AIM - Swedish Institute of Space Physics - Uppsala

AIM
Atmosphere-Ionosphere Mission
Response to the Swedish National Space Board “Call for Ideas”
Proposers:
Prof. Bo Thidé (bt@irfu.se), Doc. Kristof Stasiewicz (ks@irfu.se), Doc. Thomas Leyser(tbl@irfu.se),
M.Sc. Lennart Åhlén (ala@irfu.se)
Swedish Institute of Space Physics, Box 537, 751 21 Uppsala
Phone: 018-471 59 00. Fax: 018-471 59 05
Prof. Anders Rydberg (Anders.Rydberg@signal.uu.se), Dr. Tommy Öberg (Tommy.Oberg@signal.uu.se)
Dept. of Signals and Systems, Uppsala University, Box 528, 751 20 Uppsala
Phone: 018-471 72 83. Fax: 018-55 50 96
Dr. Richard Brenner (Richard.Brenner@tsl.uu.se), M.Sc. Fredrik Edling (Fredrik.Edling@tsl.uu.se)
Dept. of Radiation Sciences, Uppsala University, Box 535, 751 20 Uppsala
Phone: 018-471 38 48. Fax: 018-471 35 13
Dr. Sven Grahn (sg@ssc.se)
Swedish Space Corporation AB, Box 4207, 171 04 Solna
Phone: 08-627 62 00. Fax: 08-98 70 69
Prof. Vernon Cooray (Vernon.Cooray@hvi.uu.se)
Division for Electricity and Lightning Research, Uppsala University, Box 539, 751 21 Uppsala
Phone: 018-471 59 00. Fax: 018-471 59 05
Prof. Sven Nordebo (sno@pop.bth.se)
Dept. of Telecommunications and Signal Processing, Blekinge Institute of Technology, 372 25 Ronneby
Phone: 0457-38 57 24. Fax: 0457-279 14
Prof. Börje Nilsson (Borje.Nilsson@msi.vxu.se)
School of Mathematics and Systems Engineering, Växjö University, 351 95 Växjö
Phone: 0470-70 80 00. Fax: 0470-832 17
Dr. Per-Arne Lindqvist (lindqvist@plasma.kth.se)
Alfvén Laboratory, Royal Institute of Technology, 100 44 Stockholm
Phone: 08-790 76 96. Fax: 08-24 54 31
Prof. Per Lötstedt (Per.Lotstedt@tdb.uu.se)
Dept. of Scientific Computing, Uppsala University, Box 337, 751 05 Uppsala
Phone: 018-471 29 72. Fax: 018-51 19 25
Co-Proposers:
Doc. Daniel Rönnow (daniel.ronnow@racomna.se)
Racomna AB, Uppsala
Dr. Jan Bergman (jan.bergman@redsnake.se)
Red Snake Radio Technology AB, Stockholm
Dr. Per Høeg (hoeg@dmi.dk)
Danish Meteorological Institute, Copenhagen, Denmark
Dr. Torsten Neubert (neubert@dmi.dk), Dr. Fritz Primdahl (fpr@oersted.dtu.dk)
Danish Space Research Institute, Copenhagen, Denmark
Prof. Zbigniew Klos (klos@cbk.waw.pl)
Space Research Centre, Polish Academy of Sciences, Warsaw, Poland
Dr. Nataly Blagoveshchenskaya (nataly@aari.nw.ru), Dr. Viktor Kornienko (vikkorn@aari.nw.ru)
Arctic and Antarctic Research Institute, St. Petersburg, Russia
Dr. Vladimir Frolov (vf@nirfi.sci-nnov.ru), Dr. Saveliy Grach (sg@nirfi.sci-nnov.ru)
Radiophysical Research Institute, Nizhniy Novgorod, Russia
Discipline and type of project:
The AIM mission consists of a number of small high-technology satellites focusing on the use of advanced sensors
(radio, optical, UV, X-ray) for studies of electromagnetic radiation effects in the upper atmosphere and the ionosphere
and draws on the Astrid and nano-satellite technology/Nanny projects as well as the WISP proposal and the long
experience in the development of advanced radio systems for science.

