NASA to test its SLS megarocket in the coming weeks

The ongoing pandemic has slowed testing for NASA’s Space Launch System megarocket, but the process is resuming and has checked off a key milestone: powering up the core stage.

Tall orange rocket with 2 shorter auxiliary rockets on the sides at launch tower.

An artist’s rendering of the first Space Launch System (SLS) vehicle with Orion spacecraft on the pad before launch. The Orion spacecraft and SLS megarocket – together called Block 1 – and the ground systems at Kennedy Space Center in Cape Canaveral, Florida, will be part of the Artemis 1 lunar mission, scheduled for launch in 2021. Image via Wikipedia.

Although the coronavirus pandemic has slowed testing of NASA’s Space Launch System – a rocket more powerful than the Saturn V that propelled the first astronauts to the moon – the months-long process is finally resuming at the agency’s Stennis Space Center in Mississippi. Boeing, the company NASA contracted to lead the rocket’s construction, is now engaged in an eight-step core testing process dubbed the green run. It’ll culminate in a hot-fire test, where the rocket will be tied down, but will fire up its engines and endure each step of a launch as if it were really taking place. Originally scheduled to take place in early to mid-November 2020, this final testing is now expected to take place before the end of 2020, NASA says. It hopes to keep to this testing goal, to keep its schedule on track for the rocket’s debut launch on the Artemis 1 lunar mission in mid-to-late 2021.

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Clyde Sellers, a security specialist at the NASA center, told EarthSky:

It’s extremely gratifying to watch. It’s the first time this test has run and for a new, original rocket, the most powerful rocket ever built.

Although the green run series started with a modal test – a kind of vibration testing – conducted in January 2020, the ongoing coronavirus pandemic has slowed process. NASA leadership halted on-site work at Stennis in March 2020, around the same time many in the U.S. realized the seriousness of this coronavirus and began taking measures such as working from home. The center began reopening slowly in mid-May, and the green run team completed its second test on the core stage (the orange “body” of the rocket) in late June.

That test ensured that the software and other electrical interfaces involved in the rocket and the testing stand work properly.

The rocket has since undergone and passed the next four steps of the green run series:

– Test 3, in which engineers inspected all the safety systems that shut down operations during testing. During this test, they simulated potential problems.

– Test 4, the first test of each of the main propulsion system components that connect to the engines. Command and control operations were verified, and the core stage was checked for leaks in fluid or gas.

– Test 5, in which engineers ensured the thrust vector control system can move the four engines and checked all the related hydraulic systems.

– Test 6, which simulated the launch countdown, including step-by-step fueling procedures. Core stage avionics were powered on, and propellant loading and pressurization were simulated. The test team exercised and validated the countdown timeline and sequence of events.

Chart with text and labeled diagram of SLS rocket sections.

This helpful graphic illustrates what the 8 parts of the green run will test, as well as the individual components of the SLS Core Stage (orange rocket body). Image via NASA.

The final two tests scheduled for the next month or so – test 7 and test 8 – will be a “wet dress rehearsal” that sees the rocket stage loaded with fuel and the full hot-fire test to ensure the vehicle is truly ready for launch. It’s an intense procedure, but one that’s crucial for engineers to feel confident the vehicle is safe.

After the hot fire test, engineers will refurbish the core stage and configure it for its journey to NASA’s Kennedy Space Center in Florida, where still more tests await the core stage. But eventually, if all goes well, the next time the RS-25 engines fire will be for the first uncrewed mission of NASA’s Artemis 1 – the first in a series of increasingly complex missions that will enable human exploration to the moon and Mars – and perhaps, one day, deep space.

Tall orange rocket standing on high concrete platform with a lot of metal scaffolding.

The orange SLS core stage is being tested on the B-2 test stand at NASA’s Stennis Space Center. Image via NASA.

The core stage will later be assembled with the other parts of the rocket and the Orion spacecraft, the crew module designed to carry humans into space.

Drawing from more than half a century of research and development, the Orion module plans to be flexible enough to carry humans to a variety of destinations beyond our own moon. The abort system, which will provide the crew with the ability to escape if an emergency occurs on the launch pad, was successfully tested at White Sands Missile Range in New Mexico back in 2010. A series of launch and landing simulations at NASA’s Hydro Impact Basin tested how the module will fare when it splashes down in the ocean at the end of its mission.

Orion’s testing wrapped up in 2018 after a series of parachute falls, and it is expected to fly in the first Artemis launch.

Unlike previous human launch systems, SLS is designed to grow and evolve over time, with system flexibility that allows engineers to use one design today but adapt it later to future missions. Sellers added:

SLS will advance our understanding of our solar system and mankind’s capabilities.

Diagram with silhouettes of tall rockets, shuttle, and airplane.

A comparison of NASA’s SLS megarocket with the Saturn V and other rockets. What is labeled here as “initial configuration” is now called Block 1, the rocket being tested in late 2020, in preparation for a 2021 launch as part of the Artemis 1 moon mission. Illustration via

Bottom line: Although the coronavirus pandemic has slowed testing of NASA’s Space Launch System – a rocket more powerful than the Saturn V moon rocket – the months-long process is finally resuming at the agency’s Stennis Space Center in Mississippi. The green-run tests will culminate with a hot-fire test planned for the next few weeks, a schedule NASA says keeps it on track for its first launch of the Artemis 1 lunar mission by late 2021.

Read more from BBC: Nasa’s new ‘megarocket’ set for critical tests

Read more from NASA: Around the Moon with NASA’s First Launch of SLS with Orion


Lia Rovira