Space weather instruments and measurement platforms

Avaruussää on Maapallon lähiavaruuden ilmiö. Sillä on useita ilmenemismuotoja, joista tunnetuin on revontulet. Avaruussää aiheuttaa haittaa kriittisille infrastruktuureille, kuten satelliiteille ja sähköverkoille. Tämän diplomityön tarkoituksena on tutkia nykyisiä avaruussääinstrumenttejä sekä mittausjärjestelmiä ja kartoittaa niiden toimintakyky sekä heikkouksia. Magnetometri-, ionosfääri, aurinkotuuli- ja Aurinkoinstrumentaatiolle ja järjestelmille suoritetaan kattava analyysi. Lopputulokset osoittavat että nykyiset instrumentit kykenevät mittaamaan kaikkia avaruussäähän liittyviä ilmiöitä. Magnetometrimittausten peitto revontuliovaalilla ei ole riittävä tarkkaan avaruussäätutkimukseen, sillä magneettikenttää ei kyetä mittaamaan merellä. Ionosfäärimittauksilla on samanlaisia ongelmia maantieteellisen peiton kanssa ja niistä on saatavilla lyhyempiä aikasarjoja. Aurinko- ja aurinkotuulimittaukset ovat keskittyneet pienelle määrälle satelliitteja jotka ovat kalliita ja hankalia korvata. Lopputuloksina suositellaan CubeSat-satelliittien kyytiin asennettavien magnetometrien testausta, vedenalaisten magnetometrien käyttöönottoa sekä parannuksia ionosfäärin ja magnetosfäärin mittauspeitossa. Kykyä suorittaa jatkuvia Aurinko- ja aurinkotuulimittauksia avaruuteen sijoitetuilla järjestelmillä pitäisi myös ylläpitää.Space weather is a phenomenon affecting near-Earth space. It manifests itself in numerous different ways, the best known being the Aurora. Space weather causes numerous problems to several critical infrastructures, such as power grids and satellites. This master’s thesis investigates current space weather instrumentation and systems to analyze their capabilities and possibly existing gaps in measurements. Analysis of magnetospheric, ionospheric, solar and solar wind instruments and instrument platforms is conducted. Our results show that currently existing instrumentation is able to measure essentially all space weather phenomena. Magnetometer coverage in auroral regions is not sufficient for detailed space weather analysis e.g. due to the lack of capability for measuring magnetic field at the sea. Ionospheric measurements have similar problems with coverage, but they also have rather short time series. Solar and solar wind observations are concentrated on a small number of orbital observatories that are difficult to replace and expensive. In conclusion, testing of CubeSat mounted fluxgate magnetometers, adoption of underwater magnetometers and improvements in coverage of ionospheric and magnetospheric measurements are suggested. Maintenance of the ability to conduct in situ measurements of solar wind and and solar observations are recommended

ESA Dragliner - Coulomb drag based telecommunication satellite deorbiting device

editorial reviewedDragliner is an ESA project to design, manufacture, assemble and test a breadboard model of a tether-based deorbiting system for Low Earth Orbit (LEO) telecommunication satellite deorbit. It is led by the Finnish Meteorological Institute, and the consortium also contains Aurora Propulsion Technologies, GRADEL and University of Luxembourg. The chosen technology is the plasma brake microtether, which is an emerging propellantless and efficient deorbiting solution utilizing Coulomb drag to deorbit satellites in LEO. The system is very lightweight, small in size and requires little power. It is furthermore autonomous and requires no resources from the carrying satellite during deorbiting. The main goal of the project is to increase the TRL of the satcom plasma brake to 4. This consists of choice of deployment strategy, configuration of the deorbit system, choosing the material for the tether, finalizing the geometry for the tether, simulations for deorbiting performance as well as tether dynamics, tests conducted on the tether material in zero-gravity laboratory and the initial breadboard model design of the most critical components of the deorbit system. These include the reels for main tether, the main tether itself, as well as a supporting tape tether and it's housing. Current deployment strategy, design trade-offs, material selections, most critical components and simulation results will be showcased

