Steven Seipel

Image Credit: NASA/Michoud/Steven Seipel

July 11, 2016 – At over 300-feet tall and 5.75 million pounds at liftoff, NASA’s Space Launch System (SLS) will need plenty of fuel to leave Earth. Once a final dome is added to the liquid hydrogen rocket fuel tank, shown here, it will come in at 27.5-feet in diameter and over 130-feet long, making it the largest major part of the SLS core stage.

The blue section, shown here, is part of the world’s largest robotic weld tool in the Vehicle Assembly Center at NASA’s Michoud Assembly Facility in New Orleans. Inside the tool, five barrels and one dome were welded to make the tank, shown here in silver; engineers will cap it with an additional dome to complete tank welding.

While the tank is smooth on the outside, the inside appears to have ridges because the cylindrical barrels that form the tank are manufactured with square patterns created by stiffening ribs machined into them to make the walls light but uniformly strong in every direction.

The core stage forms the rocket’s backbone and has five major parts, all of which are being manufactured at NASA’s Michoud Assembly Facility in New Orleans.

The core stage tanks carry all the cryogenic liquid hydrogen and liquid oxygen combusted in four RS-25 engines to produce two million pounds of thrust. The fuel tank holds 537,000 gallons of chilled liquid hydrogen that is completely combusted in the engines in the short 8.5 minutes it will take to send the SLS and Orion crew vehicle into orbit.

When the welding is finished, a barge will carry this tank to NASA’s Marshall Space Flight Center in Huntsville, Alabama. This qualification tank won’t actually fly, but it will be tested at Marshall to verify that it can withstand launch and ascent forces.

Traveling to deep space will require a vehicle that can launch huge payloads. SLS will have the power and payload capacity needed to carry crew and cargo for exploration and scientific missions to asteroids, Mars, and beyond.

For the first flight of the SLS rocket, known as Exploration Mission-1 (EM-1) the Block I configuration can lift 70-metric-tons (77 tons). The next planned upgrade of SLS, known as Block 1B, will use a more powerful exploration upper stage for more ambitious missions with a 105-metric-ton (115-ton) lift capacity. For both configurations, SLS will use the same core stage and four RS-25 engines.

EM-1 is planned for 2018. During EM-1, Orion and NASA’s Space Launch System (SLS) will be integrated for the first time. An uncrewed Orion spacecraft will be launched into lunar distant retrograde orbit — a wide orbit around the moon that is farther from Earth than any human-rated spacecraft has ever traveled. The mission will last more than 20 days and will help certify the design and safety of Orion and SLS for human-rated exploration missions. The Orion capsule will also be returning to Earth at higher speeds than any other previous spacecraft.

The Boeing Co., headquartered in Chicago, is the prime contractor for the SLS core stage, including avionics, and Aerojet Rocketdyne of Sacramento, California, is the prime contractor for the RS-25 engines. Lockheed Martin Space Systems of Littleton, Colorado, is the prime contractor for the Orion spacecraft.