The radio plasma imager (RPI) on the IMAGE satellite is a low-frequency radar system that uses orthogonal 500-m tip-to-tip dipoles to transmit RF pulses with frequencies from 3 kHz to 3 MHz. A third 20-m tip-to-tip dipole antenna along the spin axis is used for reception together with the two long antennas providing direction of arrival capability. The minimum pulse length of 3.2 ms yields a range resolution of 480 km. When the spacecraft is in the magnetospheric cavity (altitude of 5--7 RE) RPI can receive echoes associated with the plasmasphere, the magnetopause and the cusp region, at frequencies between ∼10 and 100 kHz. At high altitudes, higher frequency echoes are found reflecting from the topside ionosphere. This paper will present some of the first echo observations measured by the RPI instrument.
Kinematika i Fizika Nebesnykh Tel Supplement
- Pub Date:
- September 2000