WHISPER: Waves of High frequency and Sounder for Probing of Electron density by Relaxation experiment
Principal Investigator: Jean Louis Rauch, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E) and Centre National de la Recherche Scientifique (CNRS), France
Near-Earth space is populated by charged particles whose density governs wave generation and energy transfers. To measure this fundamental quantity, WHISPER makes use of a resonance sounding (radar) technique. Brief radio pulses, sent out from two 50-metre-long wire antennas, trigger oscillations or 'echoes', which are detected after a short delay. Their frequencies reveal the particle concentration in the medium. In addition, WHISPER monitors natural wave activity in the frequency range (2 to 80 kHz) covered by the sounder. WHISPER is one of the five complementary experiments which form the Cluster Wave Experiment Consortium (WEC).