Ariane 5: what are the differences with NASA’s SLS rocket?

Tonight an Ariane 5 rocket will leave Earth. How is it so different from the SLS rocket that is to take the direction of the Moon?

© Arianespace

Tonight the ESA (European Space Agency) is preparing to launch an Ariane 5 rocket from Kourou, in French Guiana. Under the fairing of the rocket, 55 meters high, the communication satellite Eutelsat Konnect VHTS.

With this 118th flight, the 26-year-old rocket is well known to engineers, and if the takeoff of an Ariane 5 is still an event, the specialists are rather calm. It is the most reliable spacecraft of the past 20 years.

Ariane 5: European reliability

With these two boosters on the sides (EPA), Ariane 5 proudly poses on the Kourou launch pad. The rocket is propelled by a first stage with a Vulcain engine at its end. A monster of power that will, during the first minutes of the flight, propel the 160 tonnes of propellant into the skies of Guyana.

With this first block, the rocket takes off. Two minutes after takeoff, Ariane 5 is already speeding over 8,000 kilometers per hour. From the control center, the engineers only see a ball of fire rising in the sky. Weighing 750 tons, or a tenth of the Eiffel Tower, the European rocket is a model for launching into orbit.

Until the recent arrival of SpaceX rockets, the number 1 solution to get into space reliably and quickly was the Ariane 5 rocket. Originally built to send the Hermès space shuttle into orbit around Earth, this goal will never see the light of day.

The rocket nevertheless transported some big names from the space world. On December 25, the James Webb space telescope left Kourou, under the fairing of the European rocket. Many manufacturers recognize the expertise and quality of this rocket, especially for satellites in geostationary orbit.

For comparison, SpaceX’s Falcon 9 is capable of carrying 8 tons of payload to this orbit, and Ariane 5 can bring more than 10. 

SLS: another category

This rocket, of incredible power, is nevertheless a child next to SLS, NASA’s latest technological jewel. Built-in collaboration with Boeing, United Launch Alliance (ULA), Northrop Grumman, and Aerojet Rocketdyne, the SLS is up to 110 meters high, twice Ariane 5.

On the launch pad, more than 3,000 tons are ready to take off. NASA is aiming for the Moon with this rocket, and the American space agency needs a lot of power to reach our satellite.

She then asked Rocketdyne to produce non-reusable versions of the SSME engine. The latter had already proven itself a few years ago by propelling the space shuttle orbiter. Note that the four engines used during the Artemis 1 mission have all flown at least once with a space shuttle. They have since been stored and will be used one last time with this mission.

In addition to these high-powered engines, NASA was not stingy on the quantities with 979 tons of propellant on board at takeoff. This is 6 times more than on Ariane 5. The main tank is easily recognizable in the pictures of the machine, it is the large orange part. This color, already present on space shuttles, is due to the insulation used by NASA to protect its tank. On the Ariane 5 rocket, the latter is painted, but this adds weight and NASA wanted to save some money on this point.

Two rockets for two objectives

As with Ariane 5, NASA’s SLS rocket has two boosters used in the first minutes after liftoff. For SLS, these two “boosters” produce 80% of the thrust at the time of takeoff.

Used for years, however, solid rocket boosters have one major flaw. Once turned on, they cannot be turned off. This specificity caused in January 1986 the accident of the shuttle Challenger.

If NASA’s SLS rocket is superior in every respect to Ariane 5, it is above all because these two machines do not have the same objective. Ariane 5 offers a reliable and fast solution for sending very heavy objects into orbit around the Earth, or even further.

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