Space Technology: Satellite Design & Functionality Guide-P1

Satellite Design & Space Technology

Space Technology & Satellite Design

Space Technology & Orbital Engineering Fundamentals

Satellite Fundamentals

Satellites are automated spacecraft in orbit around Earth. Modern systems serve telecommunications, Earth observation, navigation, weather monitoring, and scientific research across various orbital regimes.

Autonomous vacuum operation
Long-term power generation
Remote command & telemetry
Precision attitude control

Global Impact

Satellite infrastructure enables global communication, GPS systems, weather forecasting, and disaster management. ISRO’s contributions ensure India’s technological sovereignty and global service capability.

Earth observation capability
Disaster management support
Environmental monitoring
Communication independence

Satellite Detection Technologies

Modern detection employs sophisticated radar and optical systems providing 2D and 3D spatial awareness.

Detection Systems Comparison

Technology	Range	Accuracy	Weather	Update
Radar 2D	5000+ km	±100 m	Low	1-10 Hz
Optical	GEO	±10 as	High	0.1-1 Hz
3D Radar	3000+ km	±50 m	Very Low	2-10 Hz
LIDAR	500 km	±5 cm	Very High	1-100 Hz

Radar Systems

S-band & X-band frequencies
Phased array technology
Multi-station triangulation
Real-time 3D positioning
Weather independent

Optical Tracking

CCD/CMOS camera arrays
Sub-arcsecond resolution
Twilight/night operation
Passive sensing (no RF)
Magnitude 16-20 visibility

ISRO Technology & Capabilities

Launch Vehicle Portfolio

PSLV

Height: 44.4 m
Mass: 294 tonnes
LEO Capacity: 10,000 kg
Reliability: 98%+

GSLV Mk-III

Height: 43.4 m
Mass: 640 tonnes
GEO Capacity: 5,600 kg
Cryogenic: CE20 engine

SSLV

Height: 34 m
Mass: 120 tonnes
Capacity: 500 kg LEO
Cost: ₹300-500 Cr

RLV-TD

Type: Spaceplane
Landing: Autonomous
Reusability: 20+ flights
Target: 2030s

Satellite Programs

IRS Series

Earth observation satellites with 1-2m resolution for resource monitoring and disaster management.

INSAT/GSAT

Communication and meteorological satellites in GEO providing weather and data relay services.

NavIC

Regional navigation system with 9 satellites providing ±5-10m accuracy over India.

Orbital Mechanics & Design

Orbital Regimes

LEO

160-2000 km | 88-120 min period

MEO

2000-35,786 km | 2-24 hours

GEO

35,786 km | 24-hour period

Orbital Parameters

Six Keplerian elements define satellite orbit:

a – Semi-major axis
e – Eccentricity
i – Inclination
Ω – RAAN
ω – Argument of perigee
ν – True anomaly

Perturbations

Earth oblateness (J2)
Atmospheric drag
Solar radiation pressure
Third-body effects
Relativistic effects

Atmospheric Density Impact

Altitude	Density	Drag Effect	Service Life
400 km	10⁻¹¹ kg/m³	Critical	Reboost needed
800 km	10⁻¹⁵ kg/m³	Moderate	5-10 years
GEO	~0	Negligible	15-20 years

Advanced Satellite Design

Structural Materials

Primary Materials

Al 7075-T73 – Primary structure
Carbon Composites – Panels & deployables
Titanium alloys – High-stress interfaces
Modular, scalable architecture

Thermal Protection

MLI – 15-25 layers
Kapton/Mylar reflective
Aluminum radiators
Heat pipe networks
-10 to +70°C control

Power System

Solar Arrays

Multi-junction cells
32-36% efficiency
400-800 W/m²
Deployment mechanisms

Energy Storage

Lithium-ion batteries
100-500 Ah capacity
28-120 VDC
70-80% DoD

Distribution

Regulated bus systems
Fault isolation units
Redundant paths
92%+ efficiency

Subsystem Architectures

Power Budget Example

Subsystem	Average	Peak
ADCS	80 W	150 W
Thermal	40 W	120 W
Avionics	100 W	150 W
RF/Comms	120 W	300 W
Payload	400 W	600 W
TOTAL	740 W	1320 W

