Space Launch System
Artist's rendering of the SLS Block 1 crewed variant launching
|Country of origin||United States|
|Diameter||8.4 m (core stage)|
|70,000 to 129,000 kg (150,000 to 280,000 lb)|
|Family||Shuttle-Derived Launch Vehicles|
|Launch sites||LC-39, Kennedy Space Center|
|First flight||17 December 2017|
|Notable payloads||Orion MPCV|
|Boosters (Block I)|
|No boosters||2 Space Shuttle Solid Rocket Boosters
|Thrust||16,013.6 kN (3,600,000 lbf)|
|Total thrust||32,027.2 kN (7,200,000 lbf)|
|Specific impulse||269 seconds|
|Burn time||124 seconds|
|First Stage (Block I) - Core Stage|
|Diameter||8.4 m (330 in)|
|Thrust||7,440 kN (1,670,000 lbf)|
|Specific impulse||363 seconds (sea level)|
|First Stage (Block IA/II) - Core Stage|
|Diameter||8.4 m (330 in)|
|Thrust||9,300 kN (2,100,000 lbf)|
|Specific impulse||363 seconds (sea level)|
|Second Stage (Block I) - ICPS|
|Length||13.7 m (540 in)|
|Diameter||5 m (200 in)|
|Empty mass||3,490 kg (7,700 lb)|
|Gross mass||30,710 kg (67,700 lb)|
|Thrust||110.1 kN (24,800 lbf)|
|Specific impulse||462 seconds|
|Burn time||1125 seconds|
|Second Stage (Block II) - Earth Departure Stage|
|Thrust||3,930 kN (880,000 lbf)|
|Specific impulse||448 seconds (vacuum)|
The Space Launch System, or SLS, is a United States Space Shuttle-derived heavy launch vehicle being designed by NASA. It follows the cancellation of the Constellation Program, and is to replace the retired Space Shuttle. The NASA Authorization Act of 2010 envisions the transformation of the Ares I and Ares V vehicle designs into a single launch vehicle usable for both crew and cargo.
The SLS launch vehicle is to be upgraded over time with more powerful versions. Its initial Block I version, without an upper stage, is to lift a payload of 70 metric tons to orbit. The final Block II version with an integrated upper Earth Departure Stage is to lift 130 metric tons, which would make SLS the most powerful rocket ever built.
SLS is to take astronauts and hardware to such destinations as near-Earth objects like asteroids, Lagrangian points, the Moon, and Mars. SLS may also support trips to the International Space Station, if necessary. The SLS Program is integrated with NASA's Orion Program, providing a multipurpose crew vehicle. SLS will use the ground operations and launch facilities at NASA's Kennedy Space Center, Florida.
Design and development 
On September 14, 2011, NASA announced its design selection for the new launch system, declaring that it would take the agency's astronauts farther into space than ever before and provide the cornerstone for future US human space exploration efforts. Since the announcement, four versions of the launch vehicle have been revealed – Blocks 0, I, IA and II. Each configuration utilizes different core stages, boosters and upper stages, with some components deriving directly from Space Shuttle hardware and others being developed specifically for the SLS. Later versions will use five RS-25E engines with upgraded boosters and an 8.4-meter diameter upper stage with 3 J-2X engines. A 5-meter class fairing with a length of 10 m or greater is being considered for allowing heavy payloads for deep space missions. The initial Block I two-stage variant will have a lift capability of between 70,000 and 77,000 kg, while the proposed Block II final variant will have similar lift capacity and height to the original Saturn V. By November 2011, NASA had selected five rocket configurations for wind tunnel testing, described in three Low Earth Orbit classes; 70 metric tons, 95 metric tons, and 140 metric tons.
Core stage 
The core stage of the SLS is common to all vehicle configurations, essentially consisting of a modified Space Shuttle External Tank with the aft section adapted to accept the rocket's Main Propulsion System (MPS) and the top converted to host an interstage structure. It will be fabricated at the Michoud Assembly Facility. The stage will utilize varying numbers and versions of the RS-25 engine depending on the configuration to be used:
- Block I– Stretched core stage with 4 RS-25D engines.
- Block IB- Stretched core stage with 4 RS-25D/E engines.
- Block IA & II – Stretched core stage with 5 RS-25E engines.
