Boeing Co.’s test of the largest rocket in U.S. history ended earlier than expected on Jan. 16 because a hydraulic-system setting exceeded a preset limit, dealing another setback to the company’s space ambitions.

The first firing of all four RS-25 engines on the Space Launch System rocket ended just 67.2 seconds into the planned eight-minute test. The so-called hot fire exercise at the NASA’s Stennis Space Center in Mississippi was designed to simulate a full flight from Earth.

Engineers from NASA, Boeing and the engines’ maker, Aerojet-Rocketdyne Holdings Inc., will assess data and determine whether a second test is needed or if the rocket is ready to ship to Florida’s Kennedy Space Center to prepare for its maiden flight. The SLS can be loaded with its super-chilled propellants — liquid oxygen and liquid hydrogen — only nine times, which will be a consideration in whether to stage a second test at Stennis, NASA said Tuesday.

“It may well not be necessary to do another test,” NASA Administrator Jim Bridenstine said at his last public event at the agency before departing Wednesday as President-elect Joe Biden’s administration takes office. NASA still hopes to fly the SLS to space later this year.

‘Intentionally Conservative’

The shutdown “was triggered by test parameters that were intentionally conservative to ensure the safety of the core stage during the test,” NASA said in a blog post Tuesday. Preliminary inspections and data reviews “show the rocket’s hardware is in excellent condition,” the agency said.

The test was cut short just as the engines began to pivot and test their thrust capability while rotating on gimbals.


The premature end, before engineers collected a full array of data, represented another hurdle for Boeing’s space program. The SLS rocket has been plagued by years of delays and billions of dollars in cost overruns. The program has broad support in Congress because of the federal contracts and jobs it offers across many states.

Boeing also is attempting to correct glitches with its Starliner spacecraft, which would ferry astronauts to and from the International Space Station under a NASA contract. Boeing said Monday it had completed qualification of Starliner’s flight software following an extensive review. A second test of the vehicle to the ISS is slated for March, following a botched flight in December 2019. A crewed flight is expected later this year.

Deep Space

The National Aeronautics and Space Administration views the SLS as America’s deep-space rocket — a larger, successor to the iconic Saturn V — to carry astronauts to the moon, Mars and beyond.

The rocket is supposed to fly in November as part of NASA’s Artemis 1 mission, an uncrewed test flight around the moon carrying the new Orion spacecraft built by Lockheed Martin Corp.

It’s also unclear if the Biden administration will continue the Artemis program to return astronauts to the moon or choose to delay the 2024 landing date that had been set by the Trump administration.

In addition to the issue that cut short the Jan. 16 exercise, a separate sensor reading for a major component failure occurred about 1.5 seconds after the engines ignited. That wasn’t related to the shutdown, NASA said.

For more articles like this, please visit us at

©2021 Bloomberg L.P.