NASA completes 8-minute static fire test of Space Launch System rocket

The US space agency NASA has conducted a second static fire test with the core booster of the Space Launch System rocket. It concerned a successful ignition of the four rocket motors of the lower rocket stage, for a duration of more than eight minutes.

NASA says the hot fire test was successful and the four RS-25 engines were ignited for 8 minutes 19 seconds. That’s about the same ignition time as what happens during a launch to the moon. Several things were tested during ignition, including moving the four engines in specific patterns to target thrust, firing the engines at 109 percent, and scaling back and upping thrust. These are elements that are also involved in a real launch.

The test was conducted at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. According to the space agency, this is a crucial test for the Artemis I mission with which an unmanned Orion spacecraft will make a test flight around the moon after launch, before returning to Earth. NASA plans to put another human on the moon by 2024.

Render of what the SLS will look like.

In January there was also a static fire test, in which the engines were ignited for 67 seconds. That test ended earlier than planned, so a second test ignition was deemed necessary. The data obtained from the January test has been used for a number of implemented changes. In total, NASA has ten different design verification objectives to certify the design and the test ignitions play an important role in collecting sufficient data for this. The current test ignition was the final step in a series of eight tests assessing the lower rocket stage. As part of this so-called Green Run test series, for example, the hydraulic systems and the drive systems were tested.

The Space Lauch System rocket is being built by Boeing, with Aerojet Rocketdyne being responsible for the RS-25 engines. These are modified variants of the engines that were also used for the Space Shuttle. The SLS will eventually also get two solid fuel engines on either side. It will be a very large and powerful rocket that can eventually be used for missions to Mars.

The development of the rocket has been criticized for years and in particular the enormous cost. Recently it became clear that NASA is conducting an internal investigation to keep costs down. More than $20 billion has already been spent and each launch is expected to cost more than $2 billion. That criticism will likely only intensify if SpaceX manages to eventually realize its fully reusable Starship rocket. This will not only get more thrust, but also be much cheaper to use.