In addition to the thrust produced by the engines on the core stage, for the first two minutes first stage flight will be aided by two booster rockets mounted either side of the core stage. Early configurations (Blocks 0 and I) of the SLS are set to use modified Space Shuttle Solid Rocket Boosters (SRBs), with either 4 or 5 segments depending on configuration. These boosters will not be recovered and will sink into the Atlantic Ocean downrange. The boosters for Block IA and Block II configurations will use upgraded boosters from the selection of improved booster bids. These boosters may be of either the solid or liquid-fuel type.
ATK, the builder of the Space Shuttle SRBs, has completed three full-scale, full-duration static tests of the five-segment booster that will be used in Blocks 0 and I. Development motor (DM-1) was successfully tested on September 10, 2009; DM-2 on August 31, 2010 and DM-3 on September 8, 2011. For DM-2 the motor was cooled to a core temperature of 40 degrees Fahrenheit (4 degrees Celsius), and for DM-3 it was heated to above 90 °F (32 °C). In addition to other objectives, these tests validated motor performance at extreme temperatures. Each 5 segment SRB has a sea level thrust of 3,600,000 lbf (16 MN).
On June 17, 2011, Aerojet announced a strategic partnership with Teledyne Brown to develop and produce a domestic version of the Soviet NK-33 LOX/RP-1 engine on ill-fated N-1 Soviet moonshot vehicle to power a booster for the SLS launch vehicle. The new engine version is to have an increased thrust of 500,000 lbf (2.2 MN) at sea level, an increase from 1.75 MN (394,000 lbf) of the original engine. This booster is to compete against Shuttle-derived solid rocket boosters. On February 14, 2013, NASA awarded a $23.3 million 30-month contract Aerojet to build a full-scale 550,000-pound thrust class main injector and thrust chamber to be used in the advanced booster. On April 21, 2013, the Antares rocket, powered by two Aerojet AJ-26 engines each producing approximately 400,000 pounds of thrust, had a successful maiden launch.
NASA's Advanced Booster Competition is to select a winning booster by the end of 2015. Pratt and Whitney, Rocketdyne, and Dynetics have presented a booster using two of the F-1B engine derived from the F-1 LOX/RP-1 engine that powered the first stage of Saturn V for the Apollo program. In 2012, it was suggested that if integrated on the SLS Block II, the payload could be 150 metric tons to low earth orbit, 20 mt above the planned payload amount. In 2013, it was reported that the F-1B engine version is to have improved efficiency and more cost effective as possible, with a simplified combustion chamber, and fewer engine parts. The F-1B is to produce 1,800,000 lbf (8.0 MN) of thrust at sea level, an increase over the 1,550,000 lbf (6.9 MN) of thrust of the initial F-1 version.
Upper stage 
- Block 0 – No upper stage.
- Block I – A Delta Cryogenic Second Stage (DCSS), referred to as the Interim Cryogenic Propulsion Stage (ICPS). This 70-metric ton configuration currently will only fly two missions: Exploration Mission 1 (EM-1) in 2017 and Exploration Mission 2 (EM-2) in 2021. Delta IV and Atlas V upper stages were noted options; the Delta IV DCSS was selected in May 2012.
- Block IA – A large Cryogenic Propulsion Stage, specifically developed for SLS and powered by liquid hydrogen fuel and liquid oxygen oxidizer. This 105-metric ton rocket will first launch as SLS-3, nominally in 2023, and be followed by SLS-4 in 2025. Currently there are four configurations of this vehicle under analysis by NASA, of which only two will be produced.
- Block IB - CPS consisting of four RL10A-4-2 engines with a 8.4 m fairing and 105 mt to LEO.
- Block II – A fully-fledged Earth Departure Stage to be powered by three J-2X engines. This 130-metric ton rocket evolution will not debut until the 2030s. As with the Block IA there are also four corresponding configurations of this vehicle under analysis by NASA.
Assembled rocket 
Prior to launch the SLS will have the ability to tolerate a minimum of 13 tanking cycles due to launch scrubs and other launch delays. The assembled rocket is to be able to remain at the launch pad for a minimum of 180 days and can remain in stacked configuration for at least 200 days without destacking.