Communication Frequencies

Uplink (Commands)

UHF/S-band frequency
1-10 kbps data rate
QPSK modulation
Convolutional coding
Encrypted commands

Downlink (Telemetry)

S/Ku/Ka-band
100 kbps – 100 Mbps
QPSK/QAM modulation
10-50 W transmitter
15-25 dBi antenna

Attitude Control

Sensors

Sun sensors (4-6 units)
Earth/Star sensors
IMU (gyroscopes)
Magnetometers
Accuracy: 0.1-1°

Actuators

Reaction wheels (3-4)
Magnetic torquers
Thrusters (micro-jets)
Control moment gyro
Authority: ±3°/s

Propulsion Systems

Type	Propellant	Isp	Thrust	Application
Monopropellant	N₂H₄	230 s	0.5-10 N	Station-keeping
Ion Engine	Xenon	3000-4500 s	10-100 mN	Mission extension

Satellite Geometry & Deployment

Bus Configurations

IRS Bus

Compact Earth observation platform for resource monitoring.

Mass: 500-1000 kg
Size: 1.5m × 1.8m × 1.2m
Power: 800-1200 W
Mission: 5-7 years

GSAT Bus

Medium-class multi-payload platform.

Mass: 2000-3000 kg
Size: 2.5m × 2.5m × 2.0m
Power: 2000-3000 W
Mission: 12-15 years

Advanced Bus

Enterprise-class heavy satellite.

Mass: 4000+ kg
Size: 3.5m × 3.0m × 3.0m
Power: 4000-6000 W
Mission: 15-20 years

Deployment Timeline

Phase	Time	Altitude	Task
Fairing Jettison	T+120s	60 km	Payload exposed
Solar Deploy	T+300s	100 km	Initial power
Apogee Kick	T+16h	Apogee	Orbit circularize
Antenna Deploy	T+24h	Final orbit	Comm established
Operations	T+48h	Final orbit	Full capability

Mass Budget Distribution

Typical 1000kg Satellite

Structure (230 kg)

23%

Power (200 kg)

20%

Thermal (150 kg)

15%

ADCS (120 kg)

12%

Propulsion (150 kg)

15%

Payload (150 kg)

15%

Center of Gravity

Requirements

CG within ±50 mm
X-axis: ±10 mm
Y-axis: ±10 mm
Z-axis: ±15 mm

Measurement Method

Laser theodolite
Optical determination
Pre-flight mandatory
Post-integration verify

Command, Control & Communications

GPS & Navigation

GPS Navigation

Accuracy: 5-10 m
Update: 1-10 Hz
Global coverage
L1/L2/L5 bands
Ionospheric correction

NavIC (ISRO GNSS)

9 satellites (3 GEO, 6 IGSO)
Accuracy: ±5-10 m
Coverage: India + 1500km
L5 & S-band signals
Authentication support

Deorbit & Landing

Deorbiting Systems

Controlled burn maneuvers
150-200 km reentry altitude
Attitude control during reentry
Safe breakup zone selection
IADC compliance

RLV Recovery

Thermal protection tiles
Hypersonic control surfaces
Autonomous guidance
Parachute deployment
3-6g load control

Launch Vehicles & Procedures

Launch Sequence Timeline

Phase	Duration	Activity
T-120 to T-60	60 min	Fuel loading, personnel clearance
T-60 to T-10	50 min	Propellant sequence, systems check
T-10 to T-0	10 min	Final GO/NO-GO, ignition sequence
T+0 to T+150s	150 s	Vertical climb, gravity turn, Max-Q
T+150s to Apogee	Variable	Stage separations, upper stage burn

Payload Integration

Integration Steps

Design Review (PDR)
Thermal Vacuum Test
Vibration & Acoustic
Interface Verification
Mass & CG Check
EMC Testing
Structural Analysis
Payload Mating
Final Validation

Launch Window

SSO: 2-3 day windows
GEO: 10-30 second windows
Frequency: 2-3 per month
Inclination optimization critical
Weather dependency low
Range clearance required

Environmental Factors & Performance

Thermal Environment

Temperature Extremes

Sunlit: +120°C to +150°C
Shadow: -50°C to -180°C
Thermal cycles: 16 per 24h (LEO)
CTE mismatch stress
Component derating: 20-30%

