NASA SLS Centaur V Upper Stage Explained: Why the Moon Rocket Is Changing and What Happens After 2028

Image: NASA — the SLS rocket launching on Artemis I in November 2022 (public domain photo via Wikimedia Commons).

TL;DR: NASA SLS Centaur V upper stage explained in short: NASA is standardising its Moon rocket around ULA's Centaur V, dropping the bigger Exploration Upper Stage and stopping work on a second mobile launcher, so it can fly crews about once a year. The first crewed Moon landing is still targeted for 2028 on Artemis IV — and the Orion capsule may keep flying into the 2030s on other rockets.

Key Highlights

• NASA Administrator Jared Isaacman laid out the plan on 10 November: a standardised SLS, a stretched Centaur V upper stage, and work on Mobile Launcher 2 stopped.
• Centaur V replaces Boeing's Exploration Upper Stage (EUS), cancelled after its costs climbed toward $2.8 billion and delivery slipped years behind schedule.
• Artemis IV in 2028 will fly either the last Interim Cryogenic Propulsion Stage (ICPS) or the first stretched Centaur V — the choice comes next summer.
• The goal is to fly crews at least once a year, ideally less than 12 months apart, with possibly two SLS launches in 2028.
• Orion is expected to outlive SLS, possibly flying on other rockets such as Blue Origin's New Glenn in the 2030s.

What happened?

NASA Administrator Jared Isaacman explained the future of the Space Launch System in interviews on 10 November, speaking to NASASpaceflight's The Flame Trench show and to Everyday Astronaut Tim Dodd inside the Vehicle Assembly Building at Kennedy Space Center. The interviews build on NASA's Artemis update of 23 October and its 4 November summary, and they give the clearest picture yet of how NASA plans to fly to the Moon for the rest of the decade.

The core message is simplification. Instead of upgrading SLS into a bigger Block 1B rocket with a brand-new upper stage, NASA will keep the rocket close to its current Block 1 form, fly it more often, and hand the upper-stage job to a stage that already exists: ULA's Centaur V. Isaacman put the cost problem bluntly, saying there are "a lot of ways to shake the $4 billion disposable rocket label that SLS has carried and one of which is launch more frequently."

That matters because SLS has flown only once — the uncrewed Artemis I in November 2022 — followed by the crewed lunar flyby of Artemis II earlier this year. At one flight every few years, each launch carries the cost of an entire standing army of engineers and facilities. Flying roughly every 10 months spreads that cost and, NASA argues, rebuilds the operational experience needed for a sustained Moon programme.

NASA SLS Centaur V upper stage explained

The upper stage is the part of the rocket that fires after the core stage and solid boosters fall away, pushing Orion out of Earth orbit and toward the Moon. SLS has used the Interim Cryogenic Propulsion Stage (ICPS) so far — a modified Delta IV stage always meant as a stopgap, and production of it has already ended. The original plan was to replace it with Boeing's Exploration Upper Stage (EUS) from Artemis IV, creating the more powerful Block 1B configuration.

That plan is now dead. EUS development ran years late and billions over budget — reporting puts its costs toward $2.8 billion — and NASA's own Inspector General noted in June 2026 that four cancelled or repurposed Artemis systems, including EUS, carried a combined contract value of $5.9 billion. Isaacman was frank about it: "Everything that touched that upper stage was a problem. I mean, the stage adapter was way behind schedule and way over budget."

Centaur V is the replacement. It is the upper stage of ULA's Vulcan rocket, powered by RL10 engines with decades of flight heritage — an earlier Centaur variant was even certified for human spaceflight under NASA's Commercial Crew Program. It first flew on Vulcan's Cert-1 mission in January 2024 and is already in production. NASA awarded ULA a sole-source contract in March 2026 for stages to fly on Artemis IV and V, plus a flight spare.

There is one honest complication: the version NASA needs is a stretched Centaur V with bigger tanks, and that version is still in development. NASA originally intended to use the existing Centaur configuration but chose the higher-performance stretched version to push Orion closer to the Moon and make the landers' job simpler. NASA's November 4 update confirms both the final ICPS and the stretched Centaur V remain options for Artemis IV, with the decision due next summer — so the first Centaur V Moon flight is not yet locked to a specific mission.

Upper stage	Status	What it means
ICPS (Interim Cryogenic Propulsion Stage)	Final unit left; production ended	Flew Artemis I and II; one option for Artemis IV
EUS (Exploration Upper Stage)	Cancelled in 2026	Block 1B upgrade abandoned; costs toward $2.8 billion
Stretched Centaur V (ULA)	In development; contract awarded March 2026	Standard upper stage from Artemis IV onward; decision next summer

Image: NASA — the Orion crew module that will carry astronauts on Artemis missions (public domain photo via Wikimedia Commons). Orion, not SLS, is the part of the system NASA expects to keep flying into the 2030s.

Why Mobile Launcher 2 was stopped

The same logic killed Mobile Launcher 2 (ML-2), the second launch tower being built for the bigger Block 1B rocket. Work on it has stopped. The partly built structure still stands outside for now, but NASA says it will eventually be moved into the Vehicle Assembly Building, and some of its parts — along with hardware from the cancelled EUS — have already been handed to Blue Origin as government-furnished equipment for its pad rebuild and landers. Other hardware is being used to give younger engineers hands-on experience.

