Satellite System and Engineering Procedure-An Introduction Instructor Roy

Satellite System and Engineering Procedure-An Introduction Instructor: Roy C. Hsu Computer Science and Information Engineering Department National Chia-Yi University 10/05/2006

OUTLINE o o Introduction Satellite System Engineering Procedure Cases Study 2

INTRODUCTION o Definition (from Wikipedia) Ø Ø A satellite is any object that orbits another object (which is known as its primary). Satellites can be manmade or may be naturally occurring such as moons, comets, asteroids, planets, stars, and even galaxies. An example of a natural satellite is Earth's moon. 3

INTRODUCTION (Cont. ) o Human-made devices: artificial satellite Ø Ø From Science Fiction o the first fictional depiction of an artificial satellite launched into Earth orbit –by Jules Verne's The Begum's Millions (1879). o Jules Gabriel Verne (February 8, 1828–March 24, 1905), a French author and a pioneer of the science-fiction genre. o Verne was noted for writing about cosmic, atmospheric, and underwater travel before air travel and submarines were commonplace and before practical means of space travel had been devised. The first artificial satellite was Sputnik 1 launched by Soviet Union on 4 October 1957. 4

INTRODUCTION (Cont. ) . o list of countries with an independent capability to place satellites in orbit, including production of the necessary launch vehicle. 5

First launch by country Country Year of first launch First satellite In orbit in 2006 Soviet Union 1957 Sputnik 1 87 United States 1958 Explorer 1 413 Australia 1964 Title Unknown ? France 1965 Astérix ? Japan 1970 Osumi ? China 1970 Dong Fang Hong I 34 United Kingdom 1971 Prospero X-3 ? India 1979 Rohini-1 33 Israel 1988 Ofeq 1 ? 6

INTRODUCTION (Cont. ) o MISSION AND PAYLOAD Ø Ø Space mission: the purpose of placing in equipment (payload) and/or personnel to carry out activities that cannot be performed on earth Payload: design of the equipment is strongly influenced by the specific mission, anticipated lifetime, launch vehicle selected, and the environments of launch and space. 7

INTRODUCTION (Cont. ) o Possible missions Ø Ø Ø Ø Ø Communications Earth Resources Weather Navigation Astronomy Space Physics Space Stations Military Technology Proving 8

SATELLITE SYSTEM Space Segment Payload Structure Bus Attitude Determination And Control Power Thermal Command Telemetry Propulsion Data Handling 9

SATELLITE SYSTEM(Cont’d) o o A satellite system is composed of the spacecraft (bus) and payload(s) A spacecraft consists of the following subsystems Ø Ø Ø Ø Propulsion and Launch Systems Attitude Determination and Control Power Systems Thermal Systems Configuration and Structure Systems Communications Command Telemetry Data Handling and Processing 10

SATELLITE SYSTEM (cont’d) o Propulsion and Launch Systems Ø Ø Launch vehicle: used to put a spacecraft into space. Once the weight and volume of the spacecraft have been estimated, a launch vehicle can be selected from a variety of the manufacturers. If it is necessary to deviate from the trajectory provided by the launch vehicle or correct for the errors in the initial condition, additional force generation or propulsion is necessary On-board propulsion systems generally require a means to determine the position and attitude of the spacecraft so that the required trust vectors can be precisely determined and applied. 11

SATELLITE SYSTEM (cont’d) o Attitude Determination and Control System (ADCS) Ø Ø Ø ADCS are required to point the spacecraft or a component, such as solar array, antenna, propulsion thrust axis, and instrument sensor, in a specific direction. Attitude determination can be accomplished by determining the orientation w. r. t. the star, earth, inertial space, geomagnetic field and the sun. Attitude control can be either passive or active or combination. 12

SATELLITE SYSTEM (cont’d) o Power Systems Ø Ø Spacecraft power can be obtained from the sun through solar cell arrays and thermal electrical generators and from on-board devices such as chemical batteries, fuel cell, and nuclear theemelectronic and therm-ionic converters. Most satellites use a combination of solar cell array and chemical batteries. 13

SATELLITE SYSTEM (cont’d) o Thermal Control Systems Ø Ø The function of thermal control system is to maintain temperatures to within specified limit throughout the mission to allow the onboard systems to function properly and have a long life Thermal balance can be controlled by using heaters, passive or active radiators, and thermal blankets of various emissivities on the exterior. 14

SATELLITE SYSTEM (cont’d) o Configuration and Structure Systems Ø Ø Ø The configuration of a spacecraft is constrained by the payload capability and the shape of the fairing of expendable launch vehicle. Large structures, such as solar arrays and antenna are erected in the space through deployable components. Explosive devices, activated by timing devices or command, are used to separate the spacecraft from the launch vehicles, release and deploy mechanisms, and cut cables. 15

