NASA launches the main stage of its massive new rocket – Space launch system (SLS) – on Saturday (January 16th) in a critical test that seems to have ended prematurely when the booster’s engines stopped earlier than planned.
Smoke and flames erupted from the four RS-25 engines that powered the amplifier of the behemoth rocket’s core, a central element of NASA’s Artemis lunar program as it roared at the top of NASA’s test bench. Stenis Space Center near St. Louis Bay, Mississippi. The ignition occurred at 5:27 p.m. (2,227 GMT), with 700,000 gallons (2.6 million liters) of cryogenic fuel passing through the engines as they roared for just over 1 minute, much earlier than planned.
The test had to last 485 seconds (or a little more than 8 minutes), which is the time that the engines will burn during the flight. After the engine was ignited, the four RS-25 engines appeared to start for about 1
“Obviously our engines were shut down before the 8-minute schedule,” NASA’s main stage engineer Alex Canola said on a NASA television show. “But we have very good data to look at and hope we can move on from here.”
Video: How NASA’s SLS mega-rocket engine test works
During a press conference Tuesday (January 12th), John Shannon, vice president and program manager for SLS at Boeing, said the engines needed to run for a period of time to get the data they needed. “If we had an early shutdown, for whatever reason, we get all the technical data we need to have high confidence in the car for about 250 seconds,” Shannon said.
Since the test was stopped for a short time of 250 seconds and before the teams could turn (or move) the engines, exactly how much data and how confident the teams are in the vehicle is yet to be determined.
The test on Saturday was initially moved an hour to 16:00 EST (1900 GMT), as test preparation was ahead of schedule. During the countdown, however, engineers set the retention counter to operate through water diversion system checks and other tests on the engine test stand. The teams were able to overcome the problems and resume counting on time to complete the test on Saturday, despite the short lead time.
The exercise, known as the hot fire test, complete the basic steps to strengthen the Space Launch System – the four main RS-25 engines, fuel tanks and rocket computers and avionics. The test simulates a launch while the rocket is held firmly in place attached to a test bench. (The same test bench was used to test the engines of both NASA Rocket Saturn V and orbital space shuttles.)
“The SLS rocket is the most powerful rocket ever created in human history,” NASA Administrator Jim Bridenstein said on NASA television shortly before the test. “This is the same rocket that will launch a capsule of the Orion crew around the moon by the end of this year.”
Anatomy of the space launch system
NASA’s space launch system was first conceived in 2011 and is finally being assembled for an extended trip around the moon later this year.
Each SLS rocket will use four RS-25 rocket engines to launch its 212-foot (65-meter) main stage. The rocket will also rely on two solid rocket accelerators and an upper stage to launch the capsule of the NASA Orion crew out of low Earth orbit.
Together, SLS and Orion are the two main components of NASA Artemis’ lunar program which seeks to return the astronauts to the moon immediately after 2024.
Currently, the agency has 16 RS-25 engines, which have been rescued by the already retired agency space shuttle program. These engines will be used in the first four launches of SLS rockets for Artemis missions from 1 to 4. (These flights include the first landing of the moon in the program crew, Artemis 3 and a subsequent flight.)
Space launch system: Explain NASA’s giant rocket for lunar missions Artemis
As the engines for these first missions are remnants of the shuttle, they have been repaired with new computer controllers, as well as improvements that ensure they can meet the higher performance requirements when launching the SLS, NASA officials said.
This is not the only part recycled from past programs. Like engines, solid rocket accelerators have also been used to propel a fleet of NASA space shuttles into orbit. They are also modified to work with SLS. But they will not be used forever. With the development of technology, side boosters will be replaced by advanced boosters.
The SLS will contain a pair of these amplifiers attached to the side of the main stage. It consists of four RS-25 engines at the base of the car, and arranged on top will be the components of the rocket with Orion capsule and service module located on top.
The entire vehicle will be limited by a launch orbit system that is designed to pull the capsule out of the rocket if something goes wrong during launch.
Road to the test site
NASA has been systematically testing the various components of the SLS rocket over the past few years.
The agency is testing each of the major engines individually to make sure they have turned on as expected. And to ensure that flight hardware meets design expectations, NASA has launched what it calls “a” Green Run Test which included vessel avionics testing, countdown and start times, refueling procedures, and more.
The testing went smoothly, but not without problems. A global pandemic, combined with an unprecedented number of tropical storms and hurricanes affecting test sites, added to delays caused by hardware problems.
NASA conducted two separate “wet dress rehearsals,” in which fuel is loaded into engines and then drained. During one such exercise, which took place on 20 December, the test ended unexpectedly earlywhich leads to the postponement of today’s test for hot fire from December, said a statement from NASA. Another attempt to refuel earlier in December was stopped due to temperature problems.
The accumulation of Saturday’s engine tests also saw a series of delays due to the ongoing coronavirus pandemicNASA officials said. Restrictions on social distancing mean that many NASA employees, engineers, and other SLS team members (as well as the media) cannot be personally on hand to witness the basic rocket test. Many members of the team sent videos for virtual participation.
Testing is key
The purpose of the test is to ensure that later this year, the rocket will be able to carry an unscrewed Orion spacecraft while traveling around the moon.
With the ignition of the four RS-25 engines, he closed a critical period of pre-flight tests for the rocket, which NASA described as its “Green Mileage”. This series of tests began with stress tests on the physical structure of the rocket and ended with today’s hot fire test.
The purpose of the test was to go through the launch procedures and start the four engines, allowing them to burn for just over 8 minutes – a little shy of the length they would burn during an actual flight.
As expected, the engines exploded alive, producing a thrust of 1.6 million pounds while burning for 485 seconds. The full-length test will provide engineers with vast amounts of data on how the basic stage was performed.
The teams will take a few days to review the data before clearing the main stage for their next task: repairing and possibly transporting it to the launch pad at the Kennedy Space Center in Florida.
Upon arrival, it will be integrated with the rest of the vehicle, which is already in place. This includes its two solid rocket accelerators, which are currently lined up in the vehicle assembly building at the Kennedy Space Center.
The boosters were previously tested before being sent in segments to Florida. Each booster consists of five segments that are stacked on top of each other.
The Orion spacecraft is complete and almost ready to be attached to the top of the SLS once the rocket is fully assembled.
Editor’s note: NASA will hold a press conference on NASA television later tonight to brief the media and the public on the results of today’s space fire test. You can watch this live here. It was expected about 2 hours after the test or so 7:30 PM EST (12:30 AM GMT). This history will be updated when new details become available.
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