Conference PaperPDF Available

Emerging Slovak space technologies and satellites

Authors:
  • Slovak Organisation for Space Activities (SOSA)
  • Slovak Organisation for Space Activities

Abstract and Figures

The Slovak Organisation for Space Activities (SOSA) has been active in various types of space-related activities since its establishment in 2009. They include launching stratospheric balloons, the development of the first Slovak suborbital rocket ARDEA, a spaceflight simulator and many others. SOSA, together with the Žilina University in Žilina, the Slovak Technical University in Bratislava, the Technical University Košice and a handful of private companies, have designed and created the first Slovak satellite skCUBE, which is due to be launched into space in 2017. The numerous unique technologies, which have been developed during the creation of skCUBE, are now being sold as products internationally. Recently, an effort to create a new space vision and strategy for Slovakia has been initiated by SOSA, together with several Slovak universities and international partners, including the Technion – Israel Institute of Technology and the ETH Zurich University. Their plan is to develop and launch a CubeSat fleet to detect gamma ray bursts from space. Part of this initiative is also the establishment of space incubators by SOSA across Slovakia to train and involve students directly space-related technologies.
Content may be subject to copyright.
Emerging Slovak Space Technologies and Satellites
Michaela Musilová, Jakub Kapuš, Robert Laszlo
Slovak Organisation for Space Activities (SOSA)
Faculty of Electrical Engineering and Information
Technology of the Slovak University of Technology in
Bratislava
Bratislava, Slovakia
e-mail: musilova@sosa.sk, jakub.kapus@sosa.sk,
robert.laszlo@sosa.sk
Norbert Werner
tvös Loránd University in Budapest, Hungary
& Department of Theoretical Physics and Astrophysics at
the Masaryk University in Brno, Czech Republic
e-mail: norbertw@stanford.edu
AbstractThe Slovak Organisation for Space Activities (SOSA)
has been active in various types of space-related activities since
its establishment in 2009. They include launching stratospheric
balloons, the development of the first Slovak suborbital rocket
ARDEA, a spaceflight simulator and many others. SOSA,
together with the Žilina University in Žilina, the Slovak
Technical University in Bratislava, the Technical University
Košice and a handful of private companies, have designed and
created the first Slovak satellite skCUBE, which is due to be
launched into space in 2017. The numerous unique
technologies, which have been developed during the creation of
skCUBE, are now being sold as products internationally.
Recently, an effort to create a new space vision and strategy for
Slovakia has been initiated by SOSA, together with several
Slovak universities and international partners, including the
Technion Israel Institute of Technology and the ETH Zurich
University. Their plan is to develop and launch a CubeSat fleet
to detect gamma ray bursts from space. Part of this initiative is
also the establishment of space incubators by SOSA across
Slovakia to train and involve students directly space-related
technologies.
Keywords-satellite technologies; stratospheric probes; sub-
orbital rockets; outreach; incubator; GALILEO
I. INTRODUCTION
SOSA is a civic association founded in 2009 with the
main purpose of supporting and boosting the space industry
in Slovakia. Specifically, members of SOSA aimed to help
make Slovakia become a full member of the European Space
Agency (ESA) by advocating the importance of the space
sector for Slovakia. It is estimated the space sector can bring
a great return for each Euro invested into it, just like NASA
worked out that over their history, for every $1 they have
invested into space technologies they received approximately
$4 back, even with all of their failed missions. Furthermore,
full membership in ESA would open the gates to a vast
amount of new research/industrial collaborations, grants,
jobs for Slovakians and generally greater access to European
and worldwide facilities and opportunities.
Initially, SOSA started off by regularly doing a great
number of outreach and educational activities, in order to
promote the importance of science and research. Nowadays,
members of SOSA are very active in organising tens of
space-related presentations, workshops and educational
activities each year for students, the general public and
companies. These include the organisation of many
competitions for school and university students, such as
Expedition Mars (a Czech and Slovak cooperative
competition) and Mission to Mars (a cooperative project with
the Slovak electricity company Slovenské elektrárne to allow
students to part-take in a simulated mission to Mars in the
USA).
Gradually, SOSA started to develop their own space-
related technologies. They began with designing and
building stratospheric balloon probes and successfully
launched 17 flights ~40 km in the atmosphere. Several
companies and universities joined in to design experiments
and technologies to test in the stratosphere, including:
biological (the monitoring of DNA degradation due to the
radiation in the stratosphere), technological (e.g. CubeSat
testing flights, FPGA GPS, etc.), physics-related (cosmic ray
detectors, whistlers and others) and astronomical studies
(meteor cameras and more) [1]-[8]. Ultimately, SOSA
wanted to show the great potential we have in Slovakia and
to prove that we are able to develop space technologies just
like all our neighbouring countries.
