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Introduction to Mission Planning System

Non Meeboon

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Course Statement

The goal of this presentation is to provide a basic knowledge of mission planning system groundsegment. It also includes how SSTL approaches the mission planning of THEOS-2 SmallSAT.

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Content

1. Overview2. Building a Mission Plan3. Satellite Constraints

a) The 3 Constraintsb) Timeline Managementc) The 5 Orbit Scenariosd) Power Managemente) Memory Management

4. Final Remarka) Roleb) Skillsc) Toolsd) Textbooks and Documents

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Overview

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What is Mission planning?

In space-based Earth observation, it is a commonwork to obtain the information about Earth andhuman activities via image acquisitions and sensorreadings. Mission planning is a process to acquire

these data by validating the user’s objective andperform the analysis in order to find the bestcompromise between user satisfaction and availablesatellite resources and constraints.

Introduction

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Building a Mission Planning

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Building a Mission Plan (1/5)

Request #1

Request #2

Request #3

Request #4

Request #5 Request #6

Request #7Request #8

To build a mission plan is like filling a stone into a jar.

Once the jar is full, no more stone can be added.

Once the spacecraft constraint is reached, no more request can be done.

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Building a Mission Plan (2/5)

Update system configuration• Update satellite system parameter such as:

• Satellite inertia• Reaction wheel• Magnetometer• Sun sensor

• DUT (Difference between Universal Time and Coordinated Universal Time)• Current day orbit

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Define request parameters• Geographical area of interest: NW (34.24°N, 118.11°W), NE

(34.20°N, 117.53°W), SW (33.27°N, 118.13°W), SE (33.31°N, 118.28°W)

• Satellite selection: THEOS-1, THEOS-2M, THEOS-2S

• Downlink station selection: Bangkok, Chonburi, Chiangmai

• Validity time interval: 2020-11-12 to 2020-11-19

• Priority definition: Normal, Urgent, Last minute

• Performance criteria: Max/min roll, max/min pitch

• Instrument selection: Optical (PAN or multispectral), SAR

• Cloud coverage: No cloud, Partial cloud, Full cloud

Building a Mission Plan (3/5)

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Strip ID: 001-01Start time: 2020-11-12 12:03:44Stop time: 2020-11-12 12:04:20Orbit number: 116Roll: 10.5°Pitch: 12°

Example of strip splitting

Feasibility Analysis• Strip splitting• Calculate access time window• Calculate roll and pitch angle to target

Building a Mission Plan (4/5)

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Request RankingDefault ranking of request according to:• Priority – Last Minute, High, Normal• Roll angle• Cloud coverage• End valid date

Request ID Rank Priority Roll (°) Cloud (%) End date Status

003 1 LAST MINUTE -3.2 10.0 2020-11-19 RANKED

002 2 URGENT 0.0 25.0 2020-12-28 RANKED

001 3 NORMAL 20.2 5.5 2020-12-29 RANKED

004 4 NORMAL -11.5 30.0 2021-01-05 RANKED

005 5 NORMAL -5.5 14.7 2021-02-15 RANKED

Building a Mission Plan (5/5)

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Satellite Constraints

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The constraints of planning algorithm consist of three aspects including:

1. Time

2. Power

3. Memory

The request is checked to see if the satellite activities overlap; if it does, the MPS rejects the mission plan.

The power and memory constraints of the satellite are checked for every timespan of one second. This is to validate a new insertion of mission plan at any given point of time.

The 3 Constraints

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In the scope of mission planning, the system needs to know the time when the equipmentneeds to be turned on and off. The operational duration of each equipment determines how amission timeline can be constructed. THEOS-2 SmallSAT can be divided into 10 onboardequipment:

1. Data Handling Unit (DHU)

2. S-band transmitter

3. X-band transmitter

4. Reaction wheel

5. GPS

Time Management

6. Star tracker

7. Primary payload imager

8. Secondary payload imager – AIS Receiver

9. Secondary payload imager – ADSB Receiver

10. Third payload imager

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THEOS-2 SmallSAT operates on a 5 orbit scenarios starting from launch until operation. Each scenariorequires different operation of equipment which lead to different power consumption. The scenarioincludes:

The 5 Orbit Scenarios

DTM (Detumble

Mode)

YTM (Y-Thompson Mode)

SBM( Safe/Stand-by

Mode)

CPM (Coarse Pointing

Mode)

NOM (Nominal Mode)

Failure Reconfiguration

Return to default mode for operation

Telecommand

No control, randomly tumble, configure onboard computer.

Dumped attitude rate by using magnetometer and magnetorquer

Spin-stabilization around Y-axis body by using magnetometer and magnetorquer, and 2 reaction wheels

Attitude and body rate estimation by using magnetometer and sun sensor. Coarse attitude control for nadir pointing by magnetorquer and 4 reaction wheels (error 10 degree)

Attitude and body rate estimation by using gyroscope, star tracker, magnetorquer, and 4 reaction wheels for fixed target tracking i.e.imaging/downlink operation (error 0.1 degree)

Telecommand

Telecommand

Telecommand

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Power management is one of the THEOS-2 SmallSAT mission planning constraint. Mission planning system needs to know the following factors in order to deliver a successful mission plan:

1. Orbit scenario

2. Power usage for each equipment

3. Duration of equipment usage

4. Rate of charge

a) Spacecraft attitude

b) Sun direction

c) Solar array specification

5. Depth of Discharge

The mission planning system calculates the Depth of Discharge using one second timestep to validate the insertion of new request on full planning horizon.

Eclipse Sunlight

Power Management

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Memory management is one of the THEOS-2 SmallSAT mission planning constraint. Mission planning system needs to know the following factors in order to deliver a successful mission plan:

1. Maximum onboard memory capacity

2. Memory size for each mode of capture

a) Imaging duration

b) Resolution

c) Bit depth

d) Frame rate

e) Overhead size

f) Memory boundary

3. Downlink rate

The mission planning system calculates the onboard memory profile using one second timestep to validate the insertion of new request on full planning horizon.

Memory

Request #1 Request #2 Request #3 Request #4

Memory Management

Final Remark

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Role

ConceptPreliminary

Design Review (PDR)

Critical Design Review (CDR)

Unit Test Integration Test

On-site Acceptance

Test (OSAT)

Operation

Understand the preliminary requirements of the spacecraft design

PDR design of the following documents:- System

Specifications Requirements

- Interface Control Document

- Design Document

CDR design of the following documents:- Interface Control

Document- Design Document- Validation Test

Plan Document

Unit testing of the each module including:- User interface- Feasibility analysis- Mission planning- Mission scheduling- Mission follow-up- Catalog browsing

End to end test of the system by integrating all functional components

On-site acceptance test by automatically allowing the system operates for 24/7

Support nominal satellite operations

Timeline

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Programming

• Java• Python• JavaScript

Math

• Linear Algebra• Optimization

Orbital Mechanics

• Basic concepts• Orbit

Satellite Knowledge

• Equipment• Memory• Power

Language

• English• Thai

Teamwork

• Communication• Emotional Intelligence

Skills

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Laravel Framework NGINX Eclipse

MongoDB GeoServer Java JDK

Python Anaconda Git

Orekit

Tools

Textbooks and Documents

Fundamentals of Astrodynamics and ApplicationsDavid A. Vallado

JAVA HOW TO PROGRAMDEITEL

THEOS-1, THEOS-2 MainSAT, and SmallSAT documents including:1. Mission planning manual2. Flight operation handbook3. Ground segment design4. Mission planning interface control

document

UNDERSTANDING SPACE: An Introduction to Astronautics

Jerry Jon Sellers