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SSUMMARY 1 27
3.1 INTRODUCTION 132
3.2 SCIENCE THEMES AN D OPPORTU N ITIES FOR THE COMI NG DECADE 1 38
Earth as a Particle Accelerator 138
Earth's Electric Field 142
Volati le Weather in the Upper Atmosphere 1 46
Micro- and Mesoscale Control of Global Processes 1 53
Dynamics of Geomagnetic Storms, Substorms, and Other Space Weather Disturbances
Sol ar Vari abi I ity and C I i mate 1 59
Magnetospheric, ionospheric, and Atmospheric Processes in Other Planetary Systems 161
3.3 SOCIETAL IMPACT OF SPACE WEATHER 164
Communications 1 65
Navigation 1 67
Electric Power Issues 168
Astronaut, Ai rl i ne, and Satel I ite Hazards 1 69
Satel I ite Drag and Col I ision Avoidance 1 69
3.4 EXISTI N G PROG RAMS AN D N EW I N ITIATIVES
3.5 TECH NOLOGIES FOR THE FUTU RE 1 71
Data Assimi ration 1 71
S pacec raft an d I n stru ment Tech n o l ogy
3.6 RECOMMEN DATIONS 173
Major NSF Initiative 1 74
NASA Orbital Programs 176
NASA Suborbital Program 178
Societal I mpact Program 1 78
Maxi mizi ng Scientific Return 1 80
BIBLIOGRAPHY 1 82
1 72
125
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
SUMMARY
Earth is the single most interesting object in the uni-
verse to its inhabitants, the only place where we can be
certain that a suitable environment for life exists. Fur-
thermore, its complex systems are close enough to study
in the sort of detail we will never obtain elsewhere.
Earth and its sister planets are embedded in the outer
atmosphere of the Sun. This outer atmosphere is con-
tinually being explosively reconfigured. During these
explosive events, Earth is engulfed in intense high-fre-
quency radiation, vast clouds of energetic particles, and
fast plasma flows with entrained solar magnetic fields.
Even though only a small fraction (generally <10 per-
cent) of this energy penetrates into geospace, the effects
are dramatic.
Space science programs to date have given us a
detai led understanding of the average behavior of the
component parts of geospace, in effect providing us with
climatologies upon which to base educated guesses
about the dynamic behavior of the global system. To go
beyond this and understand the coupling processes and
feedback that define the instantaneous response of the
global system is much more difficult. The atmosphere-
ionosphere-magnetosphere (A-l-M) system occupies an
immense volume of space. At the same time, processes
on scales from micro to macro impact the global system
response.
GOALS AND OBJECTIVES
The overarching goals are as follows:
1. To understand how Earth's atmosphere couples
to its ionosphere and its magnetosphere and to the at-
mosphere of the Sun and
2. To attain a predictive capability for those pro-
cesses in the A-l-M system that affect human ability to
live on the surface of Earth as well as in space.
Researchers currently have a tantalizing glimpse of
the physical processes controlling the behavior of some
of the individual elements in geospace. Some of the
crosscutti ng science issues are these:
· The instantaneous global system response of the
A-l-M system to the dynamic forcing of the solar atmo-
sphere,
· The role of micro- and mesoscale processes in
control I ing the global-scale A-l-M system,
1 27
· The degree to which the dynamic coupling be-
tween the geophysical regions controls and impacts the
active state of the A-l-M system,
· The physical processes that may be responsible
for the solar forcing of climate change,
· The origin of the multi-MeV electrons in the outer
magnetosphere and the cause of the pronounced fluc-
tuations in their intensity, and
· The balance between internal and external forc-
ing in the generation of plasma turbulence at low lati-
tudes.
These critical science issues thread the artificial
boundaries between the disciplines. The maturity of the
A-l-M disciplines leads to a close connection between
A-l-M science and applications for the benefit of society.
The application of space physics and aeronomy to soci-
etal needs is now referred to as space weather. The
space weather phenomena that most directly affect life
and society include radiation exposure extending from
space down to commercial airline altitudes, communi-
cations and navigation errors and outages, changes in
the upper atmosphere that affect satellite drag and or-
bital decay, radiation effects on satellite electronics and
solar panels, and power outages on the ground due to
geomagnetical Iy induced currents (GlCs), to name a few.
STRATEGY AND REQUIREMENTS
The next decade may revolutionize our understand-
ing of the dynamical behavior of the A-l-M system in
response to driving from both the solar wind and the
lower atmosphere. A carefully orchestrated collabora-
tion between agencies with interest in space weather
and space science research is required, since no one
agency has the resources to provide the global view.
Furthermore, new ground-based and space-based ob-
serving programs are required that make use of innova-
tive technologies to achieve a simultaneous global view,
highly resolved in space and time. Clusters of satellites
flying in close formation can resolve dynamical response
and separate spatial from temporal variations. New data
storage and handling technologies are necessary to man-
age the shear volume of data generated, the multisatellite
correlations, the mapping between in situ observations
and images, searches across distributed databases, and
other essenti al fu ncti ons that wi I I be necessary i n the
next decade to achieve an understanding of the entire
system.
The systems view requires enhanced efforts to de-
velop global theoretical models of the Sun-Earth system,
including the simultaneous development of new soft-
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1 28
ware technologies for efficient use of paral lel computing
environments and adaptive grid technologies to address
the large range in spatial and temporal scales character-
istic of the global system structure and response. How-
ever, the A-l-M system is not simply multiscale, but it
also requires inclusion of additional physical processes
of ionized and neutral gases made up of individual par-
ticles. Data assimilation technologies are crucial for in-
tegrating new observations into research and operational
models of the space environment. The problems associ-
ated with the transition of research models and data sets
to operations must be specifically addressed in the plan-
ning and implementation of research programs aimed at
i mprovi ng space weather forecast) ng and specification.
The National Science Foundation's (NSF's) highly
successful Solar, Heliospheric, and Interplanetary Envi-
ronment (SHINE) program, its Coupling, Energetics, and
Dynamics of Atmosphere Regions (CEDAR) program,
and its Geosphere Envi ran ment Model i ng (G EM) pro-
gram, and the recent coordination of these groups into
Sun-to-Earth analysis campaigns, highlight the need to
focus this broad range of expertise on issues involved in
coupling between the Sun, solar wind, magnetosphere,
and ionosphere/atmosphere regions. To this end, NSF
recently funded the Science and Technology Center for
I Integrated Space Weather Model i ng. NSF's i Information
technology initiatives should be utilized as much as pos-
sible to develop important collaboration technologies in
support of such major community analysis efforts.
The investigation of planetary A-l-M systems reveals
details of value to understanding the terrestrial system.
Future planetary missions should regularly be outfitted
to carry out at least a baseline set of observations of the
upper atmosphere, the ionosphere, and the magneto-
sphere. In addition, theoretical studies linking our un-
derstanding of the terrestrial environment with other
planetary environments are an effective way of bringing
extensive knowledge of plasma and atmospheric pro-
cesses in the terrestrial environment to bear on the inter-
pretation of planetary phenomena.
While the National Oceanic and Atmospheric Ad-
ministration (NOAA) and the Department of Defense
(DOD) have pursued space environment forecasting for
many years, their connection to the science community
was facilitated by the inception of the National Space
Weather Program (NSWP) in 1995 and NASA's new Liv-
ing With a Star (LOOS) program. The NSWP is a multi-
agency endeavor to understand the physical processes,
from the Sun to Earth, that result in space weather and to
transition scientific advances into operational applica-
tions. NASA's new LWS program represents an impor-
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
tent opportunity to provide measurements and develop
models that will clarify the relationship between sources
of space weather and their impact.
Enhancements and innovations in infrastructure,
data management and assi mi I ation, i nstru mentation,
computational models, software technologies, and
methods for transitioning research to operations are es-
sential to support the future exploration of geospace.
RECOMMENDATIONS
In the next decade, NASA should give highest prior-
ity to multispacecraft missions such as Magnetospheric
Mu Itiscale (MMS), Geospace Electrodynamics Constel-
lation (GEC), Magnetospheric Constellation (MagCon),
and Living With a Star's geospace missions, which take
advantage of adjustable orbit capability and the advanc-
ing technology of smal I spacecraft. Missions that involve
large numbers of simply instrumented spacecraft are
needed to develop a global view of the system and
should be encouraged. NSF, for its part, should support
extensive ground-based arrays of instrumentation to give
a global, time-dependent view of this system. Ground-
and space-based programs should be coordinated as,
for example, is being done in the Thermosphere-lono-
sphere-Mesosphere Energetics and Dynamics (TIMED)/
CEDAR program to take advantage of the complemen-
tary nature of the two distinct viewpoints. NASA, NSF,
DOD, and other agencies should encourage the devel-
opment of theories and models that support the goal of
understanding the A-l-M system from a dynamic point
of view. Furthermore, these agencies should work to-
ward the development of data analysis techniques, us-
ing modern information technology, that assimilate
multipoint data into a three-dimensional, dynamic pic-
ture of this complex system. Funding for the NASA Sup-
porting Research and Technology (SR&T) program
should be doubled to raise the proposal success rate
from 20 percent to the level found in other agencies.
SolarTerrestrial Probe (STP) flight programs should have
their own targeted postlaunch theory, modeling, and
data analysis support.