Program costs 
During the joint Senate-NASA presentation in September 2011, it was stated that the SLS program has a projected development cost of $18 billion through 2017, with $10B for the SLS rocket, $6B for the Orion Multi-Purpose Crew Vehicle and $2B for upgrades to the launch pad and other facilities at Kennedy Space Center. These costs and schedule are considered optimistic by Booz Allen Hamilton, which conducted an independent cost assessment for NASA. An unofficial NASA document estimated the cost of the program through 2025 to total at least $41B for four 70 metric ton launches (1 unmanned in 2017, 3 manned starting in 2021), with the 130 metric ton version ready no earlier than 2030. HEFT estimate Block 0 unit cost at $1.6 billion.
NASA SLS deputy project manager Jody Singer of the Marshall Space Flight Center in Huntsville, AL suggests $500 million per launch is a reasonable target cost for SLS, with a relatively minor dependence of costs on launch capability.
Criticism of SLS falls in several areas including claims of cannibalization from other areas of the space program. The Space Access Society, Space Frontier Foundation and the Planetary Society called for cancellation arguing that SLS will consume the funds for other projects from the NASA budget and will not reduce per pound launch costs. Some estimate the cost per pound to LEO at approximately $8,500. U.S. Representative Dana Rohrabacher and others added that instead a propellant depot should be developed and the Commercial Crew Development program accelerated. Two studies, one not publicly released from NASA, and another from Georgia Tech show it as a possible cheaper alternative.
Others suggest it will cost less to use an existing lower payload capacity rocket (Atlas V, Delta IV, Falcon 9) or the derivative (Falcon Heavy), with on-orbit assembly, and the development of refuelling depots as needed, rather than develop a new launch vehicle for space exploration without competition for the whole design.
Mars Society founder Robert Zubrin suggested that a heavy lift vehicle should be developed for $5 billion on fixed-price requests for proposal, finance issues aside, in the same breath however Zubrin also stated that he does not agree with those that say we don't need a heavy-lift vehicle, and stated "We absolutely do need heavy-lift". Based upon extrapolations of increased payload lift capabilities from past experience with SpaceX vehicles, from the Falcon I to Falcon 9, SpaceX CEO Elon Musk guaranteed that his company could build the conceptual Falcon XX, a vehicle in the 140-150 mt payload range, for $2.5 billion, or $300 million per launch, but cautioned that this price tag did not include a potential upper-stage upgrade.
Rep. Tom McClintock and other groups argue that the Congressional mandates forcing NASA to use Space Shuttle components for SLS amounts to a de-facto non-competitive, single source requirement assuring contracts to existing shuttle suppliers, and calling the Government Accountability Office (GAO) to investigate possible violations of the Competition in Contracting Act (CICA). Opponents of the heavy launch vehicle have critically used the name "Senate launch system".
The Competitive Space Task Force, in September 2011, said that the new government launcher directly violates NASA’s charter, the Space Act, and the 1998 Commercial Space Act requirements for NASA to pursue the "fullest possible engagement of commercial providers" and to "seek and encourage, to the maximum extent possible, the fullest commercial use of space".
Proposed missions and schedule 
- ISS Back-Up Crew Delivery – a single launch mission of up to four astronauts via a Block 1 SLS/Orion-MPCV without an Interim Cryogenic Propulsion Stage (ICPS) to the ISS if the Commercial Crew Development program does not come to fruition. This potential mission mandated by the NASA Authorization Act of 2010 is deemed undesirable since the 70 mt SLS and BEO Orion would be overpriced and overpowered for said mission requirements. Its current description is “delivers crew members and cargo to ISS if other vehicles are unable to perform that function. Mission length 216 mission days. 6 crewed days. Up to 210 days at the ISS.”
- Tactical Timeframe DRMs
- BEO Uncrewed Lunar Fly-by – Exploration Mission 1 (EM-1), a reclassification of SLS-1, is a single launch mission of a Block I SLS with ICPS and lunar Block 1 Orion MPCV with a liftoff mass around 62.2 t with SLS’ Payload Insertion of 50.4 t, which would be a six to ten day test mission with about one day around the Moon. Its current description is “Uncrewed Lunar Flyby: Uncrewed mission Beyond Earth Orbit (BEO) to test critical mission events and demonstrate performance in relevant environments. Expected drivers include: SLS and ICPS performance, MPCV environments, MPCV re-entry speed, and BEO operations,” EM-1 overview as follows; “Notional Mission Event Sequence: 1) SLS lofts Orion to high-apogee orbit, while meeting core disposal constraints,” “2) Kick-stage (TBD) performs burn to raise perigee to safe height. 3) Kick-stage (TBD) performs TLI burn,” “4) 3–5 day transit time. 5) Lunar flyby. 6) 3–5 day transit time.”
