Nasa’s Boeing-built deep space exploration rocket has cut short a crucial test, after briefly igniting all four engines of its core stage for the first time.
Mounted in a test facility at Nasa’s Stennis space centre in Mississippi, the Space Launch System’s (SLS) 64-metre core stage roared to life for just over a minute on Saturday, well short of the roughly four minutes engineers needed to stay on track for the rocket’s first launch in November.
The engine test, originally scheduled to last eight minutes, was the last leg of Nasa’s nearly year-long “Green Run” test campaign. It was a vital step for the space agency and its top contractor before a debut unmanned launch later in 2021 under Nasa’s Artemis programme, the Trump administration’s push to return US astronauts to the moon by 2024.
“Today was a good day,” Nasa administrator Jim Bridenstine said at a press conference after the test, adding “we got lots of data that we’re going to be able to sort through” to determine if a do-over is needed and whether a November 2021 debut launch date is still possible.
Nasa’s SLS program manager John Honeycutt, cautioning the data review from the test is ongoing, told reporters the turnaround time for another hot fire test could be roughly one month.
To simulate internal conditions of a real liftoff, the rocket’s four Aerojet Rocketdyne RS-25 engines ignited for roughly one minute and 15 seconds, generating 1.6m pounds of thrust and consuming 2.6m litres of propellants on Nasa’s largest test stand, towering 35 storeys tall.
Before the test, Jim Maser, Aerojet Rocketdyne’s senior vice-president of space, told Reuters: “This is a once-in-a-generation kind of test. This will be the first time four RS-25s fire together at the same time.”
The expendable, super heavy-lift SLS is three years behind schedule and nearly $3bn over budget. Critics have long argued for Nasa to transition from the rocket’s shuttle-era core technologies, which have launch costs of $1bn or more per mission, to commercial alternatives promising lower costs.
It costs as little as $90m to fly the less powerful Falcon Heavy from Elon Musk’s SpaceX, and $350m per launch for United Launch Alliance’s legacy Delta IV Heavy.
While newer and more reusable rockets from both companies – SpaceX’s Starship and United Launch Alliance’s Vulcan – promise heavier lift than Falcon Heavy or Delta IV Heavy, potentially at lower cost, SLS backers argue it would take two or more launches on such rockets to launch what SLS could carry in one mission.
Reuters reported in October that Joe Biden’s space advisers aim to delay Trump’s 2024 moon goal, casting fresh doubts on the longterm fate of SLS just as SpaceX and Jeff Bezos’s Blue Origin scramble to bring heavy-lift capacity to market.
Nasa and Boeing engineers have stayed on a 10-month schedule for the Green Run “despite having significant adversity this year”, the Boeing SLS manager John Shannon told reporters this week.
Shannon cited five tropical storms and a hurricane that swept over Stennis, as well as a three-month closure after some engineers tested positive for the coronavirus in March.