Measuring the magnetic field and following the changes requires very accurate instruments: the magnetometers (picture 1) To retrace the old magnetic field in an object, one uses a cryogenic magnetometer. When the magnetic history of a place is known, one can check this knowledge with other methods to date the objects found. Inversely, dating certain objects via other methods than the one based on magnetism, allow to trace the magnetic layers in which they where found. By comparison of the magnetic history of rocks from areas far away, one can prove that these areas where neighbours once, namely before the floating continents separated them.

Some industrial applications involve techniques of geomagnetism. For example, instruments on board of aeroplanes or instruments in airports are tuned with it. The exact time we use today is determined by atomic clocks. To compare these clocks, which are located in far-away laboratories, one uses the GPS satellite system. (picture 2) The clocks from several laboratories are simultaneously compared to the clock of one satellite by measuring the arrival time of the signals in every lab. In this way, one derives the difference between the clocks and the laboratory. The acquired precision is of the order of a billionth of a second when comparing clocks thousands of kilometres away.

Seismology studies all the earthquakes of our planet, both large as small ones are measured and mapped. In this respect, Belgium has at its disposal a network of stations with seismographs. The yearly average in our country is about ten large and medium-sized earthquakes. After every shock sensed by the population, a macro-seismological map is composed based on systematic inquiries. All research necessary for the creation of a map, which evaluates the possibility of earthquakes in our country, is done: historical research on shocks in the last thousands of years, paleoseismic research on large earthquakes in the last hundred thousands of years, study of slow tectonic disturbances of the Earth’s layers by means of an absolute absolute gravimeter (picture 3), GPS localisation, measurements with extensometers in natural caves and research of local effects in the soil during earthquakes in Belgium.

In the sixties, an important breakthrough in the field of the planet Mars was possible thanks to space exploration. In view of increasing the scientific knowledge, the missions Mars Express and Netlander were set up.

The Belgian Institute for Space Aeronomy participates in the first mission by the experiment Spicam-light. Satellite Mars Express, on which the instrument Spicam is placed, should, after dropping the Beagle 2 Lander, place oneself in an orbit and observe the whole planet during a year on Mars (being two Earth years).
The experiment Spicam-Light has as a goal, the study of the chemical composition and the dynamic evolution of the atmosphere on Mars. Therefore, one uses a UV-IR-spectrometer (ultraviolet or infra-red), completely finalised by the Belgian Institute for Space Aeronomy. The research results will have consequences on, for example, the ways of thinking about space suits and supporting life systems for future astronauts going to Mars.

The Netlander Mission will unfold a network of four geophysical measuring stations at the surface. (video 1) The stations will send their data to a satellite in an orbit around Mars, which will forward all the details to the Earth. The collection of acquired data should, just like the Mars Express Mission, allow to know better the interior, the surface and the atmosphere of the planet and its evolution.

The Royal Observatory of Belgium actively participates in the activation of an experiment on NetLander called NEIGE (NEtlander Ionosphere and Geodesy Experiment). This experiment will measure the frequency variations (Doppler Effect) of radio signals associated with the transmission of data between the stations and the satellite, and between the satellite and the Earth as well.

The use of two different frequencies for the radio signal will permit both to correct the Doppler measurements disturbed by the presence of the ionosphere, and to study the dispersion of charged particles in the ionosphere. The latter is one of the main objectives of NEIGE. The signal corrected for the ionosphere will allow the team of the Royal Observatory of Belgium to achieve the geodetic goal of the NEIGE experiment: acquiring the orientation and rotation parameters of Mars. The scientists will be able to determine very precisely the variations in rotation speed (and consequently also the duration of a day) and the variations in the position of the rotation-axis. At the same time, the polar movement of the planet will be determined.
Since the rotation of a body depends on its structure, this study will allow to capture some interesting characteristics of the internal structure of Mars (physical characteristics, density and dimensions of the core for example) and the changes in mass and pressure in the atmosphere, related to the seasonal processes of sublimation/condensation on the polar caps.

Thanks to a CCD camera, installed on a telescope of the Royal Observatory of Belgium, (picture 5) minor planets can be discovered in Belgium. In one of the methods used, the same region on the sky is observed five times in succession, with 10 to 15 minutes between every observation. Later, computer software determines the positions of all the objects on the image. The objects, which are on the same position on more than one image are coloured in grey, while objects located only once on a particular position, are coloured, respectively in blue, green, yellow, orange and red. The stars appear in grey, while moving minor planets will show up as a "rainbow" on the image. One can also combine different images to evidence the movement of the minor planets relative to the stars.

The "in situ" study of the composition of a comet and the evolution of its structure while approaching the Sun is one of the main goals of the mission Rosetta. After a long fly phase, the satellite will meet comet Wirtanen and turn around it to study its mass. (picture 6)
The Belgian Institute for Space Aeronomy participates in this mission via the so-called project ROSINA (Rosetta orbiter spectrometer for ion and neutral analysis). The main scientific goals are the determination of the abundance of gaseous elements of the comet, the study of the composition of volatile elements and the characterisation of the core.