Space Launch System

The Space Launch System (SLS) is a US super heavy-lift expendable launch vehicle, which has been under development since its announcement in 2011. It is the primary launch vehicle of NASA's deep space exploration plans,[23][24] including the planned crewed lunar flights of the Artemis program and a possible follow-on human mission to Mars.[25][26][27] SLS replaces the Constellation program's Ares V launch vehicle of 2005, which never left the development phase.

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).

Space Launch System
An artist's rendering of SLS Block 1 with Orion spacecraft on the pad before launch
FunctionSuper heavy-lift launch vehicle
Country of originUnited States
Project costUS$18.6 billion (as of 2020)
[1][2][3][4][5][6][7][8][9]
Cost per launchUS$500 million[10][11][12][13] to US$2 billion [note 1][15][16]
Cost per yearUS$2.5 billion for 2020[1]
Size
Height111.25 m (365.0 ft), Block 2 Cargo
Diameter8.4 m (28 ft), core stage
Stages2
Capacity
Payload to LEO
  • Block 1: 95,000 kg (209,000 lb) [17]
  • Block 2: 130,000 kg (290,000 lb) [18]
Payload to Moon
  • Block 1: > 26,000 kg (57,000 lb) [19]
  • Block 1B Crew: 34,000–37,000 kg (75,000–82,000 lb)
  • Block 1B Cargo: 37,000–40,000 kg (82,000–88,000 lb)
  • Block 2: > 45,000 kg (99,000 lb)
Launch history
StatusNovember 2021 [20]
Launch sitesKennedy Space Center, LC-39B
First flightArtemis 1
Notable payloadsOrion
Boosters (Block 1, 1B)
No. boosters2 five-segment Solid Rocket Boosters
Thrust16,000 kN (3,600,000 lbf)
Total thrust32,000 kN (7,200,000 lbf)
Specific impulse269 s (2.64 km/s)
Burn time126 seconds
FuelPBAN, APCP
First stage (Block 1, 1B, 2) – Core stage
Length65 m (212 ft)[21]
Diameter8.4 m (27.6 ft)[21]
Empty mass85,270 kg (187,990 lb)
Gross mass979,452 kg (2,159,322 lb)
Engines4 RS-25D/E[22]
Thrust7,440 kN (1,670,000 lbf)
Specific impulse363 s (3.56 km/s) (sea level)
452 s (4.43 km/s) (vacuum)
Burn time480 seconds
FuelLH2 / LOX
Second stage (Block 1) – ICPS
Length13.7 m (45 ft)
Diameter5 m (16 ft)
Empty mass3,490 kg (7,690 lb)
Gross mass30,710 kg (67,700 lb)
Engines1 RL10B-2
Thrust110.1 kN (24,800 lbf)
Specific impulse462 seconds (4.53 km/s)
Burn time1,125 seconds
FuelLH2 / LOX
Second stage (Block 1B, Block 2) – Exploration Upper Stage
Diameter8.4 m (28 ft)
Engines4 RL10
Thrust440 kN (99,000 lbf)
FuelLH2 / LOX

The initial variant of SLS, Block 1, was required by the US Congress to lift a payload of 70 tonnes (69 long tons; 77 short tons)[28] to low Earth orbit (LEO), but exceeded that requirement with a rated payload capacity of 95 tonnes (93 long tons; 105 short tons).[29] As of 22 December 2019, this variant is planned to launch Artemis 1, 2, and 3.[30] The later Block 1B is intended to debut the Exploration Upper Stage and launch the notional Artemis 4 through Artemis 7.[31] Block 2 is planned to replace the initial Shuttle-derived boosters with advanced boosters and would have a LEO capability of more than 130 tonnes (130 long tons; 140 short tons), again as required by Congress.[28] Block 2 is intended to enable crewed launches to Mars.[27] The SLS will launch the Orion spacecraft and use the ground operations and launch facilities at NASA's Kennedy Space Center in Florida.

Vehicle description

The SLS is a Space Shuttle-derived launch vehicle and will have the ability to tolerate a minimum of 13 tanking cycles due to launch scrubs and other launch delays before launch. The assembled rocket is to be able to remain at the launch pad for at least 180 days and can remain in a stacked configuration for at least 200 days.[32]

Core stage

The Space Launch System's core stage is 65 metres (212 ft) long and 8.4 metres (27.6 ft) in diameter and contains a Main Propulsion System (MPS) incorporating four RS-25 engines.[21][22][33] The core stage is structurally similar to the Space Shuttle external tank,[34][35] and initial flights will use modified RS-25D engines left over from the Space Shuttle program.[36] Later flights will switch to a cheaper version of the engine not intended for reuse.[37]

The core stage is fabricated at the NASA's Michoud Assembly Facility[38] and is common across all currently planned evolutions of the SLS to avoid the need for substantial redesigns to meet various payload mandates.[33][39][40][41]

Boosters

Block 1 and 1B boosters

Blocks 1 and 1B of the SLS will use two five-segment Solid Rocket Boosters (SRBs) based on the four-segment Space Shuttle Solid Rocket Boosters. Modifications to the five-segment boosters included the addition of a center booster segment, new avionics, and lighter insulation.[42] The five-segment SRBs provide approximately 25% more total impulse than the Shuttle SRB and will not be recovered after use.[43][44]

Block 2 advanced boosters (late 2020s)

The advanced boosters for Block 2[45] were intended to be selected through the Advanced Booster Competition, which was to be held in 2015.[22][46]

Several companies proposed boosters for this competition:

  • Aerojet, in partnership with Teledyne Brown, offered a booster powered by three new AJ1E6 LOX/RP-1 oxidizer-rich staged combustion engines, each producing 4,900 kN (1,100,000 lbf) thrust using a single turbopump to supply dual combustion chambers.[47] On 14 February 2013, Aerojet was awarded a $23.3 million, 30-month contract to build a 2,400 kN (550,000 lbf) main injector and thrust chamber.[48]
  • Alliant Techsystems (ATK) proposed an advanced SRB nicknamed "Dark Knight", which would switch to a lighter composite case, use a more energetic propellant, and reduce the number of segments from five to four.[49]
  • Pratt & Whitney Rocketdyne and Dynetics proposed a liquid-fueled booster named Pyrios.[50]

In 2013, the manager of NASA's SLS advanced development office indicated that all three approaches were viable.[51]

However, the 2015 competition was planned in support of Block 1A. A later study found that the advanced booster would have resulted in unsuitably high acceleration,[52] and NASA canceled Block 1A and the planned competition in 2014.[53][54] In February 2015, it was reported that SLS is expected to fly with the five-segment SRB until at least the late 2020s, and modifications to Launch Pad 39B, its flame trench, and Mobile Launcher were being evaluated.[53]

Booster Obsolescence and Life Extension program

The stock of SLS boosters is limited by the number of casings left over from the Shuttle program. There are enough to last through flight eight of the SLS, but a replacement will be required for further flights.[55] On 2 March 2019, the Booster Obsolescence and Life Extension (BOLE) program proposed to use new solid rocket boosters built by Northrop Grumman Innovation Systems for further SLS flights. These boosters would be derived from the composite-casing SRBs in development for the OmegA launch vehicle, and are projected to increase Block 1B's payload to TLI by 3-4 tonnes, 1 t below the payload capacity of Block II.[56]

