In parallel with passive monitoring of various geophysical processes on the orbit, the scientific objectives of the ACTIVE (Intercosmos-24) project also included an active stimulation of the environment by electromagnetic and plasma generators with synchronous monitoring of consequent response to the stimulation. The set of monitoring devices included also the SPE-1 (Spectrometer of Protons and Electrons),
developed and constructed at DSP-IEP-SAS.
The SPE-1 spectrometer operated with three pairs of solid state semiconductor detectors, the angle of each pair was different against the spacecraft spin axis to provide required angular resolution.
The Active/IK-24 spacecraft has had a geocentric orientation
(stabilization by a gravity dipole). The absence of the "shadow side" implied to necessity of active cooling of the detectors by six Peltier coolers that pumped the heat from the detectors to the device structure. The allocated cooling power of 3 Watts allowed to cool down the detectors for 40°C against the electronic box. The amplitude analyzers of SPE-1 recorded energetic spectra of charged particles into 5, 15, or 31 energy channels (depending on operational mode).
The SPE-1 spectrometer has been successfully working on board of the IK-24/Active during entire lifetime (5 years) of the spacecraft and provided plentitude of interesting scientific data. The SPE-1 database is still frequently used for various physical analysis and planning the future projects.