Recently in Paris there was a conference organized by the French Aerospace Academy. One of the speakers were Jean-Marc astorg, head of the CNES (national Centre for Space studies). He spent his entire career in the Directorate, working on the Vega, Ariane 5 ECA, Soyuz in French Guiana, and in 2015 was appointed Director of the boosters. He revealed a lot of technical details, shared their plans for the future and talked about the European response to American reusable launch vehicles. This article is a translated interview, supplemented by slides that he showed during his presentation.
“When I started working at CNES in 1985, immediately after graduating from engineering school multiple use had a very negative image. Mainly because of the American space Shuttle, which completely failed to achieve their original goals. The original anticipated cost was $ 30 million for the launch and a rate of one launch per week, in the end, it was worth about $ 1 billion for the launch on 6 launches per year. Thus, we Europeans built the Ariane starting from a bad experience Shuttle. Today, Ariane 6 is the first European response to the revived American rocket reusable.
Before we get into the details, let me remind you quickly about the economic realities. In the period from 2017 to 2018, NASA’s budget increased, and this increase amounted to the entire annual budget of CNES. With regard to global launches, it is a set of launched satellites per year, but only about 25 are open to global commercial competition. Most commercial launches are designed for geostationary communications satellites, but we don’t know if the market will stay the same.
A bit of history about the European launch systems: Ariane 1 was an unexpected commercial success due to the failure of the space Shuttle. He was commissioned at exactly the right time. Due to the evolution of Ariane 4, we achieved maximum performance for the concept of Ariane 1, so we have developed Ariane 5. For 20 years she was the leading commercial PH in the world. One of our advantages was the location of our launch pad, Kourou, in French Guiana.
We got a decent market share given the relatively small funding in Europe. Currently in the United States have the political will to return to the commercial market: they agreed to be thrown Arian. There is also the development of PH worldwide, from public and commercial parties due to the anticipated increase in the market. For PH it is important to be as cheap as possible. Currently, prices are around 10,000 euros per kilogram in geostationary orbit (GTO). Please note that most of the PH in the formulation are disposable, so Ariane 6 is not an anomaly in this regard.
To give a brief overview of the global efforts in development of new features, just remember that the Chinese have a space program, on all fronts, launchers and satellites, which makes us yellow envy. They announced that they were also developing reusable PH: Great March 8 to launch in 2028.
In the US, we should not oppose public and private space endeavor, SpaceX is largely a creation of NASA, with technical and financial assistance.
In Europe, the main reason for the existence of the space program and the possibility of runs is independent access to space. We saw it the same day when we wanted to launch our first communications satellite, Symphonie, American PH. They agreed to run, but only on the condition that the satellite will not be used for commercial purposes. This shows that we need to be confident in themselves and in their capabilities. However, in Europe the institutional market is small: no more than 4-5 launches per year. So we need to share in the commercial market to make a viable industrial ecosystem.
We expect the resumption of competition in the United States. The original Ariane 6 was proposed in 2009, when we realized that the Falcon 9 SpaceX was a good PH with high performance at low cost. Therefore, the main objective of Ariane 6 is to reduce costs. However, the decision on financing the programme was only adopted in 2014, which is very late. Low speed of decision making in Europe is a serious problem.
Ariane 6 is a one — time rocket that is very similar to Ariane 5, but we reduce its cost by 50% due to three things: increased frequency of launches, as it will replace the Soyuz launched from French Guiana, innovation (for example, instead of two 3-unit metal solid-fuel boosters, we will use 4 cased solid propellant booster) and an advanced production process with the implementation of lean management (lean management), for example. The goal is a value of 10 000 euros per kilo to GTO in 2020. Here are a few technological challenges, but a lot organizational.
Reuse — old and obvious idea: for the manufacture of PH requires 3 years (due to the long manufacture of the engines), it’s worth over 100 million euros, we are launching her, and in less than 30 minutes later she was sinking into the sea. However, there are various ways of implementing reusable: the Falcon 9 is fundamentally different from the Space Shuttle in this aspect. Only the first step, the most simple to reuse. It is separated at the speed of 2 kilometers per second, and its cost is 50% of the cost of the entire rocket. It’s a big difference compared to the Shuttle. Falcon 9 has reasonable technical goals that it can achieve step by step. The Shuttle had too much ambition in 1970.