- BEO Crewed Lunar Orbit – Exploration Mission 2 (EM-2), a reclassification of SLS-2, is a single launch mission of a Block I SLS with ICPS and lunar Block 1 Orion MPCV with a liftoff mass around 68.8 t with SLS’ Payload Insertion of 50.7 t, which would be a ten to fourteen day mission with a crew of four astronauts who would spend four days in lunar orbit. Its current description is “Crewed mission to enter lunar orbit, test critical mission events, and perform operations in relevant environments,” “Expected drivers include: SLS and ICPS performance, crew support for BEO mission duration, MPCV delta V, MPCV re-entry speed.”
- Strategic Timeframe DRMs
- GEO mission – a dual launch mission separated by 180 days to Geostationary Orbit. The first launch would comprise an SLS with a CPS and cargo hauler, the second an SLS with a CPS and Orion MPCV. Both launches would have a mass of about 110 t.
- A set of lunar missions enabled in the early 2020s ranging from EML-1 and low lunar orbit to a lunar surface mission. These missions would lead to a lunar base combining commercial and international aspects.
- The first two missions would be single launches of SLS with a CPM and Orion MPCV to EML-1 or LLO and would have a mass of 90 t and 97.5 t respectively. The LLO mission is a crewed twelve day mission with three in Lunar orbit. Its current description is “Low Lunar Orbit (LLO): Crewed mission to LLO. Expected drivers include: SLS and CPS performance, MPCV re-entry speed, and LLO environment for MPCV,”
- The lunar surface mission set for the late 2020s would be a dual launch separated by 120 days. This would be a nineteen day mission with seven days on the Moon's surface. The first launch would comprise an SLS with a CPS and lunar lander, the second an SLS with a CPS and Orion MPCV. Both would enter LLO for lunar orbit rendezvous prior to landing at equatorial or polar sites on the moon. Launches would have masses of about 130 t and 108 t, respectively. Its current description is “Lunar Surface Sortie (LSS): Lands four crew members on the surface of the Moon in the equatorial or Polar Regions and returns them to Earth,” “Expected drivers include: MPCV operations in LLO environment, MPCV uncrewed ops phase, MPCV delta V requirements, RPOD (Rendezvous, Proximity Operations and Docking), MPCV number of habitable days.”
- Five Near Earth Asteroid (NEA) missions ranging from “Minimum” to “Full” capability are being studied. Among these are two NASA NEO missions in 2026. A 155 day mission to NEO 1999 AO10, a 304 day mission to NEO 2001 GP2, and a Boeing proposed NEO mission to NEA 2008 EV5 in 2024. The latter would start from the proposed Earth-Moon L2 based Exploration Gateway Platform. Utilising a SLS third stage the trip would take about 100 days to arrive at the asteroid, 30 days for exploration, and a 235 day return trip to Earth.
- Forward Work Martian Moon Phobos/Deimos, a crewed Flexible Path mission to one of the Martian moons. It would include 40 days in the vicinity of Mars and a return Venus flyby.
- Forward Work Mars Landing, a crewed mission to spend 500 or more days exploring the surface of the red planet. The ambitious proposal would include the launch of seven SLS HLVs with nuclear propulsion stages, or NTRs (Nuclear Thermal Rocket). The seven payloads would then be assembled in LEO into three separate vehicles for the journey to Mars, the MLV Cargo Vehicle, MLV Habitat Vehicle, and MTV Crew Transfer Vehicle.
- Other proposed missions
- 2024+ Single Shot MSR on SLS, a crewed flight with robotic Mars sample return mission proposed by NASA's Mars Program Planning Group. The time frame suggests SLS-5, a 105 mt Block 1A rocket to deliver an Orion capsule, SEP robotic vehicle, and Mars Ascent Vehicle (MAV). “Sample canister could be captured, inspected, encased and retrieved tele-robotically. Robot brings sample back and rendezvous with a crew vehicle." The mission may also include a “Possible Mars SEP (Solar Electric Power/Propulsion) Orbiter”.
