The SSDW 2006 renewed the international and interdisciplinary approach, being a Space Station Design Workshop at the Institute of Space Systems at the Universitaet Stuttgart between 23 and 29 July 2006. Although prepared and supported for the Stuttgart students by the "Astronautics and Space Station Design" lecture series, the original one week full-time workshop character was emphasized to foster and to improve the possibilites of international participants from various backgrounds.
Out of the 27 participating students and young professionals, about half came from Aerospace Engineering at the Universitaet Stuttgart, while the study fields of the rest included aerospace and mechanical engineering, cybernetics, mechatronics, information science and architecture. Students from the nine nations Australia, France, Germany, Greece, Iran, Italy, New Zealand and Russia, participated in the SSDW 2006, making it a truly international and multidisciplinary event.

In two competing teams the participants were tasked with the development of a "Geospace Exploration Vehicle" (GEV), a manned transfer vehicle capable of shuttling between Earth orbits, libration points in the Sun-Earth-Moon system and low lunar orbit. This partly reusable vehicle, as also envisaged in the IAA Cosmic Study "Next Steps in Exploring Deep Space", provides excellent opportunity for maintenance and servicing of the sophisticated telescope systems that will be placed in orbit around the Sun-Earth libration point 2 (SEL2) within the next years, but it also is a first step in a sustained infrastructure for human exploration of the Earth-Moon system and interplanetary space.
The background scenario was set in 2008: With the International Space Station nearing completion, a European-Russian lead project will install a Lunar Space Station (LSS) at the lunar libration point 1 (LL1) between 2015 and 2018. In an agreement between ESA and Roskosmos, the GEV transfer vehicle should demonstrate and validate the in-space infrastructure by being able to reach not only the LSS, but also destinations such as the Sun-Earth libration points. The GEV should be available at “LSS core complete” which is expected for year 2017.
In particular, the GEV concept should:

1. accommodate a permanent crew of 3 astronauts for servicing missions of satellites at the Sun-Earth libration points of duration of up to 50 days, or 6 astronauts (in “taxi” or rescue mode) for missions of up to 20 days duration;
2. support mission to the LSS stationed at the Earth-Moon libration point 1 and missions to low lunar orbit (LLO) to assist in lunar exploration projects;
3. return the astronauts back to Earth in a re-entry vehicle;
4. allow for repair, maintenance and other life extension actions of telescopes and infrastructures in trans-lunar space; and
5. support long-term preparations for mankind’s next steps in space, human expeditions to the Moon and Mars.

The students used a modified SSDW methodology, and SSDW tools like COMET, IRIS++ and ELISSA, to design and analyze their space systems.

Here is some data on the spacecraft concepts that the two design teams proposed. More detailed information on the results can be found in the final reports (contact SSDW staff).

Team Blue

System and Mission Concept:

• GEV is stationed in low Earth orbit (ISS orbit)

• Launch systems: Ariane 5 ECB+ (cargo, modules), Angara 5 (re-supply), Soyuz TMA (crew)
• Installed electrical power: 12 kW
• Key feature of the transfer concept is an aerobraking maneouvre for the GEV (without crew) at Earth return.
  • minimum altitude: 110 km
  • capture time: 95 days

Space Segment Description and Assembly Sequence:

The GEV of Team Blue is designed for multiple missions in the Earth-Moon system and consists of a reusable and a non-reusable section. The reusable parts are:

• Crew and Command Module (CCM)
• Service Module (SM)
• Maintenance and Repair Module (MRM)
• Docking Node System (DNS)

The non-reusable section comprises the three segments of the main propulsion system and vehicles for assembly, re-supply and crew transfer; namely:

• Automatic Transfer Vehicle Low Duty (ATV-LD) using storable propellants
• Large External Tank Module (LETM) and Automatic Transfer Vehicle Heavy Duty (ATV-HD) with cryogenic propellants
• Vehicles: ATV-L for assembly; Soyuz and Rescue Soyuz Vehicle (RSV) for crew

The following picture illustrates the GEV configuration and lists dimensions and masses of the modules:

ECLSS Design and Simulation:

Due to the relatively short manned mission phases there is no need for a highly sophisticated or bio-regenerative life support system. Team Blue therefore decided on a semi-closed atmosphere and water management, while food and solid waste are stored and discarded for the time needed. The system is designed to support three astronauts on a 80 day mission or up to six astronauts for 30 days. Major ECLSS components are:

• Atmosphere management: Electrochemical Depolarized Concentrator (EDC), Trace Contaminant Control System (TCCS), Heat Exchanger (CHX), Sabatier Reactor (SR), Static Feed Water Electrolyzer (SFWE)
• Water management: Vapor Compressed Distillation (VCD), Multifiltration (MF)
• Food management: 150 kg for 80 day mission
• Waste management: approx. 330 kg stored and discarded at Earth re-entry
• Radiation Protection: total mass of 770 kg in water and aluminum shielding against cosmic radiation and solar particle events

Additional biological systems such as an Algae processor were investigated and might be implemented at a later stage for technology testing for long-duration missions. They can provide various synergies and reduce re-supply masses in the long run, however, their use in short-term missions of up to 80 days is not necessary.

Team Green

System and Mission Concept:

• GEV is stationed at the LSS at lunar libration point 1 (LL1)
• Spacecraft is assembled in LEO and transferred to LL1 using ATV-HD and 2 ETMs (delta-V = 3900 m/s)
  • mass at LEO = 80 t
  • mass at LSS = 34 t
• GEV provides additional capacities for LSS (crew/experiment space, propulsion, EPS, TCS, ECLSS)

• Launch systems: Ariane 5 ECB+ (cargo, modules), Soyuz TMA (crew)
• Installed electrical power: 10 kW (BOL), 8 kW (EOL)
• Re-supply and crew transfer uses existing LSS vehicles:
  • Automatic Transfer Vehicle Heavy Duty (ATV-HD) with cryogenic propellant as booster stage
  • Soyuz-Crew Transfer Vehicle (CTV) for crew
  • ATV-derived Re-Supply Vehicle (RSV) for cargo and re-supply

Space Segment Description:

Team Green's GEV is comprised of 3 to 4 modules depending on its designated mission. The re-configuration is done at the LSS station and the three core modules of the GEV are reusable. These three core modules stationed at LSS are:

These three core modules stay at LSS and are completed by a crew vehicle (Soyuz-CTV) for manned missions. The whole assembly is shown in the introduction above.

Human Factors Analysis:

Consideration of the Habitability and Ergonomics for astronauts in spaceflight is essential, especially in long-term missions. Therefore, Team Green looked intensively into the zoning and interior design of the Habitation Module (HM) in order to increase productivity and habitability. An inflatable structure was investigated as well and could be used in later development stages, but was discarded for the first GEV concept. The current HM is a 8 m long cylinder with two access to the airlock and docking module and the rescue vehicle. It is divided in to three major zones:

• Zone A: private zone (3m). Close to the return vehicle it provides living quarters and radiation shelter for the crew.
• Zone B: common zone (3m). Including fitness training equipment, 2 windows, space for meals and common activities.
• Zone C: work zone (2m). Interface panels for flight commands and robotic operations.

Radiation protection is given through a 300l water tank shell around the private zone, complementing the normal aluminium and polyethylene skins of the module. The nominal 3 crew will be composed of a flight commander, a pilot and a flight engineer supported by ground center staff during missions. They have a 24 h day with sleep, work and other activities and a social structure including a chain of command was outlined within the mission study.

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