Space Launch System

from Wikipedia, the free encyclopedia
Artist's impression: This is how the basic version of the SLS with space capsule should look like on the launch pad.
Obsolete artist rendering of an SLS in flight
A booster of the SLS on the test stand

The Space Launch System ( Engl. For "space launch system"), short SLS , is one of the NASA planned launch vehicle for manned space exploration via a low earth orbit beyond. The first unmanned launch will take place in the 4th quarter of 2021 at the earliest. A first manned launch is planned for 2022 Template: future / in 2 years. Technologically, the rocket is based on the never-realized plans for the Ares V rocket as part of the Constellation program . The basis of the development are the main engines , the solid fuel boosters and the external tank of the space shuttle program , which ended in 2011 .


After the end of the manned lunar missions as part of the Apollo program in the early 1970s, NASA concentrated again on manned missions in low Earth orbit and developed the space shuttle , which first launched into space with Columbia on April 12, 1981. When exactly this space shuttle broke up almost 22 years later, on February 1, 2003, when it re-entered the atmosphere (see Columbia catastrophe ), there was another rethink at NASA and the US government. The shuttle was now considered outdated and too expensive. In early 2004, for example, US President George W. Bush announced the end of the shuttle program after the completion of the International Space Station (ISS) in 2010. In addition, as part of the Vision for Space Exploration (VSE; German "Vision for Space Exploration") initiative, he announced the development of new rockets and a spaceship to return to the moon and ultimately flights to Mars.

From this vision, the Constellation program with the manned Ares I rocket and the Orion spaceship as well as the Ares V heavy-lift rocket developed . The whole project suffered from funding difficulties from the start and was discontinued in 2010 by the new US President Barack Obama . As a compromise, only the Orion spaceship should be preserved and further developed.

Opposition to the suspension of the Constellation program grew, and in the summer of 2011 the US Congress hired NASA to build a new heavy-lift missile. This rocket, now called the Space Launch System , was supposed to make its first unmanned flight in 2017. A first manned launch was scheduled for 2021. The rocket is to be developed using technologies from the space shuttle and the plans for the Ares V rocket.

In October 2018, NASA's Inspector General noted that there had been significant delays and budget overruns in the development of the first stage rocket, and warned of further problems. The causes would be mismanagement at the manufacturer Boeing and insufficient monitoring by NASA.

After an official presentation in the course of the stress test of the first stage of the SLS in December 2019, NASA announced that it would start the first unmanned test flight in July 2020. The first manned mission, a planned orbit around the moon, is now scheduled to start in 2022.

Structure of the missile

Development stages of the SLS
Exploded view of the Block 1 version (manned)
Exploded view of the Block 2 version (unmanned)

The SLS is to be developed in several steps into a heavy-lift rocket with a capacity of approx. 130 tons of payload in low orbit. First of all, the version called Block 1 should be used. With the rescue rocket at its head, this combination is 98 meters high and weighs around 2500 tons when launched. The payload capacity of the carrier is 95 tons for near-earth orbit (LEO) or 26 tons to the moon. It should be able to transport the Orion spaceship into a lunar orbit.

The variant called Block 1B should have a stronger upper stage (payload of 130 tons LEO or 45 tons to the moon) and be able to transport both the Orion spaceship and unmanned payloads such as planetary probes.

With new and reinforced boosters, the rocket, called Block 2, will later reach its maximum payload capacity and be able to carry larger components for asteroid and / or Mars missions into space.

Whether Block 1B and Block 2 will actually be implemented is uncertain because of the delays and the corresponding escalating costs in the SLS program. The US administration under Donald Trump wants to get a grip on the schedule by giving preference to privately operated and reusable launch vehicles. The SLS's task could be limited to putting the manned Orion spacecraft into lunar orbit, for which Block 1 is sufficient. The development of the stronger upper level required for Block 1B and 2 was frozen for an indefinite period in 2018.