1 Main objectives
1.1 Background
Several successful Swedish missions have explored auroral phenomena in the magnetosphere at the altitude range
1000–6000 km (Freja, Viking, Astrid 1-2) and the recent Odin satellite will contribute to astrophysics and atmospheric
sciences. Furthermore, a number of satellites have explored distant magnetospheric regions, the most prominent
example being the ongoing Cluster project, and several missions aimed at the investigation of other planets,
asteroids and comets are now being implemented by NASA, ESA and Japan Space Agency.
However, the international space science community is presently witnessing vibrant multi-disciplinary research
and a rapidly expanding frontier concerning the interaction of the upper atmosphere and ionosphere. This research
concerns fields such as atmospheric electricity and electrodynamics (including that of thunderstorm centres), space
weather, influence of solar activity on climate, to mention a few. In view of this important activity and, on the other
hand, the decades long trend of missions further and further out in space, we would like to see a mission “back to the
Earth” with a fresh, innovative perspective which also comprises environmental and technology aspects.
Therefore, we propose a series of advanced low-altitude multi-satellite missions for correlated studies of
electromagnetic (EM) radiation phenomena and effects, from DC, via radio, to optical, X-ray or even gamma,
together with basic gas and plasma dynamics, in the upper atmosphere/lower ionosphere. This series of missions
is motivated by the objective to bring new research groups and types of instrumentation into space research
to allow for innovative scientific and technological developments with the purpose of addressing fundamental crossdisciplinary
scientific issues in a field transcending cooperation with world-class research groups.
The atmospheric-ionospheric regions below typical space shuttle altitudes (350–400 km) are very poorly explored
by measurements in situ because of atmospheric drag which shortens satellite lifetimes. This region is of major
scientific importance because it is a transition region between the neutral atmosphere and the completely ionised
magnetosphere, with strong ionisation gradients, electric jets, complicated chemistry, turbulence, dusty plasma and
complex physical phenomena. The processes in this transition region connect the solar and magnetospheric effects
with the atmospheric response which, in fact, determine space weather in the Earth’s environment. This region is also
the part of the Earth’s atmosphere where EM radiation from natural sources such as lightnings, and artificial sources
such as radio, TV and radar transmitters, exhibit resonance and other interaction phenomena. The impact of these
natural and man-made effects on the Earth’s space environment are of major public concern. Hence, studies of such
effects are called for. On the other hand, the ionosphere is a region of closure of magnetospheric current systems and
a reflection layer for Alfvén wave resonators. Consequently, the proposed mission is of considerable interest also for
the solar wind-magnetosphere-ionosphere coupling.
1.2 Science
We suggest that the Atmosphere-Ionosphere Mission (AIM) satellites be designed for correlated studies of EM radiation
phenomena, over an unprecedented wide range of frequencies, in the upper atmosphere and ionosphere, above
typical balloon altitudes (60–80 km) and below typical space shuttle altitudes (350–400 km). The basic instruments
would measure the EM spectrum in the radio range, covering all plasma frequencies and resonances, with possible
extension to the microwave and ionising radiation frequency ranges. The electric and magnetic measurements
should be extended to the DC range, and if possible, by Langmuir probe and particle detectors. We suggest a first
constellation of two microsatellites in the same elliptical orbit in order to help resolve the spatio-temporal ambiguity.
