The general scientific objectives of the DSLP instrument, are linked to the overall PROBA2 mission scientific program. They target to statistically examine the ionospheric plasma environment in relations to relevant solar and space weather drivers with direct support of the two on board remote sensors of the solar activity (SWAP and LYRA) and other available space weather data sets like these provided by GOES and ACE spacecraft. The scientific objectives targeted by the DSLP experiment cover namely

  • mapping the bulk plasma parameters (primarily electron density and temperature) of the upper terrestrial iono- sphere in the dawn and dusk sector,

  • statistical study of mean properties of the plasma and their seasonal variations,

  • identify observed anomalies and irregularities, and

  • evaluate effect of sudden space weather events (solar flares, CME's) and trends of solar activity on global ionospheric environment.

    Classical theories for LP measurements are typically developed for isotropic plasmas in the thermodynamic equi- librium and perfect symmetric geometries of the electrode induced electric fields. However, in reality, non-thermal populations (e.g. with loss-cone and flat-top velocity distributions or extended high-energy tails) and various tem- perature anisotropies are commonly observed in most of the semi-collisional or collisionless space plasmas. Also, the ubiquitous ambient magnetic field is very often significantly affecting trajectories of charged particles on spatial scales relevant for LP measurements. One of the main experimental goal of the DSLP instrument, taking the benefit of the SLP concept, is to derive the importance of these features of the velocity distribution functions in terrestrial ionospheric plasma. By the comparison of theoretical models of LP current collection with directional measurements provided by individual segments of the two SLP sensors, the DSLP experiment shall allow us

    • asses the capabilities of the of the SLP concept in providing directional measurements of the local plasma characteristics,

    • look for existence of non-thermal ionospheric electron plasma populations,

    • analyze observed temperature anisotropies, and

    • study the effect of the local magnetic field on the current collection from different directions.

      In addition to these main objectives, the DSLP experiment implements an experimental mode for concept verification of E-field measurements with multiple LP sensors. The two SLP sensors can serve as an dipole antenna sampling E-field fluctuations at 2 kHz. For such low frequency the scientific application of E-field measurements is however limited by the accommodation of the DSLP sensors providing spatial separation of only about 1 m with effective length of the dipole even less due to proximity of the satellite's body.