It is probably the greatest adventure of mankind: a trip to the moon. With the "Artemis" program, NASA wants to return to the Earth's satellite. In the year 2025, but possibly not until 2026, a human being will set foot on the moon again. The European Space Agency ESA helped develop and build the moon spacecraft "Orion". Now the dress rehearsal is imminent: The "Artemis 1" mission is expected to start on November 16th, a test flight to the moon without astronauts. All systems should then be "put through their paces", as the German ESA engineer Dr. Tobias Langener explained in an interview with ntv.de. He is responsible for the propulsion system of the spaceship.
ntv.de: Mr. Langener, how does it feel to be involved in mankind's new moon program?
Tobias Langener: It's a bit surreal. I don't usually have much time to think about it because we have a very demanding and stressful development program. Every day there are problems that need to be solved. But when I look at it from a little distance, I do think: Wow, you're participating in the largest space program in the world. It is of course also a great responsibility, but at the same time very exciting.
They are on site at the NASA control center in Houston when "Artemis 1" is launched. Are you sitting there in the big room with the huge screens on the wall that you know from television?
This is the room where the flight controllers are located. But beyond that, there's another room that looks almost exactly like where we sit, the engineers who were involved in designing and building the spaceship. It is the so-called Mission Evaluation Room. There is constant communication between the two rooms. For example, if a problem occurs, the flight controllers call the Mission Evaluation Room. If, for example, a valve in the spaceship's propulsion system does not open, we have to think of a solution to get it open.
How is the mood in the Mission Evaluation Room? It's about a lot.
You can really feel the tension there. You have to imagine that the whole boot process begins 46 hours before the countdown hits zero. The spaceship is switched on, the systems are then booted up and the voltage slowly increases. I'll get to the control center about five hours before launch. When I leave the hotel, I can already see the rocket being refueled on TV. In the Mission Evaluation Room, the atmosphere is very calm but tense. You can tell that everyone is sitting in front of the screens with great concentration. This is of course very exciting.
There have already been several aborted starts with "Artemis 1". Is it because the moon rocket isn't working really well yet?
Start aborts are completely normal. There were shuttle flights where the start was aborted four times and the crew had to climb out again and again. But it's fine anyway. On "Apollo 1" in the early 1960s, the crew was already inside the capsule when it suddenly caught fire. The astronauts died in the process. And because of such incidents, you approach it very carefully. After all, a system like this consists of tens of thousands of components. The probability that one of them causes problems is relatively high. However, during the first two attempts to launch "Artemis 1" there were problems with the rocket, but not with the spaceship. Everything looked very good with that and we would have been "ready to launch".
For the rocket, called Space Launch System or SLS for short, it is also a first flight. Concerned that something might go wrong at launch?
I have little concern. Sure, it's a new rocket and there are always risks. However, the engines were previously used on the Space Shuttle. The entire main stage was also completely tested in advance. The solid fuel engines are also relatively robust. There have been few problems so far, except for the “Challenger” accident …
... the explosion of a space shuttle shortly after launch in 1986.
In effect, the SLS uses the same boosters. But lessons were learned from the "Challenger" disaster and there have been no more problems with these solid fuel engines since then. The rocket's upper stage is also well tested, so I'm relatively relaxed.
Is there a moment at the start of "Artemis 1" that you particularly look forward to?
Ultimately, it is the ignition of the rocket. If it works, then we fly. Once the solid fuel engines are on, they burn for about two minutes, and then you can't turn them off again. It's the point of no return.
The European Service Module ESM, built by Airbus in Bremen, provides the propulsion, electricity and water and oxygen supply for the lunar spacecraft. As the lead engineer, you are responsible for the propulsion system - what do you have to pay particular attention to when starting?
The moment that I particularly look forward to is called priming. The drive system of the ESM is put into the status in order to then be able to carry out all necessary maneuvers. The priming happens two minutes and ten seconds after launch and lasts about two minutes. If that all works out, I'll be relieved. This is one of the greatest moments of ascension. The first ignition of our main engine about five hours after take-off will also be very exciting. This engine was also used in the shuttle.
The drive of the spaceship must also be able to save lives on later manned missions...
Yes, exactly. If there is a problem with the rocket after launch, the ESM's propulsion system is responsible for the "Orion" spacecraft flying away from the rocket from a certain altitude. Then it brings the capsule with the astronauts around the earth so that they can land safely in the Pacific again. Or it puts them in an orbit from where they can land safely again. It all depends on the level at which you cancel.
Is the propulsion system you oversee also responsible for taking the spacecraft to the moon?
Generally, yes. You can also fly to the moon with the propulsion system. When this function is needed depends on the mission. With "Artemis 1" the shot to the moon is made by the upper stage of the SLS rocket, with "Artemis 2" then by the propulsion system of the spaceship. All of the maneuvers necessary to return to Earth are also provided by the spacecraft's propulsion system.
Why is the spaceship drive used differently in the "Artemis 2" mission than in "Artemis 1"?
Astronauts are flying with "Artemis 2" for the first time. After separating from the SLS rocket, the spacecraft will initially remain in Earth orbit for a day in order to test near-Earth vital systems and maneuvers. The "Orion" propulsion system then transports the capsule in the direction of the moon, which is then only flown past, i.e. into no lunar orbit, but directly back to earth. You want to keep this mission short, about nine to ten days, to minimize the risk to the astronauts. .
How about the later missions?
With "Artemis 3" and "Artemis 4" the rocket then makes the bullet to the moon again, since the fuel of the "Orion" spaceship is needed more around the moon and for the return. Astronauts are flying with these missions again and the first moon landings since 1972 are planned. Incidentally, the lunar module is being built by SpaceX.
To what extent is "Orion" actually similar to those spaceships that were used in the earlier moon flights of the "Apollo" program?
The "Orion" capsule is definitely much larger, you can take four astronauts and thus one more than with "Apollo". And you have more space inside. I was allowed to sit in an "Orion" model in Houston. It still felt very small to me personally, but it's comfortable for a spaceship. The "Orion" spaceship also has more engines and solar cells on board. In "Apollo" the electricity was generated with fuel cells. And compared to "Apollo", "Orion" is much more advanced in terms of computer technology. There is a very complex software that can relieve the astronauts of many tasks. "Orion" is also designed for longer missions.
Now aside from the technical: Why do you think it is important to fly to the moon?
First of all, it is a very important contribution for Europe. Because "Artemis" is a huge space mission, similar to "Apollo" back then, but the European space industry is very powerful today and can take part in such a large and demanding program. This also opens up the possibility of European astronauts being allowed to fly to the gateway...
... the planned station in orbit around the moon. In later missions, astronauts from the "Orion" spacecraft are to change to a landing module in order to land on the moon from there.
And research on the moon is resumed. There are also ideas for using the moon economically, which is important to justify the huge investments. On the other hand, it is also about the fact that the moon could be a stepping stone to later fly from there to Mars. "Artemis" will also be important for inspiring younger generations. "Apollo" had also inspired many and possibly contributed to the fact that people later dealt with technologies at school and university.
You mentioned Mars - would you dream of working on a spaceship going there one day?
In fact, I previously worked on ExoMars, the European rover mission that is now being redefined following the discontinued cooperation with Russia. Taking humans to Mars is of course a whole other level. But if it should come to that, it would be a big challenge for me to contribute in any way.
Kai Stoppel spoke to Tobias Langener
