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GEOSPACE
ELECTRODYNAMIC CONNECTIONS (GEC) MISSION
Due to recent budget cuts impacting the Solar Terrestrial
Probes Program, the Geospace Electrodynamic Connections (GEC)
mission is moved ouside the near-term (5-year) the budget
planning window. Status updates associated with recent Roadmap
activities currently underway will be depicted on this website.
However, beyond roadmap activity updates, minimal updates
are planned for GEC.
HISTORY
The mission, originally known as the Geospace ElectroDynamics (GED)
mission, was cited in 1997 as a desired mission in NASA’s Sun-Earth
Connection Roadmap. The broad, mission requirements were then defined
by the Geospace Multiprobes Science Definition Team and a preliminary
spacecraft feasibility study was performed by Orbital Sciences
Corporation. A Community Science Workshop in 1998 at GSFC further
discussed the best science objectives and mission scenarios for the mission. A
Science and Technology Team (STDT) was selected in 1998 that, in conjunction
with spacecraft studies by the Integrated Mission Design Center at GSFC,
produced the science definition document in 2001 for the Geospace Electrodynamics
Connections (GEC) mission. It recommended a four spacecraft mission.
Comprehensive industry studies were subsequently undertaken in 2002 and
2003 to suggest mission designs and to estimate costs for different
mission conceptions. These studies showed that a three spacecraft mission
seemed most feasible given the cost constraints and science objectives.
In 2004 the GEC Science Definition Team provided an updated overview
of the mission with a prioritization of science goals. On the basis of
all the previous studies we now have substantial enough understanding
of the mission and engineering requirements to allow the immediate writing
on an Announcement of Opportunity for the instruments should continuation
funding be made available.
GEC Science & Technology Definition Team,
+ Download | PDF | 4 Pages | 11KB
Report of the NASA Science and Technology Definition Team for GEC Mission,
+
Download | PDF | 43 Pages | 2.0MB
GEC – A Mission to the Threshold of Space: Updated overview of the
report of the NASA Science and Technology Definition Team (STDT) for the
Geospace Electrodynamic Connections Misison. May 2004
+ Download | PDF | 15 Pages | 492KB
Photo
Above: Several spacecraft in a pearls-on-a-string, 84
degree inclination configuration that can independently
change orbits and dip to low altitudes - from baseline
2000X200 km orbits down to ~130 km.
GEC
MISSION OVERVIEW
The transition region between the magnetosphere and dense
atmosphere, i.e., the ionosphere-thermosphere (IT), is a
critical sink for energy and momentum emanating from both
below and above. It is the regime in which the magnetosphere
dissipates energy (most evident in the presence of aurora)
and momentum (evident in the production of ionospheric and
atmospheric dynamics) and where there is a continual tug
of war between magnetosphere-driven and lower atmosphere
neutral wind-driven dynamics. The IT region plays an essential
role as the electrical conductivity channel that horizontally
closes the magnetic field-aligned magnetosphere electric
current loops. It is a time varying and spatially complex
medium. To understand these processes, in situ measurements
of all relevant IT physical parameters must be made down
to altitudes where atmosphere control becomes preeminent.
A single dipping spacecraft to probe this inner boundary
region of the geospace environment is not capable of separating
a spatial disturbance from a temporal one. Ground-based
remote sensing techniques such as Incoherent Scatter Radars
can examine some of these processes, but there are key parameters,
space/time scales, and locations in space that can only be
measured from in situ satellite platforms. The Geospace
Electrodynamic Connections (GEC) mission, consisting of several
satellites in a pearls-on-a-string orbital constellation,
combined with ground-based observations will make the systematic
multipoint observations required to delineate and bring to
closure our understanding of key roles the IT plays in the
Sun-Earth connection.
Varied
Spatial and Temporal Scales |
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Energetic Inputs |
Current Systems |
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IT Coupling |
Thermospheric Waves |
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