Major NSF Initiative
Simultaneous, multicomponent, ground-based ob-
servations of the A-l-M system are needed in order to
specify the many interconnecting dynamic and thermo-
dynamic variables. As our understanding of the com-
plexity of the A-l-M system grows, so does the require-
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
ment to capture observations of its multiple facets. The
proposed Advanced Modular Incoherent Scatter Radar
(AMISR) will provide the opportunity for coordinated
radar-optical studies of the aurora and coordinated in-
vestigations of the lower thermosphere and mesosphere,
a region not well accessed by spacecraft. Initial location
at Poker Flat, Alaska, will allow coordination of radar
with in situ rocket measurements of auroral processes.
Subsequent transfer to the deep polar cap will enable
studies of polar cap convection and mapping of pro-
cesses deeper in the geomagnetic tail.
1. The National Science Foundation should extend its
major observatory component by proceeding as quickly
as possible with Advanced Modular Incoherent Scatter
Radar (AMISR) and by developing one or more lidar-
centered major facilities. Further, the NSF should begin
an aggressive program to field hundreds of small auto-
mated instrument clusters to allow mapping the state
of the global system.
Ground-based sensors have played a pivotal role in
our understanding of A-l-M science and must continue
to do so in the coming decade and beyond. Anchored
by a state-of-the-art phased-array scientific radar, the
$60 million AMISR is a crucial element for A-l-M. A
distributed array of instrument clusters would provide
the high temporal and spatial resolution observations
needed to drive the assimilative models, which the panel
hopes will parallel the weather forecasting models we
now have for the lower atmosphere. Much of the neces-
sary infrastructure for such a project has already been
demonstrated in the prototype Suominet, a nationwide
network of simple Global Positioning System (GPS)/me-
teorology stations linked by the Internet. The proposed
program would add miniaturized instruments, such as
all-sky imagers, Fabry-Perot interferometers, very-low-
frequency (VLF) receivers, passive radars, magnetom-
eters, and ionosondes in addition to powerful GPS-based
systems in a flexible and expandable network coupled
to fast real-time processing, display, and data distribu-
tion capabilities. Instrument clusters would be sited at
universities and high schools, providing a rich hands-on
environment for students and training with instruments
and analysis for the next generation of space scientists.
Data and reduced products from the distributed network
would be distributed freely and openly over the Internet.
An overall cost of $100 million over the 1 0-year plan-
ning period is indicated. Estimated costs range from
$50,000 to $1 50,000 per station depend) ng on i nstru-
ments to be depl oyed. Adeq u ate fu nd i ng wou I d be i n-
1 29
eluded for the development and implementation of data
transfer, analysis, and distribution tools and facilities.
Such a system would push the state of the art in informa-
tion technology as well as instrument development and
. . . .
m~n~atur~zat~on.
Extendi ng the present radar-centered upper atmo-
spheric observatories to include one or more lidar-cen-
tered facilities is crucial if we are to understand the
boundary between the lower and upper atmosphere.
Fortunately, a number of military and nonmilitary large-
aperture telescopes may become avai fable for transition
to lidar-based science in the next few years. Highest
priority would be given to a facility at the same geo-
graphic latitude as one of the existing radar sites.
NASA Orbital Programs
The Explorer Program has since the beginning of the
space age provided opportunities for studying the geo-
space environment just as the Discovery Program now
provides opportunities in planetary science. The contin-
ued opportu n ities for U n iversity-CI ass Explorer (U N EX),
Smal I Explorer (SMEX), and Medium-Class Explorer
(MIDEX) missions, practically defined in terms of their
funding caps of $14 million, $90 million, and $180
million, respectively, allow the community the greatest
creativity in developing new concepts and a faster re-
sponse time to new developments in both science and
technology. These missions also provide a crucial train-
ing ground for graduate students, managers, and engi-
neers. Imager for Magnetopause-to-Aurora Global Ex-
ploration (IMAGE), launched in March 2000, is an
example of a h igh Iy successfu I Ml DEX mission; it was
preceded by the first two ongoing SMEX missions, Solar
Anomalous and Magnetospheric Particle Explorer
(SAMPEX) and Fast Auroral Snapshot Explorer (FAST),
launched in 1992 and 1996, which have provided enor-
mous scientific return for the investment. The Aeronomy
of Ice in the Mesosphere (AIM) SMEX was recently se-
lected for launch in 2006. The UNEX program, after the
great success of the Student Nitric Oxide Explorer
(SNOE), launched in February 1998, has effectively been
cancelled. This least expensive component of the Ex-
plorer program plays a role similar to that of the sound-
ing rocket program, with higher risk accompanying
lower cost and a great increase in the number of flight
opportunities. An increase in funding to $20 million per
mission with one launch per year would make this pro-
gram viable with modest resources.
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1 30
2. The SMEX and MIDEX programs should be vigor-
ously maintained and the U N EX program should
quickly be revitalized.
The STP line of missions defined in the NASA Sun-
Earth Connection (SEC) Roadmap (strategic planning for
2000 to 2025) has the potential to form the backbone of
A-l-M research in the next decade. The missions that are
part of the current program include TIMED, launched in
February 2002, Solar-B, the Solar Terrestrial Relations
Observatory (STEREO), MMS, G EC, and MagCon. After
TIMED, launched in February 2002, the next A-l-M/STP
mission, MMS, is in the process of instrument selection
for a 2009 launch. The STP cadence, with one A-l-M
mission per decade (TIMED was significantly delayed),
has fallen behind the NASA SEC Roadmap projections.
3. The panel heartily endorses the STP line of missions
and strongly encourages an increase in the launch ca-
dence, with GEC and MagCon proceeding in parallel.
The A-l-M research community has very success-
fully utilized the infrastructure developed within the In-
ternational Solar-Terrestrial Physics (ISTP) program. The
integration of the data from spacecraft and ground-based
programs beyond those funded by the ISTP itself such
as those of NOAA, LANE, and the DOD have contrib-
uted substantially to our understanding of the global
system.
Comparisons between the Sun-Earth system and
other Sun-planet or stellar-planet systems provide im-
portant insights into the underlying physical and chemi-
cal processes that govern A-l-M interactions. Improved
understanding of A-l-M coupling phenomena such as
planetary and terrestrial auroras would benefit from such
an approach.
4. The Sun-Earth Connection program partnership with
the NASA Solar System Exploration program should be
revitalized. A dedicated planetary aeronomy mission
should be pursued vigorously, and the Discovery Pro-
gram should remain open to A-l-M-related missions.
NASA Suborbital Program
The NASA Suborbital program has produced out-
standing science throughout its lifetime. Many phenom-
ena have been discovered using rockets, rockoons, and
teal loons, and many outstand i ng problems brought to
closure, particularly when space-based facilities are
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
teamed with ground-based facilities. These phenomena
include the auroral acceleration mechanism, plasma
bubbles at the magnetic equator, the charged nature of
polar mesospheric clouds, and monoenergetic auroral
beams. This program continues to generate cutting-edge
science with new instruments and data rates that are
more than an order of magnitude greater than typical
satellite data rates. Both unique altitude ranges and very
specific geophysical conditions are accessible only to
sounding rockets and balloons, particularly in the cam-
paign mode. Many current satellite experimenters were
trained in the Suborbital program, and high-risk instru-
ment development can occur only in such an environ-
ment. To accomplish significant training, it is necessary
that a graduate student remain in a project from start to
finish and that some risk be acceptable; both are very
difficult in satellite projects. The high scientific return,
coupled with training of future generations of space-
based experimenters, makes this program highly cost-
effective.
The sounding rocket budget has been level-funded
for over a decade, and many principal investigators (Pls)
are discouraged about the poor proposal success rate as
well as the low number of launch opportunities. The
sounding rocket program was commercialized in 2000;
in this changeover, approximately 50 civil service posi-
tions were lost and the cost of running the program
increased. Approved campaigns were delayed by up to
a year, and it is not yet clear whether the launch rate will
ever return to precommercial ized levels. Effectively,
commercialization has meant a significant decline in
funding for the sounding rocket program. An additional
concern is that, as currently structured i.e., with a
fixed, 3-year cycle for all phases of a sounding rocket
project funding is not easily extended to allow gradu-
ate students to complete their thesis work, because it is
generally thought that such work should fall under the
SR&T program, already oversubscribed. The rocket pro-
gram has a rich history of scientific and educational
benefit and provides low-cost access to space for uni-
versity and other researchers. Further erosion of this pro-
gram will result in fewer and fewer young scientists with
experience in building flight hardware and will ulti-
mately adversely affect the much more expensive satel-
lite programs.
5. The Suborbital program should be revitalized and its
funding should be reinstated to an inflation-adjusted
value matching the funding in the early 1980s. To fur-
ther ensure the vibrancy of the Suborbital program, an
independent scientific and technical panel should be
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
formed to study how it might be changed to better
serve the community and the country.
Societal Impact Program
The practical impact on society of variations in the
A-l-M system falls into two broad categories: the well-
established effects of space weather variations on tech-
nology and the less clear yet tantalizing influence of
solar variability on climate. The societal impacts of
space weather are broad commu n Cations, navigation,
human radiation hazards, power distribution, and sat-
ellite operations are all affected. Space weather is of
international concern, and other nations are pursuing
parallel activities, which could be leveraged through
collaboration. The role of solar variability in climate
change remains an enigma, but it is now at least being
recogn ized as i mportant to our understanding of the
natural as opposed to anthropogenic sources of cli-
mate variabi I ity.
