Scientists on DW

"People probably don't realise that habitable zones don't necessarily need to be close to a star - in our case, close to the Sun," explained Prof. Michele Dougherty, a Juice science team member from Imperial College London, UK.

"There are four conditions required for life to form. You need water; you need an energy source - so the ice can become liquid; you need the right chemistry - nitrogen, carbon, hydrogen; and the fourth thing you need is stability - a length of time that allows life to form.

"The great thing about the icy moons in the Jupiter system is that we think those four conditions might exist there; and Juice will tell us if that is the case," she told BBC News.

Jupiter as gas giant archetype: Progress on the Europa-Jupiter System Mission

Participants from around the world came to the European Space Research and Technology Centre (ESTEC) in Noordwijk aan Zee, The Netherlands, from 17-19 May 2010 to discuss the research potential of the Europa-Jupiter System Mission (EJSM). EJSM has been designed to study the emergence of habitable worlds around gas giants using Jupiter as an archetype. Its baseline form consists of two primary flight elements: the Jupiter Europa Orbiter (JEO), led by NASA, and the Jupiter Ganymede Orbiter (JGO), led by ESA.

JEO: image from NASA

The meeting opened with an overview of the objectives of EJSM. The development status of each of the spacecraft, JGO and JEO, was presented in detail, with emphasis on the planned trajectories. Senior scientists outlined strategies for addressing critical questions about the oceans and internal structure of the Galilean moons, their geology, composition and space environment. What are the depths and extent of the liquid water oceans on Europa, Ganymede and Callisto? What processes occurred during their evolution to produce such large differences in the internal and surface structures of the four moons? To what extent do exchange processes between the Jovian magnetosphere and the moons’ exospheres influence their atmospheres and surfaces?

JGO: image from NASA

Stimulating discussions followed each session. The potential for complementary and synergistic observations proved to be a recurring theme and strengthened the reasoning behind a two-spacecraft mission. Exciting examples included simultaneous remote/in situ scenarios such as one spacecraft performing remote sensing measurements of volcanic activity on Io while the other is in the torus making in-situ measurements of the plasma response. Simultaneous in situ scenarios could yield interesting results. For instance, while JGO is in orbit around Ganymede, JEO will make multiple flybys of the moon, permitting synchronous observation of activity in Ganymede’s intrinsic magnetic field (JGO) and its interaction with Jupiter’s surrounding magnetic field (JEO). Complementary ground measurements, spacecraft-to-ground and spacecraft-to-spacecraft occultations also provide opportunities to investigate phenomena such as atmospheric activity at Jupiter and Europa and particle size populations in Jupiter’s rings.

Subsequent short talks covered diverse topics ranging from the space plasma environment into the deep interiors of the moon and from fast processes such as auroral dynamics to those occurring on a geological time scale, such as space weathering of impact craters. The poster sessions focused on instrument design and justification for EJSM. Measurement ranging capabilities and technical design aspects, particularly radiation tolerances, were prime considerations.

JMO: image from JAXA

Potential companion Japanese and Russian missions, the Jupiter Magnetospheric Orbiter (JMO) and the Europa Lander, also present prospects for multipoint measurements and synergistic science. If JMO enters the Jovian system in 2028, JEO and JGO will be localized around their respective moons. With its plasma imaging package and high inclination orbits, JMO provides an excellent platform to observe the environment in which the moons are embedded. The Russian Europa Lander mission, a spacecraft comprised of an orbiter and a lander with shallow sub-surface access capabilities, will search for signatures of life in Europa’s crust. It will investigate Europa during JEO’s orbital tour and help establish the geophysics and chemistry of the surface and exosphere.

The meeting demonstrated the viability of the necessary technology for EJSM, the strength of the science case and the commitment of the international community to supporting it.

EJSM Science Meeting attendees, 18 May 2010

cross-posted to personal journal nanila