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On Board Data Handling System (ODHS)

The responsibilities of the ODHS subsystem are simply, the tasks pertaining to design and manufacture of the entire hardware architecture of the on board computer. This design process is complemented to the various umbrella activities, like selection of components which fit in the power budget, interfacing requirement analysis and other space related constraints. A responsive system has to be developed which helps the satellite to perform autonomous decision making in real time. Therefore, work is also carried out, in developing a Real Time Operating System for the satellites on board controller. The team is also responsible to optimize the complex control and dynamics algorithms which is used to keep check on the satellite’s position and orientation. This team is responsible for the congregation of all sensors, actuators, memory ICs, controllers and all other hardware devices of every other subsystem.

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The Communications and Ground Station Subsystem  (COMMS)

The Communications and Ground Station Subsystem has the major goal of providing a robust link between the Satellite and the Ground Station to facilitate payload data acquisition. Simply put, it gives voice to the satellite. Parikshit requires two downlink operations – one of the payload data, and the other of the beacon; and one uplink operation. The beacon, which is an intentionally conspicuous signal that carries the name of the satellite as well as the health-monitoring data of the satellite, can be received and decoded at any ground station in the planet! Transmission of beacon is multiplexed with command uplink to the satellite, in the VHF band. Payload data transmission (in the UHF band) ensures once the satellite is over PAGOS (Parikshit Ground station) and we will finally have access to images clicked by our very own thermal camera hundreds of kilometres away! PAGOS, our fully functional Ground Station here at MIT, is capable of tracking any satellite apart from Parikshit! It is equipped to receive the beacon and mission data, process and condition it, so that all these photos can be subject to intense analysis, and conclusive results can be obtained. PAGOS has an additional feature to uplink commands to the satellite.

Electrical Power Subsystem (EPS)

The ‘Electrical Power Subsystem’ as the name suggests, is responsible for harnessing, conditioning, storing and distributing power. In space we depend entirely on solar energy to ensure the continued functioning of our satellite. Solar panels that cover four faces of our satellite convert this energy into usable power. This harnessed power is conditioned and then either stored in Li-ion cells or distributed to the loads as required. In order to ensure the longevity of the satellite, the power system co-ordinates the working of all the components based on a Power Management Algorithm that runs on the Onboard Computer. An entire part of the EPS team is solely dedicated to the purpose of designing PCB’s for the components on the satellite. The designs are then manufactured by an external company and is followed by intensive testing in the Parikshit Lab.

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Attitude Determination and Control System (ADCS)

Attitude Determination and Control System (ADCS) deals with the acquisition of the position of the satellite at every instant of time. It also has to exercise control over the orientation of the satellite by pointing the satellite towards the earth. This is necessary to point the onboard payloads at the right direction, transmit the payload data over the groundstation accurately and ensure a stable satellite. This is achieved using a combination of sensors, actuators, attitude determination and complex control system algorithms.

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Payload

Payload is the purpose that the satellite is going to serve once it is in its orbit. The payload of the Parikshit Satellite is ‘Thermal Imaging for terrestrial applications’ and satellite ‘De-orbiting using Electrodynamic Tether’. Thermal Imaging Our Earth has a dynamic and a very sensitive atmospheric system. The primary payload of our satellite is concerned with Thermal Imaging for terrestrial applications like cloud cover monitoring, urban heat islands mapping and ocean surface temperatures. In our payload using very simple devices, we intend to study the same and gain better understanding of Earth’s systems. Thermal Imaging Device: Quark-640-FLIR Electrodynamic Tether Today an astounding number of more than 600,000 objects revolve around the Earth out of which only 19,000 are tracked. All these form space junk or debris, the removal of which is nearly impossible as of now. Electrodynamic tether is one mechanism by which we can avoid such debris in future and to test this we plan to deorbit our satellite by deploying this conducting wire which is nearly 300 meters in length at the end of its lifetime. Tether: Passive Spool Based Tether Mechanism

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Structures, Thermals and Mechanics System (STMS)

The Structures subsystem deals with the main structure of the satellite, consisting of the primary structure, panels and other supporting structures for internal components. Its main purpose is to protect the various subsystems housed inside from the various launch loads and the space environment in general. To keep the satellite structurally intact throughout its mission life is the main task. Other than the structure of the satellite, this subsystem has the Thermal control and the Mechanisms subsystem merged with it. Thus our task is to design the structure, the thermal protection system, and the mechanisms onboard. Our satellite is made of space-grade aluminum since it is one of the best metals which solves many issues which come up while designing satellites. Ours being a nanosatellite has a passive thermal control system. Analysis have proved structural integrity for launch and service.