A space mission, which is being developed by a research team of 20 institutions from around the world, led by the Democritus University of Thrace, aspires to study the critical, but very little-explored region between the Earth's atmosphere and space with a Greek-inspired satellite.
This is the "Daedalus" mission, which aims to make in situ measurements of plasma density and temperature, electric and magnetic fields, neutral winds, ion drift, as well as composition, density and temperature of neutral and charged elements in the Lower Thermosphere and Ionosphere (LTI) region.
This region, at an altitude of 100 to 200 kilometres from the Earth's surface, is the main transition region from the Earth's atmosphere to Space, where the neutral elements of the atmosphere and the charged elements of the space plasma coexist.
Here, the connection of the Earth's magnetosphere with the upper atmosphere and ionosphere is made, creating a giant electric circuit: huge electric currents flow along the Earth's magnetic lines and "close" an electric circuit at high latitudes through the ionosphere, while the neutral atmosphere acts as an "electrical resistance" of this circuit, resulting in resistive heating of the area (also known as Joule heating).
At the same time, as the associate professor at the Department of Electrical and Computer Engineering of the Democritus University of Thrace, Theodoros Sarris, explains to AMNA, many measurements can be made in the Earth's atmosphere by unmanned aircraft, atmospheric balloons and other instruments and in Space by satellites, "however in this interval only a few isolated measurements have been made from the ground by remote sensing methods or by atmospheric rockets."
This results in "large discrepancies between the models that simulate this region" and limits current space weather forecasting capabilities, he added.
To resolve all the questions that exist about this critical interval there is a need for measurements at different heights and multiple points of the LTI region.
In the "Daedalus" mission, a very innovative way to measure this area is proposed, with the satellite that will be deployed working "like a flying laboratory", as Mr. Sarris characteristically says.
The satellite will gradually descend into the area using thrusters and at the same time nanosatellites will be released, carrying minimal instruments and taking additional measurements on the spot. In fact, subsystems and components of the satellite could also be manufactured in Greece.
The mission was proposed to the European Space Agency (ESA) as part of a call for proposals for the '10th Earth Explorer' Earth observation programme.
It was selected in 2018 as one of the top three projects for which a feasibility study was done and then qualified as one of the top two for implementation, however at the last stage it was judged to have many risks due to the area it wants to explore.
The interest, however, was so great that the proposal was undertaken to be investigated by a joint scientific committee of NASA and ESA.
It is noted that the findings and the investigation stage of the above scientific committee were presented by Theodoros Sarris at the recent General Assembly of the European Geophysical Union, the largest European meeting for the sciences of the Earth's environment and surrounding space, held in Vienna on April 24-28 2023.
