Monday, November 10, 2008

Thoughts on the Europa Jupiter System Mission

As noted in previous posts, OPAG has presented detailed mission summaries for both proposed outer planet flagship missions: the Europa Jupiter System Mission (EJSM) and the Titan Saturn System Mission (TSSM). NASA and ESA will select between the two missions early next year. NASA intends to fly its proposed contribution to the selected mission. ESA’s contribution will be in competition with other proposed large missions, and hence may not fly.

I’ll break my observations into three posts over approximately as many days. Tonight I’ll discuss the EJSM mission (to take the missions in the order in which they were presented).

I’ve now read the EJSM presentation twice, and my simply reaction is, “Wow!” The proposed two spacecraft mission (NASA’s Jupiter Europa Orbiter (JEO) and ESA’s Jupiter Ganymede Orbiter (JGO)) would provide the kind of revolution in our understanding of this system as the three Martian orbiters of the last decade have compared to the Viking orbiters. Both the last Jupiter mission, Galileo, and the Viking orbiters were 1970s technology and instrumentation. The capabilities brought by both the NASA and ESA craft are as advanced compared to Galileo (even if its antenna had worked) as the Mars Reconnaissance Orbiter compared to the Viking orbiters.

In evaluating this proposal, it is important to remember that the two craft explore 6 bodies:

Jupiter itself through extensive observations of the atmosphere from each craft,

Io (3 science flybys with JEO plus remote monitoring by JEO and JGO (if a narrow angle camera is added to the payload)),

Europa (9+ months of study from orbit),

Ganymede (6 JEO flybys plus 6+ months of study from orbiter by JGO)

Callisto (9 JEO flybys plus numerous flybys by JGO)

Jupiter’s magnetosphere

The proposed mission has three themes that transcend the simple exploration of yet another solar system body: Explore Europa and Ganymede as possible abodes of life and examples of “The emergence of habitable worlds around gas giants”; further our understanding of the dynamics of a gas giant (a type of planet that astronomers have found is common in many solar systems) through studies of the atmosphere and magnetosphere; explore the similarities and differences of the Jovian moons as an example of a mini-solar system.

The NASA and ESA craft are presented as a joint mission, as is intended by this proposed cooperative and highly complimentary mission. However, either craft by itself would represent a major mission in its own right that could be justified on its standalone contribution. Should Titan be chosen as the destination of the next flagship mission, the ESA mission is a good example of what a moderate cost (~$1B or somewhat more than NASA’s New Frontiers missions) Jovian mission could do. If Jupiter is the chosen destination but ESA decides not to fly its craft, then the JEO mission could be easily enhanced by extending the time spent doing flybys of Ganymede and Callisto prior to entering Europan orbit.

1 comment:

  1. I have to say that I'm extremely skeptical that the ESA COULD do a Ganymede Orbiter for only $1 billion. Don't forget that -- even if you ignore the not-insignificant radiation danger -- we're talking about a mission that considerably exceeds Cassini in complexity. Let me quote Tom Spilker again for his phone comment to me that the ESA has a terrible habit of grotesquely underestimating mission costs -- something that I think is also likely to bushwhack them if they try to build that Titan Montgolfiere balloon (which is far more complex than their proposed Titan Lake Lander).