Forecasting auroras from regional and global magnetic field measurements

We use the connection between auroral sightings and rapid geomagnetic field variations in a concept for a Regional Auroral Forecast (RAF) service. The service is based on statistical relationships between near-real-time alerts issued by the NOAA Space Weather Prediction Center and magnetic time derivative (dB / dt) values measured by five MIRACLE magnetometer stations located in Finland at auroral and sub-auroral latitudes. Our database contains NOAA alerts and dB / dt observations from the years 2002-2012. These data are used to create a set of conditional probabilities, which tell the service user when the probability of seeing auroras exceeds the average conditions in Fennoscandia during the coming 0-12 h. Favourable conditions for auroral displays are associated with ground magnetic field time derivative values (dB / dt) exceeding certain latitude-dependent threshold values. Our statistical analyses reveal that the probabilities of recording dB / dt exceeding the thresholds stay below 50% after NOAA alerts on X-ray bursts or on energetic particle flux enhancements. Therefore, those alerts are not very useful for auroral forecasts if we want to keep the number of false alarms low. However, NOAA alerts on global geomagnetic storms (characterized with K-p values > 4) enable probability estimates of > 50% with lead times of 3-12 h. RAF forecasts thus rely heavily on the well-known fact that bright auroras appear during geomagnetic storms. The additional new piece of information which RAF brings to the previous picture is the knowledge on typical storm durations at different latitudes. For example, the service users south of the Arctic Circle will learn that after a NOAA ALTK06 issuance in night, auroral spotting should be done within 12 h after the alert, while at higher latitudes conditions can remain favourable during the next night.Peer reviewe

Plasma Brake for Deorbiting Telecommunication Satellites

peer reviewedDragliner is an ESA project to design, manufacture, assemble and test a breadboard model of a tether-based deorbiting system for Low Earth Orbit (LEO) telecommunication satellite deorbiting. The consortium for the project is led by the Finnish Meteorological Institute, and it also contains Aurora Propulsion Technologies, GRADEL and University of Luxembourg. The chosen technology is the plasma brake microtether, which is an emerging propellantless and efficient deorbiting solution utilizing Coulomb drag to deorbit satellites in LEO. In this project, a microtether is defined as a tether that does not exceed the mass limit of 200 milligrams per meter, which makes it safe to other space assets in the event of a collision. Though in this project, the actual mass is approximately 20 milligrams per meter, which is even lower. The plasma brake is a very thin negatively charged microtether which, when charged, causes a braking force by creating enhanced Coulomb drag with the ambient ionospheric plasma ram flow. Though the fully deployed system is of considerable size (current estimates in the range of 5 km), the system is very lightweight, small in volume at the carrying satellites end, and requires little power. It is furthermore autonomous and requires no resources from the carrying satellite during deorbiting. The system is safe to other assets in space despite its significant size, as the tether itself is of very small mass. In case of a possible impact with another satellite, the microtether impact will cause damage similar to micrometeoroid flux experienced in LEO conditions. The plasma brake microtether should be differentiated from the more well-known electrodynamic tether, as the plasma brake is much thinner and uses electrostatic drag as opposed to magnetic forces. The main goal of the project is to increase the TRL of the telecommunication satellite plasma brake to 4. This consists of choice of deployment strategy, configuration of the deorbit system, choosing the material for the tether, finalizing the geometry for the tether, simulations for deorbiting performance as well as tether dynamics, tests conducted on the tether material in zero-gravity laboratory and the initial breadboard model design of the most critical components of the deorbit system. These include the reels for main tether, the main tether itself, as well as a supporting tape tether and it's housing. Current deployment strategy, design trade-offs, material selections, most critical components and simulation results will be showcased. The system utilizes two different tethers, the main tether which is the Coulomb drag plasma brake microtether. The other one is a tape tether, which is significantly shorter and is used to provide an electron gathering surface area for the main tether functionality. The deployment of the tether presents several challenges as tethers in space have historically been very difficult to operate. The reliability of the system must be very high, and in case of deorbiting failure space debris hazard must be minimized and any debris parts must be trackable