Upper stage

ICPS - Block 1

The Interim Cryogenic Propulsion Stage (ICPS) is planned to fly on Artemis 1. It is a stretched and human rated[57] Delta IV 5 m (16 ft) Delta Cryogenic Second Stage (DCSS) powered by a single RL10B-2.[58] Block 1 will be capable of lifting 95 t to LEO in this configuration if the ICPS is considered part of the payload.[17] Artemis 1 will be launched into an initial 1,800 by −93 kilometres (1,118 by −58 mi) suborbital trajectory to ensure safe disposal of the core stage. ICPS will then perform an orbital insertion burn at apogee and a subsequent translunar injection burn to send Orion towards the moon.[59] The ICPS for Artemis 1 was delivered by ULA to NASA about July 2017,[60] and was housed at Kennedy Space Centre until at least November 2018.[61] As of February 2020, ICPS (not EUS) is planned for Artemis-1, 2, and 3.[62] ICPS will now be human-rated for the crewed Artemis-2 flight.[62]

EUS - Block 1B and 2

The Exploration Upper Stage (EUS) is planned to fly on Artemis 4. Similar to the S-IVB, the EUS would have completed the SLS ascent phase and then re-ignited to send its payload to destinations beyond low-Earth orbit.[63] It was expected to be used by Block 1B and Block 2, share the core stage diameter of 8.4 meters, and be powered by four RL10 engines.[64]

Payload carrying capacity
See also: Super heavy-lift launch vehicle § Comparison
SLS variant Payload mass to...
low Earth orbit (LEO) trans-lunar injection (TLI) heliocentric orbit (HCO)
Block 1 95 tonnes (93 long tons; 105 short tons)[17] 26 tonnes (26 long tons; 29 short tons)[17]
Block 1B 105 tonnes (103 long tons; 116 short tons)[65] 40 t[66]
Block 2 130 tonnes (130 long tons; 140 short tons)[18] 45 t [66] 45 tonnes (44 long tons; 50 short tons)[17]

Development history
Planned evolution of the Space Launch System, 2018 (not shown is a Block 1 Cargo that Europa Clipper may launch on)

SLS is intended to replace the retired Space Shuttle as NASA's flagship vehicle. Following the cancelation of the Constellation program, the NASA Authorization Act of 2010 envisioned a single launch vehicle usable for both crew and cargo. SLS is to have the world's highest-ever total thrust at launch,[67][68] but not the world's highest ever payload mass.[69][70][71] In 2013, SLS was projected to possibly be the most capable super-heavy lift vehicle ever built.[34][72]

Program history

During the joint Senate-NASA presentation in September 2011, it was stated that the SLS program had a projected development cost of $18 billion through 2017, with $10 billion for the SLS rocket, $6 billion for the Orion spacecraft and $2 billion for upgrades to the launch pad and other facilities at Kennedy Space Center.[73][74] These costs and schedule were considered optimistic in an independent 2011 cost assessment report by Booz Allen Hamilton for NASA.[75]

An unofficial 2011 NASA document estimated the cost of the program through 2025 to total at least $41 billion for four 95-tonne launches (1 uncrewed, 3 crewed),[76][77] with the 130-tonne version ready no earlier than 2030.[78]

The Human Exploration Framework Team (HEFT) estimated unit costs for Block 0 at $1.6 billion and Block 1 at $1.86 billion in 2010.[79] However, since these estimates were made the Block 0 SLS vehicle was dropped in late 2011, and the design was not completed.[80]

In September 2012, an SLS deputy project manager stated that $500 million per launch is a reasonable target cost for SLS.[81]

In 2013, the Space Review estimated the cost per launch at $5 billion, depending on the rate of launches.[82][83] NASA announced in 2013 that the European Space Agency will build the Orion service module.[84]

By April 2014, it was decided to cancel Block 1A and the related advanced booster competition due in 2015.[53][54]

In August 2014, as the SLS program passed its Key Decision Point C review and entered full development, costs from February 2014 until its planned launch in September 2018 were estimated at $7.021 billion.[85] Ground systems modifications and construction would require an additional $1.8 billion over the same time period.[86]

In October 2018, NASA's inspector general reported that the Boeing core stage contract had made up 40% of the $11.9 billion spent on SLS as of August 2018. By 2021, core stages were expected to have cost a total of $8.9 billion, which is twice the initial planned amount.[87]

In December 2018, NASA estimated that yearly budgets for SLS will range from $2.1 to $2.3 billion between 2019 and 2023.[88]

In March 2019, the Trump Administration released its Fiscal Year 2020 Budget Request for NASA. This budget did not include any money for the Block 1B and Block 2 variants of SLS. It is uncertain whether these future variants of SLS will be developed.[89] Several launches previously planned for the SLS Block 1B are now expected to fly on commercial launcher vehicles such as Falcon Heavy, New Glenn, OmegA, and Vulcan.[90] However, the request for a budget increase of $1.6 billion towards SLS, Orion, and crewed landers along with the launch manifest seem to indicate support of the development of Block 1B, debuting Artemis 3. The Block 1B will be used mainly for co-manifested crew transfers and logistical needs rather than constructing the Gateway. An uncrewed Block 1B is planned to launch the Lunar Surface Asset in 2028, the first lunar outpost of the Artemis program. Block 2 development will most likely start in the late 2020s, after NASA is regularly visiting the lunar surface and shifts focus towards Mars.[91]

In May 2019, NASA's Office of Audits reported that the SLS Block 1's marginal cost per launch is to be at least $876 million.[92] By comparison, a Saturn V launch cost roughly $1.23 billion in 2016 dollars.[93][94] A letter from the White House to the Senate Appropriations Committee revealed that the SLS's cost per launch is estimated at "over $2 billion" after development.[95] NASA did not deny this cost and an agency spokesperson stated it "is working to bring down the cost of a single SLS launch in a given year as the agency continues negotiations with Boeing on the long-term production contract and efforts to finalize contracts and costs for other elements of the rocket".[96]

Blue Origin submitted a proposal to replace the Exploration Upper Stage with an alternative to be designed and fabricated by the company, but it was rejected by NASA in November 2019 on multiple grounds. These included lower performance compared to the existing EUS design, unsuitability of the proposal to current ground infrastructure, and unacceptable acceleration in regards to Orion components.[97]

Funding history

For fiscal years 2011 through 2020, the SLS program had expended funding totaling $18.648 billion in nominal dollars. This is equivalent to $20.314 billion in 2020 dollars using the NASA New Start Inflation Indices.[98]

For fiscal year 2021, $2.257 billion.[1]

Fiscal Year Funding (nominal, in $millions) Funding (In 2020 $, in $millions)[98] Status
2011 $1,536.1 $1,819.9 Actual[9]
(Formal SLS Program reporting excludes the Fiscal 2011 budget.)[99]
2012 $1,497.5 $1,755.5 Actual[8]
2013 $1,414.9 $1,634.1 Actual[7]
2014 $1,600.0 $1,812.3 Actual[6]
2015 $1,678.6 $1,863.8 Actual[5]
2016 $1,971.9 $2,159.6 Actual[4]
2017 $2,127.1 $2,286.8 Actual[3]
2018 $2,150.0 $2,256.6 Actual[2]
2019 $2,144.0 $2,199.9 Actual[1]
2020 $2,525.8 $2,525.8 Enacted[1]
2011–2020 Total: $18,648 M Total: $20,314 M