6. The study of solar variability both of its short-term
effects on the space radiation environment, communi-
cations, navigation, and power distribution and of its
effect on climate and the upper atmosphere should
be intensified by both modeling and observation
efforts.
NASA's LivingWith a Star program should be imple-
mented, with increased resources for the geospace com-
ponent. Missions such as the National Polar-orbiting
Operational Envi ran mental Satel I ite Systems (N POESS)
and the Solar Radiation and Climate Experiment
(SORCE) are needed to provide vital data to the science
community for monitoring long-term solar irradiance.
NPOESS should be developed to provide ionosphere
and upper atmosphere observations to fill gaps in mea-
surements needed to understand the A-l-M system. An
L1 monitor should be a permanent facility that provides
the solar wind measurements crucial to determining the
response of the A-l-M system to its external driver, and
the NSWP should be strengthened and used as a tem-
plate for interagency cooperation. International partici-
pation in such large-scope programs as LWS and NSWP
is essential.
7. The NOAA, DOE/LAN L, and DOD operational
spacecraft programs should be sustained, and DOD
launch opportunities should be utilized for specialized
missions such as geostationary airglow imagers, auroral
oval imagers, and neutral/ionized medium sensors.
1 31
NASA's new Living With a Star program can, over
the next decade, provide substantial new resources to
address these goals. It is crucial that there be overlap
between the geospace and solar mission components of
LWS for the system to be studied synergistically, that
resources be adequate for the geospace component, and
that theory, modeling, and a comprehensive data sys-
tem, which will replace the ISTP infrastructure, be de-
fined at the outset, as called for in the Science Architec-
tu re Team (SAT) report fi nd i ngs. NSWP, a mu Itiagency
endeavor establ ished in 1 995, addresses the potential Iy
great societal impact of physical processes from the Sun
to Earth that affect the near-Earth environment in ways
as diverse as terrestrial weather. The program specifi-
cally addresses the need to transition scientific research
into operations and to assist users affected by the space
environment. Such multiagency cooperation is essential
for progress in predicting the response of the near-Earth
space environment to short-term solar variability.
The interagency cooperation established in the
NSWP is outstanding and is a model for extracting the
maximum benefit from scientific and technical pro-
grams. It has also been effective at bringing together
different scientific disciplines and the scientific and op-
erations communities. Interagency cooperation has
worked well in the AFOSR/NSF Maui Mesosphere and
Lower Thermosphere Program, and it has been key to
the success of the NOAA GOES and POES programs of
meteorological satellites with space environment moni-
toring capabilities. International multiagency coopera-
tion has been very successful for the ISTP program,
which involves U.S., European, Japanese, and Russian
space agencies. Global studies require such interna-
tional cooperation. The panel recognizes that much
more science can be extracted by careful coordination
of ground- and space-based programs.
Maximizing Scientific Return
Funding for NASA's Supporting Research and Tech-
nology program, including guest investigator studies and
focused theory, modeling, and data assimilation efforts,
is essential for maximizing the scientific return from large
i nvestme nts i n s pacec raft h ardware.
Supporting Research and Technology
Wh i le spacecraft hardware projects are con-
centrated at relatively few institutions, the NASA SR&T
program is the primary vehicle by which independent
investigations can be undertaken by the broader com-
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1 32
munity. Likewise, NSF helps individual investigators to
carry out targeted research through its Division of Atmo-
spheric Sciences (ATM) base programs SHINE, CEDAR,
and GEM. Such individual Pl-driven initiatives are the
most inclusive, with data analysis as well as theoretical
efforts and laboratory studies, and often lead to the high-
est science return per dollar spent. The funding for such
program elements falls far short of the scientific oppor-
tunities, with the current success rate for submitted
NASA SR&T proposals being 10 to 20 percent. Further-
more, limited available SR&T funds have been used for
guest investigator participation in underfunded STP-class
flight programs. Without adequate MO&DA funding for
NASA orbital and suborbital programs, the SR&T budget
intended for targeted research on focused scientific ques-
tions has been utilized to support broader data analysis
objectives.
8. The funding for the SR&T program should be in-
creased, and STP-class flight programs should have their
own targeted postlaunch data analysis support.
9. A new small grants program should be established
within NSF that is dedicated to comparative atmo-
spheres, ionospheres, and magnetospheres (C-A-I-M).
A new C-A-I-M grants program at NSF would allow
the techniques (modeling, ground-, and space-based
observations, and in situ measurements) that have so
successfully been applied to A-l-M processes at Earth to
be used to understand A-l-M processes at other planets.
Such a comparative approach would improve our un-
derstanding of these processes throughout the solar sys-
tem, including at Earth. Currently, a modest $2 million
planetary science program at NSF covers all of solar
system science (except for sol ar and terrestrial stud ies),
with only a small fraction going to planetary A-l-M re-
search.
Theory, Modeling, and Data Assimilation
Theory and modeling provide the framework for in-
terpreti ng, understand) ng, and visual izi ng diverse mea-
surements at disparate locations in the A-l-M system.
There is now a pressing need to develop and utilize data
assimi ration techniques not only for operational use in
specifying and forecasting the space environment but
also to provide the tools to tackle key science questions.
The modest level of support from the NSF base pro-
grams (CEDAR, GEM, SHINE) and NASA SR&T has been
inadequate to build comprehensive, systems-level mod-
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
els. Rather, individual pieces have been built, and first
stages of model integration achieved with funding from
such programs as NASA's ISTP program and its Sun-
Earth Connections Theory Program (SECTP), the AFOSR
MU RI program, NSF Science and Technology Center
programs, and the multiagency support to such efforts as
the Community Coordinated Model ing Center. Such pro-
grams enable the development of theory and modeling
infrastructure, including models to address the dynamic
coupling between neighboring geophysical regions.
Their value to the research community is clearly their
provision of longer-term funding, which has been essen-
tial to developing a comprehensive program outside the
purview of SR&T.
10. The development and utilization of data assimila-
tion techniques should be enhanced to optimize model
and data resources. The panel endorses support for
theory and model development at the level of the NASA
Sun-Earth Connections Theory Program, the AFOSR/
ONR MURI program, NSF Science and Technology
Center programs, and the multiagency support to such
efforts as the Community Coordinated Modeling Cen-
ter (CCMC). Support should be enhanced for large-
scope, integrative modeling that applies to the cou-
pling of neighboring geophysical regions and physical
processes, which are explicit in one model and implicit
on the larger scale.
The preceding science recommendations can be
grouped into three cost categories and prioritized (see
Table 3.11. Equal weight is given to STP and LWS lines,
as indicated by funding level. Smal I programs are ranked
by resource allocation, while the Advanced Modular
Incoherent Scatter Radar is the highest priority moderate
initiative at lower cost than others.
3.1 INTRODUCTION
Earth, unique in the universe as the only object
known to support life, follows an orbit in the outer at-
mosphere of the Sun an outer atmosphere that is con-
tinually being explosively reconfigured. During these
events, Earth is engulfed in intense high-frequency ra-
diation, vast clouds of energetic particles, and fast
plasma flows with entrained solar magnetic fields. Even
though only a small fraction (generally <10 percent) of
this energy penetrates into geospace, its effects are dra-
matic.
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
TABLE 3.1 Panel's Recommended Priorities for New
Initiatives
Initiatives in Geospace
Major
SolarTerrestrial Probes (2)
Living With a Star
Discovery (1)
Moderate
Advanced Modular Incoherent Scatter
Radar and Lidar Facilities
Explorer Program (assume 3 missions in
the 10 years will be devoted to AIM)
L1 Monitor (excluding tracking)
Small Instrument Distributed Ground-
Based Network
Recommended 10-Year
Funding (million $)
800
500
350
Subtotal 1,650
92
300
50
100
Subtotal 542
Small
Suborbital program
NSF Supporting Research and Technology
National Space Weather Program 50
NSF SHINE, CEDAR, GEM, C-A-I-M (new)
Theory
Living With a Star (geospace)
Sun-Earth Connection Theory Program
(geospace)
DOD MURI (ionosphere)
NSF STC (geospace)
HPCC (geospace)
NOAA, DOE/LANL, and DOD science for
the A-l-M community 50
Subtotal 848
300
200
135
138
60
18
20
20
20
Total
3,065
To date, space science programs have provided
detai led understanding of the average behavior of the
component parts of geospace, in effect providing climat-
ologies upon which to base educated guesses about the
dynamic behavior of the global system. To go beyond
this and understand the coupling processes and feed-
back that define the instantaneous response of the glo-
bal system is much more difficult. The A-l-M system
occupies an immense volume of space. At the same
time, processes on scale sizes from micro to macro im-
pact the global system response.
The ISTP program is the most ambitious program to
date to explore the A-l-M system. ISTP samples the huge
volume of the A-l-M system by simultaneous measure-
ments from a handful of satellites. Despite the sparse
a
1 33
coverage, analysis of data from ISTP satellites has al-
lowed scientists to begin to glimpse the rich variety of
coupling and feedback processes that define the global
response of the geospace environment to solar wind
disturbances. The first experiments with innovative im-
aging technologies that view large regions of geospace
in snapshots (e.g., from the IMAGE spacecraft) have al-
ready provided insights into the instantaneous response,
unattainable by past missions. The first attempts to
achieve the high spatial and temporal resolution needed
to survey the microscale controls of the global system
(e.g., from the FAST spacecraft) have revealed new de-
tails about acceleration processes and electrodynamic
coupling. With these new missions, we are replacing
our steady-state view of geospace regions with a dy-
namical view. But we are far from understanding the
complex coupling processes and interplay between
components that dictate the integrated global system
response.