1.2.1 Atmosphere–ionosphere–magnetosphere coupling
The proposed low-altitude mission has direct and immediate implications on environmental, atmospheric, ionospheric,
and fundamental space physics, as well as ionosphere-magnetosphere coupling. The experiments would be
of both the ”Earth and space watching” type to map out the characteristics of the radiation spectrum in geospace, as
well as active investigations of radiation and plasma effects coordinated with ground-based facilities for EM radiation
such as scatter radars, powerful HF transmitters, lidars, and radio telescopes, including the existing Arecibo, Sura,
EISCAT, HAARP, and HIPAS facilities and the planned LOFAR/LOIS infrastructure. 1
In the suggested altitude region a number of important atmospheric and ionospheric layers exist, which can be
studied by sensitive in situ measurements of excited atomic and molecular lines. These lines could be excited by
natural sources or by well defined ground-based sources of, e.g., radio waves, microwaves, and lasers. Similarly,
the detection of absorption bands in the intermediate atmosphere is most useful. Man-made perturbations from the
ground by radio and microwaves, and/or lasers provide promsing novel diagnostic capabilities for the upper atmosphere
and have a technological potential that should be studied by observing the plasma turbulence and associated
1 See www.wavegroup.irfu.se/LOIS
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EM emissions in a wide spectrum. The proposed mission would provide detailed information on the interaction
of microwaves with the ionospheric plasma and the atmosphere, which is important for the suggested solar power
stations at geosynchronous orbits where solar power would be collected and transmitted back to Earth in the form of
microwave beams. The microwave interaction is expected to be largest in the proposed altitude range of the upper
atmosphere/lower ionosphere.
Furthermore, the investigation of the Alfvén wave reflection layer, wave-induced ion heating and outflow from
the ionosphere, as well as energy deposition by energetic particles is of considerable interest for the traditional space
physics community.
1.2.2 Anthropogenic effects on the ionosphere–magnetosphere system
Simultaneous in situ measurements of plasma parameters and EM fields and ground-based measurements will allow
a significant progress in the investigation of ionospheric plasma self-structuring, excitation of plasma turbulence
and the generation of EM emissions both under natural conditions and under the action of EM waves from radio
transmitters on ground or on-board spacecraft.
It has been recently discovered that man-made perturbations from the ground by radio waves can have an impact
on the ionosphere-magnetosphere coupling in the form of artificial triggering of auroral activations, plasma instabilities,
EM emissions and other non-linear phenomena. It is of high importance to obtain further evidences for
such modification of the ionosphere–magnetosphere coupling due to effects of radio waves from the ground on the
high-latitude ionosphere, including the role of the plasma instabilities and non-linear phenomena.
1.2.3 High-energy radiation phenomena
The high-energy photon detector of the Department of radiation sciences (ISV), Uppsala university, would allow
studies of UV and X-ray generation in the Earth’s atmosphere, i.e., by cosmic rays interacting with the atmospheric
gas, a problem of high current interest, lightning associated generation of upper-atmosphere “sprites” and possible
associated high-energy photons, background information on the solar radiation to be used as inputs in precise and
detailed theoretical and numerical models of how ionospheres are created and maintained, and detection of highenergy
photon sources at lower altitudes down to the Earth itself.
1.2.4 Space-borne lightning research
Following some lightning flashes from energetic thunder-clouds, blue jets and red sprites are observed in the atmosphere
above the clouds and into the ionosphere. This phenomena clearly demonstrates that the EM fields generated
by thunder-clouds and lightning couple strongly with the upper atmosphere and the ionosphere. Measurement of
EM radiation up to frequencies of 10 MHz from low altitude satellite would be able to quantify the magnitude of
the electric fields produced by thunderstorms at those altitudes and compare the results with theoretical predictions.
Moreover, the data could be correlated with the weather information and radar observations from ground based stations
to observe the enhancement of the EM fields due to thunderstorms and lightning flashes with an aim to quantify
the heating of the ionospheric electrons due to terrestrial thunderstorms. The data could also be combined with the
information on lightning strikes coming out from the Swedish and US lightning direction finding systems to correlate
the individual enhancements in the EM fields observed at high altitudes with the individual lightning flashes.
Balloon-borne gamma-ray and electric field meters launched into thunderstorms detected a three-fold increase
in the gamma ray flux as the balloon ascended through the anvil of the thunder-cloud. The theory suggests that the
gamma ray bursts are produced by the acceleration of cosmic ray produced seed electrons in thunderstorm electric
fields. This theory calls for a simultaneous measurements of the EM fields and the gamma ray counts and correlation
with the presence of lightning activity.
The first positive band of N 2 is the dominant optical emission of sprites that occur in the altitude range around
70 km. An optical recorder that could detect this band would be able to record the occurrence of sprites in space
and time around the globe. This information could be coupled with the ground based lightning detection systems to
evaluate, not only the number of sprites that are created in the upper atmosphere per second, but also the conditions
under which these lightning flashes are created.