First stage

The first stage is 8.38 m in diameter, which corresponds to the diameter of the external tank of the space shuttle. It is said to use four RS-25D / E engines, which are derived from the SSME of the space shuttle. SSMEs that are left over from the space shuttle program and are to be modernized will be used on the first flights. In addition to these 16 engines, which are sufficient for four flights, NASA ordered a further six new engines from Aerojet Rocketdyne in November 2015. The tank for the liquid hydrogen is in the lower part of the first stage and the one for the liquid oxygen above. In a stress test of the tanks in December 2019, the first stage was able to withstand loads of more than 250% of the loads expected in flight before it ruptured. The main stage will be manufactured using new equipment in the Michoud Assembly Facility . This first stage is to be used for all variants of the SLS.


The Block 1 and Block 1B variants are to use two modernized boosters derived from the Space Shuttle solid rocket launch . The boosters should consist of five instead of the four segments used in the space shuttle. The two boosters are attached to the side of the first stage and, in contrast to the space shuttle program, should not be reused.

For Block 2, NASA had the industry investigate more powerful boosters with liquid or solid fuel to replace the solid-state boosters. Aerojet , Alliant Techsystems and a consortium of Dynetics and Pratt & Whitney Rocketdyne applied with various concepts. The design by Dynetics and Pratt & Whitney Rocketdyne envisaged an increase in SLS payload capacity by 20 t. However, the project was abandoned by NASA in 2014.

Upper school

In the Block 1 variant, a slightly modified second stage DCSS (Delta Cryogenic Second Stage) of the Delta IV rocket under the name ICPS (Interim Cryogenic Propulsion Stage) is to serve as the upper stage. In the variants Block 1B and Block 2, a more powerful upper stage called EUS (Exploration Upper Stage) is to be used. This upper stage has the same diameter as the first stage and is intended to use four re-ignitable RL-10 engines .


SLS should be able to withstand at least 13 refueling cycles, which can be necessary due to aborted starts and other delays. The assembled rocket can remain on the launch pad for at least 180 days and in the assembled state for 200 days.

The SLS is so powerful that it can shoot larger and heavier space probes than previously possible to the gas planets etc. Depending on the situation, the mission-extending swing-by maneuvers to increase speed can be dispensed with, which are necessary today even with lighter space probes.

Development and manufacture

In mid-November 2014, construction of the first parts for the first stage on a new welding system began in NASA's Michoud Assembly Facility , where most of the rocket parts are to be assembled.

In January 2015, NASA began test firings of RS-25 rocket engines in preparation for use for the SLS. In early 2019, the assembly of the first stage for the first SLS rocket began.

Start list

According to the planning status from 2018, it was planned to set up the LOP-G space station in a lunar orbit in the 2020s with various unmanned and manned SLS flights . In the 2030s, manned flights to Mars with the spacecraft DST should take place from there .

In 2019, US Vice President Mike Pence commissioned NASA on behalf of President Donald Trump to carry out a manned landing in the South Pole region of the moon by 2024. NASA designed the Artemis program , which initially envisages 7–8 SLS launches by 2028, including several moon landings. This planning is subject to funding in the United States budget for fiscal year 2020 beginning in October 2019. The goal of manned Mars flights in the 2030s is maintained.