It is clear that the A-l-M system actively responds to
the solar wind and that components of this system may
be preconditioned or may interact in ways that redistrib-
ute solar wind energy throughout the system, actively
limiting the entry of solar wind energy into geospace
during extreme events. A few examples are given in the
next pages to illustrate the complexity of this interaction
and the challenges that lie ahead.
Life on this planet is protected from the high-energy
radiation and dangerous particle clouds in interplan-
etary space because Earth has its own magnetic field
and is surrounded by an absorbing atmosphere. Earth's
magnetic field presents a northward-directed magnetic
field barrier to the oncoming solar wind in the ecliptic
plane (Figure 3.1~. This barrier can be breached, how-
ever, if southward-d i rected sol ar magnetic fields i mpact
it and merge or reconnect with Earth's magnetic field.
Fortunately, strongly southward-directed magnetic fields
are not a persistent feature of the quiet interplanetary
medium. They are mainly confined to structures gener-
ated in explosive solar events and in high-speed plasma
streams.
The passage of southward interplanetary magnetic
field (IMP) structures by Earth pumps energy into the
near-space environment. The tightly coupled nature of
the A-l-M system is clearly revealed by its response to
interplanetary magnetic clouds (IMCs), which have
strong and long-lived southward magnetic fields and
drive the most intense magnetic storms. Intense convec-
tion is produced, which brings particles from the mag-
netotail storage region (called the plasma sheet) deep
into the inner magnetosphere on open drift paths, ener-
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1 34
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
FIGURE 3.1 (a) A schematic of the magnetosphere showing major particle populations and current systems; (b) close-up of radiation
belts (trapped particles), including inner and outer zone populations and trapped anomalous cosmic rays (interstellar matter).
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
Sizing them to form the storm-time ring current, shown
schematically in Figure 3.1. Under extreme conditions,
the strong current produced by these particles cannot
close upon itself in the equatorial plane (to form the ring
of current that its name implies) but is forced to close
through the subauroral and midlatitude ionosphere. This
closure produces a strong electric field in the ionosphere
called a polarization jet. The electric fields in the polar-
ization jet map upward along the field lines to the mag-
netosphere, producing a penetration electric field in the
inner magnetosphere, further changing the drift paths of
the ring-current ions. The plasmasphere (corotating
plasma of ionospheric origin) responds strongly to the
penetration electric fields and enhanced convection.
Long plumes of plasmaspheric material snake out to the
dayside magnetopause, draining thermal plasma into the
dayside boundary layers. This plasma may later become
a source for the plasma sheet (Figure 3.11. Along drift
paths mapped into the ionosphere, storm-enhanced ion-
ization moves toward the dayside polar cap, where geo-
magnetic field lines connect to the interplanetary mag-
netic field. Steep plasma density gradients at the edges
of ionospheric density patches form in the changing con-
vection pattern, playing havoc with technologies like
the Global Positioning System, and ionospheric irregu-
larities form, disrupting communication systems.
There are indications that the ionosphere may, in
turn, have a major impact on the dynamics of the mag-
netosphere. Solar wind dynamic pressure variations trig-
ger ionospheric outflows from the vicinity of the polar
cap. These ionospheric "mass ejections" begin well be-
fore the storm maximum, preconditioning the tail plas-
mas with heavy ionospheric ions energized by the solar
wind interaction. Enhanced convection during magnetic
storms stresses the magnetotail, producing dramatic re-
configurations of the basic structure of the magnetotail,
called substorms. Auroral currents associated with sub-
storms also produce an outflow of ionospheric ions di-
rectly into the magnetotail. Substorms may actually sever
the outer plasma sheet from the magnetotail, producing
a major loss of plasma and energy. Dipolarization of the
magnetic field during substorms, which reduces the
stretching of magnetotail field lines, generates intense
electric fields, which accelerate the storm-enhanced
plasma sheet. Since this accelerated plasma drifts earth-
ward under conditions of strong convection to form the
ring current, there is a clear connection between mag-
netotail dynamics and magnetic storm effects in the near-
Earth region of the magnetosphere. Variations in plasma
sheet density play an important role in modulating mag-
netic storm intensity and substorm processes and repre-
1 35
sent another means by which the A-l-M system inter-
nally modulates the geo-effectiveness of solar wind dis-
turbances. The interplay between removal of plasma
sheet material and refilling of the plasma sheet from the
solar wind and the ionosphere to supply the ring current
during storms is not understood. Even the basic mecha-
nisms for refilling the plasma sheet (Figure 3.1 ) have not
yet been determined.
Earth's outer magnetosphere is often populated to a
surprising degree by relativistic electrons, which pose a
radiation hazard to space-based systems. The origin of
the multi-MeV electrons in the outer zone is not known.
They are generally correlated with increased substorm
activity driven by high-speed solar wind and favorable
coupl ing to southward interplanetary magnetic field,
both of which have semiannual and solar-cycle varia-
tions. Enhancements occur with relatively regular 27-
day periodicity during the declining phase of the 11-
year sunspot cycle and are wel I associated with
high-speed solar wind stream structures. Flux variations
at the solar activity maximum are dominated by coronal
mass ejections (CM Es) (see the report of the Panel on
Solar-Heliospheric Physics), which launch magnetic
clouds toward Earth, producing geomagnetic storms.
The mechan ism~s) by wh ich magnetospheric particles
are accelerated to relativistic energies are unknown at
present, although a number of interactions with plasma
wave modes are promising candidates. The impact of
solar wind shock structures on Earth's magnetosphere
has been shown to generate induction-electric-field
pulses that rapidly accelerate electrons and protons, gen-
erating an entire new radiation belt in a matter of min-
utes. An interesting coupling between the ring current
and radiation belts results wherein magnetic fields gen-
erated by the ring current cause scattering and loss of
radiation belt particles. In addition, waves near the ion
gyrofrequency generated by ring-current ions are be-
lieved to contribute to electron precipitation losses in
the dusk sector. Dramatic losses from the electron radia-
tion belts (Figure 3.1b) also result from interaction of
energetic electrons with lightning-generated waves,
cal led whistlers. Lightning-induced electron precipita-
tion events exemplify direct coupling of tropospheric
weather systems with the radiation belts and the iono-
spheric regions overlying thunderstorms.
Much of the energy and momentum entering Earth's
environment eventually finds its way into the upper at-
mosphere. The in situ absorption of solar EUV radiation
not on Iy protects I ife on Earth, but drives large day-night
temperature and tidal wind variations in the upper at-
mosphere, which vary dramatically with the solar cycle.
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1 72
coveri ng d iverse regions i n geospace, new i Information
technologies are required to improve data access from a
single coordinating site, to allow remote searching of
these distributed data sets, and to simplify data assimila-
tion into global models in real time and for postevent
analysis.
I Improvements i n meteorological weather forecast-
ing have demonstrated the utility of adopting sophisti-
cated data assimilation techniques. It is essential thatthe
space physics and aeronomy communities learn, further
develop, and implement these methods for both opera-
tional and scientific use. The potential benefit of new
observing systems can come to fruition only if maxi-
mum use is made of the data; this, in turn, will happen
only if a comprehensive data assimilation program is
developed. This is not a trivial task, and the effort in-
volved shou Id not be underestimated. Assimi ration mod-
els can also provide the tools to visualize a wide net-
work of data and provide guidance on when and where
to target observations to ensure efficient use of resources.
Data assimilation is the optimal combination of data
with the physical understanding embedded in physical
models. It is distinct from data synthesis, where a small
number of observations are used to adjust a model out-
put. There are numerous data assimilation methods
avai fable in meteorology and oceanography that can be
applied to the space environment.
SPACECRAFT AND
INSTRUMENT TECHNOLOGY
There are several areas of technological develop-
ment that are needed to implement A-l-M objectives on
future missions efficiently. The needed technology splits
into two areas: spacecraft subsystems and instrumenta-
tion. Both areas require active funding by NASA to fos-
ter improvement. It should be emphasized that the best
return on NASA's investment will come from a peer-
reviewed competition open to universities and industry
as well NASA centers. In the case of spacecraft sub-
systems, the return will be immediate and far-reaching.
Improvements in telemetry, command and data han-
dling (CDH), attitude control, and power systems can be
directly transferred to private industry, where they will
make American spacecraft more competitive in a global
economy. Instrumentation development has a less direct
impact, but the innovations that come from better scien-
tific instruments often lead the way for incorporating
new technology into spacecraft subsystems. It is im-
portant to realize that developments in these areas must
support traditional, highly instrumented spacecraft as
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
well as smaller, more simply instrumented spacecraft
(micro- and nanosatel I ites).
Future NASA space science missions will increas-
ingly rely on a multispacecraft approach, as is amply
discussed in this report and those of the other panels.
For such missions to be achieved at reasonable cost,
spacecraft subsystems must become more efficient in
their use of mass and power. For every scientific space-
craft built in recent memory, the majority of mass and
power go to spacecraft subsystems, not instrumentation.