1.3 Technology
1.3.1 Industrial interest and public outreach
The mission with its requirements for smart and small payloads and spacecraft is important for advanced technology
development and of express interest to industry. The same can be said about the low orbit and high data transfer
rates required. The low orbit gives an opportunity for technological developments to reduce the aeronomic drag on
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the spacecraft. The mission would also provide a study of the conditions for the use of space for telecom purposes
(”satellite phones”, ”Internet in the sky” etc.).
Further, by providing simple telemetry receiving systems for educational institutions a public outreach of unprecedented
impact would be gained, which comes in addition to that of the obvious scientific environmental issues
being addressed and the advanced technological requirements by the mission.
1.3.2 Space telecommunication
The ever-increasing quest for more bandwidth and higher signal-to-noise ratios in telecommunications has led to the
utilisation of larger portions of the radio spectrum, higher powers and energy densities, and an increased interest in
and use of low-orbit satellites in wireless point-to-point communication links. This requires a better understanding not
only of the of the effects of the interaction of EM radiation and the near-Earth propagation medium (gas, plasma) but
also development of improved technology. This encompasses “smarter” telecommunications in terms of antennas,
transmitters, receivers, as well as optimised diversity and Multiple-Input-Multiple-Output (MIMO) techniques for
satelite communications, technologies for multiple radio paths and antenna array effects. In particular, investigation
of antennas with full polarization capabilities, exploiting the complete vector nature of the electromagnetic field and
multidimensional signal processing algorithms for computed tomography and image processing with applications
to satelite technology are of high interest. The AIM satellites will be invaluable for developing and testing such
technologies.
2 Short technical description
For the first mission two spin-stabilised microsatellites in the same orbit are suggested. The elliptical orbit should
reach high latitudes and have a perigee as low as possible , thus allowing for a life time of several months. Detailed
computer simulation studies performed by the IRF Uppsala and KTH groups and the Swedish Space Corporation
clearly show that such orbits are indeed possible. To facilitate lowest possible perigee the satellites may be equipped
with on-board propulsion.
IRF in Uppsala have nearly twenty years of experience in developing advanced digital HF radio systems for
scientific use and have, during the past several years, developed similar systems for satellites within the SNSBfunded
project “Nanosatellite Technology.” The design, construction and prototyping of the digital receivers is now
finished. The technology must be considered to be mature and IRF Uppsala therefore commit themselves to providing
HF radiation sensors (antennas, receivers).
The payload would, in addition to the HF radio systems contain other EM radiation sensors, include DC electric
and magnetic field sensors and a Langmuir probe. Mature technologies for these can be provided by the Uppsala,
KTH, Copenhagen, St. Petersburg and Warsaw groups.
The Department of Signals and Systems at Uppsala University will contribute equipment for studies of the telecom
aspects of the missions. This includes communications equipment, passive antenna arrays, and radar. Antenna
systems for the telemetry transceivers will be designed with the objective to minimise the shadowing of the solar
cell from the antenna elements, where novel ways of monolithic integrating the antenna with the solar cells could
be a solution. Communication systems developed over the past years within the Nanosatellite Technology development
project, as well as the signal processing methods for satellite data, and algorithms for safe communication and
transfer of such data, have reached a considerable level of maturity.
To enable this cross-disciplinary mission to become a focal point for innovative cross-fertilisation in science and
technology it is essential that the plasma measurements are complemented by instruments from non-traditional space
users. As an example, ISV at Uppsala University are interested in providing sensors for extremely high frequencies/energies
and expertise in the detection of high-energy photons and particles.
The Digital X-ray Imaging project (DIXI) at the ISV has developed a readout circuit with 31 × 32 pixels each
consisting of a pre-amplifier, shaper, discriminator and two counters. The circuit is designed for subtractive imaging
with single photon counting capabilities. The radiation hardened electronics, which is being used in particle accelerator
experiments, is implemented as a integrated circuit so the instrument will be compact and light-weight. The
sensitivity to photons can be tuned by selecting an appropriate sensor element, typically a flip-chip bonded to the
circuit, and by setting the discrimination threshold in the discriminator. In the DIXI project the energy range 5–100
keV is covered. The technology is also easily applicable to charged particles.