SATELLITE SYSTEM (cont’d) o Command Telemetry Ø Ø Ø The Command Telemetry system provide information to and from the S/C respectively. Commands are used to provide information to change the state of the subsystems of the S/C and to se the clock. The Telemetry subsystem collects and processes a variety of data and modulates the signal to be transmitted from the S/C. 16

SATELLITE SYSTEM (cont’d) o Data Handling and Processing Ø Ø Ø Data processing is important to help control and reconfigure the spacecraft to optimize the overall system performance and to process data for transmission. Consists of processor(s), RAM, ROM, Data Storage, and implemented by machine, assembly or high level language. Low mass, volume, and power requirements, insensitivity to radiation, and exceptional reliability are important characteristics of processor. 17

SATELLITE SYSTEM (cont’d) o Communications Ø Ø Ø Radio frequency communication is used to transmit information between the S/C and terrestrial sites and perhaps other S/Cs. Information transmitted from the S/C include the state and health of the subsystems in addition to data from the primary instruments. Information transmitted to the S/C generally consists of data to be stored by on-board processors and commands to change the state of the on-board system either in real-time or through electronic logic that execute them as a function of time or as required. 18

Engineering Procedures o Space Systems Engineering Ø Ø System Definition n System, Subsystem, Components, and Parts n A large collection of subsystems is called a segment. n In a space mission, the spacecraft, the launch vehicle, the tracking stations, the mission control center, etc. , may each be considered a system or segment by their principle developers but are subsystems of the overall system. Value of a System n System’s ability to satisfy criteria generally called system level requirements or standards for judgment. 19

Engineering Procedures (Cont’d) o Engineering a Satellite Ø Ø Ø Ø Mission Needs Conceptualization and system requirements Planning and Marketing Research and Technology Development Engineering and Design Fabrication and Assembly Integration and Test Deployment, operation and phase-out 20

Engineering Procedures (Cont’d) Mission Needs Conceptualization and system requirements Planning and Marketing Research and Tech. Development Engineering and Design Fabrication and Assembly Integration and Test Development, Operation And Phase-out 21

SMALL SATELLITE CASE STUDY ROCSAT-1 o o o A low-earth orbiting (LEO) satellite jointly developed by TRW of U. S. with a resident team of NSPO engineers. Launched on January 27, 1999 into an orbit of 600 kilometers altitude and 35 degrees inclination. Three scientific research missions/Payloads: Ø Ø Ø ocean color imaging/OCI, experiments on ionospheric plasma and electrodynamics /IPEI, experiments using Ka-band (20 -30 GHz) communication payloads/ECP. 22

ROCSAT-1 COMMAND TELEMETRY SYSTEM o o o S-band Consultative Committee for Space Data Systems (CCSDS) Packet Telcommand Telemetry Uplink data rate: 2 kbps Downlink data rate: 1. 4 mbps Data storage: 2 gb 23

ROCSAT-1 COMMAND SYSTEM 2039 MHZ 2 Kbps NRZ-L SPECIAL COMMANDS BILEVEL PCU RCVR SERIAL SOFTWARE TIE OUTPUT CIRCUIT RCVR OBC ADE, GPS, PCU DDC, SAR, DIE DSE BILEVEL MDE, OBC, PCU TDE, DDC ANA 1553 MDE TIE, RIU OCI, IPEI 24

ROCSAT-1 Telemetry Processing Overview GPSE Spacecraft RF Assembly Spacecraft Subsystems 1553 BUS Transponder TIE IPEI Science Data RS 422 Recorded / Playback Data Serial OBC Science Data RS 422 SSR RIU OCI ECP Downlink FDF TT&C Station Ground MOC SDDCs SSC 25

ROCSAT-1 DATA HANDLING SYSTEM o o On Board Computer（ OBC） 80 C 186 : CPU Real-time operation system: Versatile Real-Time e. Xecutive (VRTX 32/86), a real-time multi-tasking OS Employing software engineering approach for the development of the flight software. A real-time embedded system 26

Microsatellite Case Study-MOST o o o The MOST (Microvariability and Oscillations of Stars) astronomy mission is Canada's first space science microsatellite and Canada's first space telescope. Satellite's mission: to conduct long-duration stellar photometry observations in space A secondary payload on a Delta II launch vehicle (with Radarsat-2 as the primary payload). 27

Case Study-MOST (Cont’d) o Payload: a 15 cm diameter aperture Maksutov telescope Ø p Team led by Dr. Matthews of Department of Physics and Astronomy, University of British Columbia Spacecraft: Ø Ø Dynacon Inc. as prime contractor for PM and the Attitude Control and Power subsystems designer Institute for Aerospace Studies' Space Flight Laboratory, Univ. of Toronto: structure, thermal, on-board computers and telemetry & command, along with the ground stations following AMSATNA), with support from Aero. Astro 28

