The SLS lit up against the night sky on the launch pad

Artemis I will be put through its paces in a wet dress rehearsal ahead of a potential launch later this year. Image © NASA/Joel Kowsky, licensed under CC BY-NC-ND 2.0 via Flickr.

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NASA rocket which will eventually take humans to the Moon unveiled

One of the largest rockets ever built, NASA's Space Launch System (SLS), has been revealed to the public as it undergoes its last big test before its first flight.

But what is the future of this rocket, and the Artemis mission it forms part of? And what is the future of humans in space? 

The race is on for humans to return to the Moon after the debut of NASA's new spacecraft.

Currently the most powerful rocket ever built, the SLS debuted in public yesterday after over a decade in development. It is on its way to the launchpad ahead of final testing and could take off later this year if it passes.

This initial version of the rocket is intended as a test flight for later stages of the Artemis program, which aims to put a space station in orbit around the Moon. Later versions are planned which will take the cargo necessary to build this build this space station ahead of travel to Mars.

Speaking as the SLS was brought out for the first time, NASA's administrator Senator Bill Nelson said, 'Today a new generation, not the Apollo generation but the Artemis generation, is preparing to reach new frontiers. This generation will return astronauts to the Moon and this time, we will land the first woman and the first person of colour on the surface to conduct groundbreaking science. NASA's Artemis program will pave the way for humanity's giant leap – future missions to Mars. 

'There is no doubt that we are in a golden era of human space exploration, discovery and ingenuity, and it all begins with Artemis I.'

The SLS faces competition to get to the Moon from the private company SpaceX, which hopes to get nine members of the public to the Moon by 2023. 

A diagram showing different configurations of the SLS

The SLS will be upgraded over its lifetime to serve different roles. Image © NASA, licensed under CC BY-NC 2.0 via Flickr.

What is the Space Launch System?

The SLS is among the largest rockets ever built, measuring about the same height as Big Ben (officially, the Elizabeth Tower). It consists of the core stage, two booster rockets and the Orion spacecraft, which will eventually carry crew and cargo.

This first version, or Block 1, is being used to test out the capabilities of the rocket to carry 27 metric tonnes, or about three Tyrannosaurus rex's, into orbit around the Moon. 

If these first missions are successful, it will be replaced with Block 1B which can carry 11 tonnes more. This will hopefully mean the rocket could carry crew with enough cargo to remain on the Moon for an extended period, with a view to establishing a more permanent presence on Earth's biggest satellite.

Eventually, Block 2 will be able to take even greater masses to the Moon, Mars and beyond as humans go deeper into space. 

A footprint on the Moon

Humans last set foot on the Moon in the early 1970s. Image © NASA/Buzz Aldrin, licensed under Public Domain via Wikimedia Commons.

What is happening to the Space Launch System?

The SLS was moved to Launch Pad 39B at NASA's Kennedy Space Centre, from which Apollo 10 and many other Space Shuttle missions launched. It took almost 11 hours for the rocket to make the journey, with the mobile-launch platform carrying it having a top speed of only one kilometre per hour.

Having reached its destination, it will now undergo what is known as a 'wet dress rehearsal'. This will see the rocket put through its paces on the launchpad as engineers test all of its systems ahead of a practice launch.

The SLS will be brought to the edge of launching, before the countdown clock is reset to 10 minutes before launch. Around 10 seconds before the end of the clock, the launch will be cancelled and the fuel drained, to practice what could happen if poor weather requires a postponement.

The rocket will then be taken back to the Vehicle Assembly Building where it will be prepared for its first test flight. While no date has been set yet, it is expected later this year. 

An artist's impression of an Orion spacecraft approaching Gateway in front of the Moon

The SLS was moved in an operation taking 12 hours to the launch pad. Image © NASA/Alberto Bertolin, licensed under CC BY-NC-ND 2.0 via Flickr.

What is the Artemis program?

NASA's Artemis program is the successor to Apollo, and will see humans return to the Moon for the first time in over 60 years. In Greek mythology, Artemis is the twin sister of Apollo reflecting the shared aims of both missions.

Artemis I is the first uncrewed launch of the SLS, where the rocket and Orion spacecraft will be tested to see if they operate as intended in space, as well as carrying the names of people across the world into orbit. If all goes well, then Artemis II will carry humans into space for the farthest flight ever from Earth, going beyond the Moon over a 10-day mission. 

Artemis III will then return four humans to the surface of the Moon. While an initial deadline of 2024 was set, this has now been pushed back to 2025 following the COVID-19 pandemic.

This week-long mission is hoped to bring back Moon samples that will tell us more about the history of the satellite and Earth itself. 

These will be supplemented by the construction of the Gateway space station, which will be placed in orbit around the Moon. The first of a series of modules are currently set to launch in late 2024.

Simultaneously, a lunar base camp will be set up on the Moon to provide a permanent presence for humans. Efforts to harvest the Moon for resources may also be a part of the role of this camp.

Looking beyond this, it is hoped the lunar Gateway and base camp will provide a staging post for the Deep Space Transport spacecraft. While currently still on the drawing board, this reusable vehicle would be able to shuttle astronauts between the Moon and Mars, and maybe one day even further. 

A Falcon 9 rocket launches.

SpaceX has been developing its own fleet of rockets, including the Falcon 9 (pictured). Image © Charles Boyer, licensed under CC BY 2.0 via Flickr

What about others wanting to get to the Moon?

NASA are not the only ones hoping to go to the Moon. Russia, China and Japan have all proposed sending their own astronauts to the Moon, with projects at various stages of completion.

But space travel has now moved into an era of private exploration. One of the leading companies is SpaceX, which intends to launch a Moon mission as soon as next year.

This is planned using its Starship spacecraft atop a booster rocket known as Super Heavy. Unlike NASA's SLS, SpaceX's booster and spacecraft are designed to be fully reusable, which will significantly reduce the costs of each mission. 

While the Starship has successfully flown and landed from high altitude, it is yet to be tested in flight with the Super Heavy booster, or orbit around the Moon. Once these tests are complete, it will pave the way for its planned 2023 lunar mission, named dearmoon, to launch.