Space Launch System

This article is about the NASA rocket family. For the similarly-named US Air Force project of the 1960s, see Space Launching System. For Turkey's UFS satellite launcher, see Space Launch System (Turkey). For the general topic, see space launcher.

Space Launch System

SLS with the Orion spacecraft launching from Pad 39B for Artemis II
Function	Super heavy-lift launch vehicle
Manufacturer	Aerojet Rocketdyne Boeing Northrop Grumman United Launch Alliance
Country of origin	United States
Project cost	US$31.6 billion as of 2025 (excluding Orion)
Cost per launch	US$2.5 billion (excluding Orion)
Cost per year	US$2.6 billion (FY23) (excluding Orion)
Size
Height	98 m (322 ft)
Diameter	8.4 m (27.6 ft)
Mass	2,610,000 kg (5,750,000 lb)
Stages	2+1⁄2
Maximum thrust	39 MN (8,800,000 lbf)
Capacity
Payload to LEO
Altitude	200 km (120 mi)
Orbital inclination	28.5°
Mass	95,000 kg (209,000 lb)
Payload to TLI
Mass	27,000 kg (59,500 lb)
Associated rockets
Based on	Ares V Delta IV Space Shuttle
Comparable	Energia Falcon Heavy Long March 9 N1 Saturn V Starship
Launch history
Status	Active
Launch sites	Kennedy, LC-39B
Total launches	2
Success(es)	2
First flight	November 16, 2022
Last flight	April 1, 2026 (most recent)
Carries passengers or cargo	Orion (crew of 4)
Boosters – five-segment SRB
No. boosters	2
Height	54 m (177 ft)
Diameter	3.7 m (12 ft)
Gross mass	730,000 kg (1,600,000 lb)
Maximum thrust	SL: 14.6 MN (3,280,000 lbf) vac: 16 MN (3,600,000 lbf)
Total thrust	SL: 29.2 MN (6,560,000 lbf) vac: 32 MN (7,200,000 lbf)
Specific impulse	269 s (2.64 km/s)
Burn time	126 seconds
Propellant	APCP (Al / AP / PBAN)
First stage – Core
Height	64.6 m (212 ft)
Diameter	8.4 m (28 ft)
Empty mass	97,940 kg (215,910 lb)
Gross mass	1,085,410 kg (2,392,910 lb)
Propellant mass	LH2: 144,000 kg (317,000 lb) LOX: 840,000 kg (1,860,000 lb)
Powered by	4 × RS-25
Maximum thrust	SL: 7.4 MN (1,672,000 lbf) vac: 9.1 MN (2,049,200 lbf)
Specific impulse	SL: 366 s (3.59 km/s) vac: 452 s (4.43 km/s)
Burn time	480 seconds
Propellant	LH2 / LOX
Second stage – ICPS
Height	13.7 m (45 ft)
Diameter	LH2 tank: 5 m (16 ft) LOX tank: 3.2 m (10 ft)
Empty mass	3,490 kg (7,690 lb)
Gross mass	32,066 kg (70,693 lb)
Powered by	1 × RL10
Maximum thrust	110.1 kN (24,800 lbf)
Specific impulse	465.5 s (4.565 km/s)
Burn time	1,125 seconds
Propellant	LH2 / LOX
Second stage – Centaur V (Planned)
Height	CV-L: 10.66 m (35 ft) CV-HE: 12.6 m (41 ft)
Diameter	5.4 m (17.7 ft)
Empty mass	CV-HE: 7,100 kg (15,700 lb)
Gross mass	CV-HE: 53,600 kg (118,200 lb)
Powered by	2 × RL10C 2 × RL10E (planned upgrade)
Maximum thrust	RL10C: 203.6 kN (45,780 lbf) RL10E: 214.6 kN (48,240 lbf)
Specific impulse	RL10C: 453.8 s (4.450 km/s) RL10E: 460.9 s (4.520 km/s)
Burn time	CV-HE: 1,077 seconds
Propellant	LOX / LH2

The Space Launch System (SLS) is an American two-stage super heavy-lift expendable launch vehicle used by NASA. The primary launch vehicle for the Artemis program, SLS is designed to launch the four-person Orion spacecraft. The rocket first launched in November 2022, carrying the uncrewed Artemis I mission. Its only crewed launch has been for the Artemis II lunar flyby in April 2026, becoming the second launch vehicle to carry humans beyond low Earth orbit (LEO), after NASA's Saturn V of the Apollo program.

Development of SLS began in 2011 as a congressionally mandated replacement for the retiring Space Shuttle program and the cancelled Ares I and Ares V launch vehicles of the Constellation program, incorporating some hardware from both programs. Costing US$31.6 billion as of 2025, the project has been criticized for mismanagement, budget overruns, and delays, but ultimately succeeded in human spaceflight in 2026.

All SLS launches take place from Launch Complex 39B at the Kennedy Space Center in Florida. The new Boeing-built core stage is powered by four ex-Shuttle RS-25 engines. Attached to the core are two Northrop Grumman five-segment Solid Rocket Boosters, built for the Ares vehicles, tested on Ares I-X, developed from the Shuttle's four-segment SRB. SLS currently uses the Interim Cryogenic Propulsion Stage (ICPS) as its second stage, for the insertions to low Earth orbit and trans-lunar injection. ICPS uses the RL10 engine, and was derived from the Delta Cryogenic Second Stage designed by Japan's space agency. Aerojet Rocketdyne builds the RS-25 and RL10 engines.

Starting from Artemis V, no earlier than late 2028, SLS will use the Centaur V upper stage, developed for the Vulcan Centaur, instead of ICPS. NASA previously planned to upgrade SLS from its current Block 1 configuration to a Block 1B and Block 2, but cancelled these plans in February 2026, aiming to standardize on Block 1, to "reduce risk and maintain schedule stability". Block 1B was to use the Exploration Upper Stage, and Block 2 would have used new solid rocket boosters.

While SLS has the highest liftoff thrust of any rocket to ever carry humans, 39 meganewtons (8,800,000 pounds-force), SLS's payload capacity to trans-lunar injection of 27 metric tons (59,525 lb) is only around half that of the Saturn V's 48.6 metric tons (107,145 lb) payload. Thus for Artemis lunar landings, beginning with Artemis IV targeted early 2028, Orion is planned to dock with the Human Landing System (HLS) in lunar orbit or low Earth orbit, separately launched on a non-SLS rocket; SpaceX's Starship HLS and Blue Origin's Blue Moon are under development as HLS vehicles.

Its next scheduled flight is Artemis III, a 2027 low Earth orbit docking test between Orion and HLS vehicles. Beginning with Artemis V, NASA will transfer SLS operations to the Deep Space Transport LLC, a commercial launch provider consortium of Boeing and Northrop Grumman.