- Potential sample return missions to Europa and Enceladus have also been noted.
- Deep Space Habitat (DSH), NASA's planned usage of spare ISS hardware, experience, and modules for future missions to asteroids, Earth-Moon Lagrangian point and Mars.
- Skylab II, Proposal by Brand Griffin, an engineer with Gray Research Inc working with NASA Marshall, to use upper stage hydrogen tank from SLS to build a 21st century version of Skylab for future NASA missions to asteroids, Earth-Moon Lagrangian point (EML2) and Mars.
- SLS DoD Missions, the HLV will be made available for Department of Defense and other US Government agencies to launch military or classified missions.
- Commercial payloads, such as the Bigelow Commercial Space Stations have also been referenced.
- Additionally “Secondary Payloads” mounted on SLS via an Encapsulated Secondary Payload Adapter (ESPA) ring could also be launched in conjunction with a "primary passenger" to maximize payloads.
A very preliminary and unofficial schedule based on a worst case budget has outlined some early SLS flights as:
|SLS-1/EM-1||December 2017||Block I||Send Orion/MPCV on unmanned trip around the Moon.|
|SLS-2/EM-2||2021||Block I||Send Orion MPCV with four members into lunar orbit.|
|SLS-3||August 2022||Block IA|
|SLS-4||August 2023||Block IA|
|SLS-5||August 2024||Block IA||Mars Sample Return Mission[specify]|
|SLS-6||August 2025||Block IA||Manned "Exploration" Mission: Orion BEO picks up Mars sample & returns to Earth|
|SLS-7||August 2026||Block IA||Cargo launch|
|SLS-8||August 2027||Block IA||Manned launch|
|SLS-9||August 2028||Block IA||Cargo launch|
|SLS-10||August 2029||Block IA||Manned launch|
|SLS-11||August 2030||Block IA||New configuration, Cargo launch|
|SLS-12||August 2031||Block IA||Manned mission|
|SLS-13||August 2032||Block II||New configuration, Cargo launch|
See also 
- Space Shuttle successors
- Comparison of orbital launchers families
- Comparison of orbital launch systems
- Exploration of Mars
- Manned mission to Mars
- Space policy of the Barack Obama administration
- Space Exploration Vehicle
- Saturn MLV, a modified super heavy lift Saturn V design of the late 1960s, designed for crewed Mars missions by the 1980s.
- Saturn V ELV, an enlarged Saturn V design concept of the late 1960s with strapon Titan IV solid rocket boosters.
- Saturn V-3, an upgraded Saturn V, another design concept of the late 1960s which would use F-1A 1st stage engines and HG-3 2nd stage engines.
- Ares V, the cargo vehicle design for the Constellation Program of the 2000s.
- DIRECT, a competitor to the Ares V, but with a lower and smaller payload capacity, it was to use the concept Jupiter (rocket family) of vehicles.
- Shuttle-Derived Heavy Lift Launch Vehicle, a concept vehicle that would have had a lower lift capability than the baseline Saturn V.
- Energia, a comparable vehicle to SLS Block I in terms of lift capability, but for Low Earth Orbit excursions.
- Nautilus-X, a proposed deep space habitat module.
- "Space Launch System: How to launch NASA’s new monster rocket". NASASpaceFlight.com. 20 February 2012. Retrieved 9 April 2012.
- "The NASA Authorization Act of 2010". Featured Legislation. Washington DC, USA: United States Senate. July 15, 2010. Retrieved May 26, 2011.
- Stephen Clark (March 31, 2011). "NASA to set exploration architecture this summer". Spaceflight Now. Retrieved 26 May 2011.
- "NASA Announces Design For New Deep Space Exploration System". NASA. 14 September 2011. Retrieved 14 September 2011.
- "Press Conference on the Future of NASA Space Program". C-Span. 14 September 2011. Retrieved 14 September 2011.
- Kenneth Chang (September 14, 2011). "NASA Unveils New Rocket Design". New York Times. Retrieved 14 September 2011.
- Chris Bergin (4 October 2011). "SLS trades lean towards opening with four RS-25s on the core stage". NASASpaceflight.com. Retrieved 26 January 2012.
