After several unsuccessful attempts, the American space agency will try again this Wednesday, November 16 to launch its new rocket, the SLS. This is the first mission of the Artemis program aimed at a return of man to the Moon.
From our special correspondent in Florida,
« It’s an incredible chance to be here. This is history: this is the new Apollo program. We’re still days away from launch, but Ryan’s eyes are already shining. Sunglasses on his nose, a NASA T-shirt on his shoulders, this 30-year-old spends his Sunday with his feet in the water of the Atlantic Ocean, on Cocoa Beach, not far from the Kennedy Space Center. It is here, on what is called the ” Space Coast Florida, that he came from distant Colorado to attend the launch of the Space Launch System (SLS), NASA’s new lunar rocket. Like him, more than a hundred thousand Americans had made the trip at the end of August during the first launch attempt. Another, equally unsuccessful, took place at the end of September. This will be the third campaign, and despite previous failures, Americans are still moving in numbers: all the hotels in the region are sold out despite the stratospheric prices.
It must be said that the show promises. Standing proudly on the Space Center’s 98.3-meter-high launch pad 39-B, SLS impresses, in keeping with its status as the most powerful rocket ever built. ” SLS is quite simply the propulsion system of the Artémis program “, explains with a smile Chris Cinciola, deputy program manager at NASA. In Greek mythology, Artemis is the twin sister of Apollo. She is also associated with the Moon.
A perfect name for the ambitious American program which aims to put astronauts on our satellite again in 2025. And for that, you need a powerful rocket: “ We are going a thousand times further than low Earth orbit where the International Space Station (ISS) is, and we have to take everything on board: the ship and everything the astronauts need “, details Chris Cianciola.
A story of engines
Here is the SLS, one of NASA’s most ambitious programs, whose affiliation with the Saturn 5 of the Apollo missions and the space shuttle is obvious. ” The teams that built Saturn 5 understood a lot. Besides, they went to the moon! laughs the program manager. This can be seen in the general design of the two machines, whose similarities are striking.
But by its very principle, SLS had to be more powerful than its predecessor: “ They went to the moon, but for a few days. We want to be true pioneers. We want to stay there. So you have to take more stuff. In space, it’s a constraint to scare away an engineer: more things means that it will be heavier, therefore more power at take-off. It is for this reason that there have also been borrowings from the side of the space shuttle. ” That was one of the challenges when designing the SLS: we needed the best engines, the best thrusters and we realized that we already had them, the RS-25s. »
These engines, among the most powerful ever built, Doug Bradley knows them well, since he is one of the people who designed them at the industrial Aerojet Rocketdyne. ” The principle is simple, it’s a rocket engine, it uses hydrogen and oxygen and mixes them in the combustion chamber to obtain thrust. The RS-25 happens to do this particularly well, and that’s why NASA used it to equip its space shuttle. ” When defining the needs of the SLS, we asked ourselves: “What is required for this mission”. This told us about the capacity of the engine. In this case, the most sensible thing is to see if it already exists rather than developing a new one. The RS-25 was perfect. »
Another advantage, the shuttle being reusable at the time, everyone had already flown. One of them completed twelve stays in space before being installed at the base of the SLS. Engineers therefore already know them like the back of their hand and know exactly how they will behave. The adaptations to be made to mount them on their new vehicle were also reasonably minimal, apart from the on-board computers which had to be upgraded. ” It would have been silly not to take the past into account when designing this new moon rocket », poursuit Doug Bradley. « What was done on Saturn 5 helped us build the shuttle. What was done on the shuttle helps us for the SLS. These are the foundations that allow us to go further. »
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test everything
It is generally considered that without good engines, a rocket is just a pile of metal sheets that does not serve much purpose. It is therefore important for NASA to have reliable engines with known behavior. However, the stacking of metal sheets on top is not incidental either, and it should also be tested. ” We tested on the ground, we did simulations, we tested the central body, the thrusters, we did all the tests we could “, explained Chris Cianciola. ” But at some point, to fully test the rocket before putting astronauts on board, it has to be flown. This is precisely the purpose of this Artemis 1 mission.