Planned SLS missions (as of May 26, 2019)
mission Target date variant comment
Artemis 1 2021 Block 1 crew Test flight to the moon with an unmanned Orion spaceship . Total duration 26 days, including 6 in lunar orbit. In addition, 13 cubesats are to be exposed, including several lunar orbiters and a moon lander.
Artemis 2 2022Template: future / in 2 years Block 1 crew Test flight; Circumnavigation of the moon in a manned Orion capsule
Artemis 3 2024Template: future / in 4 years Block 1B crew Manned Orion capsule and “Surface Logistics” to the LOP-G , from there with a lander to the moon and back again. The LOP-G itself and the individual components of the lunar module - transfer, descent and ascent module - have meanwhile been brought into lunar orbit with privately operated rockets. This also applies to the following missions.
Europe clipper 2024-2025Template: future / in 4 years Block 1 Cargo Unmanned research mission to Jupiter's moon Europa . Alternatively, the mission could be rebooked to a Falcon Heavy or Delta IV Heavy.
Artemis 4 2025Template: future / in 5 years Block 1B crew Manned Orion capsule and living module to the LOP-G, from there with a lander to the moon and back again.
Artemis 5 2026Template: future / in 5 years Block 1B crew Manned Orion capsule and “Surface Logistics” to the LOP-G, from there with a lander to the moon and back again.
Artemis 6 2027Template: future / in 5 years Block 1B crew Manned Orion capsule and gateway components including a gripper arm to the LOP-G, from there with a lander to the moon and back again.
Artemis 7 2028Template: future / in 5 years Block 1B Cargo Transport of a residential module to the lunar surface ("surface asset"). This flight is not mentioned in all NASA plans.
Artemis 7
or 8
2028Template: future / in 5 years Block 1B crew Manned Orion capsule and gateway components including a gripper arm to the LOP-G, from there with a lander to the moon and back again.
An Orion spacecraft visits the Lunar Orbital Platform gateway
Canceled SLS missions (as of April 16, 2019)
mission Target date variant Remarks
Asteroid Redirect

Crewed mission

2026 Block 1B Send an Orion capsule with four crew members to a near-Earth asteroid, which is detected robotically.

Comparison with other heavy-duty rockets

The most powerful launch vehicles currently available or under development for low earth orbit (LEO) transport are:

Starship / SH Long March 9 SLS Falcon Heavy New Glenn Angara A5B Vulcan Centaur Heavy Delta IV Heavy
Manufacturer United StatesUnited States SpaceX China People's RepublicPeople's Republic of China CALT United StatesUnited States Boeing United StatesUnited States SpaceX United StatesUnited States Blue Origin RussiaRussia Khrunichev United StatesUnited States ULA United StatesUnited States ULA
stages 2 3 2 2 2 2-3 2 2
Side booster - 4th 2 2 - 4th 2 2
Max. Payload (LEO) 150 t 3 140 t 95–130 t 1 64 t 45 t 3 37.5 t 35 t 29 t
Max. Payload ( GTO ) 20 t
(150 t 5 )
66 t no information 27 t 13 t 3 8 t 16 t 10 t
reusable Completely ? No First stage, side boosters,
payload fairing 4
First stage possibly first stage and side booster First stage 2 engines No
interplanetary missions planned planned planned Yes possible planned planned Yes
manned missions planned planned planned not planned planned planned planned No
First flight approx. 2021 not before 2028Template: future / in 5 years not before 2021 2018 not before 2021 not before 2027Template: future / in 5 years not before 2023Template: future / in 3 years 2004

1 Maximum of 95 t LEO payload in the first expansion stage of the rocket (Block 1), 105 t in the second (Block 1B) and 130 t in the third (Block 2).

2 Planned for a later expansion stage; the engine unit should then return on a parachute and be recovered by helicopter.

3 Maximum payload when reusing all reusable components. A larger payload would be possible without reuse. With the New Glenn this is not planned, with the Starship it is a conceivable option.

