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Solar and Space Physics: A Science for a Technological Society
104
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
and southern aurorae. Simultaneous two-point in situ measurements are closely coordinated with plasma
imaging from state-of-the-art instruments to uncover transport and electrodynamic connections at different
spatial scales throughout the magnetosphere-ionosphere-thermosphere system, enabling major new insights
into cross-scale dynamics and complexity in geospace.
MEDICI will examine how the magnetosphere-ionosphere-thermosphere system is coupled and
responds to solar and magnetospheric forcing. In particular, MEDICI would provide definitive, comprehensive answers to two overarching, fundamental science questions that have been outstanding for decades.
Each question contains a set of subtopics:
1. How are magnetospheric and ionospheric plasma transported and accelerated by solar wind forcing
and magnetosphere-ionosphere (MI) coupling?
a. How is the cross-scale, dynamic, three-dimensional plasma structure of the ring current, plasmasphere, and aurora reshaped by acceleration and transport?
b. What controls when and where ionospheric outflow occurs?
c. What are the cross-scale effects on the system?
2. How do magnetospheric and ionospheric plasma pressure and currents drive cross-scale electric
and magnetic fields, and how do these fields in turn govern the plasma dynamics?
a. What are the cross-scale, interhemispheric structure and timing of currents and fields that mediate MI coupling?
b. How do these MI coupling electromagnetic fields feed back into the system to affect the plasmas
that generated them?
Each of these two main questions and five subquestions focuses on a crucial aspect of the coupled
dynamics of geospace. The first question set looks at plasma transport, and the second question set targets
the electrodynamics of MI coupling. Previous missions such as IMAGE or TWINS have provided substantial steps toward addressing these problems; however, only MEDICI’s comprehensive instrumentation will
supply the necessary complete set of measurements to answer these questions.
MEDICI Mission Concept
MEDICI is a cross-scale science mission concept that uses both high-resolution stereo imaging and
multipoint in situ measurements. It also incorporates an array of contemporaneously existing groundbased and orbiting observatories. MEDICI employs two spacecraft that share a high circular orbit (see
Figure 4.9), each hosting multispectral imagers, magnetometers, and particle instruments. Building on
knowledge obtained from TWINS, the MEDICI science payload captures the dynamics of the ring current,
plasmasphere, aurora, and ionospheric-thermospheric plasma redistribution through a comprehensive set
of measurements. In combination with ground-based and low-Earth-orbit data that yield detailed information on field-aligned currents, ionospheric electron densities, temperatures, and flows, MEDICI’s imagers
and onboard in situ instruments will provide the means to link the global-scale magnetospheric state with
detailed ionospheric conditions, and will yield data for global-model validation. The MEDICI instrumentation is summarized in Table 4.5.
The MEDICI mission uses two nadir-viewing spacecraft, each with an identical spacecraft bus, in a
shared 8-R E circular polar orbit with adjustable orbital phase separation (between 60° and 180° separation
along track) to enable global stereo, multispectral imaging, and simultaneous in situ observations. Circular
orbits that avoid the most intense radiation environments provide continuous imaging and in situ measurements and enable a long-duration (up to 10 years) lifetime well beyond the required 2-year mission.
Solar and Space Physics: A Science for a Technological Society
104
SOLAR AND SPACE PHYSICS: A SCIENCE FOR A TECHNOLOGICAL SOCIETY
and southern aurorae. Simultaneous two-point in situ measurements are closely coordinated with plasma
imaging from state-of-the-art instruments to uncover transport and electrodynamic connections at different
spatial scales throughout the magnetosphere-ionosphere-thermosphere system, enabling major new insights
into cross-scale dynamics and complexity in geospace.
MEDICI will examine how the magnetosphere-ionosphere-thermosphere system is coupled and
responds to solar and magnetospheric forcing. In particular, MEDICI would provide definitive, comprehensive answers to two overarching, fundamental science questions that have been outstanding for decades.
Each question contains a set of subtopics:
1. How are magnetospheric and ionospheric plasma transported and accelerated by solar wind forcing
and magnetosphere-ionosphere (MI) coupling?
a. How is the cross-scale, dynamic, three-dimensional plasma structure of the ring current, plasmasphere, and aurora reshaped by acceleration and transport?
b. What controls when and where ionospheric outflow occurs?
c. What are the cross-scale effects on the system?
2. How do magnetospheric and ionospheric plasma pressure and currents drive cross-scale electric
and magnetic fields, and how do these fields in turn govern the plasma dynamics?
a. What are the cross-scale, interhemispheric structure and timing of currents and fields that mediate MI coupling?
b. How do these MI coupling electromagnetic fields feed back into the system to affect the plasmas
that generated them?
Each of these two main questions and five subquestions focuses on a crucial aspect of the coupled
dynamics of geospace. The first question set looks at plasma transport, and the second question set targets
the electrodynamics of MI coupling. Previous missions such as IMAGE or TWINS have provided substantial steps toward addressing these problems; however, only MEDICI’s comprehensive instrumentation will
supply the necessary complete set of measurements to answer these questions.
MEDICI Mission Concept
MEDICI is a cross-scale science mission concept that uses both high-resolution stereo imaging and
multipoint in situ measurements. It also incorporates an array of contemporaneously existing groundbased and orbiting observatories. MEDICI employs two spacecraft that share a high circular orbit (see
Figure 4.9), each hosting multispectral imagers, magnetometers, and particle instruments. Building on
knowledge obtained from TWINS, the MEDICI science payload captures the dynamics of the ring current,
plasmasphere, aurora, and ionospheric-thermospheric plasma redistribution through a comprehensive set
of measurements. In combination with ground-based and low-Earth-orbit data that yield detailed information on field-aligned currents, ionospheric electron densities, temperatures, and flows, MEDICI’s imagers
and onboard in situ instruments will provide the means to link the global-scale magnetospheric state with
detailed ionospheric conditions, and will yield data for global-model validation. The MEDICI instrumentation is summarized in Table 4.5.
The MEDICI mission uses two nadir-viewing spacecraft, each with an identical spacecraft bus, in a
shared 8-R E circular polar orbit with adjustable orbital phase separation (between 60° and 180° separation
along track) to enable global stereo, multispectral imaging, and simultaneous in situ observations. Circular
orbits that avoid the most intense radiation environments provide continuous imaging and in situ measurements and enable a long-duration (up to 10 years) lifetime well beyond the required 2-year mission.