Swayam
Swayam is a 1-U picosatellite (CubeSat) developed by the undergraduate students of College of Engineering, Pune. With size constraints of 1-U standards and weight 1Kg they have successfully completed assembly of their flight model under the guidance of Indian Space Research Organisation (ISRO).The Satellite will be launched by ISRO as soon as a suitable launch vehicle is identified.The satellite is to placed in low earth orbit around earth at a height of 500-800 kms.
Payload of the Satellite is point to point packet communication with which an user can send/receive message from one point to other point on earth.Scientific objective of the satellite is to demonstrate Passive stabilisation of the satellite ,this is India's first satellite to do so.Without consuming any power the satellite will stabilise in the orbit. Another prominent mission objective is to provide Low earth orbit channel characterization in UHF HAM band.
About The CSAT Programme
Mission Swayam is the first satellite project of COEP student's Satellite Initiative under the CSAT programme. The team has its members spread over all the years and disciplines of engineering establishing itself as a truly interdisciplinary project.
Timeline
This programme was initiated by a group of few students in late 2008.Then in early 2009 this project was approved officially by the college and the team expanded.Team cleared the preliminary design review of mission Swayam in September 2010. Development of ground station was done by October 2012 and is functional there after. College established a Class 10000 clean room. Qualification model along with the Environmental tests was completed in May 2014. Flight model along with all the environmental tests completed in February 2015.
Subsystems
The Satellite team is divided broadly into five subsystems
Attitude Control System
This is the First Indian Satellite with passive magnetic attitude control system.The primary objective of is to attain a favourable configuration suitable for communication payload. Earth's magnetic field will be used for achieving this.Components of ACS include permanent magnets and hysteresis rods.It also has an onboard MEMS gyroscope for stabilisation detection. Using the data from gyro sensor On-Board Computer declares stability of the satellite.
Communication
The Communication subsystem is responsible for enabling half-duplex communication of the satellite with various ground stations in the HAM band of 434-438 MHz which is used both for up-linking and down-linking data. The frequency used by satellite will be 437.025 MHz. Communication subsystem can be subdivided further into two parts:
Spacecraft
The subsystem consists of the amplifiers (LNA & HPA), the antenna, the transceiver and the terminal node controller.
Ground station segment
The team has established a fully functional Ground Station in the premises with uplink and downlink capability in both the 435 MHz as well as the 145 MHz bands.
On-Board Computer
The onboard computer subsystem is a fault tolerant microcontroller based system. This system carries out periodic data collection and storage, Telecommand handling, Messaging and redundant Load protection control.
Power
The power subsystem is completely analog in nature and also fully autonomous in its functioning, being the first subsystem to start up after the launch.It provides power to all the electrical systems on board the satellite and protects them from electrical faults.DC DC converters are used for regulation and conditioning of power. Load protection circuits designed have triple redundancy with On-board computer's and terminal node controller's control.The Power system is responsible for the deployment of the antenna for the communication system through a surge of current.Li ion battery is used for energy storage. It has on-board voltage/current and temperature sensors which form a part of health monitoring data(HMD) for monitoring electrical status of the satellite.
Structure
The structure subsystem is responsible for providing a robust body for the satellite which can house all the components and protect them from the harsh conditions of space. Comparative studies of different materials revealed that Al 6061-T6 is better suited. Hence it has been used for the main frame of the satellite. Other materials like ABS, FR4 have also been used as per the specific requirements. All these materials were first tested for their properties before being put into use. The main structure of the satellite consists of four rails and two frames. Three PCB’s are arranged in a U deck, with the battery pack in the middle.
Vibration Analysis: During launch, the satellite undergoes intense vibrations. It must be able to sustain these. For the same, simulations have been run and validated by performing tests on both the qualification and flight models.
Thermal Management and Control: Temperature of the satellite has to be maintained within a particular range in order to ensure proper functioning. A passive thermal system has been employed in Swayam. Insulating materials like kapton, white paint, low emittance tape, black tape and optical solar reflector are used. The thermal system has been put to test in the thermo vacuum test (on QM and FM) and hot and cold test (on QM).
Achievements
The team has published and presented various papers in various conferences