Various views of the crew module

Bangalore: The Indian Space Research Organisation (ISRO), which has finalised several aspects of the mission planning for G1 (the first uncrewed mission), has proposed to send unpressurised crew modules during both the test vehicle demonstrations that will precede G1 and the G1 too reports TOI.

As per ISRO: “The structure has been designed considering two configurations — unpressurised crew module for G1 and both test vehicle demonstrations (TV-D1 and TV-D2), and pressurised inner structure for the G2 (second uncrewed) and H1 (human spaceflight) missions.”

For both versions, outer and inner mould lines have been defined. ISRO added that inputs and requirement documents have been generated for each of the crew module subsystem designs.

The crew module will accommodate subsystems like aero thermal structure, ECLSS (environmental control and life support system), propulsion system, parachute and separation systems, avionics, power and communication system, crew auxiliary systems like crew seat, hatches and viewports, and crew console which consists of display units and alert/command buttons.

Systems Configuration

“Configuration and accommodation/layout of subsystems like apex cover, parachutes, propulsion avionics, up-righting system, separation system, crew seat assembly has been carried out accounting inter and intra dependencies between systems. Except for ECLSS, all functional systems have been retained as the same for H1 (human spaceflight mission) and G1,” ISRO said.

Also, the crew module-service module umbilical is configured with a two plane separation system with an auto sealing device for ECLSS oxygen and heat exchanger lines and electrical connectors for transfer of electrical signals, power, pyro commands between the modules, ISRO added.

“Assisted separation force connectors (ASF) have been realised, and functional demonstration tests of the same have been carried out,” ISRO said.

Propulsion & Up-righting

The crew module propulsion system, ISRO said, has been configured with 12 bi-propellant thrusters at the leeward side (the direction in which the wind goes) of the module.

The required propellant tanks, gas bottles, propulsion deck with control components, fill and drain valves have also been configured and accommodated.

Further, ISRO said that an up-righting system — which will prevent the crew module from remaining upside down even if it lands that way in sea — has also been designed.

“Considering two stable orientations (6° and 170° from vertical) for the crew module after a touchdown in the sea, the up-righting system is designed to maintain the module in a mono-stable position. Six inflatable floats — three primary and three secondary — are planned and are accommodated as packed units in the module,” ISRO added..

And based on expert recommendation, ISRO has worked out the design for a pyro-based cold gas generator system for inflating the floats upon touchdown. This new system will replace the conventional gas storage system.