SpaceUpClose.com & RocketSTEM
KENNEDY SPACE CENTER, FL/MICHOUD ASSEMBLY FACILITY, LA – The last of four RS-25 engines that will ultimately help power the first launch of NASA’s Space Launch System (SLS) rocket to the Moon on the first Artemis mission has been mated to the mammoth rockets core stage by engineers and technicians at NASA’s Michoud Assembly Facility in New Orleans.
NASA announced the joining of the final RS-25 engine onto the bottom engine section of the 212-foot-long SLS core stage on Nov. 8.
The SLS-1 core stage will propel the unpiloted Artemis I mission on the first integrated flight of the SLS rocket and NASA’s Orion deep space human spacecraft to the Moon.
Launch of the first SLS on the Artemis 1 could take place as soon as late 2020 but more likely in early 2021.
The overall goal is to build the rockets for NASA’s Artemis moon exploration program aimed at landing US astronauts on the Moon by 2024 at the lunar south pole – including the first woman and the next man.
The multistep engine attachment work was led by lead engine contractor Aerojet Rocketdyne in coordination and collaboration with NASA and SLS lead contractor Boeing.
The fourth and final RS-25 engine integration process was completed on Nov. 6, just one day after structurally mating the third engine.
The first two RS-25 engines were structurally mated to the stage in October.
Read our story about this and earlier continuing series on SLS milestones – including our first hand reports and photos of the arrival of all 4 RS-25 engines at Michoud in June.
The SLS core stage is the largest rocket stage the agency has built since the Saturn V that sent Apollo astronauts to the Moon.
The engine attachment work has proceeded well and according to the aggressive schedule NASA officials told to Space UpClose this summer on June 28.
NASA has invited media to see the 1st completed SLS core stage destined for the Artemis 1 moon mission in early December – and myself and Space UpClose will be on hand for eyewitness reporting.
Engineers and technicians are now “attaching the engines to propulsion and avionics systems inside the core stage, which also houses the flight computers that control the rocket during its first eight minutes of flight,” says NASA.
The RS-25 engines along with two side mounted solid rocket boosters provide the necessary thrust for the SLS rocket to reach space and propel the Orion deep space capsule to the Moon.
Thereafter when all the propulsion and avionics systems efforts are completed, engineers will thoroughly check out that the attachment work to confirm it was accomplished correctly by performing additional testing on all the avionics and electrical systems.
The team will “conduct an integrated functional test of flight computers, avionics and electrical systems that run throughout the 212-foot-tall core stage in preparation for its completion later this year.”
This testing is the first time all the flight avionics systems will be tested together to ensure the systems communicate with each other and will perform properly to control the rocket’s flight.
After all that NASA’s Pegasus barge will transport the completed core stage from Michoud to Stennis for the Green Run test series in 2020.
It is expected to arrive at KSC sometime around the middle of next year in 2020 to prepare for the Artemis 1 launch.
Major structural assembly of this first SLS core stage itself was only just completed a month ago on Sept. 19 by Boeing workers at Michoud after years of effort and much delay after they attached the last of five sections of the 212-foot-tall core stage – namely the bottom engine section which is one of the most complicated pieces of hardware for the SLS rocket and has been problematic to design and build and caused much of the delay.
“SLS is part of NASA’s backbone for deep space exploration, along with Orion and the Gateway in orbit around the Moon. SLS is the only rocket that can send Orion, astronauts and supplies to the Moon on a single mission.”
The core stage engine section “is the attachment point for the four RS-25 engines and the two solid rocket boosters that produce a combined 8.8 million pounds of thrust to send Artemis I to space.
“In addition, the engine section includes vital systems for mounting, controlling and delivering fuel from the stage’s two liquid propellant tanks to the rocket’s engines.”
The RS-25 engines are recycled from NASA’s space shuttles where clusters of three then called Space Shuttle Main Engines or SSMEs powered the orbiters and propelled 135 missions to space.
NASA now has 16 RS-25 engines in inventory. They have been modified and upgraded to power SLS. They were originally built and then refurbished by Aerojet Rocketdyne.
Among the significant upgrades is the new engine controller which functions as the ‘brain’ to command the engines. See our photos.
The RS-25 engines have been ready for installation since Oct. 2017 when they completed qualification testing at Stennis.
But SLS is years behind schedule and billions over budget and Boeing has encountered numerous hardware manufacturing problems and difficulties resulting in substantial delays.
NASA originally hoped to launch SLS-1 by the end of 2017 – so the rocket is at least 3 years behind schedule. And I’ve been visiting and documenting progress over the years.
NASA will conduct a full duration ‘green run’ engine fire test of the completed core stage at Stennis to fully confirm its readiness for flight on Artemis 1. But that test will require six months of intense work by NASA and contractor teams.
Meanwhile the Orion Artemis 1 crew capsule is nearing completion nearby in the Operations and Checkout building I recently visited at KSC.
Watch for our upcoming Orion update.
Furthermore the recently arrived and massive 212 foot long, 228,000 pound core stage Pathfinder mock-up for NASA’s Space Launch System (SLS) megarocket was lifted to the vertical position inside the Vehicle Assembly Building’s (VAB) transfer aisle and then into High Bay 3 this past week at NASA’s Kennedy Space Center – by KSC and contractor teams carrying our critical work to practice offloading, moving, and stacking maneuvers required for assembly when the real SLS hardware for launch of the first Artemis moon mission arrives sometime around the middle of next year in 2020.
Pegasus and Pathfinder sailed into and docked at the Turn Basin wharf by the world famous countdown clock at Kennedy nearly three weeks ago Sept. 27 after being towed by ocean-going and river-going tugboats for a nearly 1000-mile and week-long trek from NASA’s Stennis Space Center in Mississippi to KSC.
More about the RS-25 engines:
The LOX/LH2 fueled RS-25 engines are a wonder of engineering from the Space Shuttle era and designed to be reusable from the start.
However for SLS they will be utilized for their final time and discarded at the conclusion of the launch sequence and ditched in the ocean since the core stage cannot land – unlike the shuttle orbiters.
The 4 RS-25 engines for the SLS Artemis 1 core stage have flown on a combined 21 space shuttle missions. They are engines E2045, E2056, E2058, and E2060.
“For SLS, they have been upgraded with new controllers, to perform under SLS environments and with nozzle insulation, for protection and prevention of metal overheating during launch and flight,” says NASA.
The engine controllers regulate the thrust levels of each engine and monitor health and performance. See them in our photos.
At launch the RS-25 engines will produce a combined 2 million pounds of liftoff thrust.
Each engine offers 512,000 pounds of thrust – which is 109% of their operational thrust level and higher than the 104.5% thrust commonly used during the shuttle era.
They will fire non-stop along with the two side mounted solid rocket boosters for approximately eight and one half minutes all the way to orbit.
The RS-25s measure 14 feet long and 8 feet in diameter and weigh 7775 pounds
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news: www.kenkremer.com –www.spaceupclose.com – twitter @ken_kremer – email: ken at kenkremer.com
Dr. Kremer is a research scientist and journalist based in the KSC area, active in outreach and interviewed regularly on TV and radio about space topics.
Ken’s photos are for sale and he is available for lectures and outreach events
Ken’s upcoming outreach events:
Nov 23, 1 PM, Titusville, FL: “50th Anniversary Apollo 12 and NASA’s Human Return to the Moon with Project Artemis” at American Space Museum, Titusville, FL. Lecture free. Open to the public.
Dec 3/4: 7 PM, Quality Inn Kennedy Space Center, Titusville, FL. “SpaceX CRS-19 Launch to ISS Dec 4.” Free in hotel lobby