Excluded from the prior SLS costs are:

  • Costs of the predecessor Ares V / Cargo Launch Vehicle (funded from 2008 to 2010)[100]
  • Costs for the Ares I / Crew Launch Vehicle (funded from 2006 to 2010, a total of $4.8 billion[100][101] in development that included the 5-segment Solid Rocket Boosters that will be used on the SLS)
  • Costs to assemble, integrate, prepare and launch the SLS and its payloads such as Orion (funded under the NASA Ground Operations Project,[102] currently about $400M[6] per year)
  • Costs of payloads for the SLS (such as Orion)

Included in the prior SLS costs are:

  • Costs of the interim Upper Stage for the SLS, the Interim Cryogenic Propulsion Stage (ICPS) for SLS, which includes a $412M contract[103]
  • Costs of the final Upper Stage for the SLS, the Exploration Upper Stage (EUS) (funded at $85M in 2016,[104] $300M in 2017[105] and $300M in 2018[106])

There are no current NASA estimates for the average costs per flight of SLS, nor for the SLS program recurring yearly costs once operational. In 2016, the projected annual cost for Orion, SLS, and ground systems was $2 billion or less.[107] NASA associate administrator William H. Gerstenmaier has said that per flight cost estimates will not be provided by NASA.[108]

On 1 May 2020, NASA awarded a contract extension to Aerojet Rocketdyne to manufacture 18 additional RS-25 engines with associated services for $1.79 billion, bringing the total RS-25 contract value to almost $3.5 billion.[109]

Constellation

From 2009 to 2011, three full-duration static fire tests of five-segment SRBs were conducted under the Constellation Program, including tests at low and high core temperatures, to validate performance at extreme temperatures.[110][111][112] The 5-segment SRB would be carried over to SLS.[53]

Early SLS

During the early development of the SLS a number of configurations were considered, including a Block 0 variant with three main engines,[33] a Block 1A variant with upgraded boosters instead of the improved second stage,[33] and a Block 2 with five main engines and the Earth Departure Stage, with up to three J-2X engines.[41] In February 2015, it was determined that these concepts would exceed the congressionally mandated Block 1 and Block 1B baseline payloads.[53]

On 14 September 2011, NASA announced the new launch system,[113] which is intended to take the agency's astronauts farther into space than ever before and provide the cornerstone for future US human space exploration efforts in combination with the Orion spacecraft.[114][115][116]

On 31 July 2013, the SLS passed the Preliminary Design Review (PDR). The review included not only the rocket and boosters but also ground support and logistical arrangements.[117] On 7 August 2014, the SLS Block 1 passed a milestone known as Key Decision Point C and entered full-scale development, with an estimated launch date of November 2018.[85][118]

In 2013, NASA and Boeing analyzed the performance of several EUS engine options. The analysis was based on a second-stage usable propellant load of 105 metric tons, and compared stages with four RL10 engines, two RL60 engines, or one J-2X engine.[119]

In 2014, NASA also considered using the European Vinci instead of the RL10. The Vinci offers the same specific impulse but with 64% greater thrust, which would allow for the same performance at lower cost.[120][121]

Northrop Grumman Innovation Systems has completed full-duration static fire tests of the five-segment SRBs. Qualification Motor 1 (QM-1) was tested on 10 March 2015.[122] Qualification Motor 2 (QM-2) was successfully tested on 28 June 2016.

Current SLS
The Artemis 1 SLS core stage being loaded onto the Pegasus barge
The Green Run testing will be the first top-to-bottom integrated testing of the stage's systems prior to its maiden flight.

As of 2020, three SLS versions are planned: Block 1, Block 1B, and Block 2. Each will use the same core stage with four main engines, but Block 1B will feature the Exploration Upper Stage (EUS), and Block 2 will combine the EUS with upgraded boosters.[28][65][123]

In mid-November 2014, construction of the first core stage hardware began using a new welding system in the South Vertical Assembly Building at NASA's Michoud Assembly Facility.[124] Between 2015 and 2017, NASA test fired RS-25 engines in preparation for use on SLS.[37]

As of late 2015, the SLS program was stated to have a 70% confidence level for the first crewed Orion flight by 2023.[125][126][127]

Confidence article builds for the core stage began on 5 January 2016 and were expected to be completed in late January of that year. Once completed the test articles will be sent to ensure structural integrity at Marshall Spaceflight Center. A structural test article of the ICPS was delivered in 2015, with the core stage for Artemis 1 completing assembly in November 2019.[128]

The first flight of SLS has slipped multiple times: first to 2019,[129] then to June 2020,[130] then to April 2021,[131] and most recently to November 2021.[20]

The first core stage left Michoud for comprehensive testing at Stennis in January 2020.[132] The static firing test program at Stennis, known as the Green Run, will operate all the core stage systems simultaneously for the first time.[133][134]

Criticism

The SLS has been criticized on the basis of program cost, lack of commercial involvement, and the non-competitive nature of a vehicle legislated to use Space Shuttle components.

In 2009, the Augustine commission proposed a commercial 75 tonnes (74 long tons; 83 short tons) launcher with lower operating costs, and noted that a 40–60 t (39–59 long tons; 44–66 short tons) launcher was the minimum required to support lunar exploration.[135]

In 2011–2012, the Space Access Society, Space Frontier Foundation and The Planetary Society called for cancellation of the project, arguing that SLS will consume the funds for other projects from the NASA budget.[136][137][138] U.S. Representative Dana Rohrabacher and others proposed that an orbital propellant depot should be developed and the Commercial Crew Development program accelerated instead.[136][139][140][141][142] A NASA study that was not publicly released[143][144] and another from the Georgia Institute of Technology showed this option to be possibly cheaper.[145][146] In 2012, the United Launch Alliance also suggested using existing rockets with on-orbit assembly and propellant depots as needed. The lack of competition in the SLS design was highlighted.[147][148][149][150][151] In the summer of 2019, a former ULA employee claimed that Boeing, NASA's prime contractor for SLS, viewed orbital refueling technology as a threat to SLS and blocked further investment in it.[152]

In 2011, Mars Society/Mars Direct founder Robert Zubrin suggested that a heavy lift vehicle could be developed for $5 billion on fixed-price requests for proposal.[153]

In 2010, SpaceX's CEO Elon Musk claimed that his company could build a launch vehicle in the 140- to 150-tonne payload range for $2.5 billion, or $300 million (in 2010 dollars) per launch, not including a potential upper-stage upgrade.[154][155] In the early 2010s, SpaceX went on to start development of SpaceX Starship, a planned fully reusable super-heavy launch system. Reusability is claimed to allow the lowest-cost super-heavy launcher ever made.[156] If the price per launch and payload capabilities for the Starship are anywhere near Musk's claimed capabilities, the rocket will be substantially cheaper than the SLS.[157]

