Four reusable RS-25 engines will propel NASA's SLS rocket as it ascend into space and then throw it away.
NASA administrator Jim Bridenstine said on Friday that he was "very confident" that the large rocket space launch system could launch in November 2021.
Bridenstine expressed confidence in this date, but added that uncertainties still exist. One of them is technical: The core stage of the SLS rocket has to undergo a series of tests this summer and autumn before it goes to the launch pad. The second problem is the ongoing COVID-19 pandemic that is spreading across multiple NASA centers.
Green run test
In January, NASA and the contractor for the core stage of the SLS rocket, Boeing, moved the vehicle to the Stennis Space Center in southern Mississippi. Since then, workers have undergone a series of tests on the stage – which consists of four main space shuttle engines and very large tanks for storing liquid hydrogen and liquid oxygen.
This week, Boeing officials said they expect to do the last and most important of these tests in October: fire all four of the missile's engines and fire them for about eight minutes to mimic an actual launch.
If this test is successful, the core stage is expected to be bargeed to the Kennedy Space Center in early 2021. Then two side-mounted boosters, an upper stage and the Orion spacecraft are added. This full stack is then subjected to further tests before finally being launched on an unscrewed test flight. A launch date in late 2021 assumes that all of these activities are proceeding as planned, which is anything but certain when dealing with a new missile.
On Friday, Bridenstine also expressed concern about the COVID 19 pandemic. In a webinar created by Aviation Week, he said the virus has the potential to affect schedules for all NASA programs, including SLS.
"I think we're okay for now, but if we don't get the coronavirus pandemic under control in the near future, it will be difficult," said Bridenstine. "If the coronavirus pandemic is not a problem, I am very confident in November 2021."
NASA's major human space centers – in Texas, Florida, and Alabama – are all located in countries where COVID-19 cases are growing rapidly. The situation in Mississippi is also not particularly good. The rolling seven-day average has more than quadrupled in the past month to more than 800 cases per day. Stennis was closed for a few months this spring because of the pandemic, but has since reopened.
Bridenstine said that if a Stennis employee tests positive, they may be able to stop operating for a week to assess the situation and conduct contact tracking. If that happens enough, he said, it will devour the scheduled margin to complete testing on the major Mississippi test stand this year.