To improve the performance of these systems, NASA
will need to foster research and innovation. Develop-
ment of highly power-efficient CDH systems with good
flexibility and increased-capacity mass memories with
small impact on spacecraft resources will be critical to
these missions. NASA is currently working on high-effi-
ciency thruster systems. Multispacecraft missions can
require frequent station keeping to maintain optimum
spacecraft positioning; more efficient thrusters can have
a direct impact on spacecraft size and mission longevity.
This work should be continued and expanded.
Both power generation and power storage improve-
ments are needed. Although solar cells have become
more efficient, development of still higher efficiency
solar cells should be encouraged. For planetary mis-
sions to the outer solar system, radioisotope thermal
generators (RTGs) are needed. The development and
use of RTGs is a politically sensitive issue, but if NASA is
to continue exploration of Jupiter and beyond, these
power sources must be developed so that the public is
satisfied that they are safe. Without safe, politically ac-
ceptable RTGs, exploration of the solar system and be-
yond will be significantly limited. Battery development
should also be encouraged. By decreasing the mass re-
quirements for a given amount of stored power, smaller,
more efficient spacecraft can be constructed.
Multispacecraft missions will also place significant
new demands on telemetry reception capacity. Much of
this reception capacity is currently contained within the
Deep Space Network (DSN). However, the DSN, as pres-
ently configured, consists of relatively large, expensive
receiving antennas. Recent experiences with Cluster and
other missions suggest that DSN is stretched very thin.
The next generation of multispacecraft missions will not
fly at extremely large distances from Earth; most are
envisioned to be within its magnetosphere. This sug-
gests that NASA should consider augmenting the DSN
with arrays of smaller, less-expensive antennas that can
handle missions that stay within 20-30 RE of Earth. If
each of the main DSN stations (Canberra, Goldstone,
Madrid) had two, three, or four smaller dishes, then the
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
upcoming multispacecraft missions could have their te-
lemetry reception offloaded onto these smaller dishes,
freeing the larger ones for planetary or other low-signal-
level missions. As part of making such a system efficient,
automation of receivers must be considered to reduce
operating costs. NASA should develop options for man-
aging data reception to find solutions that will give effi-
cient and sufficient capacity.
On the instrumentation side of new technology, the
key is to provide funding to scientists to develop the
instrumentation. This support must be for the develop-
ment of new basic technologies and materials as well as
specific instrumentation designs. As an example, basic
research in magnetoresistive materials may lead to new,
highly efficient magnetometers. However, we also need
novel designs for electrostatic detector optics to improve
the efficiency of detection of low- and mid-energy ion
mass analyzers. In the current environment, instru-
mentation innovation does occur, but it tends to be spo-
radic, and nonuniversity groups that have internal over-
head return tend to be favored, because they can
internally finance modest development efforts. By pro-
viding steady, regular funding for instrument develop-
ment that is openly competed for and peer-reviewed,
along with support for suborbital and UNEX-class flight
opportu n ities, NASA wi I I al I ow researchers to cou nt on
continuing funding for their efforts to come up with new
detector designs that wi 11 measure more accurately and
more efficiently.
An important part of the development of new, com-
pact systems for both instrumentation and spacecraft is
the microelectronics that is at the heart of these systems.
Central to microelectronics is the development of mod-
ern parts with good radiation tolerance. In particular,
NASA must foster the development of red-hard micro-
processors, programmable gate arrays, and other digital
and analog electronic components so that the United
States can remain competitive with the rest of the world.
3.6 RECOMMENDATIONS
Future research in atmosphere-ionosphere-magneto-
sphere science must prominently support projects, theo-
ries, and models that address the three-dimensional,
dynamic behavior of the coupled A-l-M system. Crucial
to understanding dynamic, complex geophysical phe-
nomena such as magnetic reconnection, auroral pro-
1 73
cesses, and electrodynamic ionosphere-thermosphere
coupling are measurements from multiple platforms
(e.g., the recently launched four-satellite Cluster 11 mis-
sion and the planned Magnetospheric Multiscale mis-
sion). Also critical to achieving such understanding are
advances in the area of numerical simulation, including
the development of mature coupled ionosphere models
and the incorporation in global models of proper physi-
cal representations of sub-grid-scale effects.
Future measurements and models must pay even
greater attention to these essential aspects of near-Earth
space. The overarch i ng goal s are these:
1. To understand how Earth's atmosphere couples to
its ionosphere and its magnetosphere and to the atmo-
sphere of the Sun and
2. To attain a predictive capability for those pro-
cesses in the A-l-M system that affect human ability to
live on the surface of Earth as well as in space.
We currently have a tantalizing glimpse of the physi-
cal processes controlling the behavior of some of the
individual elements in geospace. We must now address
cross-cutting science issues, which include
· the instantaneous global system response of the
A-l-M system to the dynamic forcing of the solar atmo-
sphere.
For example, how does the magnetosphere limit solar
wind power input, manifest in saturation of the polar
cap potential ? How do the neutral atmosphere and the
ionosphere respond to sudden and long-term changes
on the Sun? In view of the multiple temporal and spatial
scales we must understand
· the role of micro- and mesoscale processes in
controlling the global-scale A-l-M system.
The exchange of mass, momentum, and energy between
the geophysical domains (e.g., connection of solar wind
plasma at the magnetopause, ionospheric outflow, up-
ward propagation of electromagnetic and mechanical
energy from the lower atmosphere) is a key element in
the coupled A-l-M system. It is now imperative that we
understand
· the degree to which the dynamic coupling be-
tween the geophysical regions controls and impacts the
active state of the A-l-M system.
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1 74
The Sun is now recognized as one of the important
factors in global change. Accordingly, we must resolve
· the physical processes that may be responsible
for the solar forcing of climate change.
These critical science issues thread the artificial bound-
aries between the discipl ines, but within each discipl ine,
important science questions remain. For example,
Earth's outer magnetosphere, acting as a powerful par-
ticle accelerator, is often populated by a surprising de-
gree of relativistic electrons that pose a radiation hazard
to space-based systems. It is important that we deter-
mine
· the origin of the multi-MeV electrons in the
outer magnetosphere and the cause of the pronounced
fluctuations in their intensity.
In the thermosphere and ionosphere, one of the funda-
mental science issues that must be resolved is to deter-
mlne
· the balance between internal and external forc-
ing in the generation of plasma turbulence at low lati-
tudes.
To accomplish our goals we note that simultaneous,
multiplatform remote-sensing observations of the A-l-M
system as well as in situ measurements are urgently
needed in order to specify the many interconnected dy-
namic, thermodynamic, and composition variables. As
our understanding of the complexity of the thermo-
sphere, ionosphere, and magnetosphere grows, so does
the requirement to capture observations of these mul-
tiple facets of the coupled media.
In the next decade, NASA should give highest prior-
ity to multispacecraft missions such as Magnetospheric
Multiscale (MMS) (Box 3.1), Geospace Electrodynamics
Connections (GEC), Magnetospheric Constellation (Mag-
Con), and Living With a Star's geospace missions, which
take advantage of adjustable orbit capability and the
advancing technology of small spacecraft. Missions that
involve large numbers of simply instrumented space-
craft are needed to develop a global view of the system
and should be encouraged. NSF, for its part, should sup-
port extensive ground-based arrays of instrumentation
to give a global, time-dependent view of this system.
Ground- and space-based programs should be coordi-
nated as, for example, is being done in the Thermo-
sphere-lonosphere-Mesosphere Energetics and Dynam-
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
ics (TIMED)/CEDAR program to take advantage of the
complementary nature of the two distinct viewpoints.
NASA, NSF, DOD, and other agencies should encour-
age the development of theories and models that sup-
port the goal of understanding the A-l-M system from a
dynamic point of view. Furthermore, these agencies
should work toward the development of data analysis
techniques, using modern information technology, that
assimilate the multipoint data into a three-dimensional,
dynamic picture of this complex system. Funding for the
NASA Supporting Research and Technology (SR&T) pro-
gram should be doubled to bring the proposal success
rate up from 20 percent to the level found in other agen-
cies. SolarTerrestrial Probe (STP) flight programs should
have their own targeted postlaunch theory, modeling,
and data analysis support.
MAJOR NSF INITIATIVE
Simultaneous, multicomponent, ground-based ob-
servations of the A-l-M system are needed in order to
specify the many interconnecting dynamic and thermo-
dynamic variables. As our understanding of the com-
plexity of the A-l-M system grows, so does the require-
ment to capture observations of its multiple facets. The
proposed Advanced Modular Incoherent Scatter Radar
(AMISR) (Box 3.2) will provide the opportunity for coor-
dinated radar-optical studies of the aurora and coordi-
nated investigations of the lower thermosphere and me-
sosphere, a region not well accessed by spacecraft.
Initial location at Poker Flat, Alaska, will allow coordi-
nation of radar with in situ rocket measurements of au-
roral processes. Subsequent transfer to the deep polar
cap will enable studies of polar cap convection and the
mapping of processes deeper in the geomagnetic tail.
1. The National Science Foundation should extend its
major observatory component by proceeding as quickly
as possible with Advanced Modular Incoherent Scatter
Radar (AMISR) and by developing one or more lidar-
centered major facilities. Further, the NSF should begin
an aggressive program to field hundreds of small auto-
mated instrument clusters to allow mapping the state
of the global system.
