| Which will be the future launcher systems for | | | | semi-reusable rockets with so called Liquid |
| Europe? To answer this question ESA started | | | | Fly-Back Boosters (LFBBs) or Reusable First |
| in 2004 the Future Launcher Preparatory | | | | Stage (RFS). As the Russians explore the |
| Program (or FLPP). But let us first look at | | | | capabilities of Fly-Back Boosters since |
| the current situation. | | | | several years, a cooperation between Europe |
| | | | and Russia is considered from the start on. |
| Currently ESA has access to space through the | | | | |
| Ariane-5 launcher, operated by its commercial | | | | As these designs, mainly the Fly-Back |
| offset Arianespace. Developed as a cheaper | | | | Boosters, are somewhat conventional, the cost |
| and more powerful successor of the very | | | | reduction is not for sure. In contrast, the |
| successful launcher family Ariane-4, the | | | | more complex reusable technology is still a |
| Ariane-5 is available in three models. The | | | | major barrier. That’s why ESA will also |
| generic version GS, the heavy-lift model ECA | | | | investigate and test technologies to reduce |
| and a modified vehicle for transporting the | | | | this complexity. For example there are |
| ISS supply craft ATV, called Ariane-5 ES-ATV. | | | | already structures in evaluation and testing |
| | | | with embedded fiber-optic health monitoring |
| Through the alliance, called Starsem, of | | | | systems. |
| Arianespace, EADS, and Russian partners, ESA | | | | |
| can and does also use the Soyuz launchers, | | | | The most advanced concepts are certainly |
| especially for interplanetary probes. | | | | fully reusable Two Stage to Orbit (TSTO) |
| Currently, the Kourou spaceport gets an | | | | concepts. Especially for this kind of |
| additional launch pad for the Soyuz rocket, | | | | launchers, as also for a Reusable First Stage |
| so in future it will possible to launch the | | | | for a semi-reusable concept, investigation in |
| Soyuz from the equator-near Kourou with an | | | | high performance reusable engines are seen as |
| increased payload. | | | | a key objective. |
| | | | |
| For smaller payloads ESA develops the Vega | | | | Up to today, only the Space Shuttle and the |
| launcher, consisting of three solid | | | | Energia/Buran spacecrafts used reusable |
| propellant stages and one liquid propellant | | | | engines. Both are seen as robust but also as |
| stage. The solid rocket engines are based on | | | | technically demanding and relatively |
| the Ariane-5 booster engines. It is planned | | | | expensive. |
| to first-launch the Vega in 2008. | | | | |
| | | | If SpaceX with its Merlin engine, which also |
| Recently ESA announced a cooperation with the | | | | should be reusable, can achieve a successful |
| Russian Space Agency to build a new | | | | complexity and cost reduction, time will |
| spacecraft together. As this craft needs a | | | | still have to tell. An analysis of the |
| new launcher or at least a modified launcher, | | | | possible cost reductions is underway at the |
| ESA could also use that launcher for future | | | | Space Fellowship Forum. The potential cost |
| payloads. The rockets currently in | | | | reduction is surely the highest but the |
| consideration are a modified Soyuz launcher, | | | | development costs will also be the highest. |
| called Soyuz-3, a further improved Ariane, or | | | | |
| another launcher currently in development, | | | | Another key objective would be the |
| the Angara-3. | | | | development (and maturing) of light-weight |
| | | | reusable stage structures with cryogenic |
| These launchers will give Europe space access | | | | propellant tanks. Also the second stage would |
| for the next several years. As the private | | | | need a reentry system, which would add |
| launcher business is yet unclear, Europe will | | | | structural mass. Additionally reentry systems |
| need a new launcher family around 2015 to | | | | showed to be complex and very labor-intensive |
| 2020. | | | | for reuse. |
| | | | |
| The FLPP calls for a future launcher to be | | | | Structural mass and additional operational |
| operational around 2020. Currently the first | | | | costs for inspection and re-qualification of |
| studies are conducted. Now we will take a | | | | the system after a launch are the main |
| look at the potential launchers, reusable and | | | | difficulties to handle with reusable systems, |
| expendable both. | | | | as compared to an expendable vehicle. |
| | | | |
| One important condition for the whole program | | | | As the reusability adds structural mass, e.g. |
| is the use of matured technologies and | | | | increasing the structural and engine |
| concepts. Designs like Single Stage to Orbit | | | | robustness for withstanding several launches |
| (SSTO) vehicles or air-breathing propulsion | | | | or adding health monitoring systems, |
| systems like scramjets are not considered | | | | it’s necessary to focus on materials |
| because they are not yet proven and | | | | and systems science. Inspection and |
| sufficiently developed. | | | | particularly re-qualification of the hardware |
| | | | is an expensive area as this work is very |
| The most conservative concepts are expendable | | | | labor-intensive. |
| launchers. Aside from a payload increase, | | | | |
| they would incorporate better and especially | | | | Also new procedures are necessary to be |
| cheaper manufacturing and components like low | | | | developed. How much of damage to a certain |
| cost engines. But as the launchers would be | | | | part is tolerable before it will be necessary |
| rather conventional, the launch costs would | | | | to replace it? In aviation we have this |
| be not very different from today’s. | | | | expertise today, we can predict for example |
| | | | how a small crack will develop and when |
| If that would be (on the background of a | | | | it’s necessary to replace or repair it. |
| potential emerging private rocket market) | | | | In the aerospace sector we nearly have no |
| enough to compete with others, that is likely | | | | such experience yet. |
| to be a question. The advantages clearly | | | | |
| would be no dependancies on new breakthrough | | | | The clear advantage if all these challenges |
| technologies and a manageable budget. | | | | are mastered is a low-cost high-performance |
| | | | launcher system which will strengthen |
| On the other side, reusable concepts are | | | | Europe’s future role in spaceflight. |
| investigated. The first idea are | | | | |