Subsatellite system of remote sensing of arctic terrain

Polar region is considered to be "difficult" for any geophysical surveys. One of the alternatives is stratospheric balloon survey. Many important parameters of an environment are expedient for measuring at lower altitudes, than satellite ones. The balloon flight altitudes cover the range from 20 to 50 km. At such altitudes there are steady zone air flow due to which the balloon flight trajectories can be of any direction, including - round-the-world (round-the-pole) or in a mode "boomerang", i.e. when the balloon can return to an initial point by changing the flight altitudes. The modern technology allows executing continuous balloon flight within one year. Taking into account mentioned above and that the use of a balloon is incommensurably cheaper than any other carrier (satellite, airborne, ground borne or marine), it is possible to expect hereafter-significant extension of areas of its application, especially at remote sounding of the Earth.
There are a few launching pads where balloons with long duration of flight (more than two weeks) could start on a regular basis. Most of the pads are located in polar regions: Longyearbyen (Svalbard Islands, Norway), Esrange (Kiruna, Sweden) and McMurdo (Antarctica). Note, that polar caps are the most challenging regions for the geomagnetic modelling due to extremely irregular and very large contributions from the external sources.
One of the example of such sounding system have been designed, developed and maintained at IZMIRAN during already about 20 years. This system consists of three instrumental containers uniformly placed along a vertical 6 km line. System allows measuring a module and vertical gradient of the geomagnetic field along the whole flight trajectory and so one’s name is - STRATOSPHERIC BALLOON MAGNETIC GRADIOMETER (SMBG). The GPS-receivers, located in each instrumental container, fix the flight coordinates to within several tens meters. Data transmission is carried out by satellite link. Two-way satellite link provide us the possibility for the operational control of devices and data transfer via Internet in the real-time mode that implemented from one center controlling the experiment.
The obtained data are used in solving the problems of deep sounding of the Earth’s crust magnetic structure - an extraction of magnetic anomalies, determination of a depth of bedding of magnetoactive rocks and others.
The developed launching technology, deployment in flight, assembly, data processing, transfer and landing the containers with the equipment can be used for other similar problems of monitoring and sounding an environment. Useful flight weights of each instrumental container may be reaching 50 kg. More than ten testing flights (1986-2007) at stratospheric altitudes (20-30 km) have proven the reliability of this system.
Work is partially supported by grants N06-05-64329 and N07-05-00190 of the Russian Foundation for Basic Research.