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ICI4 rocket

Scientific objectives

The polar cap is one of the regions of the Earth’s ionosphere that is in direct interaction with the solar wind via injections of magnetosheath particles, during magnetic reconnection events, more or less sporadic and localized. ICI-4 Mission (4th rocket of the "Ionospheric Cusp Irregularities " program) aims at studying the impact of plasma structures, the polar cap patches, on the scintillation phenomena affecting the propagation of signals used by GPS-like navigation systems. These structures propagate from the polar cusp towards the night side of the magnetosphere through the polar cap.

Conditions for the rocket launch

ICI-4 rocket was launched from the Andoya space center, situated at 66 ° of magnetic latitude, on a Norwegian island. The trajectory of the rocket, which rises up to 350 km altitude (F region of the ionosphere) is northwards, in the direction of the Svalbard Islands. The rocket is launched when Andoya station is facing the night side of the magnetosphere, between 18h and 01h in magnetic local time. The EISCAT radar, located in Svalbard, provides data to detect polar cap patches arriving from the polar cusp.
The objective is to launch the rocket when these patches enter the auroral arcs. Andoya being located at relatively low latitude, it requires that the patches have crossed the border between closed and open lines of force. In practice, this means that a type of magnetic substorm phenomenon had occurred. For this it is necessary that the interplanetary magnetic field be oriented south for long enough to fill the magnetosphere with plasma, as a result of magnetic reconnection, and make the magnetosphere to became unstable. It typically takes 2 hours to allow this to occur. But it can be faster, depending on the density of particles in the solar wind for example. During magnetic substorms, the energy stored in the magnetic tail is re-injected into the auroral regions in the form of a plasma heated to an energy of several keV and of bursts of electromagnetic energy. The acceleration of the electrons that create the aurora occurs in the auroral acceleration region, typically between 3,000 and 10,000 km of altitude, by converting electromagnetic energy into kinetic energy. These energy conversion phenomena are still poorly understood. We can see the development of a magnetic substorm by monitoring magnetic disturbances recorded by a network of magnetic observatories located at different latitudes. The horizontal component of the magnetic field drops sharply, with a delay between the different observatories, the disturbance propagating from the lowest to the highest latitudes.
At this time, the Svalbard and Andoya all sky cameras, if cloud cover permits, show very intense auroral emissions. During that time, the rocket team monitors the scintillation of GPS signals. These drift more and more southward, and the rocket is launched at the time at which its trajectory intercepts an auroral arc, a "patch" and a scintillation region. The sequence leading to the firing of the ICI-4 rocket is complex. It can last from 3 to 8 hours. Weather conditions on the ground and in the lower atmosphere are also analyzed by the Space Center using probe balloons released at regular intervals. A wind on ground exceeding 10 m / s or a high altitude wind exceeding 20m / s does not allow the firing. The countdown is halted if the weather or geophysical conditions are not favorable. For this reason, a rocket campaign takes about 2 weeks during which the scientific team is mobilized to make the right choice for launch.

Participation of LPP

The participation of LPP in this research program allows us to understand very concretely research topics related to the large-scale dynamics of the Earth’s magnetosphere and the auroral acceleration, by means of the real-time study of data provided by ground based observations (EISCAT, magnetometers, all sky cameras). The LPP provides expertise in terms of in situ measurements by providing wave or particle instruments that will characterize the ionospheric plasma and its associated electromagnetic perturbations.
This program also allows testing at low cost, both human and material, new instruments developed for larger space missions. For the ICI-4 program, the LPP has designed a magnetic sensor, a search coil, including a miniaturized preamplifier, a plasma analyzer with high time resolution, and a magnetic gradiometer for reconstructing the trajectory of the rocket. The latter is derived from work in collaboration with the Sysnav Company. The magnetic induction antenna (search coil) is the result of a completed development in the context of the preparation of the JUICE mission of the European Space Agency. Having this instrument and its integrated electronic mounted onboard ICI-4 validates the instrumental concept of the future SCM instrument of the JUICE mission.

Magnetic search-coil onboard ICI4

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Directeur de la publication : Pascal Chabert (Directeur)