NASA decided to kick off the year in a major way, by performing the latest test on the core stage engines of the Space Launch System destined to put the first woman and next man on the moon. But things didn’t go quite as expected. In fact, the unsuccessful completion of this test actually warrants a re-do, before we’re ready to take one small step or even a giant leap again.
So it comes as no surprise, that after almost 50 years NASA is sending the first crewed mission back to the lunar surface since Apollo 17. This time utilizing the Artemis Program, which is a series of lunar missions that will be the catalyst for future explorations beyond the Moon.
But how will we get back to the moon, or even further out into our own solar system? NASA has been prepping its new SLS rocket, and working with partners to build a new crew capsule known as Orion. In addition to the capsule, SLS can also carry astronauts and cargo to the Moon in a single mission.
But the rocket wasn’t just designed to get humans back to the Moon. In fact, it’s the first deep space rocket developed for crewed missions by NASA since the famous Saturn V rocket, which was used for the Apollo Program.
NASA defines the design of SLS as flexible and evolvable, which will allow for longer scientific robotics missions deeper into space. This is possible because of the multiple configurations of SLS that can achieve not only various payload capacities, but also maximum thrust. Making it adaptable for crewed and cargo missions to the Moon as well as other planets.
Standing at roughly 64 meters tall, the Core Stage of the SLS contains more than 2.7 million liters of propellant. Broken down into five major sections, each plays a critical part in the success of the mission. The top of the Core Stage or the Forward Skirt holds the on-board flight computers and avionics, which is basically the “Brains” of the rocket. The Liquid Oxygen and Liquid Hydrogen tanks each contain cooled propellant, clocking in at roughly 2 million liters of liquid hydrogen and about 742,000 liters of liquid oxygen. Joining the two tanks together is the Intertank, which also functions as an attachment point for the forward booster, and holds some onboard electronics for the Core Stage.
Finally, channeling the propellant from the tanks into the 4 RS-25 Engines is the Engine Section, which also functions as the avionics needed to steer the engines.
Together, this system produces a total of about 8.9 Meganewtons of thrust, accelerating SLS to a speed of Mach 23! The real engineering genius behind SLS is that NASA has incorporated technology and lessons from past crewed missions into the different configurations for SLS. Most noticeably, is the famous orange foam-covered external tank, which was seen on Shuttle launches and is used in the core stage of the SLS. And as for power, when compared to the Saturn V’s 34.5 meganewtons of thrust, the smallest configuration of SLS puts out a hefty 15% more thrust.
Which leads us to the partially successful test of these retro engines. Just recently NASA conducted the eighth Green Run series test on the RS-25 engines of SLS. Which is basically a series of evaluations to guarantee the completed system is primed for flight. This specific test requires the engines to fire for a little over eight minutes, which mimics the amount of time it would take to launch SLS into space. And this test is known as the “Hot Fire Test” … for obvious reasons.
However, just 67 seconds into the 8-minute test, there was an automatic shut down because one of the engine's hydraulic systems exceeded the preset parameters, which were kind of low to begin with.
Despite completing several operations, the Green Run team has decided that an approximately four-minute test would give them all the necessary data to confirm the core stage and engines are fully prepared for a real flight. And before the next test can happen, the team is refurbishing the engines, while also tweaking the thermal protective system and adjusting the logic parameters that engaged the automatic shutdown from the previous test.
All and all once these preparations are made, the re-run of the test will be executed and then if all goes well, it should only take about one month to prepare the core stage for transport to NASA’s Kennedy Space Center. And hopefully, we’ll be using SLS to get to the moon and beyond.