Space Launch System: everything you need to know about the SLS, the Artemis program rocket

This gigantic rocket is one of the centerpieces of the Artemis program. It is the Space Launch System (SLS) launcher, designed by NASA, which will have the mission of sending humans to the Moon. Here’s what you need to know about it.

« The most powerful rocket in the world “: NASA thus qualifies the Space Launch System (SLS), its rocket which must play a crucial role in the Artemis program and the return of the United States to the Moon. This imposing launcher is preparing to make its first flight in 2022, in order to launch the first mission of this program, Artémis I, into space.

His flight, originally scheduled for Monday August 29, nevertheless had to be postponed. For now, NASA has not confirmed a new launch date. However, it seems quite likely that another attempt to launch the Artemis I rocket to the Moon will take place on Friday, September 2.

Here is everything you need to know about the Space Launch System (SLS), NASA’s imposing rocket, in 10 questions.

1. The SLS is a super heavy space launcher: what is it?

The Space Launch System is a rocket. But not all rockets are the same size and do not have the same objective (sending satellites, ships or humans into space, for example). The NASA describe his gear as a super heavy launcher (in English, ” super heavy-lift launch vehicle », or SHLV). This means that the SLS is able to send a payload (the name given to elements intended to fulfill a mission, as opposed to the vehicle that carries them) into low Earth orbit. more than 50 tons. The space agency estimates that when the rocket launches, it will carry far more than any other launcher has ever done.

This rocket is therefore particularly imposing: on its launch pad, the SLS launcher is higher than the Statue of Liberty (98 meters high for the rocket, 93 meters for the monument) and weighs 3 million kilos.

2. Who designed the SLS rocket?

The development of the Space Launch System is provided by NASA, the American space agency. Launcher assembly took place at Launch Complex 39, which is located at Kennedy Space Center in Florida. These are the facilities that had once been used for the American Space Shuttle that have been adapted, in order to be able to launch the SLS.

3. How long did the construction of the SLS launcher take?

The project was formalized in September 2011, when NASA announced that it had decided on the new design of its Space Launch System. The first tests started in January 2015, with the test of one of the engines. In 2011, Congress had demanded of NASA that the rocket flies before the end of 2016. In the end, the project was more than 5 years late, since the first flight of the rocket is scheduled for 2022.

4. How many stages does the Space Launch System have?

NASA’s big rocket is made up of 4 main pieces, including 2 stages, for the Artemis program:

  • The upper stage, in white, below the Orion capsule,
  • The central floor, recognizable by its orange color,
  • The two thrusters, white in color,
  • As well as 4 motors, at the bottom of the central stage of the SLS.

However, this configuration is not final. One of the advantages of this launcher is that it can evolve, according to the needs of the different missions. For the Artemis program, it must be able to send the Orion capsule into space, with a crew of astronauts on board. But, NASA is already anticipating other versions of the SLS, so that it sends heavy equipment to the Moon, or even to Mars.

The top of the SLS rocket. // Source : Flickr/CC/Nasa Kennedy (cropped photo)

5. How is the SLS rocket propelled?

In all its configurations, the SLS launcher integrated always the central stage, with its 4 RS-25 engines, which burn hydrogen and liquid oxygen for propulsion. In its version called Block 1 (the one to be used for the Artemis I, II and III missions), the SLS is powered by its two boosters and the 4 engines.

The maximum speed of the SLS launcher is over 9.7 kilometers per second. At this speed, the rocket could circle our planet in just 1 hour and 6 minutes.

6. What is the payload of the SLS?

The Space Launch System rocket is expected to carry different kinds of payloads. For the Artemis program, the rocket is designed to install the Orion spacecraft (at first without a crew, then inhabited). Subsequent versions of the SLS may involve other payloads, including robotic solar system exploration missions.

7. Can the SLS rocket be reused?

NASA did not plan that its Space Launch System rocket could be recovered and reused after a launch. All the power of the launcher is mobilized to maximize the payload that the rocket can send to the Moon, Explain the space agency. Therefore, on board the SLS there is no additional fuel or propulsion systems that would allow the various stages of the rocket to return to Earth.

8. From where does the SLS launcher take off?

The SLS rocket lifts off from NASA’s Kennedy Space Center in Florida. Launch pad 39B, which used to launch the US Space Shuttle, has been renovated to accommodate Space Launch System launches.

9. How is the take-off from the SLS going?

The takeoff of the SLS rocket follows several stages:

  • Several hours before the opening of the firing window, the filling of the tanks begins, with hydrogen and oxygen. It was at this stage that, on August 29, NASA noticed a fuel leak in the Artemis I rocket.
  • At 0 hours, 0 minutes and 0 seconds, it’s time for takeoff. Barely 2 minutes after the launch of the rocket, it is already far away: it releases its propellants as soon as they no longer contain fuel.
  • 3 minutes and 40 seconds after launch, the SLS is at an altitude of 91 kilometers.
  • After 8 minutes and 14 seconds, the central stage (orange) is no longer useful. We only keep the upper floor, which continues to push Orion upwards.
  • 1 hour and 25 minutes after launch, Orion is at an altitude of 601 kilometers.
  • After 1 hour and 53 minutes, the capsule is 3,850 kilometers from us. The SLS has accomplished its mission: its upper stage has been jettisoned. The Orion ship continues its journey to the Moon on its own.

10. What will be the missions of the SLS rocket?

The Space Launch System rocket must at least be used during the following missions:

  • Artemis I (2022) which consists of a test flight, with the unmanned Orion capsule. The ship must circumnavigate the Moon and return to Earth.
  • Artemis II (2024), which this time consists of sending a crew aboard this capsule (4 astronauts) again to go around the Moon (without landing there) and return.
  • Artemis III (2025), which involves sending 4 astronauts aboard Orion again, along with cargo, this time to go to the lunar South Pole and study it.

Source: Numerama by

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