- NASA interested in payload fairing options for multi-mission SLS capability
- Karl Tate (16 September 2011). "Space Launch System: NASA's Giant Rocket Explained". Space.com. Retrieved 26 January 2012.
- Chris Gebhardt. "SLS: NASA identifies DAC-1 configuration candidates for wind tunnel tests". NASASpaceflight.com. Archived from the original on unknown.
- "NASA Announces Key Decision For Next Deep Space Transportation System". NASA. 24 May 2011. Retrieved 26 January 2012.
- Chris Bergin (14 September 2011). "SLS finally announced by NASA – Forward path taking shape". NASASpaceflight.com. Retrieved 26 January 2012.
- Chris Bergin (April 25, 2011). "SLS planning focuses on dual phase approach opening with SD HLV". NASASpaceflight.com. Retrieved January 26, 2012.
- Bergin, Chris (June 16, 2011). "Managers SLS announcement after SD HLV victory". NASASpaceflight.com. Retrieved January 26, 2012.
- Keith Cowing (September 14, 2011). "NASA's New Space Launch System Announced – Destination TBD". SpaceRef. Retrieved January 26, 2012.
- "NASA and ATK Successfully Test Ares First Stage Motor". NASA. 10 September 2009. Retrieved 30 January 2012.
- "NASA and ATK Successfully Test Five-Segment Solid Rocket Motor". NASA. 31 August 2010. Retrieved 30 January 2012.
- NASA Successfully Tests Five-Segment Solid Rocket Motor, NASA, 31 August 2010, retrieved 8 September 2011
- Frank Morring (17 June 2011). "NASA Will Compete Space Launch System Boosters". Aviation Week. Retrieved 20 June 2011.
- Rachel Kraft (February 14, 2013). "NASA Awards Final Space Launch System Advanced Booster Contract". NASA. Retrieved February 19, 2013.
- Lee Hutchinson (2013-04-15). "New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of thrust". Ars Technica. Retrieved 2013-04-15.
- Lee Hutchinson (2013-04-15). "New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of thrust". Ars Technica. Retrieved 2013-04-15.
- "Acronyms to Ascent – SLS managers create development milestone roadmap". NASASpaceFlight.com. 23 February 2012. Retrieved 9 April 2012.
- "Exploration Mission 1: SLS and Orion mission to the Moon outlined". NASASpaceFlight.com. 29 February 2012. Retrieved 9 April 2012.
- Rosenberg, Zach. "Delta second stage chosen as SLS interim". Flight International, May 8, 2012.
- "SLS to be robust in the face of scrubs, launch delays and pad stays". NASASpaceFlight.com. 4 April 2012. Retrieved 9 April 2012.
- Marcia Smith (14 September 2011). "New NASA Crew Transportation System to Cost $18 Billion Through 2017". Space Policy Online. Retrieved 15 September 2011.[dead link]
- "Independent Cost Assessment of the Space Launch System, Multi-purpose Crew Vehicle and 21st Century Ground Systems Programs: Executive Summary of Final Report". Booz Allen Hamilton. NASA.gov. 19 August 2011.
- "ESD Integration, Budget Availability Scenarios" (PDF). Space Policy Online. 19 August 2011. Retrieved 15 September 2011.
- Marcia Smith (9 September 2011). "The NASA Numbers Behind That WSJ Article". Space Policy Online. Retrieved 15 September 2011.
- "Human Exploration Framework Team (HEFT) DRM Review – Phase 1 (page 69)". nasawatch.com. September 2010.
- "NASA's huge new rocket may cost $500 million per launch". MSNBC. September 12, 2012.
- Henry Vanderbilt (15 September 2011). "Impossibly High NASA Development Costs Are Heart of the Matter". moonandback.com. Retrieved 26 January 2012.
- Ferris Valyn (15 September 2011). "Monster Rocket Will Eat America’s Space Program". Space Frontier Foundation. Retrieved 16 September 2011.
- "Statement before the Committee on Science, Space, and Technology US House of Representatives Hearing: A Review of the NASA's Space Launch System" (PDF). The Planetary Society. 12 July 2011. Retrieved 26 January 2012.
- "The SLS: too expensive for exploration?". thespacereview.com. 28 November 2011.