MOST ARCHITECTURE 29

MOST ARCHITECTURE (Cont’d) o o AMSAT based designs housekeeping computer: V 53 processor with 29 MHz Communication: two 0. 5 W RF output BPSK transmitters and two 2 W FM receivers. All radios operate at S-band frequencies 30

MOST ARCHITECTURE (Cont’d) o Power subsystem Ø Ø Ø based on a centralized switching, decentralized regulation topology switches are controlled via the housekeeping computer 35 W in fine pointing operations and 9 W in safehold or tumbling operations Ni. Cd battery provides power during eclipses and supports peak power draws from equipment such as the transmitters High-efficiency silicon solar cells on all sides of the satellite 31

MOST ARCHITECTURE (Cont’d) o o ACS equipment: consists of magnetometers, sun sensors, and a star tracker for sensing, and magnetorquers and reaction wheels for actuation. maintain pointing accuracy of less than 25 arcseconds by using Ø Ø o reaction wheels: for three-axis attitude control, star tracker: a fundamental part of the science telescope attitude control computers : Motorola 56303 DSP 32

MOST ARCHITECTURE (Cont’d) o Structure: Ø Ø a tray stack design consists of aluminum trays that house the satellite's electronics, battery, radios, and attitude actuators these trays are stacked forming the structural backbone of the satellite Six aluminum honeycomb panels, acting as substrates for solar cells and carriers for attitude sensors, enclose the tray stack/telescope assembly 33

Nanosatellite Case Study-Can. X-1 o o The Canadian Advanced Nanospace e. Xperiment 1 (Can. X-1) Canada's first nanosatellite Built by graduate students of the Space Flight Laboratory (SFL) at University of Toronto Institute for Aerospace Studies (UTIAS) Launched on June 30, 2003 at 14: 15 UTC by Eurockot Launch Services from Plesetsk, Russia 34

Case Study-Can. X-1 (Cont’d) o one of the smallest satellites ever built Ø Ø Ø p mass under 1 kg, fits in a 10 cm cube, and operates with less than 2 W of power mission: to evaluate several novel technologies in space Ø Ø a low-cost CMOS horizon sensor and star-tracker active three-axis magnetic stabilization GPS-based position determination central computer 35

Case Study-Can. X-1 (Cont’d) 36

Case Study-Can. X-1 (Cont’d) o CMOS Imager Ø Ø Ø comprised of color and monochrome CMOS imagers used for ground-controlled horizon sensing and star-tracking experiments Both communicate with the On-Board Computer (OBC) 37

Case Study-Can. X-1 (Cont’d) o Active Three-Axis Magnetic Stabilization Ø Three custom magnetorquer coils and a Honeywell three-axis digital magnetometer are used in conjunction with a B-dot control algorithm for spacecraft detumbling and coarse pointing experiments 38

Case Study-Can. X-1 (Cont’d) o GPS Position Determination Ø p Accurate position determination is accomplished using a low-cost commercial Global Positioning System (GPS) receiver that has been modified to work in low Earth orbit ARM 7 On-Board Computer (OBC) Ø Ø operates at 3. 3 V, consumes 0. 4 W at a speed of 40 MHz, equipped with 512 KB of Static-RAM and 32 MB of Flash-RAM Runs housekeeping and payload application routines, as well as B-dot detumbling and errordetection and correction algorithms, No OS. 39

Case Study-Can. X-1 (Cont’d) o Telemetry and Command Ø Ø Ø handled by a half-duplex transceiver operating on fixed frequencies in the 430 MHz amateur satellite band 500 m. W transmitter downlinks data and telemetry at 1200 bps using a MSK over FM signal The antenna system consists of two quarterwave monopole antennas oriented at 90° and combined in phase to produce a linearly polarized signal 40

Case Study-Can. X-1 (Cont’d) o Power system with Triple-Junction Solar Cells and Lithium-Ion Ø Ø Ø Power: provided by Emcore triple-junction cells (26% maximum efficiency) Energy: stored in a Polystor 3. 7 V, 3600 m. Ah lithium-ion battery pack to handle peak loads and provide power during eclipse periods incorporates peak-power tracking, over-current protection, power shunting, and an emergency load shed system 41

Case Study-Can. X-1 (Cont’d) o Structure: Aluminum 7075 & 6061 -T 6 Ø Ø total mass of structure is 373 g, 37% of the total satellite mass, including the frame, all exterior surfaces, and internal mounting hardware Simulations with 12 G loads showed a 30% margin to the maximum allowable stress thermal analysis predicted a -20 to +40°C temperature range using passive thermal control Vibration testing shown a natural frequency of approximately 800 Hz 42

Q&A More Case Studies from Student Teams