  The ionospheric scattering of pulses emitted by PSR B0950+08 is measured
using the 10-m RadioAstron Space Radio Telescope, the 300-m Arecibo Radio
Telescope and the 14x25-m Westerbork Synthesis Radio Telescope (WSRT) at a
frequency band between 316 and 332 MHz. We analyse this phenomenon based on a
simulated model of the phase difference obtained between antennas that are
widely separated by nearly 25 Earth diameters. We present a technique for
processing and analysing the ionospheric total electron content (TEC) at the
ground stations of the ground-space interferometer. This technique allows us to
derive almost synchronous half-hour structures of the TEC in the ionosphere at
an intercontinental distance between the Arecibo and WSRT stations. We find
that the amplitude values of the detected structures are approximately twice as
large as the values for the TEC derived in the International Reference
Ionosphere (IRI) project. Furthermore, the values of the TEC outside these
structures are almost the same as the corresponding values found by the IRI.
According to a preliminary analysis, the detected structures were observed
during a geomagnetic storm with a minimum Dst index of ~75 nT generated by
interplanetary disturbances, and may be due to the influence of interplanetary
and magnetospheric phenomena on ionospheric disturbances. We show that the
Space Very Long Baseline Interferometry provides us with new opportunities to
study the TEC, and we demonstrate the capabilities of this instrument to
research the ionosphere.