These experiences helped members of SOSA acquire
enough know-how to attempt to build the first Slovak
satellite skCUBE [9], due to be launched into space in 2017.
It is important to note that most of the members of SOSA
work on the great variety of SOSA projects voluntarily, in
their spare time and with no financial reward. The first
Slovak satellite is thus a purely volunteer project, launched
by a group of students and amateurs, later joined by several
universities and companies. Today, SOSA actively
cooperates with a number of foreign companies, universities
and organizations, including the German Space Agency,
International Space University (ISU), the Czech Academy of
Sciences and many others.
The many years of SOSA’s efforts payed off, as thanks
them in great part and what they proved with skCUBE, the
Slovak government signed a cooperating agreement with
ESA in 2010, and then the ECS agreement in 2015.
Consequently, Slovak companies and research institutions
now have an opportunity to participate in ESA grant calls,
various new space-related collaborations and young people
have countless new possibilities to study and work in ESA
member countries. Other SOSA successes include SOSA
being the first in the world verify the GALILEO navigation
system in a car, while driving in 2014. SOSA’s spin-off
company GOSPACE received a certificate from ESA for
carrying out a successful test of GALILEO. Moreover,
members of SOSA include a few Slovak top scientists and
engineers, who have received many grants and awards, for
example from NASA, ESA, the Forbes ranking of the 30
most talented Slovaks under 30, the Emerging Space Leaders
Grant from the International Astronautical Federation and
others.
II. FIRST SLOVAK SATELLITE SKCUBE
A. Unique Technologies
skCUBE is the first satellite completely designed and
built in Slovakia, which is due to be sent to outer space in
2017 (Fig. 1). The satellite is a 1U cubesat and it was built
essentially from scratch by SOSA. It was based on
experiences from precursor projects of sending cubesat-like
payloads and probes attached to meteorological balloons,
called skBalloon, into the Earth's stratosphere [1]-[8]. They
were designed in a modular fashion, and equipped with
communication/navigation systems and sensor platforms.
This technology was further developed, with multiple
enhancements, and incorporated into the skCUBE over 5
years. A specialized team, brought together by SOSA,
designed and constructed almost all of the satellite and its
subsystems: circuit boards, sensors, power system unit, on-
board computer, parts of the testing equipment, software,
testing and calibration methods, etc.
Figure 1. skCUBE on a vacuum chamber plate at the Institute for
Experimental Physics in Košice, shortly before vacuum tests.
The heart of the satellite is a redundant computer with a
radiation hardened processor and a custom real-time
operating system [10], [11]. The communication module is
redundant as well. It has a specially designed code, which
ensures that it functions properly even at a low signal to
noise ratio. Its primary channel operates at 437 MHz.
Experimental transmission of pictures from the on-board
camera is performed at 2.4 GHz with a unique patch antenna.
The power supply occupies the most complicated circuit
board, which gains and stores energy delivered from the
solar panels. The stabilization and orientation system is a
complex piece of engineering. It controls the orientation
using data from a gyroscope, magnetometer, sensors looking
at the position of the Sun and Earth’s horizon, and active
coils pushing the satellite against the Earth’s magnetic field
as is necessary.
B. Very Low Frequency Receiver
The first Slovak satellite skCUBE carries an
experimental very low frequency (VLF) receiver. It is the
main on-board scientific detector and its main purpose is to
detect VLF radio waves (with frequencies up to 30 kHz)
from different natural sources. The VLF receiver consists of
a nearly square-shaped air-core coil antenna (Fig. 2),
commonly known as a magnetic loop [12]. An operational
amplifier amplifies the signal from the coil. The signal is
then delivered to an internal analog-to-digital (AD) converter
in a microcontroler, which subsequently processes it. Its
digital filtration, Fourier analysis and event detection, based
on a power flux density, is performed directly on-board the
satellite. The receiver works in 2 modes. The first slow one
allows for the monitoring of the evolution of spectral
changes throughout skCUBE’s orbit and the detection of
potential anomalies. The second mode executes very fast
sampling of the detected signal, based on an excess of power
flux density over specific limits.
Figure 2. Two identical coils, of which one was enclosed into a plastic
container and attached to the experimental power circuit board of skCUBE.
