NASA will need another set of Orion and Space Launch System (SLS) vehicle hardware for its Artemis Program goal of returning Americans to the surface of the Moon by the end of 2024, but the contracts to buy all the parts and put them together aren’t completely in place. The civilian space agency is now moving to start building a new set of the critical path “long lead” items for the elements that took the longest to build for the first joint Orion/SLS mission now expected to fly in 2021.



Development and production of the initial flight units of the SLS Core Stage and the Orion European Service Module (ESM) were for a long time the pacing items in the schedule for their first flight together, now called Artemis 1.

NASA recently started authorizing orders for the long lead parts for a third Core Stage and ESM, with a joint NASA and European Space Agency (ESA) agreement announced to start building a third ESM for Orion.

At least three Artemis missions flown by Orion and launched by SLS to cislunar space are needed to reach the Trump Administration’s mandated lunar landing goal in 2024, but hardware for only two missions are under contract and being built. Some contracts are in place beyond the Artemis 1 and Artemis 2 integrated Orion/SLS vehicles, but only the next two have critical path components like the Orion ESM and the SLS Core Stage under contract.

Long lead items are the parts and materials that take the longest to produce; by moving to purchase those now NASA is keeping the door open to flying Artemis 3 in time to meet the lunar landing goal in five years, but other commitments could mean even more hardware needs to be started.

In the meantime, procurement of all of the hardware for the second vehicle for the Artemis 2 mission still needs to be completed following that mission’s reassignment to a Block 1 SLS configuration.

ESM-3 agreement latest “long lead” contract action

The time it takes to build spacecraft and launch vehicles is usually much longer than the desired time between launches. NASA’s initial goal of an annual flight of Orion and SLS is a lower frequency rate than other crewed spacecraft and heavy-lift launchers, but it is still much shorter than the approximately four-year long lead time from ordering a new Orion or SLS vehicle to delivery.

In order to reach the annual launch cadence, NASA and its contractors are establishing lines of production to work on multiple vehicles at the same time. While assembly and production of the Artemis 1 vehicles are nearing completion, most of the critical Orion and SLS structures for the Artemis 2 flight have already been fabricated and are now being assembled for a flight as soon as 2022 or by the Orion Program’s April, 2023 baseline commitment.

The Artemis 1 and Artemis 2 vehicles will complete the existing development contracts for the initial operating capability of Orion and SLS. At the end of March, the Trump Administration directed NASA to land Americans on the Moon again by the end of 2024, with the Artemis 3 mission of Orion and SLS sending the crew in Orion to dock with the cislunar Gateway where a lunar lander would be waiting.

(Photo Caption: SLS and Orion structures machined from aluminum alloy forgings. On the left, AMRO Fabricating Corporation shows finished SLS panels in 2015 at its South El Monte, California facility. The panels are subsequently welded and bolted into barrel and cone subassemblies by NASA and Core Stage prime contractor Boeing at the Michoud Assembly Facility (MAF) in New Orleans. On the right, one of the three cone panels for the Artemis 2 Orion pressure vessel at AMRO in 2017. The Orion pressure vessel structural elements are also welded at MAF by Lockheed Martin.)

Few elements of an Artemis 3 vehicle exist or are currently under contract, but NASA has started to order the long lead items to build the pieces that were the critical paths for Artemis 1, the SLS Core Stage and the Orion ESM.

“It’s the first part of the build, so the structural pieces are extremely important, getting the aluminum parts forged and milled and assembled and sent to MAF,” John Shannon, Boeing’s Vice President and Program Manager for SLS, said in a June interview. MAF is the Michoud Assembly Facility, where SLS Stages prime contractor Boeing manufactures and assembles Core Stages.

“It’s about an eighty-one week process from when you order it to when it comes out of the mill to being formed, so it’s about a year and a half that it takes to get the structural elements into the factory.” Shannon noted the other main area of Core Stage long leads were mechanical systems: “The complex systems, the things like prevalves, things like CAPUs (Core Auxiliary Power Units), things like helium vent valves.”

“The avionics we’re in pretty good shape on, because they’ve gone through a very rigorous design and qualification phase,” Shannon noted. The Core Stage houses a significant amount of the launch vehicle avionics, including the flight computers for the launch vehicle.

