In another finding, data from India’s Chandrayaan-2 orbiter has shown that plasma density in Moon’s ionosphere in the wake region — a region of the Lunar ionosphere that does not directly interact with the solar wind — is at least one order of magnitude more than that present in the day side.


  1. India’s second lunar mission, which was launched on 22 July 2019, carried several payloads, among which, the Dual Frequency Radio Science (DFRS) was designed to study the lunar ionosphere.
  2. It was conceptualised and jointly developed by Space Physics Laboratory (SPL) of Vikram Sarabhai Space Centre (VSSC), UR Rao Space Centre (URSC) and Isro Telemetry, Tracking, and Command Network (Istrac).
  3. Pointing out that Moon’s ionosphere, which derives its origin from the atmosphere believed to be very tenuous, Isro said, the plasma density was considered to be only a few hundred ions per cubic centimetre.
  4. DFRS uses two coherent signals at the S-band and X-band of radio frequencies, transmitted from Chandrayaan-2 orbiter and received at the ground station in Byalalu, Bengaluru, to explore the lunar plasma ambiance using the radio occultation (RO) — a remote sensing technique used to measure physical properties of a planetary atmosphere — technique.
  5. Isro said that 12 RO experiments have been conducted in campaign mode on four different occasions based on carefully selected geometry suitable for RO measurements.