Goals of the workshop
After successful missions to Titan, Mars, and Venus, the European Space Agency (ESA) has plans to embark on another planetary mission. Following ESAís Cosmic Vision call for plans for space missions to be launched in the 2015-2020 timeframe, planetary scientists in Europe and elsewhere collaborated on writing several mission proposals. In close collaboration with NASA, ESA selected from these proposals two large missions that it thought to be interesting: one to Jupiter and two of the Galilean moons, and the other to Saturn and its largest moon, Titan. In the spring of 2009, ESA and NASA announced that the Jupiter mission, now called the Europa-Jupiter-System-Mission (EJSM), had their priority, and that the Saturn mission, the Titan-Saturn-System-Mission (TSSM), might be launched later.
In this workshop, we brought together scientists from both missions to identify and discuss the missionsí science cases and instruments. The focus of the workshop was EJSM, because this mission has been prioritized and will likely play a major role in planetary sciences for decades to come. Fostering collaborations between planetary scientists from the different missions (note that some scientists were involved in both msissions) is not only important for improving the scientific output of the mission, but it is also essential for the next phase of ESAís selection procedure: EJSM still has to be approved for launch.
Besides planetary scientists from several European countries, we also invited Dutch scientists that are currently working in the field of Earth Sciences, in order to stimulate their interest in the growing field of Planetary Sciences in the Netherlands and to improve the exchange of knowledge between the two fields. Furthermore, students that take courses on Planetary Sciences in the Netherlands were encouraged to attend the workshop, in order to increase their enthusiasm for the field by confronting them with outstanding scientific questions and with the several technical issues surrounding the development of planetary missions.†
Description of the missions to Jupiter and Saturn
The Europa-Jupiter-System-Mission will consist of two spacecraft that will each start their exploration of the Jovian system (after arriving around 2026) by orbiting the gas giant Jupiter for several months. Then, NASAís Jupiter-Europa Orbiter (JEO) will get into orbit around the moon Europa, while ESAís Jupiter-Ganymede orbiter (JGO) will start orbiting the moon Ganymede. The missionís science objectives for Jupiter itself are to study the composition, structure, chemistry, and dynamics of the planetary atmosphere, and the structure of the planetís huge magnetic field and associated intense radiation field. The scientific interest in Europa is mainly driven by the layer of water ice that completely covers this large moon. There are indications of an ocean of liquid water below this ice layer, and astrobiologists have argued that this ocean might harbor life. Ganymede, a moon that is larger than our own moon, is the only moon with a magnetosphere, which hints at the presence of subsurface liquid layers, and has striking surface features that could be caused by tectonic activity.
The Titan-Saturn-System-Mission would consist of a spacecraft to orbit Saturn, and a montgolfiere (a hot air balloon), that would float for months through the thick atmosphere of the moon Titan. The scientific objectives of the Saturn orbiter would be to study the atmospheric composition, structure, chemistry, and dynamics. From the instrumentation tethered to the balloon, the composition, structure, chemistry, and dynamics of Titanís atmosphere would be studied and they would offer the opportunity to observe and map the moonís surface, which is hidden from observers on Earth and in space by a thick, photochemical smog.††
Because of the broad scientific objectives of the Jupiter and Saturn missions, the workshop program covered various topics, spread over the week:
- A scientific overview of the Jupiter and Saturn-missions
- An overview of the instruments proposed for the missions
- The atmospheres of Jupiter, Saturn, and Titan
- The internal structures of Jupiterís moons Europa, Ganymede, Io, and Callisto
- Properties of planetary ices
- Astrobiological prospects of Europa
- Surface features of Jupiterís moons
The last day was spent on summarizing the results from the workshop, on discussing the open scientific issues for the Europa-Jupiter-System-Mission and the Titan-Saturn-System-Mission.
Few of the international participants had known about the Lorentz Center before the workshop. They as well as the other participants were very enthusiastic about the available facilities and the excellent assistance of the Lorentz Center staff. The atmosphere at the workshop was very relaxed and fruitful.
The organizers are very grateful to the Lorentz Center staff that supported the workshop, to the financial sponsors of the Lorentz Center, and to TNO, DutchSpace, NSO, and SRON Netherlands Institute for Space Studies for the additional financial support.
Wim van Westrenen (VU, Netherlands)
Gareth Davies (VU, Netherlands)
Tanja Zegers (University Utrecht, Netherlands, and ESA)
Bert Vermeersen (TU Delft, Netherlands)
Daphne Stam (SRON, Netherlands)