“Then it’s just producing more of them, but it’s mechanical systems more that have the longer lead time required and I’m happy to say that NASA has recognized the need to go order the Core Stage-3 long leads and we have as of yesterday over two-hundred purchase orders out with our suppliers to start filling those needs plus some spares for the Core Stage-2 build that we’re doing right now,” he added back on June 11.

(Photo Caption: An image of the Orion Integrated Test Laboratory (ITL) at Lockheed Martin’s Waterton facility near Littleton, Colorado, showing some of the spacecraft avionics. Some of the internal electronics in the avionics boxes are “long lead” parts that need to be ordered early in the Orion spacecraft build process.)

For Orion, Michael Hawes, Vice President and Orion Program Manager for Lockheed Martin, said: “Most of the long leads are electronic parts that will go into the avionics and so there’s a whole series of those that we have worked off with the NASA team, but one of the things that jumped out and kind of surprised us were things like the large aluminum ingots that we machine the structure out of.”

“So the first things we put on contract were some of the long lead electronic parts, the forgings for the major structural pieces, and then right behind it are things like the engines both for the Crew Module and the ones that we provide ESA for the Service Module,” Hawes added.

NASA and Orion prime contractor Lockheed Martin are relatively close to finalizing an Orion Production and Operations Contract (OPOC), but the space agency went ahead with orders for long leads including those for the third ESM. “The teams have been negotiating. We’ve been negotiating on price, we’ve been negotiating on the phasing of the funding, we’ve been negotiating on the number of vehicles to buy, so there have been lots of things that have been going on and we’re really, really close,” Hawes said on July 2.

“We’re down to a few words now, really,” he noted. “NASA has found a way to authorize us even though we’re not quite signed off on the new contract yet, but they’ve actually authorized us to do some work ahead of that so that we’re not losing time on the parts, because we really want to make sure we’re getting those on order so that we can keep schedule.”

Third SLS assignment still depends on long-term commitments

SLS was designed around existing Space Shuttle Main Engines (SSME) and Solid Rocket Boosters originally evolved from Shuttle for the since-cancelled Constellation program. Four SLS flights worth of SSMEs, now called RS-25 engines, were inherited by SLS from the Space Shuttle Program and three flight sets of five-segment solid rocket motors (RSRMV) are either complete or in production; however, the rest of the SLS vehicle needed to be developed.

The contract for ground-up development of the most complicated piece of SLS and the backbone of the vehicle, the Core Stage, only covers production of two working, flight units. Besides engines and boosters, a third SLS vehicle is missing everything else — two stages and two adapters to connect them.

(Photo Caption: The Core Stage is the major new development for the SLS vehicle. The RS-25 engines were already built and flying Space Shuttle missions and the evolved Solid Rocket Booster design was already in development testing when the predecessor to SLS, the Constellation program, was cancelled in 2010-2011. Boeing is currently assembling the only two Core Stages under contract for NASA.)

NASA and SLS Stages prime contractor Boeing are still focused on the challenge of completing production of the first flight article, which is far behind original schedule estimates and there is no signed contract for a third Core Stage yet. As reported by NASA’s Office of Inspector General (OIG) last October, the existing Stages contract was going to overrun its total cost this year; while that is being renegotiated, work on Core Stage-1 (for Artemis 1) and Core Stage-2 (for Artemis 2) continues under Undefinitized Contract Actions (UCA).

NASA spokesperson Tracy McMahan said in an email that the UCA for the existing Stages contract was modified to authorize long lead items for the third Core Stage.

OIG also said in their report last October that the lead time for a Core Stage was 52 months; this would leave some margin in the overall schedule for the Artemis 3 target by the end of 2024, but would not be enough time to field a Core Stage for the Europa Clipper mission currently mandated to fly on SLS in July, 2023. The space agency is still required by law to launch that mission in less than four years, which would also mean that a fourth SLS vehicle would be needed for Artemis 3.