Ground-based sensors have played a pivotal role in
our understanding of A-l-M science and must continue
to do so in the coming decade and beyond. Anchored
by a state-of-the-art, phased-array scientific radar, the
$60 million AMISR is a crucial element for A-l-M. A
distributed array of instrument clusters would provide
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
1 75
The Magnetospheric Multiscale (MMS) mission is a multispacecraft Solar Terrestrial Probe to study magnetic
reconnection, charged particle acceleration, and turbulence in key boundary regions of Earth's magnetosphere. These
three processes which control the flow of energy, mass, and momentum within and across plasma boundaries occur
throughout the universe and are fundamental to our understanding of astrophysical and solar system plasmas. Only in
Earth's magnetosphere, however, are they readily accessible for sustained study through the in situ measu remeet of plasma
properties and of the electric and magnetic fields that govern the behavior of the plasmas. But despite four decades of
magnetospheric research, much about the operation of these fundamental processes remains unknown or poorly under-
stood.This state of affairs is in large part attributable to the limitations imposed on previous studies by their dependence
upon single-spacecraft measurements,which are not adequate to reveal the underlying physics of highly dynamic, highly
structured space plasma processes.
To overcome these limitations, MMS will employ four co-orbiting spacecraft, identically instrumented to measure
electric and magnetic fields, plasmas, and energetic particles.The initial parameters of the individual spacecraft orbits will
be designed so that the spacecraft will form a tetrahedron near apogee.Thus configured, the MMS ~cluster"will be able to
measure three-dimensional fields and particle distributions and their temporal variations and three-dimensional spatial
gradients with high resolution while dwelling in the key magnetospheric boundary regions,from the subsolar magneto-
pause to the high-latitude magnetopause, and from the near tail to the distant tail. Adjustable interspacecraft separa-
tions from 10 km up to a few tens of thousands of kilometers will allow the cluster to probe the microphysical aspects
of reconnection, particle acceleration, and turbulence and to relate the observed microprocesses to larger-scale phenom-
ena. MMS will uniquely separate spatial and temporal variations over scale lengths appropriate to the processes being
studied down to the kinetic regime beyond the approximations of MHD. From the measured gradients and curls of the
fields and particle distributions, spatial variations in currents, densities, velocities, pressures, and heat fluxes will be calcu-
lated.
In order to sample all of the magnetospheric boundary regions, MMS will employ a unique four-phase orbital strategy
involving carefully sequenced changes in the local time and radial distance of apogee and, in the third phase, a change in
the inclination of the orbit from 10 degrees to 90 degrees. In the first two phases, the investigation will focus on the near-
Earth tail and the subsolar magnetopause (Phase 1; 12 RE apogee) and on the low-latitude magnetopause flanks and near-
Earth neutral line region (Phase 2; apogee increasing from 12 to 30 RC). In Phase 3, MMS will use a lunar Gravity assist to
C, ,
~ - -,
achieve a deep-tail orbit with apogee at 120 RE and to effect the inclination change to 90 degrees. In this phase, MMS will
study plasmoid evolution and reconnection at the distant neutral line. In the final, high-inclination phase, perigee will be
increased to 10 RE and apogee reduced to 40 RE on the night side, and the MMS cluster will skim the dayside magneto-
oause from pole to pole, sampling reconnection sites at both low and high latitudes.
The nominal MMS mission has an operational duration of 2 years.While some mission-enhancing technologies such as
an interspacecraft ranging and alarm system are desirable, no new mission-enabling technologies are required for the
successful accomplishment of the MMS science objectives.
MMS is a mission of both exploration and understanding. Its primary thrust is to study on the mesa- and microscales
the basic plasma processes that transport, accelerate, and energize plasmas in thin boundary and current layers the
processes that control the structure and dynamics of the magnetosphere. With sensitive instrumentation and variable
spacecraft orbits and interspacecraft spacing, MMS will integrate for the first time observations and theories over all
geomagnetic scale sizes, from boundary layer processes that operate at the smallest scale lengths to the mesoscale
dynamics that couple solar wind energy throughout the Earth's space environment.
The major science goals of the MMS mission include an understanding of the following:
Reconnection at the magnetopause at high and low latitudes,
Reconnection in the magnetotail and the associated magnetotail dynamics,
Plasma entry into the magnetosphere,
Physics of current sheets,
Substorm initiation processes, and
Cross-scale coupling between micro- and mesoscale phenomena.
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1 76
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
The Advanced Modular Incoherent Scatter Radar (AMISR) is a state-of-the-art phased-array incoherent scatter radar
(ISR).This highly versatile instrument will be ringed by less expensive complementary systems, typically optical in nature.
The science plan is to target unsolved problems in aeronomy by placing AMISR in appropriate geographic locations for
periods of 3 to 5 years.The first science goal is to understand the coupling between the neutral atmosphere and the high-
speed current-carrying plasma in the auroral oval.This interaction involves electrodynamic forcing via momentum transfer
from the plasma to the neutrals,Joule heating due to the currents that flow, composition changes of the thermosphere,
and particle impact ionization associated with the aurora, to name just a few aspects.The first AMISR site will be in the
Fairbanks area to take advantage of existing instrumentation and the Poker Flat Rocket Range.
Subsequent sites will be decided on the basis of community input by a panel of research scientists. Candidates include
a location in the deep polar cap,which has never been studied using the ISR technique,and a location in the off-equatorial
zone to study development of the ionospheric anomaly and its severe effects on communications systems.
The full AMISR will have three faces, each of which is a phased-array ISR capable of pulse-to-pulse beam swinging.The
system will provide measurements of electric fields, ion and electron temperatures, electron density, ion composition, and
neutral winds in the meridian plane.Three faces will allow a very wide area to be studied from a single location. Alterna-
tively, the faces can be deployed separately since each is in its own right a very powerful system. A complementary set of
optical- and radiowave-based sensors will accompany the deployment of the AMISR and extend its capabilities.
The design of the AMISR is completed and a prototype element has been constructed and tested successfully. Once
the project is approved, a first face can be constructed in about 2 years. Subsequent faces will be online in about the same
time scale.The total cost is $60 million, including the associated additional instrumentation.
the high temporal and spatial resolution observations
needed to drive the assimilative models, which the panel
hopes will parallel the weather forecasting models we
now have for the lower atmosphere. Much of the neces-
sary infrastructure for such a project has already been
demonstrated in the prototype Suominet, a nationwide
network of simple Global Positioning System/meteorol-
ogy stations linked by the Internet. The proposed pro-
gram would add miniaturized instruments, such as all-
sky imagers, Fabry-Perot interferometers, very-low-
frequency receivers, passive radars, magnetometers, and
ionosondes in addition to powerful GPS-based systems
in a flexible and expandable network coupled to fast,
real-time processing, display, and data distribution ca-
pabilities. Instrument clusters would be sited at universi-
ties and high schools, providing a rich hands-on envi-
ronment for students and training with instruments and
analysis for the next generation of space scientists. Data
and reduced products from the distributed network
would be distributed freely and openly over the Internet.
An overall cost of $100 million over the 1 O-year plan-
ning period is indicated. Estimated costs range from
$50,000 to $150,000 per station depending on the in-
struments to be deployed. Adequate funding would be
included for the development and implementation of
data transfer, analysis, and distribution tools and facili-
ties. Such a system would push the state of the art in
information technology as well as instrument develop-
ment and miniaturization.
Extendi ng the present radar-centered upper atmo-
spheric observatories to include one or more lidar-cen-
tered facilities is crucial if we are to understand the
boundary between the lower and upper atmosphere.
Fortunately, a number of military and nonmilitary large-
aperture telescopes may become avai fable for transition
to lidar-based science in the next few years. Highest
priority would be given to a facility at the same geo-
graphic latitude as one of the existing radar sites.
NASA ORBITAL PROGRAMS
The Explorer program has since the beginning of the
space age provided opportunities for studying the geo-
space environment just as the Discovery program now
provides opportunities in planetary science. The contin-
ued opportunities for University-Class Explorer (UNEX)
(Box 3.3), Small Explorer (SMEX), and Medium-Class
Explorer (MIDEX) missions, practically defined in terms
of their funding caps of $1 4 mi l l ion, $90 mi l l ion, and
$180 million, allow the community the greatest creativ-
ity in developing new concepts and a faster response
time to new developments in both science and technol-
ogy. These missions also provide a crucial training
grou nd for graduate students, managers, and engi neers.
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1 77
Small spacecraft missions can be extremely productive scientifically and can also provide a fertile training ground for
students of science and engineering. NASA has attempted to establish several new lines of small-end missions, including
the UNEX mission line in space science. Of course, the Small Explorer (SMEX) program (at a larger scale size and cost) has
been a remarkable success, and the smaller sounding rocket and balloon programs have in the past been immensely rich
and rewarding programs. In carrying out the Student Explorer Demonstration Initiative (STEDI) program,the Universities
Space Research Association set an excellent tone for how to manage small missions. Appropriate levels and numbers of
reviews were employed and key types of help were provided to STEDI teams, as needed.
It has been widely acknowledged that small-spacecraft missions can provide a profound educational experience for
university students. It has been from the ranks of such highly trained students that many present-day principal investiga-
tors of NASA space science missions have emerged.To have a future space science program with strong experimental
content, the United States must ensure that student training continues to be a high priority. This demands that small,
focused spacecraft missions be available to the university research community,which in turn means that an ample number
of spacecraft payloads must be made available to researchers.