In 2011, Rep. Tom McClintock and other groups called on the Government Accountability Office (GAO) to investigate possible violations of the Competition in Contracting Act (CICA), arguing that Congressional mandates forcing NASA to use Space Shuttle components for SLS are de facto non-competitive, single source requirements assuring contracts to existing shuttle suppliers.[137][158][159] Opponents of the heavy launch vehicle have critically used the name "Senate launch system".[58] 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".[136]

In 2013, Chris Kraft, the NASA mission control leader from the Apollo era, expressed his criticism of the system as well.[160] Lori Garver, former NASA Deputy Administrator, has called for canceling the launch vehicle alongside Mars 2020 rover.[161] Phil Plait has voiced his criticism of SLS in light of ongoing budget tradeoffs between Commercial Crew Development and SLS budget, also referring to earlier critique by Garver.[162]

In 2019, the Government Accountability Office found that NASA had awarded Boeing over $200 million for service with ratings of good to excellent despite cost overruns and delays. As of 2020, the maiden launch of SLS is expected in 2021.[163][164]

On 1 May 2020, NASA awarded a $1.79 billion contract extension for the manufacture of 18 additional RS-25 engines. Ars Technica, in an article published on the same day, highlighted that over the entire RS-25 contract the price of each engine works out to $146 million, and that the total price for the four expendable engines used in each SLS launch will be more than $580 million. They critically commented that for the cost of just one engine, six more powerful RD-180 engines could be purchased, or nearly an entire Falcon Heavy launch with two thirds of the SLS lift capacity.[109][165]

Planned launches
Main article: List of Space Launch System launches
Flight No. Date / time (UTC) Configuration Payload Orbit Outcome
1 November 2021[166] Block 1 Crew
TLI Planned
Uncrewed Maiden flight of the SLS, carrying the Artemis 1 mission hardware and cubesats for ten missions in the CubeSat Launch Initiative (CLSI), and three missions in the Cube Quest Challenge.[167][168] The payloads will be sent on a trans-lunar injection trajectory.[169][170]
2 2023[171] Block 1 Crew
TLI Planned
Crewed, lunar flyby. Carrying the Artemis 2 mission hardware, along with numerous cubesats to be selected through the CSLI.[172][173]
3 2024 Block 1 Crew[174]
Selenocentric Planned
Crewed lunar rendezvous and landing. Carrying the Artemis 3 mission hardware.[175]
4 2025[lower-alpha 1] Block 1 Cargo[lower-alpha 1]
Jovian Planned
Carrying the Europa Clipper spacecraft to Jupiter via a direct Hohmann transfer orbit.[178]
  1. As of 2019, it is mandated for launch aboard the Block 1 Cargo in 2025,[175][176][177][171] though may alternatively launch on a Block 1B Cargo.[178][179][180]
  • RS-25D engine testing at Stennis Space Center
  • SLS Mobile Launcher
  • The Core Stage for the Space Launch System rocket for Artemis I
  • The Space Launch System Core Stage rolling out of the Michoud Facility for shipping to Stennis
  • SRB segment
  • ICPS on the move
  • Block 1 configuration
  • Block 1B configuration
  • Block 2 configuration

See also

References

Notes
  1. Assuming 1 launch per year and accounting for yearly programmatic costs.[14]

