Pratham, IITB Student Satellite

Saptarshi BandyopadhyaySystem Engineer, PrathamIIT Bombay27th August, 2008

"There are some who question the relevance of space activities in a developing nation. To us, there is no ambiguity of purpose. We do not have the fantasy of competing with the economically advanced nations in the exploration of the moon or the planets or manned space-flight. But we are convinced that if we are to play a meaningful role nationally, and in the community of nations, we must be second to none in the application of advanced technologies to the real problems of man and society. "

Indian Space Research Organization

Over 40 years of experience in space.

31 Indian satellites successfully launched.

Indigenous profitable launch vehicles.

We are going to the Moon!

Student satellite – The Idea!

The aim is to develop a satellite which can be made within a time frame of two or three years, be of low cost, low mass (< 10kgs) and launch it into orbit.

Use of COTS instruments to reduce costs.

Success of the mission attached to process of learning and not just the final output.

‘The first Cubesat was used as an technology evaluation mission’ – AAU Cubesat mission statement

1. MINI – SPUTNIK2. ASUSAT3. NCUBE4. SSETI5. AAU Cubesat6. SNOE7. ICARUS8. CATSAT9. DTUSAT10. MEROPE11. COMPASS12. SEEDS

Grand Plan for the Student Satellite Project at IIT Bombay!

We wish to make IIT Bombay a respected center for advancement in Satellite Technology, in the world.

We should launch at least 5 satellites within the next 20 years.

The Satellites could be test-beds for new technology that is being developed in the institute and need space qualification.

We need success in our first Mission!!

The IITB Student Satellite Team for Pratham

List of Professors

Prof K. Sudhakar (Aero) Prof H. Arya (Aero) Prof P. M. Mujumdar

(Aero) Prof S. P.Bhat (Aero) Prof K. Chatterjee (Elec) Prof B. G. Fernandes

(Elec) Prof K. N. Iyer (Mech) Prof R. K.Pant (Aero) Prof K. K.Isaac (Mech) Prof U.N.Gaitonde

(Mech)

Prof R.K.Shevgaonkar (Elec)

Prof R. N. Banavar (Elec) Prof Madhu N. Belur

(Elec) Prof V. Ramgopal Rao

(Elec) Prof D.K.Sharma (Elec) Prof Krithi

Ramamritham (CS) Prof Subhananda

Chakrabarti (Elec)

Mission Statement for Pratham

Acquiring knowledge in the field of Satellite and Space Technology.

Develop the Satellite through the phases of Design, Analysis, Fabrication and Testing.

Launch the satellite, Measure TEC of the Ionosphere and create TEC map of India.

Involve students from other universities in our Satellite project.

Timeline for Pratham till now

Period Description

August 07 Concept feasibility proved to the Aerospace Department

Sept – Oct 07 IITB Satellite Team was selected

Dec 07 First trial at modeling satellite subsystems

Jan – Apr 08 Detailed study of all subsystems with TEC and Thermopile as Payload for the satellite. Requirements capture report was written.

May 08 – July 08

TEC has been finalized as the only Payload. Conceptual Design Phase finished.

August 08 – Present

Preliminary Design Phase. Engineering Model will be built.

Documentation and Reviews

Major Emphasis on Documentation. We want to preserve our knowledge.

Regular review done by the team and faculty. Reports written and circulated within the

team. Reviews done in ISAC and other ISRO scientist. All our documents are available on our website

For Password: Contact any of the people mentioned in the Contacts List (On website)

Payload

Total Electron Count of the Ionosphere

Method used for measuring TEC on our Satellite: Faraday rotation linearly polarized radio waves

at 405MHz and 437MHz Difference in polarization

measured on ground using crossed yagi.

TEC maps of India Ionosphere Tomography (?)

Social Goal

The greater the number of ground stations, greater is the number of locations at which TEC will be recorded.

We plan to approach universities across India requesting them to serve as a ground station for our satellite.

This will motivate the participating students and get them interested in satellite technology.

Communication and Ground Station

Low bit rate Beacon. (Freq = 437MHz) High bit rate (1.2kbps) Monopole for

downlink of data. (Freq = 405MHz) We do not have uplink Linearly polarized radio signals. 2 crossed yagis at ground stations to receive

data and measure their polarization. PDR

Simulation of onboard Monopoles and circuit Ground Stations for IITB, Tomography and Social

Goal

Attitude Determination and Controls

Goal To stabilize the satellite

after deployment and to maintain the 3 axis attitude of the satellite within

Functional Requirements Detumbling Mode Nominal Operation Mode Emergency Mode

Control law Linear controller

Sensors GPS (1) Single Rate gyro (3) Single axis sun sensor (6) Magnetometer (1)

Actuators Magnetorquer (3)

PDR Hardware Software

On Board Computer

Hardware Microcontroller

Atmel AT91M40080 PROM

One time programmable EPROM AT27BV040

NVRAM TI bq4015LYMA-70N

Software Stages of Operation Minimal pre-empting of

running task Cyclic Scheduler

PDR Hardware Software

Power Systems

Major power inputs Direct solar radiation Solar radiation reflected

from Earth (albedo) Earth’s thermal radiation

Average useful power incident on the faces.

A A’ B B’ C C’ Tot

21W 7W 17W 17W 20W 2W 84W

Hardware Solar cells Batteries 3.3V regulator 5V regulator Microcontroller Power distribution Battery protection Power OR-ing diodes RBF pin, kill and

charging switches PDR

Structures, Thermals and Mechanisms

Structures Weight budgeting Qualification of the

satellite structure as per launch loads

Qualification of structure based on thermal loads in orbit

Configuration Layout Deployment of 2 parallel

monopoles PDR – Structure PDR – Mechanisms

Thermal Maintain suitable

temperature for components.

Temporal cycle of temperatures experienced in each orbit

Spatial gradient of temperature at an instant

Dissipation of heat from components onboard

Active thermal control of critical components

PDR - Thermals

System Engineer’s Tasks

Stages and Functions of Satellite System and Sub-System Requirements Budget for Weight, Power and Data Interface, Connectors and Wires Configuration Layout Launch Vehicle Interface and Access

Ports PDR

Future Plan

Period Description

Present – Sept Preliminary Design Phase(Engineering Model)

Sept – Dec 08 Detailed Design Phase(Qualification Model)

Jan – Feb 09 Prototype Testing and Qualification Phase

Mar – April 09 Flight Testing phase(Flight Model)

New Satellite

Thermal Imaging using the sensors developed by Prof Subhananda Chakrabarti (Elec).

Use of Mems sensors Launch Vehicle Interface Try uplink! . . .

Team starts work by December 2008 Satellite should be launched by 1st quarter

2010

Inducting new Students

Quiz (24th September) Student Satellites Our Reports Sub-System specific

For registering mail: shashanktamaskar@iitb.ac.in

Presentation (October) Members become formal in

Dec 08

System Engineering Payload Communication Controls On Board Computer Power Structures Thermal Mechanisms