Background:
With the upcoming launch of MMS (March 2015) the Heliophysics community has
the unique opportunity to coordinate the THEMIS and MMS orbits to perform
simultaneous measurements at/near apogee from opposite sides of the Earth
and integrate other current and upcoming missions (ERG, Geotail, Cluster,
GOES, ...) into a global observatory. This is at the heart of the
Heliophysics Decadal Survey recommendation to implement a "Heliophysics
System Observatory" (HSO). The scientific objectives that can be addressed
are unparalleled, since kinetic measurements can (for the first time) be
placed in the global context of drivers and effects in an organized and
pre-planned fashion. Ground based assets are key to the success of the
field. The THEMIS-MMS coordination plan aims to position the spacecraft at
apogee at ~6:00UT when MMS is at the dayside and THEMIS is at pre-midnight
(23 Local time) such that ground based assets in the American sector will be
optimally observing the polar cap and the nightside oval (this occurs during
fall/winter seasons in the next several years), while Svalbard, other
imagers and radars at the cusp and polar cap will be also well positioned
near noon. In the summers (when THEMIS is at the dayside magnetopause and
MMS at the nightside) the optimal time is ~15:30UT as the South Pole and
nearby Antarctic stations will be observing the cusp and while southern
radars and other assets will be observing the nightside.
One, but not the only, motivation for doing this is to understand the global
connections of magnetic reconnection: the drivers, effects and coupling of
dayside and nightside reconnection. This flow of energy has manifestations
across the entire magnetosphere, including the inner magnetosphere, where
Van Allen Probes is now, to be joined soon by the Japanese ERG mission.
Cluster's high latitude and Geotail equatorial measurements provide
additional reference points on the global system responses. A number of
ground based assets already exist and new ones are being currently deployed
by several nations.
The questions to be discussed during this meeting can be summarized as:
1) What are the critical, unique science questions that can be addressed by
an HSO coordination?
2) What are the operational modes for ground/space assets that will enable
breakthrough science?
3) What type of coordination is needed to ensure those optimal modes can
happen?
If you would like more information regarding the current proposal for using
THEMIS fuel resources (and low-impact orbit tweaks to MMS) to enable this
coordination, please see: ftp://apollo.ssl.berkeley.edu/pub/vassilis/HSO
THEMIS orbit elements exist at http://sscweb.gsfc.nasa.gov/ (you can use 4D
viewer, or tipsod to view orbits and ground projections). These represent
one science goal (day-night link of regional flows related to reconnection
impulses) but are by no means the only one.
If you are interested in coordinating ground or space observations during
this exciting period ahead, please join us with your ideas on how to extract
the most science out of our field's hardware. Feel free to ask questions by
email in the interim.
Best regards,
Vassilis Angelopoulos (THEMIS PI) and
Thomas E. Moore (MMS Sr. Project Scientist