4 Reuse of payload fairings is planned.

5 When refueling in orbit.

Web links

Commons : Space Launch System  - collection of pictures, videos and audio files

Individual evidence

  1. a b Eric Berger: Space Launch System rocket now targeted for a late 2021 launch. In: Ars Technica. May 14, 2020, accessed May 15, 2020 .
  2. ^ A b c d e Forward to the Moon: NASA's Strategic Plan for Lunar Exploration. (PDF) NASA, May 2019, accessed on May 26, 2019 .
  3. The Vision for Space Exploration - February 2004 (PDF). NASA, February 15, 2004, accessed January 17, 2016 .
  4. ^ Obama Vows Renewed Space Program. New York Times, April 15, 2010, accessed January 17, 2016 .
  5. Preliminary NASA plan shows Evolved SLS vehicle is 21 years away., July 27, 2011, accessed January 17, 2016 .
  6. SLS finally announced by NASA - Forward path taking shape., September 14, 2011, accessed January 17, 2016 .
  7. ^ Jeff Foust: NASA inspector general sharply criticizes SLS core stage development. In: Spacenews. October 10, 2018, accessed on March 12, 2019 .
  8. a b c Loren Grush: The first three missions of NASA's next big rocket will have to settle for a less powerful ride. May 22, 2018. Retrieved December 20, 2018 .
  9. ^ Moon to Mars . NASA, accessed May 15, 2019.
  10. ^ Eric Berger: New White House budget spells trouble for NASA's SLS rocket. In: Ars Technica. March 11, 2019, accessed March 11, 2019 .
  11. ^ Philip Sloss: Administration proposes the end of EUS while Administrator considers full Exploration manifest rewrite. In: Nasaspaceflight. March 19, 2019, accessed March 19, 2019 .
  12. a b NASA announces new rocket for deep space missions. Spaceflight Now, September 14, 2011, accessed October 6, 2013 .
  13. Aerojet Rocketdyne wins propulsion contracts worth nearly $ 1.4 billion. Spaceflight Now, November 27, 2015, accessed January 19, 2016 .
  14. SLS Core Stage Fact Sheet PDF (English)
  15. Stephen Clark: Rocket companies hope to repurpose Saturn 5 engines. Spaceflight Now, April 18, 2012, accessed October 6, 2013 .
  16. ^ Dan Leone: News from the 30th Space Symposium | Second SLS Mission Might Not Carry Crew. In: Spacenews. May 21, 2014, accessed March 12, 2019 .
  17. SLS to be robust in the face of scrubs, launch delays and pad stays . April 4, 2012. Retrieved April 9, 2012.
  18. David Hitt, NASA's Marshall Center (January 14, 2014): . Retrieved February 9, 2014.
  19. ^ SLS Engine Section Barrel Hot off the Vertical Weld Center at Michoud . NASA
  20. Chris Bergin: Stennis conducts SLS engine firing marking RS-25 return . Accessed January 2015.
  21. ^ NASA Invites Media for Look at NASA's Space Launch System Progress. NASA, February 20, 2019, accessed March 12, 2019 .
  22. a b c d Moon 2 Mars , NASA, accessed May 26, 2019.
  23. Kathryn Hambleton: Around the Moon with NASA's First Launch of SLS with Orion. March 7, 2018, accessed December 21, 2018 .
  24. Kathryn Hambleton: Exploration Mission-1 Map. February 9, 2018, accessed December 21, 2018 .
  25. Karen Northon: Space Launch System's First Flight to Send Sci-Tech Sats to Space. February 2, 2016, accessed December 20, 2018 .
  26. Jeff Foust: Europa Clipper passes key review. In: Spacenews. August 22, 2019, accessed on August 23, 2019 : "... it is not possible to launch Europa Clipper on an SLS in 2023 since there won't be an available SLS for that mission then."
  27. (January 4, 2016): Archive link ( Memento from January 18, 2016 in the Internet Archive ) (English). This article tells about the 2020 Mars Rover and the Europa Clipper. Retrieved June 23, 2017.
  28. Van Kane (The Planetary Society) (January 5, 2016): (English). Retrieved June 23, 2017.
  29. Management of NASA's Europe Mission. (PDF) NASA Office Inspector General, May 2019, accessed May 30, 2019 .
  30. ^ Note from the Project Manager. (PDF) Jet Propulsion Laboratory, May 2018, accessed on March 11, 2019 .
  31. Caleb Henry: SpaceX targets 2021 commercial Starship launch. In: Spacenews. June 28, 2019, accessed June 28, 2019 .
  32. ^ Sandra Erwin: Falcon Heavy's first commercial launch to pave the way for reusable rockets in national security missions. In: Spacenews. March 25, 2019, accessed April 25, 2019 .
  33. Twitter message from Elon Musk, March 29, 2019.