The NASA UNEX program was generally viewed as a direct successor to the STEDI program. However, UNEX has been
effectively cut from future NASA budgets. It is regrettable that this program and the opportunities afforded by the STEDI
concept will not be available to university scientists for research and educational opportunities. Moreover,the stresses that
apparently continue to occur in the sounding rocket and balloon programs of NASA suggest that the suborbital program
also is very limited in the access to space it gives for young scientists and engineers and as a hands-on training ground for
them. See A Space Physics Paradox for further discussion.3
It would seem that NASA has identified larger-spacecraft missions as its primary focus of attention and funding.This
means that very small, Pl-class spacecraft missions are not a high priority for it. NASA and other agencies could serve the
university community in a most beneficial and effective way if they would offer low-cost launch possibilities to university
groups. This would allow the community to revivify the UNEX program, establish appropriate small-spacecraft launch
capabilities, strengthen the engineering and science education program, and fully develop this nation's small satellite
program potential. In carrying out these steps, the agencies would perform an immense service for university researchers
throughout the nation. At a cost of ~$20 million per mission and with launches once or so per year, the program would
make very modest resource demands.
NRC. 1994. A Space Physics Paradox: Why Has Increased Funding Been Accompanied by Decreased Effectiveness in the Conduct of Space Physics Research?
National Academy Press,Washington, D.C.
Imager for Magnetopause-to-Aurora Global Exploration
(IMAGE), launched in March 2000,is an example of a
highly successful MIDEX mission; it was preceded by
the first two ongoing SMEX missions, Solar Anomalous
and Magnetospheric Particle Explorer (SAMPEX) and
FastAuroral Snapshot Explorer (FAST), launched in 1992
and 1996, which have provided enormous scientific re-
turn for the investment. The Aeronomy of Ice in the
Mesosphere (AIM) SMEX was recently selected for
launch in 2006. The UNEX program, after the great suc-
cess of the Student Nitric Oxide Explorer (SNOE),
launched in February 1998, has effectively been can-
celled. This least expensive component of the Explorer
program plays a role similar to the sounding rocket pro-
gram, with higher risk accompanying lower cost and a
great increase in the number of flight opportunities. An
increase in funding to $20 million per mission with one
launch per year would make this program viable with
modest resources.
2. The SMEX and MIDEX programs should be vigor-
ously maintained and the U N EX program should
quickly be revitalized.
The Solar Terrestrial Probe (STP) line of missions
defined in the NASA Sun-Earth Connection (SEC) Road-
map (strategic planning for 2000 to 2025) has the poten-
tial to form the backbone of A-l-M research in the next
decade. The missions that are part of the current pro-
gram includeTIMED, launched in February 2002, Solar-
B, Solar Terrestrial Relations Observatory (STEREO),
MMS, G KC, and MagCon. After TIMED, launched in
February 2002, the next A-l-M/STP mission, MMS, is in
the process of instrument selection for a 2009 launch.
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1 78
The STP cadence, with one A-l-M mission per decade
(TIMED was significantly delayed), has fallen behind the
NASA SEC Roadmap projections.
3. The panel heartily endorses the STP line of missions
and strongly encourages an increase in the launch ca-
dence, with GEC and MagCon proceeding in parallel.
The A-l-M research community has very success-
fully utilized the infrastructure developed within the ISTP
program. The integration of the data from spacecraft and
ground-based programs beyond those funded by the
ISTP project itself such as those of NOAA, LANE, and
the DOD have contributed substantially to our under-
standing of the global system.
Comparisons between the Sun-Earth system and
other Sun-planet or stellar-planet systems provide im-
portant insights into the underlying physical and chemi-
cal processes that govern A-l-M interactions. Improved
understanding of A-l-M coupling phenomena such as
planetary and terrestrial auroras would benefit from such
an approach.
4. The Sun-Earth Connection program partnership with
the NASA Solar System Exploration program should be
revitalized. A dedicated planetary aeronomy mission
should be pursued vigorously, and the Discovery pro-
gram should remain open to A-l-M-related missions.
NASA SUBORBITAL PROGRAM
The NASA Suborbital program has produced out-
standing science throughout its lifetime (Box 3.4~. Many
phenomena have been discovered using rockets, rock-
oons, and balloons, and many outstanding problems
brought to closure, particularly when space-based fa-
cilities are teamed with ground-based facilities. These
phenomena include the auroral acceleration mecha-
nism, plasma bubbles at the magnetic equator, the
charged nature of polar mesospheric clouds, and mono-
energetic auroral beams. This program continues to gen-
erate cutting-edge science with new instruments and
data rates that are more than an order of magnitude
greater than typical satellite data rates. Both unique alti-
tude ranges and very specific geophysical conditions
are accessible only to sounding rockets and balloons,
particularly in the campaign mode. Many current satel-
lite experimenters were trained in the Suborbital pro-
gram, and high-risk instrument development can occur
only in such an environment. To accomplish significant
training, it is necessary that a graduate student remain in
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
a project from start to finish and that some risk be ac-
ceptable; both are very difficult in satellite projects. The
high scientific return, coupled with training of future
generations of space-based experimenters, makes this
program h igh Iy cost-effective.
The sounding rocket budget has been level-funded
for over a decade, and many principal investigators are
discouraged about the poor proposal success rate as
well as the low number of launch opportunities. The
sounding rocket program was commercialized in 2000;
in this changeover, approximately 50 civil service posi-
tions were lost and the cost of running the program
increased. Approved campaigns were delayed by up to
a year, and it is not yet clear whether the launch rate will
ever return to precommercialization levels. Effectively,
commercialization has meant a significant decline in
funding for the sounding rocket program. An additional
concern is that, as currently structured i.e., with a
fixed, 3-year cycle for all phases of a sounding rocket
project funding is not easily extended to allow gradu-
ate students to complete their thesis work, because it is
generally thought that such work should fall under the
SR&T program, already oversubscribed. The rocket pro-
gram has a rich history of scientific and educational
benefit and provides low-cost access to space for uni-
versity and other researchers. Further erosion of this pro-
gram will result in fewer and fewer young scientists with
experience in building flight hardware and will ulti-
mately adversely affect the much more expensive satel-
lite programs.
5. The Suborbital program should be revitalized and its
funding should be reinstated to an inflation-adjusted
value matching the funding in the early 1980s. To fur-
ther ensure the vibrancy of the Suborbital Program, an
independent scientific and technical panel should be
formed to study how it might be changed to better
serve the community and the country.
SOCIETAL IMPACT PROGRAM
The practical impact on society of variations in the
A-l-M system falls into two broad categories: the well-
established effects of space weather variations on tech-
nology and the less clear yet tantalizing influence of
solar variability on climate. The societal impacts of
space weather are broad commun ications, navigation,
human radiation hazards, power distribution, and satel-
lite operations are all affected. Space weather is of in-
ternational concern, and other nations are pursuing par-
allel activities, which could be leveraged through
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
1 79
NASAL Suborbital program provides regular, inexpensive access to near-Earth space for a broad range of space science
disciplines, including space plasma physics, astronomy, and microgravity. The program has been extremely successful
throughout its history, consistently providing high scientific return for the modest funding invested. Phenomena from
auroral physics to supernovae have been investigated with sounding rocket and balloon experiments, and many key
discoveries in these fields have come from this program. For the science of lower-altitude regions such as equatorial
ionospheric irregularities and mesospheric physics, this program provides the only access because these regions are too
high for airplanes and too low for satellites. Moreover, the use of new, advanced instrumentation concepts coupled with
data rates that exceed those of satellites by a factor of more than 10 have provided measurements of a resolution and
quality that are simply unobtainable elsewhere.This science is exciting and central to NASAL mission.
The program also has a spectacular track record in training future scientists and engineers. More than 300 Ph.D.theses
have been based on rocket data alone.This has provided a regular flow of technically adept individuals who have first-
hand experience in building space flight instrumentation. Indeed, most of today's successful satellite experimenters were
trained in this program.The experience that students receive developing, flying, and interpreting data from instruments
they themselves have built is only possible within this program.This is an unparalleled learning experience that satellite
programs cannot match because they are too risk-averse and span too long a period for a graduate student to be involved
from start to finish.
Despite this tremendous track record in which the Suborbital program has continually demonstrated its scientific
validity (made clear through a series of reviews over the past decade), funding for the program has seriously eroded. Its
conversion to a government-owned, contractor-operated program, coupled with loss of many civil servant positions, has
left the program severely underfunded for operations. Additionally, funding for scientific investigations has remained
stagnant, resulting in a significant decline in the number of funded investigations over the past 15 years.There is -treat
.~ , .~ .~ .~ , , .~
. . . . . . . . . . . . . .
concern among the scientific community that NAbA management does not deem the program sutticlently Important to
restore and protect its funding.This attitude must be changed and the program must be restored to a healthy level that will
allow it to continue to play its important scientific and student training roles in which it is so uniquely effective.SeeA Space
Physics Paradox for further discussion.3
NRC. 1994. A Space Physics Paradox: Why Has Increased Funding Been Accompanied by Decreased Effectiveness in the Conduct of Space Physics Research?
National Academy Press,Washington, D.C.
collaboration. The role of solar variability in climate
change remains an enigma, but it is now at least being
recogn ized as i mportant to ou r u nderstand i ng of the
natural as opposed to anthropogenic sources of cli-
mate variabi I ity.