- Rohrabacher, Dana (14 September 2011). "Nothing New or Innovative, Including It's Astronomical Price Tag". Retrieved 14 Sept 2011.
- "Rohrabacher calls for "emergency" funding for CCDev". parabolicarc.com. 24 August 2011. Retrieved 15 September 2011.
- Jeff Foust (15 September 2011). "A monster rocket, or just a monster?". The Space Review.
- Jeff Foust (1 November 2011). "Can NASA develop a heavy-lift rocket?". The Space Review.
- Mohney, Doug (21 October 2011). "Did NASA Hide In-space Fuel Depots To Get a Heavy Lift Rocket?". Satellite Spotlight. Retrieved 10 November 2011.
- "Propellant Depot Requirements Study". HAT Technical Interchange Meeting. 21 July 2011.
- Cowing, Keith (12 October 2011). "Internal NASA Studies Show Cheaper and Faster Alternatives to the Space Launch System". SpaceRef.com. Retrieved 10 November 2011.
- "Near Term Space Exploration with Commercial Launch Vehicles Plus Propellant Depot". Georgia Institute of Technology / National Institute of Aerospace. 2011.
- "Affordable Exploration Architecture" (PDF). United Launch Alliance. 2009.
- Grant Bonin (6 June 2011). "Human spaceflight for less: the case for smaller launch vehicles, revisited". The Space Review.
- Robert Zubrin (14 May 2011). "How We Can Fly to Mars in This Decade—And on the Cheap". Mars Society.
- Rick Tumlinson (15 September 2011). l "The Senate Launch System – Destiny, Decision, and Disaster". Huffington Post.
- Andrew Gasser (24 October 2011). "Propellant depots: the fiscally responsible and feasible alternative to SLS". The Space Review.
- Alan Boyle (7 December 2011). "Is the case for Mars facing a crisis?". MSNBC.
- John K. Strickland, Jr. "The SpaceX Falcon Heavy Booster: Why Is It Important?". National Space Society. Retrieved 4 January 2012.
- "NASA Studies Scaled-Up Falcon, Merlin". Aviation Week. 2 December 2010.
- Review of U.S. Human Space Flight Plans Committee; Augustine, Austin, Chyba, Kennel, Bejmuk, Crawley, Lyles, Chiao, Greason, Ride. "Seeking A Human Spaceflight Program Worthy of A Great Nation". Final Report. NASA. Retrieved 15 April 2010.
- "Congressman, Space Frontier Foundation, And Tea Party In Space Call For NASA SLS Investigation". moonandback.com. 4 October 2011. Retrieved 20 October 2011.
- "The Senate Launch System". Competitive Space. 4 October 2011. Retrieved 20 October 2011.
- Chris Bergin (15 December 2011). "Building the Roadmap for SLS – Con Ops lays out the LEO/Lunar Options". NASASpaceflight.com. Retrieved 26 January 2012.
- Chris Bergin (24 January 2012). "SLS Exploration Roadmap evaluations provide clues for human Mars missions". NASASpaceflight.com. Retrieved 26 January 2012.
- "SLS interest in DoD launch market and Secondary Payloads potential". NASASpaceFlight.com. 4 February 2012. Retrieved 9 April 2012.
- "NASA Exploration Roadmap: A return to the Moon’s surface documented". NASASpaceFlight.com. 19 March 2012. Retrieved 9 April 2012.
- Markus Hammonds (14 April, 2013). "Skylab II:Living Beyong the Dark Side of the Moon". Discovery.
- Frank Morring, Jr. (22 October, 2012). "NASA Deep-Space Program Gaining Focus". Aviation Week & Space Technology.
- Chris Bergin (27 July 2011). "Preliminary NASA Plan Shows Evolved SLS Vehicle 21 Years Away". NASASpaceflight.com. Retrieved 28 July 2011.
- "Orion's First Test Flight Offers Space Launch System a First Look at Hardware Operation, Integration". NASA. June 29, 2012. Retrieved December 11, 2012.
|Wikimedia Commons has media related to: Space Launch System|
- Space Launch System & Multi-Purpose Crew Vehicle page on NASA.gov
- Preliminary Report on Multi-Purpose Crew Vehicle and Space Launch System (PDF). NASA
- SLS Future Frontiers video
- Video animations of mission to asteroid, moon and mars