Unfortunately, flying the SLS turns out to be more complicated than expected. NASA has been trying to launch it for almost three months without success. It’s not so much the rocket itself that has caused concern, but rather what is called the ground segment, the launch base facilities. In this case, it is the systems allowing the filling of the tanks which experienced some failures, canceling the take-off scheduled for the end of August and the beginning of September. Three weeks later, when everything seemed to allow the engines to fire, it was storm Ian that forced NASA to return the machine to the VAB, the assembly building. Now in mid-November, a third opportunity looms, the rocket is again installed on its launch pad, and it is storm Nicole that arises. This time, the teams did not have time to bring in the launcher, which had to face the strong winds outside, but without damage according to the engineers of the American space agency. A few hours before the scheduled launch, all the lights are green for Artemis 1.
The mission is simple: do a dress rehearsal to qualify all the systems. SLS will therefore turn on its engines at 1:04 a.m. this Wednesday in Florida. Two minutes and 12 seconds later, her powder boosters will be empty and ejected. The launcher will then be at an altitude of 50 kilometers. After 8 minutes 30 of flight, it is the main stage which will separate after having accomplished its function. SLS will then be in space at an altitude of 167 kilometers, speeding at a speed of 28,000 kilometers per hour. Finally, after a two-hour mission, at an altitude of 4,000 kilometers, the Orion spacecraft will be released and propelled towards its lunar trajectory. It will take six days to reach our satellite, around which it will orbit for two weeks, before returning to Earth.
A new spaceship
Orion is the ship that will transport the astronauts of the Artemis program, the successor to the Apollo capsule. It is designed to reach distances never before achieved while protecting its crew, which can include up to four people, and bring them back to Earth safely. The vehicle has already been tested. It was placed atop a Delta IV Heavy rocket, which propelled it into orbit. After two orbits of the Earth, its ability to withstand the shock of atmospheric re-entry and to correctly deploy its parachutes was validated. But now, a return to our planet from the Moon will be at a much higher speed. Its ability to get into orbit and return is one of the major challenges of this mission.
The behavior of another element of Orion will also be closely analyzed: its service module. Developed by the European Space Agency (ESA) in partnership with NASA, it plays an essential role for the spacecraft. ” It’s like the engine of a car: Orion is the car, the service module provides its propulsion. It also provides all the regulation systems that allow the capsule to travel in space by providing a suitable atmosphere for the astronauts explains Philippe Deloo, program manager at ESA. Here too, the goal is to check everything: “ We have to make sure that all the systems we have developed work as we anticipated, that there are no surprises or anomalies. The next flight will be with astronauts and we obviously don’t want to risk their lives. »
Generation Artemis
Indeed, after this mission, will come Artemis 2 in 2023 if all goes well. A first crew will settle at the top of the 98 meters of the SLS for a replica of Artemis 1 or Apollo 8 at the time: a few moon tours to check all the systems again, but with astronauts at board this time. Next will come Artemis 3 in 2025 at the earliest, or for the first time since Apollo 17 in 1972, two humans will tread the lunar soil. The names of the two astronauts are not yet known but NASA has already announced its intention that a woman and an African-American make up the crew. ” We’re going back to the moon, and that’s just cool », sourit Doug Bradley. « It reminds me of the end of Apollo 13, the movie with Tom Hanks. He reflects on the end of the Apollo program, and wonders when we will return to the Moon and with whom. It’s with us, our rocket is on the launch pad! »
For many, Artemis is a story of legacy. By its technologies and its approach, but also by the imagination it carries: the Apollo program of a new generation. Chris Cianciola agrees: “ I was a young child when we launched Apollo 11 in 1969. My family and I parked in Titusville, three miles from the space center, and watched the launch from the road. Afterwards, we came home and saw the first steps on the Moon. It is always in my memory. Today, I work with a team that does the same. And when it launches on Wednesday, there’s sure to be a kid watching from the road, like I did. In 40 years, this child will have taken up the torch. This is what it takes if you want to go even further into space and explore! »
@NASA_SLS is on launch pad 39-B, where she weathered the last storm without flinching too much. Engine ignition at 1:04 a.m. here, 7:04 a.m. Paris, 6:04 a.m. UT. To follow live commented by yours truly on @rfi . The launch window lasts two hours. pic.twitter.com/lnJGIPcflU
— Simon Rozé (@simonroze) November 15, 2022
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