Space launch system performs a dramatic hot-fire test, blasting with all 4 engines at a time

Today, around 4:30 p.m. local time (CST), NASA took a major step forward with the development of the Space Launch System (SLS) – the heavy launch system that they will use to return astronauts to the moon and missions in crew Mars. In a Green Run Hot Fire Test, all four RS-25 engines in the SLS Core Stage were fired at the same time as part of the first integrated top-to-bottom test of the stage systems.

This test is the final hurdle in an eight-step validation process before the Core Stage can be mated with its Solid Rocket Boosters (SRBs) and sent on its maiden voyage around the Moon (Artemis I) – what is currently planned for the month of November 2021.

The event was held at the Stennis Launch Center near St. Louis, Mississippi, and was broadcast live via NASA Live. NASA has also posted regular updates (and continues to do so) on its NASA Artemis Blogs page. The fire test began at exactly 04:27:51 PM CST (02:27 PST; 05:27 EST) with engine 1 firing, followed by engines 3, 4 and 2 – which were separated by a few hundredths of a second.

The total test fire lasted just over a minute, with the engines shutting down at 4:29:07 CST (a total burn time of approximately 76 seconds). This did not correspond to the 8 minutes (480 seconds) that ground controllers were aiming for as it is estimated that a burn of 485 to 493 seconds is required to simulate a launch. They also planned to perform two 30-second engine gimbal tests, which would simulate the pilot controls in flight.

At this time, the exact cause of the abandonment has not been announced. But according to an update just posted on NASA’s Artemis Blogs page, the shutdown came as a result of the triggering of the automated security systems:

“All four RS-25 engines fired successfully, but the test was stopped early after about a minute. At this point, the test was fully automated. During the firing, the on-board software acted appropriately and triggered a safe shutdown of the engines. “

However, even at a little over a minute, the test was largely passed. Not only was this the first time that the four RS-25 engines had fired together, but the process also validated many key systems and allowed mission controllers to collect data from the Core stage, as its many integrated components worked together.

“During the test, the propellant tanks were pressurized, and this data will be invaluable as the team plans the way forward,” the NASA statement added. “Over the next few days, engineers will continue to analyze the data and inspect the main stage and its four RS-25 engines to determine next steps.”

As noted, this was the last leg of the Green Run, designed to test new hardware (aka “green”) and prepare the Core Stage to go live. The first three steps are to simulate launch conditions on an unpowered Core Stage and power up the avionics. Steps four and five involve testing the various engine components, such as propulsion system components, thrust vector controls, and their hydraulics.

Steps six and seven involve establishing a launch schedule and simulating a countdown, followed by a load test where approximately 2.65 million liters (700,000 gallons) of thruster is loaded and emptied from the stage. main. The eighth and final test is the hot fire test (aka “wet dress rehearsal”) where the main stage is fully loaded with propellant and conducts a static fire in place – in this case on test stand B-2 at Stennis.

The maximum thrust that the four RS-25 engines can generate during launch and climb is over 900,000 kg (2 million pounds) or approximately 8,900 kilonewtons (kN) of thrust. For hot fire tests aboard the B-2 test stand, however, the RS-25 engines will peak at 725 750 kg (1.6 million pounds) or 7117 kN of thrust, which corresponds to the maximum thrust qu ‘they will generate at sea level (on the launch pad).

Once the tests are complete, the Core Stage will be paired with two Solid Rocket Boosters (SRBs) like the space shuttle. Together, these will be used for all configurations of the SLS rocket, which are grouped into two blocks. For Block 1, the SLS will be able to generate 4 million kg (8.8 million pounds) of thrust and deliver 24.5 to 38 tons (27 to 42 US tons) of crew or payloads in orbit or on the Moon.

For Block 2, the SLS will be able to generate 5.4 million kg (11.9 million pounds) and be configured to deliver 39 to 41 metric tons (43 to 46 US tons) or more in orbit around the moon. In these latter configurations, the SLS will be the most powerful rocket that NASA has built since the Apollo era and the retirement of the venerable. Saturn V rocket. Likewise, NASA hopes that this rocket will be the workhorse of Artemis project, NASA’s program to send “the first woman and the next man to the moon”.

It is also central to their long-term vision for space exploration, which includes the deployment of elements of the Orbiting Lunar Gateway and Artemis Base Camp on the lunar surface. These will allow a “sustainable lunar exploration program” and the preparation of possible “Moon to Mars” missions.

You can see the full event via NASA Live (see below). And stay tuned for the post-test panel discussion, which starts at 4:30 p.m. PST (7:30 p.m. EST).

Further reading: NASA