Citations
  1. "FY 2021 President's Budget Request Summary" (PDF). NASA. p. DEXP-4. Retrieved May 10, 2020. This article incorporates text from this source, which is in the public domain.
  2. "FY 2020 President's Budget Request Summary" (PDF). NASA. p. DEXP-4. Retrieved May 10, 2020. This article incorporates text from this source, which is in the public domain.
  3. "FY 2019 President's Budget Request Summary" (PDF). NASA. p. DEXP-20. Retrieved May 10, 2020. This article incorporates text from this source, which is in the public domain.
  4. "FY 2018 President's Budget Request Summary" (PDF). NASA. p. EXP-22. Retrieved May 10, 2020. This article incorporates text from this source, which is in the public domain.
  5. "FY 2018 Budget Estimates" (PDF). NASA. p. BUD-3. Retrieved December 16, 2018. This article incorporates text from this source, which is in the public domain.
  6. "FY 2016 Presidents Budget Request Summary" (PDF). NASA. p. BUD-5. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  7. "FY 2015 Presidents Budget Request Summary" (PDF). NASA. p. BUD-5. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  8. "FY 2014 Presidents Budget Request Summary" (PDF). NASA. p. BUD-8. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  9. "FY 2013 Presidents Budget Request Summary" (PDF). NASA. p. BUD-4. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  10. Town Hall with Administrator Bridenstine and NASA's New HEO Associate Administrator Douglas Loverro (YouTube). NASA. December 3, 2019. Event occurs at 25:09. Retrieved December 4, 2019. I think at the end [NASA is] going to be in the 800-million- to 900-million-dollar range This article incorporates text from this source, which is in the public domain.
  11. "Management of NASA's Europa Mission" 2019, p. 19, Table 3.
  12. "Habitable Exoplanet Observatory Final Report" 2019, p. 9-11, 9.4.1 Basis of Estimate.
  13. "Origins Space Telescope Mission Concept Study Report" (PDF). October 11, 2019: ES-11. Retrieved May 14, 2020. The launch cost ($500M for the SLS launch vehicle, as advised by NASA Headquarters) is also included. Cite journal requires |journal= (help) This article incorporates text from this source, which is in the public domain.
  14. Berger, Eric (November 8, 2019). "NASA does not deny the "over $2 billion" cost of a single SLS launch". arstechnica. The White House number appears to include both the "marginal" cost of building a single SLS rocket as well as the "fixed" costs of maintaining a standing army of thousands of employees and hundreds of suppliers across the country. Building a second SLS rocket each year would make the per-unit cost "significantly less.
  15. Vought, Russell T. "Letter to the Chair and Vice Chair of the Senate Appropriations Committee with respect to 10 of the FY 2020 annual appropriations bills" (pdf). whitehouse.gov. p. 7. estimated cost of over $2 billion per launch for the SLS once development is complete
  16. "White House warns Congress about Artemis funding". SpaceNews.com. November 7, 2019. Retrieved November 13, 2019.
  17. Harbaugh, Jennifer (July 9, 2018). "The Great Escape: SLS Provides Power for Missions to the Moon". NASA. Retrieved September 4, 2018. This article incorporates text from this source, which is in the public domain.
  18. Creech, Stephen (April 2014). "NASA's Space Launch System: A Capability for Deep Space Exploration" (PDF). NASA. p. 2. Retrieved September 4, 2018. This article incorporates text from this source, which is in the public domain.
  19. Mohon, Lee (March 16, 2015). "Space Launch System (SLS) Overview". NASA. Retrieved July 6, 2019. This article incorporates text from this source, which is in the public domain.
  20. Clark, Stephen (May 1, 2020). "Hopeful for launch next year, NASA aims to resume SLS operations within weeks". Retrieved May 3, 2020.
  21. Harbaugh, Jennifer (December 9, 2019). "NASA, Public Marks Assembly of SLS Stage with Artemis Day". nasa.gov. NASA. Retrieved December 10, 2019. NASA and the Michoud team will shortly send the first fully assembled, 212-foot-tall core stage...27.6-feet-in-diameter tanks and barrels. This article incorporates text from this source, which is in the public domain.
  22. "space launch system" (PDF). NASAfacts. 2012. Archived from the original (PDF) on August 13, 2012. This article incorporates text from this source, which is in the public domain.
  23. Siceloff, Steven (April 12, 2015). "SLS Carries Deep Space Potential". Nasa.gov. Retrieved January 2, 2018. This article incorporates text from this source, which is in the public domain.
  24. "World's Most Powerful Deep Space Rocket Set To Launch In 2018". Iflscience.com. Retrieved January 2, 2018.
  25. Chiles, James R. "Bigger Than Saturn, Bound for Deep Space". Airspacemag.com. Retrieved January 2, 2018.
  26. "Finally, some details about how NASA actually plans to get to Mars". Arstechnica.com. Retrieved January 2, 2018.
  27. Gebhardt, Chris (April 6, 2017). "NASA finally sets goals, missions for SLS – eyes multi-step plan to Mars". NASASpaceFlight.com. Retrieved August 21, 2017.
  28. "The NASA Authorization Act of 2010". Featured Legislation. Washington, D.C., United States: United States Senate. July 15, 2010. Archived from the original on April 10, 2011. Retrieved May 26, 2011.
  29. Harbaugh, Jennifer (May 2, 2018). "The Great Escape: SLS Provides Power for Missions to the Moon". NASA. Retrieved December 22, 2019. This article incorporates text from this source, which is in the public domain.
  30. Gebhardt, Chris (August 15, 2019). "Eastern Range updates 'Drive to 48' launches per year status". NASASpaceFlight.com. Retrieved January 6, 2020. NASA, on the other hand, will have to add this capability to their SLS rocket, and Mr. Rosati said NASA is tracking that debut for the Artemis 3 mission in 2023.
  31. "Space Launch System". aerospaceguide.net.
  32. "SLS to be robust in the face of scrubs, launch delays and pad stays". NASASpaceFlight.com. April 4, 2012. Retrieved April 9, 2012.
  33. Chris Bergin (October 4, 2011). "SLS trades lean towards opening with four RS-25s on the core stage". NASASpaceFlight.com. Retrieved January 26, 2012.
  34. Stephen Clark (March 31, 2011). "NASA to set exploration architecture this summer". Spaceflight Now. Retrieved May 26, 2011.
  35. Chris Bergin (September 14, 2011). "SLS finally announced by NASA – Forward path taking shape". NASASpaceFlight.com. Retrieved January 26, 2012.
  36. Sloss, Philip. "NASA ready to power up the RS-25 engines for SLS". NASASpaceFlight.com. Retrieved March 10, 2015.
  37. Campbell, Lloyd (March 25, 2017). "NASA conducts 13th test of Space Launch System RS-25 engine". SpaceflightInsider.com. Retrieved April 29, 2017.
  38. "NASA's Space Launch System Core Stage Passes Major Milestone, Ready to Start Construction". Space Travel. December 27, 2012.
  39. Chris Bergin (April 25, 2011). "SLS planning focuses on dual phase approach opening with SD HLV". NASASpaceFlight.com. Retrieved January 26, 2012.
  40. Bergin, Chris (June 16, 2011). "Managers SLS announcement after SD HLV victory". NASASpaceFlight.com. Retrieved January 26, 2012.
  41. Bergin, Chris (February 23, 2012). "Acronyms to Ascent – SLS managers create development milestone roadmap". NASASpaceFlight.com. Retrieved April 9, 2012.
  42. OUR TO FIVE: ENGINEER DETAILS CHANGES MADE TO SLS BOOSTER Jan 2016
  43. Priskos, Alex. "Five-segment Solid Rocket Motor Development Status" (PDF). ntrs.nasa.gov. NASA. Retrieved March 11, 2015. This article incorporates text from this source, which is in the public domain.
  44. "Space Launch System: How to launch NASA's new monster rocket". NASASpaceflight.com. February 20, 2012. Retrieved April 9, 2012.
  45. Keith Cowing (September 14, 2011). "NASA's New Space Launch System Announced – Destination TBD". SpaceRef. Retrieved January 26, 2012.
