NASA Will Have 8 Minute Hold Down Test in 2020

NASA Administrator Jim Bridenstine announced July 25 the agency will conduct a “Green Run” core stage test for the Space Launch System rocket ahead of the upcoming Artemis 1 lunar mission.

Perhaps in November, 2019, NASA and ULA could start assembling the Space Launch System (SLS) on the pad for a roughly 5-month preparation phase for the test. This means they should have the test in the second quarter of 2020.

This clearly means that the actual first mission launch around the moon cannot take place until 2021. Months will be needed to analyze the test results. Months will be needed to clean up and prepare for the real launch.

The first eight minutes of every Artemis mission with NASA’s Space Launch System (SLS) rocket will begin with core stage and solid rocket boosters producing 8.8 million pounds of thrust to launch the agency’s Orion spacecraft to the Moon. NASA will test the rocket’s 212-foot tall core stage- the tallest rocket stage the agency has ever built- with a “Green Run” test on Earth before launch day to help ensure mission success and pave the way for future Artemis missions carrying crew to the Moon. Missions at the Moon will be a stepping stone to prepare for human exploration of Mars.

During the Green Run testing, engineers will install the core stage that will send Orion to the Moon in the B-2 Test Stand at NASA’s Stennis Space Center near Bay St. Louis, Mississippi for a series of tests that will build like a crescendo over several months. The term “green” refers to the new hardware that will work together to power the stage, and “run” refers to operating all the components together simultaneously for the first time. Many aspects will be carried out for the first time, such as fueling and pressurizing the stage, and the test series culminates with firing up all four RS-25 engines to demonstrate that the engines, tanks, fuel lines, valves, pressurization system, and software can all perform together just as they will on launch day.

“The SLS core stage is an engineering feat that includes not only the largest rocket propellant tanks ever built but also sophisticated avionics and main propulsion systems,” said Lisa Bates, SLS deputy stages manager. “While the rocket is designed to evolve over time for different mission objectives, the core stage design will remain basically the same. The Green Run acceptance test gives NASA the confidence needed to know the new core stage will perform again and again as it is intended.”

The SLS core stage includes state-of-the-art avionics, miles of cables and propulsion systems and two huge liquid propellant tanks that collectively hold 733,000 gallons of liquid oxygen and liquid hydrogen to power the four RS-25 engines. Together, they will produce more than 2 million pounds of thrust to help send Artemis 1 beyond Earth’s orbit to the Moon.

The test program for the core stage at Stennis will begin with installing the stage into the test stand. Then, engineers will turn the components on one by one through a series of initial tests and functional checks designed to identify any issues. Those tests and checks will culminate in an eight-minute-long test fire, mimicking the full duration of the stage’s first flight with ignition, ascent and engine shutdown. The results of this test also will provide important data that will confirm how the system reacts as the fuel is depleted from the propellant tanks.

The “Green Run” test of the core stage for NASA’s Space Launch System (SLS) will be conducted at the B-2 Test Stand at NASA’s Stennis Space Flight Center near Bay St. Louis, Mississippi. The historic test stand has been used to test stages for multiple programs, including the Saturn V and the space shuttle. The test stand was renovated to accommodate the SLS rocket’s core stage, which is the largest stage NASA has ever built.
Credits: NASA


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