There are several strategies for re-use. Since the objective is to minimize the impact on the step, landing by parachute in the ocean is not an option: salt water makes complicates the repair. For example, for the Falcon 9 SpaceX use the return loop of the trajectory engine forward with several braking pulses. We worked with the national aerospace laboratory of France, and realized that it was quite difficult.
A key aspect is that this approach allows you to experiment with landing: after the second stage separated, the first stage may try to change the trajectory and speed of movement without affecting the main mission and without major changes in the design of the first stage. In solutions that use the winged return, on the contrary, we consider the wings should be installed on the stage during the entire flight of the first stage that could interfere with the mission. Thus, the method SpaceX is working that allows you to experiment with a one-time launches, when you add a minimum of components of the rocket. So this is the least expensive and most fun option.
Repeated use has pros and cons. The disadvantages is the reduction of the useful load, up to 50% off if you use part of the fuel for return to the launch pad, an increased risk on the return stage to the launch pad in French Guiana — which is located near the town of Kourou, and the problem of accessibility of the landing site in the ocean. To land on the barge, the weather conditions must be suitable within a radius of 400 km and when the weather is bad launch may not take place.
The pros is the ability to have a higher frequency of starts and have more flexibility when planning paid of starts, as we don’t have to wait long to start. In addition, re-use saves money if repair costs are low. This is a key factor in the whole formula of mnogorazovogo. For example, in Falcon 9 Block V engine Merlin have been cases of cracks in the turbopump, which means it had to be replaced and to limit the run without major repairs to two usages.
The problem with reusable is that if you no longer need to create first stage, then you close its production line. However, if at some point you need to build the stage you need to re-open and develop the production, which will require huge amounts of money. Therefore, it is important to use the same engine for first and second stages so that production is not stopped.
What could be the strategy of Europe reusable? First, we will not only do reusable launches. Mission in geostationary orbit and a mission to other space bodies would be disposable. For the mission in earth orbit, we will use the trajectory back to the starting place. This would allow us to do repeated launches first stages and maintain production while decreasing costs by 30%. Such partial, reasonable re-use is available. However, this requires a lot of development because we need to learn many complex physical phenomena. Nevertheless, it is interesting, even in today’s reality. If the market is expanding, and it even becomes necessary.
Among the events that needs to be done, — modulation of engine thrust. This can cause problems with combustion instability, and we have not studied it in detail, because it wasn’t necessary. Therefore, in the short term Ariane 6 is the only solution to reduce costs and the cost of launches. In the long term reusable use and other technologies such as 3D printing will further reduce them. 3D printing can revolutionize the manufacturing of combustion chambers, which currently takes a very long time.
We aim to implement a phased pilot approach. We need to check how it works. As for engines, we currently use Vulcain, which is the hydrogen engine based on the old design. We develop the methane-oxygen engine Prometheus, whose goal is to reduce the cost. This does not mean that we abandon hydrogen industrial base, we’ll see. The advantage of methane is that it is in the middle between hydrogen and kerosene. Since it is much easier to handle than hydrogen, having a better specific impulse than kerosene, so the engine can be cheaper. It is also denser than hydrogen, making the tanks smaller and cheaper. We are building two prototypes for fire tests by 2021.
Prometey can be used in the new architecture, which we call Ariane Next. It will have 7 of these engines on the first stage and 1 second stage and can be used in
disposable or reusable version that allows you to easily experiment with reusability. The aim is to study for tests that are not the strength of the European aerospace industry.
Prior to implementation, Ariane Next, we have from the previous stages, first with Callisto. For this demonstrator of a reusable first stage we don’t have a reusable engine in Europe, so we cooperate with the Japanese. After, we will move to a larger demonstrator Themis engines Prometheus. The concept is still in the phase of definition.
Ultimately, we will need to make a choice between evolution and the new Ariane 6 launch vehicle, which will be ready in 2028-2030.
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