  46. Frank Morring (June 17, 2011). "NASA Will Compete Space Launch System Boosters". Aviation Week. Retrieved June 20, 2011.
  47. "NASA's Space Launch System: Partnering For Tomorrow" (PDF). NASA. Retrieved March 12, 2013. This article incorporates text from this source, which is in the public domain.
  48. Rachel Kraft (February 14, 2013). "NASA Awards Final Space Launch System Advanced Booster Contract". NASA. Retrieved February 19, 2013. This article incorporates text from this source, which is in the public domain.
  49. "The Dark Knights – ATK's Advanced Boosters for SLS revealed". NASASpaceFlight.com. January 14, 2013.
  50. Lee Hutchinson (April 15, 2013). "New F-1B rocket engine upgrades Apollo-era design with 1.8M lbs of thrust". Ars Technica. Retrieved April 15, 2013.
  51. "SLS Block II drives hydrocarbon engine research". thespacereview.com. January 14, 2013.
  52. "Wind Tunnel testing conducted on SLS configurations, including Block 1B". NASASpaceFlight.com. July 2012.
  53. Bergin, Chris. "Advanced Boosters progress towards a solid future for SLS". NasaSpaceFlight.com. Retrieved February 25, 2015.
  54. "Second SLS Mission Might Not Carry Crew". spacenews.com. May 21, 2014. Retrieved July 25, 2014.
  55. Bergin, Chris (May 8, 2018). "SLS requires Advanced Boosters by flight nine due to lack of Shuttle heritage components". NASASpaceFlight.com. Retrieved November 15, 2019.
  56. Tobias, Mark E.; Griffin, David R.; McMillin, Joshua E.; Haws, Terry D.; Fuller, Micheal E. (March 2, 2019). "Booster Obsolescence and Life Extension (BOLE) for Space Launch System (SLS)" (PDF). NASA Technical Reports Server. NASA. Retrieved November 15, 2019. This article incorporates text from this source, which is in the public domain.
  57. https://www.reddit.com/r/SpaceLaunchSystem/comments/g5xbee/a_comparison_of_icps_eus_and_several_other
  58. Rosenberg, Zach. "Delta second stage chosen as SLS interim". Flight International, May 8, 2012.
  59. "Space Launch System Data Sheet". SpaceLaunchReport.com. Retrieved July 25, 2014.
  60. SLS Upper Stage set to take up residence in the former home of ISS modules July 2017
  62. Upper Stage RL10s arrive at Stennis for upcoming SLS launches Feb 2020
  63. "SLS prepares for PDR – Evolution eyes Dual-Use Upper Stage". NASASpaceFlight.com. Retrieved March 12, 2015.
  64. "NASA confirms EUS for SLS Block 1B design and EM-2 flight". NASASpaceFlight.com. Retrieved July 24, 2014.
  65. "Space Launch System" (PDF). NASA Facts. NASA. October 11, 2017. FS-2017-09-92-MSFC. Retrieved September 4, 2018. This article incorporates text from this source, which is in the public domain.
  66. "Space Launch System Lift Capabilities and Configurations" (PDF). This article incorporates text from this source, which is in the public domain.
  67. Harbaugh, Jennifer (May 12, 2017). "NASA Continues Testing, Manufacturing World's Most Powerful Rocket". Nasa.gov. This article incorporates text from this source, which is in the public domain.
  68. Wall, Mike (August 16, 2016). "Yes, NASA's New Megarocket Will Be More Powerful Than the Saturn V". Space.com. Retrieved September 13, 2018.
  69. The Congress of the United States. Congressional Budget Office, October 2006, pp. X,1,4,9. "The Apollo Saturn V launch vehicle had a lift capability of 140 metric tons to low Earth orbit" This article incorporates text from this source, which is in the public domain.
  70. Wells, Jane (January 26, 2016). "Boeing builds the most powerful rocket ever made". cnbc.com.
  71. Wood, Anthony (July 25, 2015). "Most powerful rocket ever edges closer to lift-off". New Atlas. Retrieved September 13, 2018.
  72. Dwayne Day (November 25, 2013). "Burning thunder".
  73. Marcia Smith (September 14, 2011). "New NASA Crew Transportation System to Cost $18 Billion Through 2017". Space Policy Online. Retrieved September 15, 2011.
  74. Bill Nelson, Kay Bailey Hutchison, Charles F. Bolden (September 14, 2011). Future of NASA Space Program. Washington, D.C.: Cspan.org.
  75. Booz Allen Hamilton (August 19, 2011). "Independent Cost Assessment of the Space Launch System, Multi-purpose Crew Vehicle and 21st Century Ground Systems Programs: Executive Summary of Final Report" (PDF). NASA. This article incorporates text from this source, which is in the public domain.
  76. Andy Paszior (September 7, 2011). "White House Experiences Sticker Shock Over NASA's Plans". The Wall Street Journal. Retrieved February 22, 2015.
  77. "ESD Integration, Budget Availability Scenarios" (PDF). Space Policy Online. August 19, 2011. Retrieved September 15, 2011.
  78. Marcia Smith (September 9, 2011). "The NASA Numbers Behind That WSJ Article". Space Policy Online. Retrieved September 15, 2011.
  79. "HEFT Phase I Closeout" (PDF). nasawatch.com. September 2010. p. 69.
  80. Chris Bergin (October 4, 2011). "SLS trades lean towards opening with four RS-25s on the core stage". NASASpaceFlight.com. Retrieved September 16, 2013.
  81. "NASA's huge new rocket may cost $500 million per launch". NBC News. September 12, 2012.
  82. Lee Roop (July 29, 2013). "NASA defends Space Launch System against charge it 'is draining the lifeblood' of space program". AL.com. Retrieved February 18, 2015.
  83. John Strickland (July 15, 2013). "Revisiting SLS/Orion launch costs". The Space Review. Retrieved February 18, 2015.
  84. NASA Content Administrator, ed. (April 12, 2015) [January 16, 2013]. "NASA Signs Agreement for a European-Provided Orion Service Module". NASA. Archived from the original on January 18, 2013. This article incorporates text from this source, which is in the public domain.
  85. Foust, Jeff (August 27, 2014). "SLS Debut Likely To Slip to 2018". SpaceNews.com. Retrieved March 12, 2015.
  86. Davis, Jason. "NASA Budget Lists Timelines, Costs and Risks for First SLS Flight". The Planetary Society. Retrieved March 11, 2015.
  87. "NASA'S MANAGEMENT OF THE SPACE LAUNCH SYSTEM STAGES CONTRACT" (PDF). NASA OIG. NASA Office of Inspector General Office of Audits. October 10, 2018. Retrieved October 14, 2018. This article incorporates text from this source, which is in the public domain.
  88. "NASA FY 2019 Budget Estimates" (PDF). nasa.gov. p. BUD-2. Retrieved December 16, 2018. This article incorporates text from this source, which is in the public domain.
  89. Smith, Rich (March 26, 2019). "Is NASA Preparing to Cancel Its Space Launch System?". The Motley Fool. Retrieved May 15, 2019.
  90. "NASA FY 2019 Budget Overview" (PDF). Quote: "Supports launch of the Power and Propulsion Element on a commercial launch vehicle as the first component of the LOP–Gateway, (page 14) This article incorporates text from this source, which is in the public domain.
  91. "Space Launch Report". www.spacelaunchreport.com. Retrieved May 22, 2019.
  92. "MANAGEMENT OF NASA'S EUROPA MISSION" (PDF). NASA Office of Audits. Retrieved November 8, 2019. This article incorporates text from this source, which is in the public domain.
  93. "SP-4221 The Space Shuttle Decision- Chapter 6: ECONOMICS AND THE SHUTTLE". NASA. Retrieved January 15, 2011. This article incorporates text from this source, which is in the public domain.
  94. "Apollo Program Budget Appropriations". NASA. This article incorporates text from this source, which is in the public domain.
  95. "NASA does not deny the "over $2 billion" cost of a single SLS launch" (PDF). Retrieved November 15, 2019.
  96. BERGER, ERIC. "NASA does not deny the "over $2 billion" cost of a single SLS launch". arstechnica. Retrieved November 15, 2019.
  97. Berger, Eric (November 5, 2019). "NASA rejects Blue Origin's offer of a cheaper upper stage for the SLS rocket". Ars Technica. Retrieved December 19, 2019.
  98. "NASA FY19 Inflation Tables - to be utilized in FY20". NASA. p. Inflation Table. Retrieved May 10, 2020. This article incorporates text from this source, which is in the public domain.
