Cross-Scale

September 2006: Cross-Scale update

These notes, from Steve Schwartz, were emailed to the Cross-Scale community mailing list in September 2006.

Contents

• Meeting Summary
• Present Status
• Next Steps

Dear Colleagues,

For those of you who could not attend the Cross-Scale meeting two weeks ago, and for those of you who did attend, here is a very brief summary together with some organisational matters for the future.

Meeting Summary

The meeting was attended by approximately 70 scientists from around the globe. This is just under half the 170 of you who have registered as interested scientists on the mission web-site.

The meeting ran quite smoothly, with my thanks to local people from MSSL and Imperial who handled many of the local details and helped out on the day. Monday's presentations generally set the scene and enabled everyone
present to judge the present state of mission concept and definition. The poster session/ice breaker saw numerous groups discussing instrumentation, practicalities, and politics. One aspect which everyone seemed to understand would play a vital role was that the available financial budget, likely mass budget, and other constraints demanded a clear targetted approach to the mission instrumentation and operations.

Tuesday's Splinter Sessions divided into a session on Shocks (chaired by David Burgess), Reconnection (chaired by Iku Shinohara), Waves and Turbulence (chaired by Vlodya Krasnoselskikh), and Mission Practicalities (chaired by Matt Taylor). These were lively discussions which raised questions and ideas not present or emphasised in the present Science Priorities Document thanks to the enthusiastic participation of the audience.

All the presentations, including excellent summaries by the Splinter chairs, can be found on the mission web-site at: http://www.cross-scale.org/Documents.html#Sept2006

Present Status

Cosmic Vision
It seems likely that a call from ESA for Cosmic Vision mission proposals will not be issued until November at the earliest, and could be as late as sometime early next year. Nonetheless, when it does appear we shall need to be able to respond on a relatively short timescale. The ESA Technical Reference Study has already been helpful (see Marcel van den Berg's presentation) and I expect more useful details will emerge as the study matures. Of course, that TRS is not being conducted for us, but rather by ESA for its own information, so we should not expect it to provide us with definitive answers.

Cross-Scale Science Objectives
Interestingly, the meeting revealed that even within the Cross-Scale community the science priorities are not all clear to everyone; typically, people who work on shocks understand why Cross-Scale is needed to advance shock physics but perhaps not why it is needed for reconnection, etc. This points to the need to refine and strengthen the science arguments. I think here the actual proposal will need to have some specific examples, e.g., with present Cluster data, of what can and
cannot be studied without consideration of the coupling across scales. That is, if we were (as we are with Cluster and will do with MMS and Themis) to study each scale (electron, ion, fluid) on its own, why can we not just put those results together in some statistical/parametric sense to see the whole picture? What will the simultaneous measurements of Cross-Scale reveal in terms of the dynamic coupling amongst the scales? One or two killer detailed examples would be very helpful.

Mission Practicalities
Several aspects of the mission crystalised a bit in the light of better information on costs, orbit trade-offs, and science. Here are the main points:

Orbit: 1-4 Re x 25-30 Re seems to hit the science best and offers the most launch mass (the original 10x25 orbit has fallen out of favour).

Baseline Concept: incorporate a JAXA-supplied large mother ship plus daughter with 10 ESA-built spacecraft (all the same bus with 30 kg of payload; different payload on different spacecraft utilising a common interface wherever possible). 1 JAXA launch of mother + JAXA-daughter + 2 ESA; 1 ESA Soyuz launch of 8 ESA spacecraft. This depends of course on the nature of the ESA AO and on decisions within JAXA.

Instrumentation: Strong suggestion to equip mother and (some) fluid scale spacecraft with energetic particle instruments. Some ion composition will be needed, perhaps on more than one spacecraft. The sensitivity of particle detectors needs investigation to meet the conditions in the tail, solar wind, ... Three-D electric field measurements of DC field seems too difficult, but 3-D AC measurements with 10m tip-to-tip antennae may be feasible.

Next Steps

In anticipation of the ESA call for missions, we need to begin refining and completing the mission proposal. There are a lot of details that we'll need to flesh out for a real mission proposal, such as a real operations plan, various costs, instrument capabilities, etc. Some of these will be very challenging if we are to submit a believable proposal. The following have agreed to act as coordinators:

Steve Schwartz (s.schwartz@imperial.ac.uk) overall proposal

Steve Schwartz (s.schwartz@imperial.ac.uk) will also coordinate the science case and requirements for the study of collisionless shocks

Andris Vaivads (andris@irfu.se) will coordinate the science case and requirements for the study of magnetic reconnection

Alain Roux (alain.roux@cetp.ipsl.fr) will coordinate the science case and requirements for the study of turbulence

Philippe Louarn (philippe.louarn@cesr.fr) will coordinate some of the mission practicality information (orbit, instrumentation, ...)

Masaki Fujimoto (fujimoto@geo.titech.ac.jp) will coordinate the JAXA elements.

PLEASE provide us with your thoughts and inputs. Send them to the appropriate coordinator (see above) or directly to me if you prefer. We have a lot of work ahead of us, but I am optimistic that we can turn our dream into a reality. I look forward to your active participation in this venture.

Warm regards,
Steve