Isaacman acknowledged the decision stings for people who watched the tower rise, but said its visible progress did not mean it was close to working: "If you're going to launch even on an eight-month cadence, you do not need the second mobile launcher. I know that's heartbreaking for some out there and believe me that was nowhere near as ready as people believe it to be." He did not rule out using ML-2 again, but described that as highly unlikely. Instead, NASA will concentrate on getting very good at operating the single existing launcher, Mobile Launcher 1, whose modifications are already being designed with hardware on order.

What it means for the Moon landing timeline

The near-term sequence is unchanged. Artemis III, targeted for 2027, becomes a 14-day test flight in low Earth orbit with four astronauts aboard Orion, practising rendezvous and docking with test versions of both commercial landers — SpaceX's Starship and Blue Origin's Blue Moon Mark 2 — without leaving Earth orbit. It will fly without a functioning upper stage at all, using a spacer in place of one. Read how Artemis IV will refuel Starship in orbit for the landing itself.

Artemis IV remains targeted for the first crewed landing since Apollo 17 in 1972, in 2028. Two astronauts will go to the surface near the lunar south pole in either the Starship or Blue Moon lander — NASA has still not picked which one — while two remain aboard Orion. NASA has also floated a second landing, Artemis V, in late 2028. Beyond that, the agency's request for information on commercial lunar transportation, issued in March with responses in April, found industry could not offer an end-to-end replacement for SLS in 2028 or 2029; the answers pointed to the 2030s. The longer-term goal is two transport routes supporting crewed lunar missions every six months.

The most striking hint concerns Orion itself. Isaacman said "Orion will clearly live on beyond SLS," suggesting the capsule could fly on other launch vehicles and transfer stages in the 2030s. Blue Origin's larger New Glenn 9x4 variant — recently added to NASA's launch-services contract for bidding on missions in 2030–2032 — is one candidate. Lockheed Martin, which builds Orion, said on 5 November it is expanding the workforce for the next three Artemis missions. The rocket may be disposable; the spaceship, it seems, is not. And the rocket that will attempt the next giant leap in reusability, Starship Flight 15's double-catch attempt, is part of the same lunar story.

Why it matters for India readers

India signed the Artemis Accords in 2023, so the rules and timetable of the Artemis programme shape the lunar environment India is joining — and ISRO's own human spaceflight programme, Gaganyaan, is progressing toward its first crewed flight in parallel. A NASA that can fly to the Moon once a year, rather than once every few years, means a faster-moving lunar economy: more landers, more surface infrastructure, and more opportunities for partner nations and their industries.

There is also a direct hardware link. The same Centaur V that NASA wants for SLS flies today on ULA's Vulcan rocket — the vehicle now launching Amazon's Leo broadband satellites, with 40 satellites on the LV-01 mission retargeted for Saturday 14 November after Friday's scrub. The satellite-broadband race those launches feed includes India, where Amazon Leo, Starlink and Jio-SES are all lining up to serve. And for the bigger picture, see NASA's Moon Base plan, which this cheaper, steadier SLS cadence is meant to support.

Should you care?

Yes — if you follow the race back to the Moon. NASA has finally answered the question that has hung over Artemis for years: it will keep SLS, make it cheaper by flying it more often, and stop paying for the upgrades it could not finish. The 2028 landing date is still a target, not a promise — the landers and the stretched Centaur V both have to prove themselves first. Watch two dates: Artemis III's Earth-orbit test in 2027, and next summer's decision on which upper stage flies Artemis IV.

FAQs

Why did NASA cancel the Exploration Upper Stage?
NASA cancelled the EUS because it was years behind schedule and billions over budget, with development costs reported toward $2.8 billion. Rather than keep funding a bespoke stage for SLS alone, NASA chose ULA's Centaur V, which already flies on the Vulcan rocket and shares the RL10 engine heritage.

What is the Centaur V upper stage?
Centaur V is ULA's current upper stage, powered by RL10 engines, which first flew on Vulcan's Cert-1 mission in January 2024. NASA will use a stretched version with larger tanks as the standard SLS upper stage from Artemis IV onward, with the first flight decision due next summer.

Will Orion outlive the SLS rocket?
That is NASA Administrator Jared Isaacman's expectation — he said "Orion will clearly live on beyond SLS." The capsule could fly on other launch vehicles and transfer stages in the 2030s, with Blue Origin's New Glenn 9x4 variant one candidate now eligible for NASA launch-service bidding.

When will NASA land astronauts on the Moon again?
Artemis IV is targeted for the first crewed landing since Apollo 17 in 1972, in 2028, using either SpaceX's Starship or Blue Origin's Blue Moon lander. Artemis III flies first, in 2027, as a 14-day Earth-orbit test of the landers and Orion. All dates are targets, not guarantees.

Takeaway

NASA is betting that a simpler, more frequently flown Moon rocket beats a bigger, more expensive one — and that the Orion capsule, not the rocket under it, is the part of Artemis built to last.

If you want the full landing sequence, read our explainer on how Artemis IV will refuel Starship in orbit — it is the other half of the 2028 plan.

Sources

NASA — Artemis program
NASASpaceflight — Isaacman lays out SLS path to the 2030s (11 November 2026)
The Space Launches — Isaacman lays out SLS path to the 2030s (mirror, 10 November 2026)
Starlust — 'Orion will clearly live on beyond SLS' (11 November 2026)
The Register — NASA ditches delayed SLS upper stage for ULA's Centaur V (9 March 2026)
NASA Office of Inspector General — Interim Memorandum ML-26-002 on cancelled Artemis systems (24 June 2026)