THE Indian Space Research Organisation (ISRO) on Thursday said that the RAMBHA-LP, a payload attached to the lander module Vikram, which is on the lunar surface, of the Chandrayaan-3 mission, has made the first-ever measurements of the near-surface Lunar plasma environment over the south polar region. Taking to social media platform X, ISRO said, “Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere - Langmuir Probe (RAMBHA-LP) payload onboard Chandrayaan-3 Lander has made first-ever measurements of the near-surface Lunar plasma environment over the south polar region.”“The initial assessment indicates that the plasma near the lunar surface is relatively sparse,” ISRO wrote on X. Langmuir (after Irving Langmuir) probe is a device used for characterising a plasma.

 

It features a 5 cm metallic spherical probe mounted on a 1-meter boom attached to the Chandrayaan-3 Lander’s upper deck. The probe is deployed using a hold-release mechanism after the lander’s lunar touchdown. The extended boom length ensures that the spherical probe operates within the undisturbed lunar plasma environment, isolated from the lander’s body. According to the country’s space agency, the system can detect minute return currents, as low as pico-amperes, with a dwell time of 1 millisecond. By applying a sweeping bias potential ranging from -12 to +12 V in increments of 0.1 V to the Langmuir probe, the system can accurately determine ion and electron densities as well as their energies based on the measured return current.