Beyond the RS-25 engines, Solid Rocket Boosters, and Core Stage, the contracts for the rest of the Artemis 2 vehicle hardware are also still being negotiated. NASA rebaselined the SLS vehicle for Artemis 2; the first crewed Orion mission is back on the SLS Block 1 configuration. Switching back to Block 1 over a year ago meant that NASA would now need another set of the upper stage elements that will first fly on Artemis 1: another Interim Cryogenic Propulsion Stage (ICPS), Launch Vehicle Stage Adapter (LVSA), and Orion Stage Adapter (OSA).

(Photo Caption: Slide from a presentation to a joint meeting of the NAC HEO and Science committees in August, 2018, showing current mandated SLS commitments for two development flights now named Artemis 1 and Artemis 2, launch of Europa Clipper directly to Jupiter in 2023, and Artemis 3. The Trump Administration and NASA leadership subsequently committed Artemis 3 to a U.S. lunar landing mission in 2024. Four SLS vehicles would be needed to fly these missions, but only the main elements of the first two are currently under contract.)

United Launch Alliance (ULA) built a structural test article (STA) and single flight article ICPS for NASA, but options for additional ICPS flight articles and the adapters that connect the ICPS to the Orion above and the Core Stage below were dropped in 2016 in favor of the Exploration Upper Stage (EUS).

With the move of Artemis 2 and Europa Clipper back to Block 1, NASA spokesperson Tracy McMahan said in an email that a Systems Requirements Review was in work for additional Block 1 hardware needed for Artemis 2, which includes an OSA, LVSA, and a human-rated ICPS, and for Science Mission-1 (SM-1), which would include an LVSA and ICPS.

NASA is still working out contract details with ULA for additional ICPS upper stages and has started other procurement work to build new LVSA and OSA units. McMahan also noted that NASA has UCAs for two additional ICPS units and two additional LVSA units, with proposals already received or expected soon.

Spare parts support next flights

In addition to authorizing Artemis 3 long lead hardware, Hawes also noted that NASA acted recently to maintain as much schedule flexibility between the Artemis 1 and Artemis 2 missions as they can. NASA moved up ordering a second set of core Orion avionics boxes last year to decouple the Exploration Mission-1 (now Artemis 1) launch from preparations for Exploration Mission-2 (now Artemis 2).

“They authorized us for what we coined as the ‘Core avionics’ and so we’ve had those parts on order and we’ve been working to build all those parts up,” Hawes said on July 2. “That helps us decouple Artemis 1 and Artemis 2.”

“Well as part of the long lead discussion we just had probably a month, six-weeks ago, Mark (NASA Orion Program Manager Mark Kirasich) also authorized us for that non-core set, the additional ones that fill out the whole set of avionics, to further give us flexibility. And now we’re so close to the OPOC contract, we’re basically buying those as an early part of the OPOC contract. So NASA gets the advantage of multiple buys and the price is renegotiated as part of that contract deal.”

(Photo Caption: Slide from a late May presentation to the NASA Advisory Council Human Exploration and Operations Committee showing Artemis 2 Crew Module integration milestones. The new set of “core avionics” ordered are expected at KSC in the middle of next year. NASA has recently ordered the balance of the avionics set, which will give the assembly and test team more flexibility to continue processing Artemis 2 independently of the Artemis 1 launch schedule.)

The core avionics set for the Artemis 2 Crew Module is expected to be available in the middle of 2020, which is now expected to be well before Artemis 1 is ready to launch.

For the SLS Core Stage, there are only enough parts for some of the equipment being directly reused from Space Shuttle Orbiters or modified for the first two flight articles. “For Core Stage-1 of course with the first build, if we found issues especially in avionics but also in some things like fittings or tubes we would go modify the Core Stage-2 part and then install it in the Core Stage-1 vehicle and then take the Core Stage-1 parts and then have them modified for the Core Stage-2 vehicle,” Shannon explained. “We did that sometimes when you needed to have a quick turnaround for a part like that.”

“We don’t really have that luxury for Core Stage-2.” After Artemis 1 flies, maintenance of parts on the Core Stage-2 vehicle as it is assembled and tested and prepared for launch could require removal and replacement by spare parts that are only now being authorized for purchase as a part of the long lead orders for the third Core Stage.