  99. "NASA, Assessments of Major Projects" (PDF). General Accounting Office. March 2016. p. 63. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  100. "Fiscal Year 2010 Budget Estimates" (PDF). NASA. p. v. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  101. "FY 2008 Budget Estimates" (PDF). NASA. p. ESMD-14. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  102. "NASA's Ground Systems Development and Operations Program Completes Preliminary Design Review". NASA. Retrieved June 23, 2016. This article incorporates text from this source, which is in the public domain.
  103. "Definitive Contract NNM12AA82C". govtribe.com. Retrieved December 16, 2018.
  104. "Consolidated Appropriations Act 2016" (PDF). house.gov. p. 183. Retrieved December 16, 2018.
  105. "NASA outlines plan for 2024 lunar landing". SpaceNews.com. May 1, 2019. Retrieved May 15, 2019.
  106. Berger, Eric (May 20, 2019). "NASA's full Artemis plan revealed: 37 launches and a lunar outpost". Ars Technica. Retrieved May 20, 2019.
  107. Berger, Eric (August 19, 2016). "How much will SLS and Orion cost to fly? Finally some answers". arstechnica.com. Retrieved December 16, 2018.
  108. Berger, Eric (October 20, 2017). "NASA chooses not to tell Congress how much deep space missions cost". arstechnica.com. Retrieved December 16, 2018.
  109. "NASA Commits to Future Artemis Missions with More SLS Rocket Engines" (Press release). NASA. May 1, 2020. Retrieved May 4, 2020. This article incorporates text from this source, which is in the public domain.
  110. "NASA and ATK Successfully Test Ares First Stage Motor". NASA. September 10, 2009. Retrieved January 30, 2012. This article incorporates text from this source, which is in the public domain.
  111. "NASA and ATK Successfully Test Five-Segment Solid Rocket Motor". NASA. August 31, 2010. Retrieved January 30, 2012. This article incorporates text from this source, which is in the public domain.
  112. "NASA Successfully Tests Five-Segment Solid Rocket Motor". NASA. August 31, 2010. Retrieved September 8, 2011. This article incorporates text from this source, which is in the public domain.
  113. "NASA Announces Key Decision For Next Deep Space Transportation System". NASA. May 24, 2011. Retrieved January 26, 2012. This article incorporates text from this source, which is in the public domain.
  114. "NASA Announces Design For New Deep Space Exploration System". NASA. September 14, 2011. Retrieved September 14, 2011. This article incorporates text from this source, which is in the public domain.
  115. "Press Conference on the Future of NASA Space Program". C-Span. September 14, 2011. Retrieved September 14, 2011.
  116. Kenneth Chang (September 14, 2011). "NASA Unveils New Rocket Design". The New York Times. Retrieved September 14, 2011.
  117. "NASA's Space Launch System Program PDR: Answers to the Acronym". NASA. August 1, 2013. Retrieved August 3, 2013. This article incorporates text from this source, which is in the public domain.
  118. "NASA Completes Key Review of World's Most Powerful Rocket in Support". NASA. Retrieved October 26, 2015. This article incorporates text from this source, which is in the public domain.
  119. Chris Gebhardt (November 13, 2013). "SLS upper stage proposals reveal increasing payload-to-destination options". NASASpaceFlight.com.
  120. David Todd (June 3, 2013). "SLS design may ditch J-2X upper stage engine for four RL-10 engines". Seradata. Archived from the original on March 4, 2016.
  121. David Todd (November 7, 2014). "Next Steps for SLS: Europe's Vinci is a contender for Exploration Upper-Stage Engine". Seradata. Archived from the original on March 4, 2016.
  122. Bergin, Chris (March 10, 2015). "QM-1 shakes Utah with two minutes of thunder". NASASpaceFlight.com. Retrieved March 10, 2015.
  123. Karl Tate (September 16, 2011). "Space Launch System: NASA's Giant Rocket Explained". Space.com. Retrieved January 26, 2012.
  124. "SLS Engine Section Barrel Hot off the Vertical Weld Center at Michoud". NASA. This article incorporates text from this source, which is in the public domain.
  125. Foust, Jeff (September 16, 2015). "First Crewed Orion Mission May Slip to 2023". SpaceNews.com. Retrieved June 23, 2016.
  126. Clark, Stephen (September 16, 2015). "Orion spacecraft may not fly with astronauts until 2023". spaceflightnow.com. Retrieved June 23, 2016.
  127. Clark, Smith (May 1, 2014). "Mikulski "Deeply Troubled" by NASA's Budget Request; SLS Won't Use 70 Percent JCL". spacepolicyonline.com. Retrieved June 23, 2016.
  128. "All Four Engines Are Attached to the SLS Core Stage for Artemis I Mission". NASA.gov. Retrieved November 12, 2019. This article incorporates text from this source, which is in the public domain.
  129. Clark, Stephen (April 28, 2017). "NASA confirms first flight of Space Launch System will slip to 2019". Spaceflight Now. Retrieved April 29, 2017.
  130. Clark, Stephen (November 20, 2017). "NASA expects first Space Launch System flight to slip into 2020". Spaceflight Now. Retrieved May 24, 2018.
  131. Gebhardt, Chris (February 21, 2020). "SLS debut slips to April 2021, KSC teams working through launch sims". NASASpaceFlight. Retrieved February 21, 2020.
  132. Rincon, Paul (January 9, 2020). "Nasa Moon rocket core leaves for testing". Retrieved January 9, 2020.
  133. "Boeing, NASA getting ready for SLS Core Stage Green Run campaign ahead of Stennis arrival". NASASpaceFlight.com. December 14, 2019. Retrieved January 9, 2020.
  134. "NASA Will Have 8 Minute Hold Down Test in 2020". Retrieved August 2, 2019.
  135. Review of U.S. Human Space Flight Plans Committee; Augustine, Austin; Chyba, Kennel; Bejmuk, Crawley; Lyles, Chiao; Greason, Ride (October 2009). "Seeking A Human Spaceflight Program Worthy of A Great Nation" (PDF). NASA. Retrieved April 15, 2010. This article incorporates text from this source, which is in the public domain.
  136. Henry Vanderbilt (September 15, 2011). "Impossibly High NASA Development Costs Are Heart of the Matter". moonandback.com. Retrieved January 26, 2012.
  137. Ferris Valyn (September 15, 2011). "Monster Rocket Will Eat America's Space Program". Space Frontier Foundation. Archived from the original on October 6, 2011. Retrieved September 16, 2011.
  138. "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. July 12, 2011. Archived from the original (PDF) on March 29, 2012. Retrieved January 26, 2012.
  139. Rohrabacher, Dana (September 14, 2011). "Nothing New or Innovative, Including It's Astronomical Price Tag". Archived from the original on September 24, 2011. Retrieved September 14, 2011.
  140. "Rohrabacher calls for "emergency" funding for CCDev". parabolicarc.com. August 24, 2011. Retrieved September 15, 2011.
  141. Jeff Foust (September 15, 2011). "A monster rocket, or just a monster?". The Space Review.
  142. Jeff Foust (November 1, 2011). "Can NASA develop a heavy-lift rocket?". The Space Review.
  143. Mohney, Doug (October 21, 2011). "Did NASA Hide In-space Fuel Depots To Get a Heavy Lift Rocket?". Satellite Spotlight. Retrieved November 10, 2011.
  144. "Propellant Depot Requirements Study" (PDF). HAT Technical Interchange Meeting. July 21, 2011.
  145. Cowing, Keith (October 12, 2011). "Internal NASA Studies Show Cheaper and Faster Alternatives to the Space Launch System". SpaceRef.com. Retrieved November 10, 2011.
  146. "Near Term Space Exploration with Commercial Launch Vehicles Plus Propellant Depot" (PDF). Georgia Institute of Technology / National Institute of Aerospace. 2011.
  147. "Affordable Exploration Architecture" (PDF). United Launch Alliance. 2009. Archived from the original (PDF) on October 21, 2012.
  148. Grant Bonin (June 6, 2011). "Human spaceflight for less: the case for smaller launch vehicles, revisited". The Space Review.