The VLF receiver will allow for the detection of fast
events occurring in Earth’s atmosphere and signals
originating from lightning discharges in the Earth's
atmosphere, such as whistlers [13]-[15]. These signals can be
used to analyse the Earth’s ionosphere, magnetosphere and
terrestrial lightning. Emissions of a whistler-mode chorus or
hiss [16], [17] at higher geomagnetic latitudes (above 65°)
might be observable by this receiver as well. Space-born
detectors with magnetic loop antennas have the advantage of
being sensitive in the VLF radio band, which is very
interesting from a scientific perspective. Moreover, they are
small and can be easily placed on the printed circuit boards
of CubeSats. However, the receiver suffers from the
proximity of internal electronics, hence boosting
electromagnetic noise to a higher level.
SOSA is currently planning on using skCUBE for the
measurements of electric discharges originating in the
atmosphere. Furthermore, SOSA is also keen on
collaborating with other researchers/institutions interested in
using the VLF and other skCUBE data.
Although this satellite’s mission started off as a
demonstration of Slovak research and development
capabilities in the space sector, for education and public
outreach intentions, the SOSA team has also developed
several unique technologies and the VLF scientific
experiment. The unique technologies include the design of a
special Sunsensor with a precision under and high-speed
data transfer on the 13cm band (2401 MHz) using a
deployable patch antenna. The skCUBE project allowed for
the acquisition of the know-how and training of many Slovak
engineers in the design and development of satellite
technologies as well. Furthermore, several start-ups emerged
from this project and SOSA is now planning greater
international satellite projects.
III. NEW SATELLITE TECHNOLOGIES
In recent years, nano-satellites (CubeSats) have become
very popular in the space industry and research, due to their
small size, modularity and low costs associated with building
and launching them. They offer a new world of possibilities
in space research and technology development. Projects,
which used to be considered very expensive to perform using
large satellites could now be performed relatively cheaply
using CubeSats. This is what SOSA has great experience
with building nanosatellites with limited resources (for
approximately a third of the typical cost of a nanosatellite
mission).
Despite the practicality of CubeSat mission, many critical
technologies are still missing for more complex missions,
even though hundreds of CubeSats have been launched to
date. For instance, CubeSat technologies for astrophysical,
Earth observation and deep-space missions have yet to be
developed. These include a very precise attitude
determination and attitude control system. SOSA has
developed a highly precise sun sensor for CubeSat
applications, with an accuracy under 1°. However, extremely
precise star trackers will be crucial for astrophysical and
deep space missions. Similarly, the widely used
magnetorquers will not be sufficient for directing CubeSats.
There will be no reliable magnetic field to use during deep-
space missions. Instead, small reaction wheels, ion engines
or cold-gas engines are alternative ways to reach the required
pointing accuracy. NASA JPL MARCO twin CubeSats are
about to test this kind of propulsion during a mission to Mars
next year.
Another critical technology for deep-space CubeSat
missions, and also for the proposed CubeSat fleet to detect
GRBs, are reliable deployable structures. Deployable solar
panels can give us extra solar power, while deployable
scintillator plates can give us more detection area and
increase the chances of positive GRB detection. SOSA, for
example, has experience building a deployable antenna
system for CubeSats, which we are planning on enhancing
for the fleet’s technologies.
Moreover, a reliable, long distance and high-speed
communication link is crucial for any space mission success.
SOSA is experimenting with communication on the 13 cm
band (2.4Ghz) with a downlink speed up to 40-240 kbps, as
well as using auto-corrective codes for repairing damaged
packets. Finally, 3D printed or composite CubeSat structures
are also possible ways of reducing manufacturing costs and
time, and also the weight of the CubeSat. Using composite
structures may further decrease radio noise levels too.
Equally, their impact on the satellite’s thermoregulation may
be the subject of further research.
SOSA plans to develop all of these technologies in the
near future, in collaboration with several international
partners, such as the Technion Israel Institute of
Technology and the ETH Zurich University.
IV. FUTURE PLANS
Recently, an effort to create a new space vision and
strategy for Slovakia has been initiated by SOSA, together
with several Slovak universities. Part of this initiative is the
establishment of space incubators by SOSA across Slovakia,
to train students to gain skills in making space technologies.
The plan is to involve students directly in SOSA’s ongoing
and future projects. Thus, SOSA hopes to increase the
knowledge-based economy in Slovakia and allow students to
get hands-on experience in space-related electronics,
mechanics, programming on microprocessors and other
engineering activities. Currently there are two space
incubators in Bratislava and Kosice, and more will be
established in the next couple of years in more cities in
Slovakia.
