6 research outputs found
Auroral imaging with combined Suomi 100 nanosatellite and ground-based observations: A case study
Auroras can be regarded as the most fascinating manifestation of space
weather and they are continuously observed by ground-based and, nowadays more
and more, also by space-based measurements. Investigations of auroras and
geospace comprise the main research goals of the Suomi 100 nanosatellite, the
first Finnish space research satellite, which has been measuring the Earth's
ionosphere since its launch on Dec. 3, 2018. In this work, we present a case
study where the satellite's camera observations of an aurora over Northern
Europe are combined with ground-based observations of the same event. The
analyzed image is, to the authors' best knowledge, the first auroral image ever
taken by a cubesat. Our data analysis shows that a satellite vantage point
provides complementary, novel information of such phenomena. The 3D auroral
location reconstruction of the analyzed auroral event demonstrates how
information from a 2D image can be used to provide location information of
auroras under study. The location modelling also suggests that the Earth's limb
direction, which was the case in the analyzed image, is an ideal direction to
observe faint auroras. Although imaging on a small satellite has some large
disadvantages compared with ground-based imaging (the camera cannot be
repaired, a fast moving spinning satellite), the data analysis and modelling
demonstrate how even a small 1-Unit (size: 10 cm x 10 cm x 10 cm) CubeSat and
its camera, build using cheap commercial off-the-shelf components, can open new
possibilities for auroral research, especially, when its measurements are
combined with ground-based observations.Comment: Accepted manuscript 34 pages, 17 figure
Radar—CubeSat Transionospheric HF Propagation Observations: Suomi 100 Satellite and EISCAT HF Facility
Radio waves provide a useful diagnostic tool to investigate the properties of the ionosphere
because the ionosphere affects the transmission and properties of high frequency (HF) electromagnetic
waves. We have conducted a transionospheric HF-propagation research campaign with a nanosatellite on a
low-Earth polar orbit and the EISCAT HF transmitter facility in Tromsø, Norway, in December 2020. In the
active measurement, the EISCAT HF facility transmitted sinusoidal 7.953 MHz signal which was received
with the High frEquency rAdio spectRomEteR (HEARER) onboard 1 Unit (size: 10 Ă— 10 Ă— 10 cm) Suomi
100 space weather nanosatellite. Data analysis showed that the EISCAT HF signal was detected with the
satellite's radio spectrometer when the satellite was the closest to the heater along its orbit. Part of the observed
variations seen in the signal was identified to be related to the heater's antenna pattern and to the transmitted
pulse shapes. Other observed variations can be related to the spatial and temporal variations of the ionosphere
and its different responses to the used transmission frequencies and to the transmitted O- and X-wave modes.
Some trends in the observed signal may also be associated to changes in the properties of ionospheric plasma
resulting from the heater's electromagnetic wave energy. This paper is, to authors' best knowledge, the first
observation of this kind of “self-absorption” measured from the transionospheric signal path from a powerful
radio source on the ground to the satellite-borne receiver
Oxidative Spin-Spray-Assembled Coordinative Multilayers as Platforms for Capacitive Films
Radar – CubeSat Transionospheric HF Propagation Observations: Suomi 100 Satellite and EISCAT HF Facility
Radio waves provide a useful diagnostic tool to investigate the properties of the ionosphere because the ionosphere affects the transmission and properties of High Frequency (HF) electromagnetic waves. We have conducted a transionospheric HF-propagation research campaign with a nanosatellite on a low-Earth polar orbit and the EISCAT HF transmitter facility in Tromsø, Norway, in December 2020. In the active measurement, the EISCAT HF facility transmitted sinusoidal 7.953 MHz signal which was received with the HEARER radio spectrometer onboard 1 Unit (size: 10 cm × 10 cm × 10 cm) Suomi 100 space weather nanosatellite. Data analysis showed that the EISCAT HF signal was detected with the satellite’s radio spectrometer when the satellite was the closest to the heater along its orbit. Part of the observed variations seen in the signal was identified to be related to the heater’s antenna pattern and to the transmitted pulse shapes. Other observed variations can be related to the spatial and temporal variations of the ionosphere and its different responses to the used transmission frequencies and to the transmitted O- and X-wave modes. Some trends in the observed signal may also be associated to changes in the properties of ionospheric plasma resulting from the heater’s electromagnetic wave energy. This paper is, to authors’ best knowledge, the first observation of this kind of "self-absorption" measured from the transionospheric signal path from a powerful radio source on the ground to the satellite-borne receiver.Peer reviewe
Radar—CubeSat transionospheric HF propagation observations:Suomi 100 satellite and EISCAT HF facility
Abstract
Radio waves provide a useful diagnostic tool to investigate the properties of the ionosphere because the ionosphere affects the transmission and properties of high frequency (HF) electromagnetic waves. We have conducted a transionospheric HF-propagation research campaign with a nanosatellite on a low-Earth polar orbit and the EISCAT HF transmitter facility in Tromsø, Norway, in December 2020. In the active measurement, the EISCAT HF facility transmitted sinusoidal 7.953 MHz signal which was received with the High frEquency rAdio spectRomEteR (HEARER) onboard 1 Unit (size: 10 × 10 × 10 cm) Suomi 100 space weather nanosatellite. Data analysis showed that the EISCAT HF signal was detected with the satellite’s radio spectrometer when the satellite was the closest to the heater along its orbit. Part of the observed variations seen in the signal was identified to be related to the heater’s antenna pattern and to the transmitted pulse shapes. Other observed variations can be related to the spatial and temporal variations of the ionosphere and its different responses to the used transmission frequencies and to the transmitted O- and X-wave modes. Some trends in the observed signal may also be associated to changes in the properties of ionospheric plasma resulting from the heater’s electromagnetic wave energy. This paper is, to authors’ best knowledge, the first observation of this kind of “self-absorption” measured from the transionospheric signal path from a powerful radio source on the ground to the satellite-borne receiver
Between political rhetoric and realpolitik calculations: Western diplomacy and the Baltic independence struggle in the Cold War endgame
Fifteen years after the Baltic SSRs' independence declarations, this article sheds new light on the Estonian, Latvian and Lithuanian struggle to regain statehood in the context of international relations between 1988 and 1991. Based on declassified archival sources from Western and Eastern archives, memoirs and official histories, it reveals the nature of 'Western' Baltic policies and analyses how (far) they impacted on the Soviet Union's demise. Second, the role universal normative values played in Western, Soviet and Baltic politics will be discussed in historical perspective; with the article concluding by offering some reflections on the general relationship between political rhetoric and foreign policy