Thermal Control

Passive radiators: 60-80%
Active heat pipes
Thermal switches
MLI: 5-20 cm thickness
Emissivity optimization

Space Environment Hazards

Radiation

Solar cosmic rays
Van Allen belts
Dose: 0.1-1 Gy/year
SEUP upsets risk
100-300 mil Al shielding

Atomic Oxygen

LEO: 10¹⁴-10¹⁶ atoms/cm³
Hyper-thermal erosion
Material degradation
Protective coatings
5-10 year life impact

Micrometeorites

Flux: 10⁻⁶ impacts/m²/day
Velocity: 20-70 km/s
Whipple shields
Redundancy critical

Atmospheric Drag Impact

Altitude	Density	Drag	Service Life
400 km	10⁻¹¹	Critical	Continuous reboost
800 km	10⁻¹⁵	Moderate	5-10 years
1200 km	10⁻¹⁹	Minor	20-50 years
GEO	~0	Negligible	15-20 years

System Integration & Testing

Test Matrix Overview

Test Category	Test Type	Acceptance	Duration
Structural	Modal Analysis	1st mode > 5 Hz	2 hrs
Structural	Vibration	20-2000 Hz @ 5g	8 hrs
Thermal	TVAC	-50 to +80°C	20 hrs
Thermal	Cycling	500+ cycles	50+ days
Electrical	EMC	IEC 61000-6-2	5-10 days
Functional	FMEA	100% coverage	20+ hrs

ATP Levels

Unit-Level

Component qualification testing

MTBF verification
Burn-in at 125% stress
Functional parameter mapping
Failure mode analysis

System-Level

Complete satellite validation

Mission mode operations
Orbital scenario simulation
Failure recovery modes
End-to-end verification

Quality Standards

Soldering (IPC-A-610)

Visual Class 3
X-ray sampling
Thermal cycling
Pull strength ≥1.5kg

Adhesives

Class A/B structural
Outgassing <1%
COTE <0.5%
Shear strength verify

Cleanliness

Particle: <200 μm
Ionic residue: <100 μg
Protected environment
ESD Class 0

Troubleshooting & Failure Management

Common Failures & Recovery

Power System Failures

Battery Undervoltage

Cause: Eclipse duration or panel degradation

Check panel orientation
Load shedding sequence
Reconditioning cycle

Solar Array Damage

Cause: Debris strike or thermal

Deploy emergency array
Attitude redirection
Power reduction

Thermal Control Failures

Electronics Overheating

Cause: Radiator failure

Reduce clock speed
Switch processors
Adjust louvers

Cold Bias State

Cause: Heater malfunction

Activate secondary heaters
Attitude adjustment
Monitor cold-soak

ADCS Anomalies

Uncontrolled Tumbling

Cause: Wheel failure

Magnetic desaturation
Switch to 3-axis mode
Thruster stabilization

Thruster No Response

Cause: Line blockage

Purge lines
Switch to backup
Use ion engine

Communication Failures

No Downlink Signal

Cause: Antenna mismatch

Check deployment
Transmitter cycling
Attitude adjustment

Commands Not Accepted

Cause: High BER

Reduce data rate
Increase power
Switch receiver

Advanced Technologies & Future Systems

Next-Generation Technologies

Electric Propulsion

Hall thrusters
Ion engines
Isp: 1500-4500 s
Multi-mission capable
5-10 year extension

High-Power Solar

35-40% efficiency
500-800 W/kg
Deployable designs
Self-healing layers
Megawatt potential

Autonomous Operations

Onboard fault detection
Autonomous planning
Self-healing software
Reduced ground dependency
AI-enhanced control

ISRO Future Vision

Space Station Program

LEO research facility
400 km altitude
3-4 astronaut crew
180-360 day missions
Scientific experimentation

Reusable Systems

RLV-Technology Demonstrator
80% cost reduction
3-5 day turnaround
20+ vehicle lifetime
Operational 2030s

Skills Development Path

Core Competencies	Specialization	Tools & Software
Orbital mechanics	Structures	STK
Control systems	Power systems	GMAT
Thermal analysis	Attitude determination	ANSYS
RF communication	Propulsion	MATLAB/Simulink
Materials science	Ground operations	SPICE