Apart the satellite technologies and research projects
mentioned above, SOSA is planning of getting more
involved in developing receivers and making measurements
for GALILEO, following their success with ESA in 2014.
The sub-orbital hybrid rocket ARDEA is still in development
and its first launch tests are currently scheduled for launch in
2018. The rocket is made out of very light composite
materials and it is extremely affordable. It will be used to test
scientific and technological payloads up to 120 km in the
atmosphere. In a similar way, SOSA is planning on using the
near-space (stratosphere) for testing small probes as pseudo-
satellites, which could provide communication and Earth
observation capabilities. These are all projects, which will be
developed in the space incubators.
Finally, SOSA will continue with its original plans in
making space more accessible to Slovak companies, research
organisations, students and the public. Members of SOSA
are hence hoping to give young people interesting research
and work opportunities in Slovakia, so that they will not be
forced to move abroad in search for involvement in the space
sector. This is why SOSA will continue with more outreach
and educational projects, in parallel with their technological
plans.
ACKNOWLEDGMENT
Authors would like to thank INGMETAL Moulds &
Tools, Prešov, Slovakia; the RISE Association, Prague,
Czech Republic; and TOMARK, s.r.o. division TomarkAero,
Prešov, Slovakia for supporting this paper and its
presentation, and all partners supporting project of the first
Slovak satellite skCube mentioned on its official website
www.skcube.sk.
REFERENCES
[1] J. Erdziak, B. Chrenko, J. Kapu_s, M. Kocka, A. Krovina, L.
Krp_alek, A. Kutka, R. Slosiar, and M. Zat'ko. Project skBalloon. In
L. Ouwehand, editor, 20th Symposium on European Rocket and
Balloon Programmes and Related Research, volume 700 of ESA
Special Publication, pages 233{236, October 2011.
[2] L. Lenza, J. Kapus, O. Zavodsky, J. Erdziak, J. Zitka, R. Kizek, and T.
Peciva. Project Together into the Stratosphere. In L. Ouwehand,
editor, 22nd ESA Symposium on European Rocket and Balloon
Programmes and Related Research, volume 730 of ESA Special
Publication, page 641, September 2015.
[3] Lukas Nejdl, Jan Zitka, Kristyna Cihalova, Vedran Milosavljevic,
Amitava Moulick, Ondrej Zavodsky, Zbynek Heger, Jakub Kapus,
Libor Lenza, Vojtech Adam, et al. Fluorescence detection of carbon
quantum dots assessed by stratospheric platform. 2015.
[4] Dagmar Chudobova, Kristyna Cihalova, Pavlina Jelinkova, Jan Zitka,
Lukas Nejdl, Roman Guran, Martin Klimanek, Vojtech Adam, and
Rene [3] Kizek. Effects of stratospheric conditions on the viability,
metabolism and proteome of prokaryotic cells. Atmosphere,
6(9):1290{1306, 2015.
[5] R. Kizek. Projekt preshranicne centrum pro balonove a dalkovo
rizene roboticke systemy.
http://web2.mendelu.cz/nanotech/strato/www/dok/strato-sbornik-29-
5-final.pdf, 2015a. Accessed: 2016-01-10.
[6] R. Kizek. Z_avere_cn_a konference projektu spolecne pro v_Yzkum,
rozvoj a inovace.
https://katalog.mendelu.cz/documents/155176?locale=cs, 2015b.
Accessed: 2016-01-10.
[7] Zbynek Heger, Jan Zitka, Lukas Nejdl, Amitava Moulick, Vedran
Milosavljevic, Pavel Kopel, Ondrej Zavodsky, Jakub Kapus, Libor
Lenza, Milan Rezka, et al. 3d printed stratospheric probe as a
platform for determination of dna damage based on carbon quantum
dots/dna complex uorescence increase. Monatshefte fur Chemie-
Chemical Monthly, pages 1{8, 2016.
[8] J. Koukal. Strato 02/2015 { the perseids 2015 stratospheric balloon
mission. http: //imo.net/news/wgn44-1, 2016. Accessed: 2016-01-10.
[9] Kapuš, J., et al., First Slovak satellite skCUBE. Proceedings of the
Small Satellites, System & Services Symposium (4S), 30 May, 2016
[10] Juraj Slacka and Miroslav Halas. Safety critical rtos for space
satellites. In Process Control (PC), 2015 20th International
Conference on, pages 250{254. IEEE, 2015.
