Trevor Mahlmann
After NASA completed a review of the data collected during a fire test of its Space Launch System rocket in mid-December, NASA decided to test the large vehicle again. The start of engines is expected to take place in the fourth week of February.
During the December 16 test firing, when NASA planned to propel the rocket’s four main engines for eight minutes, the test was stopped after only 67.2 seconds. NASA said the firing of engines was halted due to a strict restriction on hydraulic pressure in the thrust vector propulsion mechanism used to steer or steer the engines.
In the days after the mid-December test firing, NASA and Boeing officials were puzzled as to whether they would have to test the rocket a second time. While it would be helpful to gather additional data, they said there are concerns about placing the nuclear phase with its four main engines in the spacecraft and large liquid oxygen and hydrogen fuel tanks through the stress of repeated tests. (The SLS rocket is consumable, so it is meant to be launched only once.)
According to the agency, the original fire test completed 15 of its 23 targets. Four other targets received most of the data, while three had partial data, and one had no data. This last one was a test of how the liquid oxygen tank’s pressure would react when liquid oxygen was largely depleted and the tank emptied. Because the test objectives were not met, engineers within the agency urged the leadership of NASA and Boeing to conduct a second test to reduce the risk of failure during launch.
On Friday, NASA made it official. “After evaluating data from the first hot fire and the previous seven Green Run tests, NASA and main contractor Boeing determined that a second, longer hot fire test should be performed and that this poses a minimal risk to the Artemis I. core phase will involve, while it is valuable data to confirm the core stage for flight, ”the space agency said in a blog post.
NASA said that using the engines during this second test for four minutes should provide enough data to provide confidence in the core performance, but that the main engines will burn up to eight minutes if it goes well.
After the second fire test – assuming NASA and Boeing get the necessary data – it will take about a month to refurbish the core stage and its engines. The vehicle will then be loaded onto a vessel, shipped across the Gulf of Mexico and the Atlantic Ocean and delivered to Kennedy Space Center in Florida. This will probably not happen before the end of March or April.
In its blog post, NASA says that the SLS core stage will once again be assembled in Florida with its solid rocket amplifiers and paired with the Orion spacecraft in preparation for the first launch “later this year”. Since a launch date of 2021 in January was set for the launch of the nuclear phase from Stennis Space Center in January, a 2021 launch of the SLS rocket now appears highly unlikely.