  149. Robert Zubrin (May 14, 2011). "How We Can Fly to Mars in This Decade—And on the Cheap". Mars Society. Archived from the original on March 19, 2012.
  150. Rick Tumlinson (September 15, 2011). "The Senate Launch System – Destiny, Decision, and Disaster". Huffington Post.
  151. Andrew Gasser (October 24, 2011). "Propellant depots: the fiscally responsible and feasible alternative to SLS". The Space Review.
  152. Eric Berger (August 1, 2019). "The SLS rocket may have curbed development of on-orbit refueling for a decade".
  153. Alan Boyle (December 7, 2011). "Is the case for Mars facing a crisis?". MSNBC. Archived from the original on January 7, 2012.
  154. John K. Strickland, Jr. "The SpaceX Falcon Heavy Booster: Why Is It Important?". National Space Society. Retrieved January 4, 2012.
  155. "NASA Studies Scaled-Up Falcon, Merlin". Aviation Week. December 2, 2010. Archived from the original on July 27, 2012.
  156. "Spacex BFR to be lower cost than Falcon 1 at $7 million per launch". nextbigfuture.com. Retrieved January 17, 2019.
  157. Bergin, Chris (August 29, 2014). "Battle of the Heavyweight Rockets – SLS could face Exploration Class rival". NASAspaceflight.com. Retrieved May 16, 2019.
  158. "Congressman, Space Frontier Foundation, And Tea Party In Space Call For NASA SLS Investigation". moonandback.com. October 4, 2011. Retrieved October 20, 2011.
  159. "The Senate Launch System". Competitive Space. October 4, 2011. Retrieved October 20, 2011.
  160. "NASA veteran Chris Kraft upfront with criticism". August 2013.
  161. "Garver: NASA Should Cancel SLS and Mars 2020 Rover". Space News. January 2014.
  162. "Why NASA Still Can't Put Humans in Space: Congress Is Starving It of Needed Funds". 2015.
  163. "New Report Finds Nasa Awarded Boeing Large Fees Despite SLS Launch Slips". ArsTechnica. 2019.
  164. "Space News: Contractors continue to win award fees despite SLS and Orion delays". Space News. 2019.
  165. Berger, Eric (May 1, 2020). "NASA will pay a staggering 46 million for each SLS rocket engine". Ars Technica. Retrieved May 4, 2020.
  166. "Hopeful for launch next year, NASA aims to resume SLS operations within weeks". spaceflightnow.com. May 2, 2020. Retrieved May 2, 2020.
  167. Foust, Jeff (May 21, 2019). "In 2020, NASA Will Send Living Things to Deep Space for First Time Since Apollo". Space.com. Archived from the original on August 6, 2019. Retrieved August 6, 2019. BioSentinel is one of 13 cubesats flying aboard the Artemis 1 mission, which is currently targeted for mid-2020. [...] The other 12 cubesats flying aboard Artemis 1 are a diverse lot. For example, the Lunar Flashlight and Lunar IceCube missions will hunt for signs of water ice on the moon, and Near-Earth Asteroid Scout will use a solar sail to rendezvous with a space rock.
  168. Northon, Karen (June 9, 2017). "Three DIY CubeSats Score Rides on Exploration Mission-1". National Aeronautics and Space Administration (NASA). Archived from the original on August 6, 2019. Retrieved August 6, 2019. NASA's Space Technology Mission Directorate (STMD) has awarded rides for three small spacecraft on the agency's newest rocket, and $20,000 each in prize money, to the winning teams of citizen solvers competing in the semi-final round of the agency’s Cube Quest Challenge.
  169. Crane, Aimee (June 11, 2019). "Artemis 1 Flight Control Team Simulates Mission Scenarios". National Aeronautics and Space Administration (NASA). Archived from the original on August 6, 2019. Retrieved August 6, 2019. ...after the Space Launch System performs the Trans-Lunar Injection burn that sends the spacecraft out of Earth orbit and toward the Moon.
  170. Clark, Stephen (July 22, 2019). "First moon-bound Orion crew capsule declared complete, major tests remain". SpaceflightNow. Archived from the original on August 6, 2019. Retrieved August 6, 2019. The Artemis 1 mission profile. Credit: NASA [...] The Artemis 1 mission will send the Orion spacecraft into a distant retrograde lunar orbit and back...
  171. UNITED STATES COMMERCIAL LAUNCH MANIFEST
  172. Hill, Denise (August 6, 2019). "NASA's CubeSat Launch Initiative Opens Call for Payloads on Artemis 2 Mission". National Aeronautics and Space Administration (NASA). Archived from the original on August 6, 2019. Retrieved August 6, 2019. NASA is seeking proposals from U.S. small satellite developers to fly their CubeSat missions as secondary payloads aboard the SLS on the Artemis 2 mission under the agency's CubeSat Launch Initiative (CSLI).
  173. Klotz, Irene (August 5, 2019). "NASA Scouting Cubesats For Artemis-2 Mission". Aviation Week. Archived from the original on August 6, 2019. Retrieved August 6, 2019. NASA on Aug. 5 released a solicitation for cubesats to ride along with the first crewed flight of the Space Launch System rocket and Orion capsule, with the caveat that selected projects fill strategic knowledge gaps for future lunar and Mars exploration.
  174. Loff, Sarah (October 15, 2019). "NASA Commits to Future Artemis Missions With More SLS Rocket Stages". NASA. Retrieved October 16, 2019. Quote:"NASA aims to use the first EUS on the Artemis IV mission"
  175. Grush, Loren (May 22, 2018). "The first three missions of NASA's next big rocket will have to settle for a less-powerful ride". The Verge. Archived from the original on August 6, 2019. Retrieved August 6, 2019. But now NASA is going to fly all three missions — EM-1, EM-2, and Europa Clipper — on Block 1. [...] According to the memo, NASA will aim to have the second platform ready for a Block 1B launch in the beginning of 2024.
  176. Sloss, Philip (May 7, 2019). "NASA puts SLS Europa Clipper option in the wind tunnel". NASASpaceFlight.com. Archived from the original on August 6, 2019. Retrieved August 6, 2019. Data was collected during several hundred supersonic test runs in the Unitary Plan Wind Tunnel at Langley of a scale model of the Block 1 Cargo vehicle that is the currently mandated booster for the upcoming Europa Clipper mission.
  177. Sloss, Philip (September 11, 2018). "NASA updates Lunar Gateway plans". NASASpaceFlight.com. Archived from the original on August 6, 2019. Retrieved August 6, 2019. Although U.S. federal appropriations bills enacted into law for the last three fiscal years mandate a Europa Clipper launch on SLS and "no later than 2022," the presentations to the HEO committee show that launch on a Block 1 Cargo vehicle in 2023.
  178. Sloss, Philip (May 25, 2018). "NASA digging into SLS Block 1 revival plans after getting second Mobile Launcher money". NASASpaceFlight.com. Archived from the original on August 6, 2019. Retrieved August 6, 2019. In the wake of ML-2 funding and the change in direction, NASA began looking at "Jupiter Direct" trajectories with Block 1 again. NASA's early analyses of launch windows for Europa Clipper in 2022, 2023, 2024, or 2025 indicate that direct trajectories are feasible for SLS Block 1.
  179. Foust, Jeff (May 10, 2018). "House bill keeps Europa Clipper on track despite launch vehicle uncertainties". SpaceNews. Retrieved August 6, 2019. He added that both the original Block 1 version of SLS, as well as the Block 1B with the more powerful Exploration Upper Stage, are the only vehicles with C3 values high enough to allow for a direct trajectory for the six-ton Europa Clipper spacecraft. The less-powerful Block 1 is still sufficient, he said, mitigating concerns about any delays in the development of the Block 1B.
  180. Gebhardt, Chris (November 3, 2017). "Europa Clipper's launch date dependent on SLS Mobile Launcher readiness". NASASpaceFlight.com. Archived from the original on August 7, 2019. Retrieved August 7, 2019. The mission will be the first cargo flight of the SLS and will likely – though not confirmed – be the first SLS Block 1B launch.

Sources
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.