3 Outline of implementation and execution plan
The satellite platform would be based on Astrid-2 (3) technology and on miniaturised subsystems developed in the
nano-satellite technology project. It seems appropriate to have the spacecraft spin stabilised. A precise attitude
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determination is highly desirable, while the need for attitude control is less stringent. The avionic system should
preferably be the CAN-bus based micro-satellite avionics architecture designed by the Swedish Space Corporation
and used in the SMART-1 spacecraft. The Danish Space Reserach Institute is willing to provide a thre-axis magnetic
sensor-star camera combination.
For the HF radio measurements three orthogonal antennas (electric or magnetic) sensing the momentary wave
fields will be needed. The antenna currents are to be sampled digitally with at least 14 bit linear quantisation and
the digital signals are then processed partially on-board and on the ground after being transferred over the telemetry.
The processing will be made with the help of the advanced HF radio signal after-the-fact HF radio signal processing
software that has been developed and refined over nearly two decades at IRF Uppsala as part of their major digital
HF radio receiver development work over the same period of time.
We estimate that the development of an AIM satellite will take two years, with an additional year for each extra
satellite developed if manufactured in a “pipelined” fashion.
Recently a major EU contract for the training of young scientists in space turbulence and turbulent layers was
obtained and this will ensure that optimum utilisation of the AIM data will be made. Synergetic advantages will be
provided by a VINNOVA contract for the development of a high-performance, GRID-enabled database manager for
heterogeneous earth and space observation data. Uppsala University is currently investing heavily in the formation
of a Centre for Studies of Dynamic Processes and Structure Formation (CDP) where high-quality research at the
absolute international forefront will be carried out. Physics of atmospheres, with particular emphasis on turbulence,
has been mentioned to be a prime area for the CDP. The combination of world-leading research in Uppsala in this
area and the proposed AIM satellites holds enormous promise for very significant breakthroughs.
4 User community
One role of the mission is to catalyse an interaction and cross-fertilisation of traditionally rather independent research
areas, such as atmospheric and space physics. An equally important role is to complement and build on the solid
Swedish experience of space plasma experiments with new and advanced measurements capabilities from existing
research groups, which traditionally have not taken part in space missions. In addition to constituting the mission’s
overall multi-disciplinary character such an activity is expected to be rewarding also from the traditional space engineering
point of view. To allow for technological and conceptual development which is important to successively
enable new users of space missions a series of missions are considered.
The atmosphere-ionosphere mission will supported by ground-based facilities such as scatter radars, powerful HF
transmitters, lightning detection systems, lidars, and radio telescopes, including the existing Arecibo, Sura, EISCAT,
HAARP, and HIPAS facilities and the planned LOFAR/LOIS radio and radar infrastructure.
AIM with its timely cross-disciplinary scientific scope is expected to be of interest to the general public and
lends itself very well to public outreach activities. We propose that simple telemetry channels be prepared for at
least some of the data from the mission and receiving facilities be placed at educational institutions such as Swedish
schools (grundskola, gymnasium, högskola). This would provide an excellent opportunity for education and real
involvement of students and the general public in scientific research and environmentally geared projects during an
ongoing high-technology space mission. The public outreach and educational impact is thus expected to become
significantly broader than previous Swedish space missions. It appears particularly important these days to boost the
interest of the general public in the natural sciences.
The Department of Scientific Computing at Uppsala University has a well established high competence in using
and developing numerical methods for the solution of partial differential equations typical for the type of physical
problems to be studied in the AIM mission (such as flow problems, EM radiation and wave propagation). The
department will in December install a new parallel computer with 48 processors wihch together with their special
competence will be available to this cooperative project in space physics to ensure maximum return from the measurements.
5 Internationalisation
The science questions addressed and the cross-disciplinary way in which these questions are asked with AIM are
of utmost significance for the international space research community as well as the general public. In view of the
rapidly growing interest in the outlined scientific problems it is expected that the mission will have significant impact
on international environmental, atmospheric, and space physics research.
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