[11] Andrea _Sagatov_a, Martin Magyar, Marko Fulop, Vladimr Necas,
and Michal Rafaj. Radiation hardness of commercial semiconductor
devices for first slovak cubesat. 2015.
[12] Musilova et al, 2016, Very low frequency radio waves detector of the
first Slovak satellite skCUBE, Proceedings of the 67th International
Astronautical Congress (IAC) by the International Astronautical
Federation (IAF), 20-30 September 2016, Mexico, Paper
[13] Robert A Helliwell. Whistlers and related ionospheric phenomena,
volume 1. Stanford University Press Stanford, 1965.
[14] O Santolik, M Parrot, US Inan, D Bure_sov_a, DA Gurnett, and J
Chum. Propagation of unducted whistlers from their source lightning:
A case study. Journal of Geophysical Research: Space Physics,
114(A3), 2009.
[15] Michel Parrot, Jean-Jacques Berthelier, J Blecki, JY Brochot, Y
Hobara, Dominique Lagoutte, Jean-Pierre Lebreton, F N_emec,
Tatsuo Onishi, Jean-Louis Pin_con, et al. Unexpected very low
frequency (vlf) radio events recorded by the ionospheric satellite
demeter. Surveys in Geophysics, 36(3):483{511, 2015.
[16] O Santolik, J Chum, M Parrot, DA Gurnett, JS Pickett, and N
Cornilleau-Wehrlin. Propagation of whistler mode chorus to low
altitudes: Spacecraft observations of structured elf hiss. Journal of
Geophysical Research: Space Physics, 111(A10), 2006.
[17] [Michel Parrot, Ondrej Santolik, and Frantisek Nemec. Chorus and
chorus-like emissions seen by the ionospheric satellite demeter.
Journal of Geophysical Research: Space Physics, 121(4):3781{3792,
2016.
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
The application of ultraviolet (UV) radiation to inhibit bacterial growth is based on the principle that the exposure of DNA to UV radiation results in the formation of cytotoxic lesions, leading to inactivation of microorganisms. Herein, we present the impacts of UV radiation on bacterial cultures’ properties from the biological, biochemical and molecular biological perspective. For experiments, commercial bacterial cultures (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) and isolates from patients with bacterial infections (Proteus mirabilis and Pseudomonas aeruginosa) were employed. The above-mentioned strains were exposed to UV using a laboratory source and to stratospheric UV using a 3D printed probe carried by a stratospheric balloon. The length of flight was approximately two hours, and the probe was enriched by sensors for the external environment (temperature, pressure and relative humidity). After the landing, bacterial cultures were cultivated immediately. Experimental results showed a significant effect of UV radiation (both laboratory UV and UV from the stratosphere) on the growth, reproduction, behavior and structure of bacterial cultures. In all parts of the experiment, UV from the stratosphere showed stronger effects when compared to the effects of laboratory UV. The growth of bacteria was inhibited by more than 50% in all cases; moreover, in the case of P. aeruginosa, the growth was even totally inhibited. Due to the effect of UV radiation, an increased susceptibility of bacterial strains to environmental influences was also observed. By using commercial tests for biochemical markers of Gram-positive and Gram-negative strains, significant disparities in exposed and non-exposed strains were found. Protein patterns obtained using MALDI-TOF mass spectrometry revealed that UV exposure is able to affect the proteins’ expression, leading to their downregulation, observed as the disappearance of their peaks from the mass spectrum.
Conference Paper
In many practical applications, that can be found in control engineering, the functionality and safety of the overall control process rely on a proper function of the respective operating system. This fact makes the software one of the most safety critical elements of such practical applications, especially when the control process is placed in an inhospitable environment not directly accessible to man. One of such environments is Space. In this paper a problem of designing a safety critical real time operating system for a small space satellite called CubeSat is discussed. It is shown how to design such an operating system and how to increase its reliability and to protect it against single upset events.
