Copyright © National Academy of Sciences. All rights reserved.
Solar and Space Physics: A Science for a Technological Society
REPORT OF THE PANEL ON SOLAR WIND-MAGNETOSPHERE INTERACTIONS
245
energization, losses, and plasma sources and resolving cross-scale currents, fields, and flows that bind the
system together.
The second goal is to image and measure the ionosphere-thermosphere system using multiple wavelengths of far ultraviolet (FUV): LBH long and short cameras, and spectrographic imaging (SI) at 121.6 nm
and 135.6 nm. FUV imaging provides estimates of multiple geophysical quantities: precipitating particle
flux, ionospheric electron density and conductivity, and thermospheric O/N 2 ratio. Dynamical features in
the ionosphere (e.g., polar cap ionization patches, positive and negative storm effects, neutral atmospheric
responses to auroral heating, ionospheric scintillations and plasma bubbles) are tracked with global imaging
at 5- to 10-km resolution. Variable phasing of the two circular-orbiting spacecraft provides simultaneous
conjugate views of both northern and southern auroral emissions, uncovering the little-understood role of
inter-hemispheric asymmetry on the global system behavior.
The third goal is to measure, in situ, the critical near-Earth plasmas and magnetic field in the cusp
and near-Earth plasma sheet plasma. Onboard each of the two MEDICI spacecraft, plasma composition,
electron plasma conditions, and magnetic field measurements characterize the plasma conditions, field
distortions, and storm/substorm activity, and in combination with imaging allow researchers to follow the
flow of ionospheric plasma and energy between the ionosphere and magnetosphere.
Complementing and augmenting the high-altitude observations, MEDICI includes funded participation
for significant low-altitude components: measurements from a large range of resources, including DMSP or
its follow-on Defense Weather Satellite System, IRIDIUM/AMPERE current maps, radar arrays from high to
mid latitudes (SuperDARN, Millstone Hill, AMISR), GPS TEC maps, and magnetometer and ground-based
auroral all-sky camera arrays. The result will be global specification of the ionospheric electric field and
electric current patterns in both hemispheres, essentially completing the electrodynamic picture at low
altitude. In principle, MEDICI measurements tackle a broader comparative planetary question, namely, the
extent to which magnetospheres can act as shields against atmosphere erosion by the solar wind: Does
ion outflow escape or remain in the magnetosphere to be recycled?
Contributions to the Heliophysics Systems Observatory. MEDICI will both benefit from and enhance the
science return from almost any geospace mission that flies contemporaneously, such as upstream solar
wind monitors, geostationary satellites, and low Earth orbit missions. In particular, by providing global
context and quantitative estimates for magnetospheric-ionospheric plasma and energy exchange, MEDICI
has significant value for missions investigating ionospheric conditions, outflow of ionospheric plasma
into the magnetosphere, energy input from the magnetosphere into the ionosphere, and AIM coupling in
general. Thus it will add value to a host of possible ionospheric strategic missions, Explorers, and rocket
and balloon campaigns. A mission providing continuous imaging and in situ observations from two separate platforms also plays an important role in providing to geospace predictive models the indispensable
validating observations of system-level interactions and processes. The likely long duration of the MEDICI
mission will allow it to provide a transformative framework into which additional future science missions
can naturally fit.
Table 9.2 summarizes MEDICI’s expected level of contribution to the SWMI science goals. In recognition of the need for crucial new observations to enable the accomplishment of these science objectives,
the panel identified the following SWMI imperative:
SWMI Imperative: Initiate the development of a strategic mission, like MEDICI, to determine how the
magnetosphere-ionosphere-thermosphere system is coupled and responds to solar and magnetospheric
forcing.
Solar and Space Physics: A Science for a Technological Society
REPORT OF THE PANEL ON SOLAR WIND-MAGNETOSPHERE INTERACTIONS
245
energization, losses, and plasma sources and resolving cross-scale currents, fields, and flows that bind the
system together.
The second goal is to image and measure the ionosphere-thermosphere system using multiple wavelengths of far ultraviolet (FUV): LBH long and short cameras, and spectrographic imaging (SI) at 121.6 nm
and 135.6 nm. FUV imaging provides estimates of multiple geophysical quantities: precipitating particle
flux, ionospheric electron density and conductivity, and thermospheric O/N 2 ratio. Dynamical features in
the ionosphere (e.g., polar cap ionization patches, positive and negative storm effects, neutral atmospheric
responses to auroral heating, ionospheric scintillations and plasma bubbles) are tracked with global imaging
at 5- to 10-km resolution. Variable phasing of the two circular-orbiting spacecraft provides simultaneous
conjugate views of both northern and southern auroral emissions, uncovering the little-understood role of
inter-hemispheric asymmetry on the global system behavior.
The third goal is to measure, in situ, the critical near-Earth plasmas and magnetic field in the cusp
and near-Earth plasma sheet plasma. Onboard each of the two MEDICI spacecraft, plasma composition,
electron plasma conditions, and magnetic field measurements characterize the plasma conditions, field
distortions, and storm/substorm activity, and in combination with imaging allow researchers to follow the
flow of ionospheric plasma and energy between the ionosphere and magnetosphere.
Complementing and augmenting the high-altitude observations, MEDICI includes funded participation
for significant low-altitude components: measurements from a large range of resources, including DMSP or
its follow-on Defense Weather Satellite System, IRIDIUM/AMPERE current maps, radar arrays from high to
mid latitudes (SuperDARN, Millstone Hill, AMISR), GPS TEC maps, and magnetometer and ground-based
auroral all-sky camera arrays. The result will be global specification of the ionospheric electric field and
electric current patterns in both hemispheres, essentially completing the electrodynamic picture at low
altitude. In principle, MEDICI measurements tackle a broader comparative planetary question, namely, the
extent to which magnetospheres can act as shields against atmosphere erosion by the solar wind: Does
ion outflow escape or remain in the magnetosphere to be recycled?
Contributions to the Heliophysics Systems Observatory. MEDICI will both benefit from and enhance the
science return from almost any geospace mission that flies contemporaneously, such as upstream solar
wind monitors, geostationary satellites, and low Earth orbit missions. In particular, by providing global
context and quantitative estimates for magnetospheric-ionospheric plasma and energy exchange, MEDICI
has significant value for missions investigating ionospheric conditions, outflow of ionospheric plasma
into the magnetosphere, energy input from the magnetosphere into the ionosphere, and AIM coupling in
general. Thus it will add value to a host of possible ionospheric strategic missions, Explorers, and rocket
and balloon campaigns. A mission providing continuous imaging and in situ observations from two separate platforms also plays an important role in providing to geospace predictive models the indispensable
validating observations of system-level interactions and processes. The likely long duration of the MEDICI
mission will allow it to provide a transformative framework into which additional future science missions
can naturally fit.
Table 9.2 summarizes MEDICI’s expected level of contribution to the SWMI science goals. In recognition of the need for crucial new observations to enable the accomplishment of these science objectives,
the panel identified the following SWMI imperative:
SWMI Imperative: Initiate the development of a strategic mission, like MEDICI, to determine how the
magnetosphere-ionosphere-thermosphere system is coupled and responds to solar and magnetospheric
forcing.