Development of Deployment Mechanism for RAMBHA-LP Payload Onboard Chandrayaan-3 Lander

Abstract

<div class="section abstract"><div class="htmlview paragraph">RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere—Langmuir Probe) was one of the key scientific payloads onboard the Indian Space Research Organization’s (ISRO) Chandrayaan-3 mission. Its objectives were to estimate the lunar plasma density and its variations near the lunar surface. The probe was initially kept in a stowed condition attached to the lander. A mechanism was designed and realized for deploying the probe at a distance of 1 meter to avoid the plasma sheath effect in the moon’s plasma environment. The RAMBHA-LP deployment system consists of a metallic spherical probe with Titanium Nitride coating on its surface, a long carbon-fiber-reinforced polymer boom, a spring-assisted deployment mechanism, a dust-protection subsystem, and a hold release mechanism (HRM) based on a shape-memory alloy-based actuator. The entire RAMBHA-LP system weighed nearly 1.3 kilograms. The system had undergone many sub-system and system-level tests in ambient, dynamic, and thermo-vacuum environments, simulating interplanetary mission conditions. After completion of all developmental, qualification, and acceptance level tests, the system was integrated with the ‘Vikram’ Lander and launched using ISRO’s Launch Vehicle Mark III (LVM 3) on July 14, 2023. The Chandrayaan-3 lander made history by landing on the lunar south pole on August 23rd, 2023. The RAMBHA-LP payload was successfully deployed the next day. The deployment of the payload was confirmed by two status confirmation switches in the mechanism. This paper describes the design and configuration of the payload deployment mechanical system, with a focus on the design of the various mechanical subsystems, the results of software simulation and analysis, and the details of the large number of tests conducted to make the deployment system ready for the mission.</div></div>