Article
A lot of different emissions have been detected by the low-altitude satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), and the aim of this paper is to study extremely low frequency (ELF) electromagnetic waves with elements drifting in frequency. It is shown that only some of them can be considered as usual chorus. These chorus elements are emitted in the equatorial plane, and their propagation analysis indicates that they are going downward at low altitudes in the ionosphere to be detected by the satellite. The study of one remarkable event recorded along the same orbit in both the Northern and the Southern Hemispheres on 8 May 2008 indicates that this propagation mechanism is reinforced at the location of the ionospheric trough, which corresponds to the plasmapause at higher altitudes. It has been observed that usual chorus elements at low frequencies are always in a frequency band which overlaps with a hiss band limited by a frequency cutoff close to the proton gyrofrequency. Other drifting elements can be attributed to emissions triggered by PLHR (power line harmonic radiation). It means that without a high-resolution spectral analysis, chorus-like elements triggered by PLHR can be wrongly considered as natural chorus. These drifting elements can also appear as filamentary structures emerging at the upper frequencies of a hiss band or quasiperiodic emissions. There are events where the elements even have certain similarities to quasiperiodic emissions. The difference between these elements and the chorus emissions will be emphasized.
Article
We present a utilization of carbon quantum dots (CQDs), passivated with polyethylene glycol as a fluorescent recognition probe for DNA damage. Synthesized CQDs were characterized in detail, using optical and electrochemical methods. Further, fluorescent behavior of CQDs was monitored in the presence of genomic DNA, isolated from Staphylococcus aureus. In laboratory conditions, after 30 min of exposure to UV irradiation (λ = 254 nm), the DNA/CQDs complex significantly increased its fluorescence. Further, stratospheric probe was suggested and crafted by using technology of 3D printing (acrylonitrile–butadiene–styrene as a material). CQDs were exploited to evaluate the DNA damage in stratospheric conditions (up to 20,000 m) by determination of fluorescence increase (λ exc = 245 nm, λ em = 400 nm), together with other parameters (temperature, humidity, altitude, pressure, UV intensity, and X-ray irradiation). The obtained data showed that the sensor utilizing the DNA/CQDs was able to identify the DNA damage, together with external conditions. It was shown the proposed concept is able to operate at temperatures lower than −70 °C. The proposed protocol may by applicable as a biosensor for long-term space missions, like international space station, missions to the Moon or Mars.
Article
DEMETER was a low Earth orbiting microsatellite in operation between July 2004 and December 2010. Its scientific objective was the study of ionospheric perturbations in relation to seismic activity and man-made activities. Its payload was designed to measure electromagnetic waves over a large frequency range as well as ionospheric plasma parameters (electron and ion densities, fluxes of energetic charged particles). This paper will show both expected and unusual events recorded by the satellite when it was in operation. These latter events have been selected from the DEMETER database because they are rare or even have never been observed before, because they have a very high intensity, or because they are related to abnormalities of the experiments under particular plasma conditions. Some events are related to man-made radio waves emitted by VLF ground-based transmitters or power line harmonic radiation. Natural waves, such as atypical quasi-periodic emissions or uncommon whistlers, are also shown.
Article
The project skBalloon aims to construct and launch near-space balloons (Nobuyuki et al, 2004) connected to a pay-load being able to transport various instruments as CCD cameras, different detectors or commercial load to the earth's stratosphere in approximately 40 km height above the ground. The project intends mainly to raise awareness and interest about space sciences within broad public and remind them on importance of space exploration. Com-pared to many other countries Slovakia lag behind during last years in this research field with few exceptions. This should be changed in near future by a Slovakian coop-eration agreement with the European Space Agency and activities of the Slovak Organization for Space Activities.
Article
1] We analyze nightside measurements of the DEMETER spacecraft related to lightning activity. At the 707 km altitude of DEMETER, we observe 3-D electric and magnetic field waveforms of fractional-hop whistlers. At the same time, the corresponding atmospherics are recorded by a very low frequency (VLF) ground-based station located in Nançay (France). The source lightning strokes are identified by the METEORAGE lightning detection network. We perform multidimensional analysis of the DEMETER measurements and obtain detailed information on wave polarization characteristics and propagation directions. This allows us for the first time to combine these measurements with ray-tracing simulation in order to directly characterize how the radiation penetrates upward through the ionosphere. We find that penetration into the ionosphere occurs at nearly vertical wave vector angles (as was expected from coupling conditions) at distances of 100–900 km from the source lightning. The same distance is traveled by the simultaneously observed atmospherics to the VLF ground station. The measured dispersion of fractional-hop whistlers, combined with the ionosonde measurements at the Ebro observatory in Spain, allows us to derive the density profile in the topside ionosphere.
First Slovak satellite skCUBE
  • J Kapuš
Kapuš, J., et al., First Slovak satellite skCUBE. Proceedings of the Small Satellites, System & Services Symposium (4S), 30 May, 2016