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