SLS program suffers further delays after NASA postpone second hot fire test

NASA has made the decision to postpone the second hot fire test of its first SLS core stage after the agency discovered an issue with a liquid oxygen valve.
A problem with a value used to feed oxygen to one of the SLS core stage’s four RS-25 engines has forced NASA to postpone a planned second hot fire test | Image credit: NASA

NASA’s Space Launch System development program has suffered yet another blow with the postponement of a second hot fire test. The delay is the latest in a long line that has put the program behind schedule and over budget.

NASA began testing the first SLS core stage to roll off the production line over a year ago. The testing was initially intended to be concluded with a hot fire test of the stage on January 16, 2021. However, the test was automatically aborted 60 seconds into a planned eight-minute burn.

Following an investigation into the incident, NASA identified conservative test parameters as the root cause of the early shutdown. On January 29, the agency announced it would proceed with a second test toward the end of February in order to collect additional data required to certify the stage for flight.

In a February 22 statement, NASA announced that it had discovered an issue with a valve that feeds liquid oxygen to one of the stage’s four RS-25 engines. According to the agency, all four liquid oxygen valves performed as expected during the maiden hot fire test. It is, as a result, unclear at what point the identified valve was damaged.

SLS prime contractors Boeing are currently identifying a path forward in order to reschedule the test. Neither NASA nor Boeing gave any indication of how much of a delay the faulty liquid oxygen valve would result in.

The postponement of the second hot fire test is the latest in a series of setbacks that have delayed the maiden SLS launch by several years.

The maiden launch of the SLS rocket had most recently been scheduled for late 2021. Despite the delay caused by the need to perform a second hot fire test, NASA officials seemed to remain confident that a maiden launch this year was possible. With this latest issue to hit the rocket’s development, a launch in 2021 appears highly unlikely.

Andrew Parsonson is a space enthusiast and the founder of Rocket Rundown. He has worked as a journalist and blogger for various industries for over 5 years and has a passion for both fictional and real-life space travel. Currently, Andrew is the primary writer for Rocket Rundown as we look to expand our reach and credibility.