6. To maximize the societal impact of studies and
knowledge of the A-l-M system, the study of solar vari-
ability both of its short-term effects on the space ra-
diation environment, communications, navigation, and
power distribution and of its effect on climate and the
upper atmosphere should be intensified by both mod-
eling and experimentation.
NASA's Living With a Star program, as defined by
the Science Architecture Team report, should be imple-
mented, with increased resources for the geospace com-
ponent. The share of resources required for the Solar
Dynamics Observatory, already defined before the start
of LOOS, has resulted in an unbalanced portfolio.
Missions such as the National Polar-orbiting Opera-
tional Environmental Satellite Systems (NPOESS) and
Solar Radiation and Climate Experiment (SO RCE) should
provide vital scientific data for monitoring long-term
solar irradiance, and NPOESS should provide iono-
sphere and upper atmosphere observations to fill gaps in
measurements needed to understand the A-l-M system.
An L1 monitor should be a permanent facility, to
provide solar wind measurements crucial to determin-
ing the response of the A-l-M system to its external driver.
The National Space Weather Program should be
strengthened and used as a template for interagency
cooperation. International participation in such large
scope programs as LWS and NSWP is essential.
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1 80
NASA's new Living With a Star program can, over
the next decade, provide substantial new resources to
address these goals. It is crucial that there be overlap
between the geospace and solar mission components of
LWS for the A-l-M system to be studied synergistical Iy,
that resources be adequate for the geospace compo-
nent, and that theory, modeling, and the comprehensive
data system that will replace the ISTP infrastructure be
defined at the outset, as called for in the Science Archi-
tecture Team report.2 The National Space Weather Pro-
gram, a multiagency endeavor establ ished in 1 995, ad-
dresses the potentially great societal impact of the
physical processes from the Sun to Earth that affect the
near-Earth environment in ways as diverse as terrestrial
weather. The program specifically addresses the need to
transition scientific research into operations and to assist
users affected by the space environment. Such
multiagency cooperation is essential for progress in pre-
dicting response of the near-Earth space environment to
short-term solar variabi I ity.
Several potential mechanisms for a solar variability-
climate connection have been suggested: (1 ) changes in
the Sun's total irradiance or luminosity, which is the
basic driver of the climate system; (2) changes in spec-
tral irradiance, particularly in the UV, which drives the
chemistry and dynamics of the middle atmosphere and
has been shown by modeling studies to influence the
dynamics of the troposphere; and (3) the possible influ-
ence of cosmic-ray and electric-field variations on cloud
nucleation, which could significantly modify Earth's ra-
diation balance.
7. The NOAA, DOE/LAN L, and DOD operational
spacecraft programs should be sustained and DOD
launch opportunities should be utilized for specialized
missions such as geostationary airglow imagers, auroral
oval imagers, and neutral/ionized medium sensors.
The interagency cooperation established in the
NSWP is outstanding and is a model for extracting the
maximum benefit from scientific and technical pro-
grams. It has also been effective at bringing together
different scientific disciplines and the scientific and op-
erations communities. Interagency cooperation has
2NASA, Living With a Star, Science Architecture Team. 2001 . Report
to the Sun-Earth Connection Advisory Subcommittee, August. Avail-
able on I i ne at .
THE SUN TO THE EARTH AND BEYOND: PANEL REPORTS
worked well in the AFOSR/NSF Maui Mesosphere and
Lower Thermosphere Program, and it has been key to
the success of the NOAA GOES and NPOESS programs
of meteorlogical satellites with space environment moni-
toring capabilities. International multiagency coopera-
tion has been very successful for the ISTP program,
which involves U.S., European, Japanese, and Russian
space agencies. Global studies require such inter-
national cooperation. The panel recognizes that much
more science can be extracted by careful coordination
of ground- and space-based programs.
MAXIMIZING SCIENTIFIC RETURN
Funding for NASA Supporting Research and Tech-
nology, including guest investigator studies and focused
theory, modeling, and data assimilation efforts, is essen-
tial for maximizing the scientific return from large in-
vestments in spacecraft hardware.
Supporting Research and Technology
While spacecraft hardware projects are concen-
trated at relatively few institutions, the NASA SR&T
program is the primary vehicle by which independent
investigations can be undertaken by the broader com-
munity. Likewise, NSF helps individual investigators to
carry out targeted research through its Division of Atmo-
spheric Sciences base programs SH I N E, CEDAR, and
GEM. Such individual Pl-driven initiatives are the most
inclusive, with data analysis as wel I as theoretical efforts
and laboratory studies, and often lead to the highest
science return per dollar spent. The funding for such
program elements falls far short of the scientific oppor-
tunities, with the current success rate for submitted
NASA SR&T proposals being 10 to 20 percent. Further-
more, limited available SR&T funds have been used for
guest investigator participation in underfunded STP-class
flight programs. Without adequate MO&DA funding for
NASA orbital and suborbital programs, the SR&T budget
intended for targeted research on focused scientific ques-
tions has been utilized to support broader data analysis
objectives.
8. The funding for the SR&T program should be in-
creased, and STP-class flight programs should have their
own targeted postlaunch data analysis support.
9. A new small grants program should be established
within NSF that is dedicated to comparative atmo-
spheres, ionospheres, and magnetospheres (C-A-I-M).
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PANEL ON ATMOSPHERE-IONOSPHERE-MAGNETOSPHERE INTERACTIONS
1 81
The comparison of the Sun-Earth system to other Sun-planet systems can provide unique insights into how atmo-
spheres, ionospheres, and magnetospheres (A-l-M) respond to solar inputs.The physical and chemical processes control-
ling these responses manifest themselves very differently at each solar system body,yet are essentially the same at a basic
level.AII the techniques that have been used so successfully to understand solar-terrestrial physics (e.g., modeling,ground-
based and remote observations, and in situ measurements) need to be applied to other planets and bodies, so that the
study of solar-planetary relations becomes the natural extension of the terrestrial space weather effort.Achieving this goal
will require several elements, including NASA planetary missions dedicated to A-l-M goals (or including significant A-l-M
capabilities),a Discovery program in which A-l-M missions are included,and a grants program within NSF that is dedicated
to comparative atmospheres, ionospheres, and magnetospheres (C-A-I-M).
A new C-A-I-M grants program at NSF would play a key role in addressing the interdisciplinary issues needed to
understand and relate A-l-M processes throughout our solar system, or even at other stellar systems. Such a grants pro-
gram would provide much needed resources for analysis of both past and future data sets (from ground- or space-based
observatories, or from in situ missions), modeling and data interpretation related to A-l-M objectives, telescope time,
special meetings devoted to terrestrial-planetary issues, and the nonmission research support needed to encourage
C-A-I-M science activities in the community. Such a grants program would need about $5 million per year in order to
adequately develop and explore the linkages between the terrestrial and planetary manifestations of atmosphere-
ionosphere-magnetosphere physics.
A new C-A-I-M grants program at NSF (Box 3.5) such programs as NASAls ISTP and its Sun-Earth Con-
would allow the techniques that have been applied so nections Theory Program, the AFOSR/ONR Multidisci-
successfully to A-l-M processes at Earth (modeling, plinaryUniversityResearch Initative program, NSFSci-
ground- and space-based observations, and in situ mea- ' - ' ' ^ ' '
surements) to be used to understand A-l-M processes at
other planets. Such a comparative approach would im-
prove understanding of these processes throughout the
sol ar system, i ncl ud i ng at Earth. Presently, a modest $2
million Planetary Science program at NSF covers all of
solar system science (except for solar and terrestrial stud-
ies), with only a small fraction going to planetary A-l-M
research.
Theory, Modeling, and Data Assimilation
Theory and modeling provide the framework for in-
terpreti ng, understand) ng, and visual izi ng diverse mea-
surements at disparate locations in the A-l-M system.
There is now a pressing need to develop and utilize data
assimi ration techniques not only for operational use in
specifying and forecasting the space environment but
also to provide the tools to tackle key science questions.
The modest level of support from the NSF base pro-
grams (CEDAR, GEM, SHINE) and NASA SR&T has been
inadequate to build comprehensive, systems-level mod-
els. Rather, individual pieces have been built and first
stages of model integration achieved with funding from
, , ,
ence and Technology Center programs, and the
multiagency support for such efforts as the Community
Coordinated Modeling Center. Such programs enable
the development of theory and model ing infrastructure,
including models to address the dynamic coupling be-
tween neighboring geophysical regions. Their value to
the research community is clearly their provision of
longer-term funding, which has been essential to devel-
oping a comprehensive program, outside the purview of
SR&T.
10. The development and utilization of data assimila-
tion techniques should be enhanced to optimize model
and data resources. The panel endorses support for
theory and model development at the level of the NASA
Sun-Earth Connections Theory Program, the AFOSR/
ONR MURI program, NSF Science and Technology
Center programs, and the multiagency support for such
efforts as the Community Coordinated Modeling Center
(CCMC). Support should be enhanced for large-scope,
integrative modeling that applies to the coupling of
neighboring geophysical regions and physical pro-
cesses, which are explicit in one model and implicit on
the larger scale.
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Representative terms from entire chapter:
space weather
182
The preceding science recommendations are
grouped into three cost categories and prioritized in
Table 3.1. Equal weight is given to STP and LWS lines, as
indicated by funding level. Small programs are ranked
by resource allocation, while the Advanced Modular
Incoherent Scatter Radar is the highest-priority moder-
ate initiative at lower cost than others.
BIBLIOGRAPHY
GEM documents. Available online at
