general supporting informationemits.sso.esa.int/emits-doc/astriumlim/swarm... · file:...

SWARM Doc. No: SW-LI-EAD-SY-0004

Issue: 3

Swarm General Supporting

Information Date: 30.01.2007

© EADS Astrium GmbH Page - II File: SW-LI-EAD-SY-0004_3_General Supporting Information.doc

DOCUMENT CHANGE DETAILS

ISSUE DATA SHEET DESCRIPTION

1 24.03.2006 all Initial Issue

2 10.04.2006 all Approved issue for ITT

3 30.01.2007 all Update for System PDR


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© EADS Astrium GmbH Page - III - File: SW-LI-EAD-SY-0004_3_General Supporting Information.doc

CONTENTS

1. SCOPE ..........................................................................................................................................................2

2. DOCUMENTS ...............................................................................................................................................3 2.1 Applicable Documents............................................................................................................................3 2.2 Reference Documents............................................................................................................................3

3. SWARM OVERVIEW ....................................................................................................................................4 3.1 SWARM Mission and System Overview ................................................................................................4

3.1.1 Mission Goals...............................................................................................................................4 3.1.2 The SWARM System ...................................................................................................................6 3.1.3 SWARM Configuration .................................................................................................................8

3.2 Flight Operations ..................................................................................................................................11 3.3 Mission Phases ....................................................................................................................................12

3.3.1 Launch and Early Orbit Phase (LEOP) ......................................................................................12 3.3.2 Commissioning Phase ...............................................................................................................12 3.3.3 Operational Phase .....................................................................................................................13 3.3.4 End-of-life Phase........................................................................................................................13

4. TERMS AND DEFINITIONS........................................................................................................................14 4.1 Company Designations ........................................................................................................................14 4.2 General System Designations..............................................................................................................14 4.3 Reference Frames................................................................................................................................15

4.3.1 International Celestial Reference Frame (ICRF)........................................................................15 4.3.2 International Terrestrial Reference Frame (ITRF)......................................................................15 4.3.3 North-East-Centre (NEC) Frame ...............................................................................................16 4.3.4 Orbit Reference Frame (ORF) ...................................................................................................16

4.4 Engineering ..........................................................................................................................................17 4.5 Software ...............................................................................................................................................18 4.6 Characterisation/Calibration.................................................................................................................19 4.7 Magnetic Field Sources........................................................................................................................19

5. MODELS .....................................................................................................................................................20 5.1 Simple E-field distribution model..........................................................................................................20

6. ABBREVIATIONS........................................................................................................................................22

FIGURES Figure 3-1: Functional breakdown of the SWARM system, including the major data flows..............................8 Figure 3-2: SWARM S/C Configuration (General Information Only !) ...............................................................9 Figure 3-3: SWARM S/C Overall Dimensions (General Information Only !) ...................................................10 Figure 3-4: Three-Satellite Single Launch Configuration (General Information Only !) ..................................10 Figure 3-5: Spacecraft Reference System ......................................................................................................11


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© EADS Astrium GmbH Page - IV - File: SW-LI-EAD-SY-0004_3_General Supporting Information.doc

INTENTIONALLY BLANK


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© EADS Astrium GmbH Page 2 File: SW-LI-EAD-SY-0004_3_General Supporting Information.doc

1. SCOPE

This document provides general supporting information on the overall SWARM system to supplement the various subsystem requirements specifications. It does not contain any formal requirements to the Contractor.

On the one hand this document provides helpful information to understand the overall system context.

On the other hand it defines the constraints and boundary conditions under which the various SWARM sub-systems shall operate.

It further explains the used abbreviations and defines the understanding of keywords within SWARM to create a common understanding and avoid misunderstandings.


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© EADS Astrium GmbH Page - 3 - File: SW-LI-EAD-SY-0004_3_General Supporting Information.doc

2. DOCUMENTS

2.1 Applicable Documents

AD-1 System Requirements Document SW-RS-ESA-SY-001 Issue 3.0

amended by

EOP-PR/42/2006/EN/uw 31. July 2007

EOP-PR/90/2007/RB/rb 15. January 2007

EOP-PR/94/2007/RB/rb 29. January 2007

2.2 Reference Documents none


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• identifying the ocean circulation by its magnetic signature,

• quantifying the magnetic forcing of the upper atmosphere

h his will

eeded for the analysis. The aim is to recover the finest scales of this table with sufficient accuracy.

3. SWARM OVERVIEW

3.1 SWARM Mission and System Overview

3.1.1 Mission Goals

Earth Explorer Missions are part of the Earth Observation Envelope Programme (EOEP). They are small missions led by the European Space Agency (“ESA” or the “Agency”) to cover primary research objectives. The Swarm Mission, (hereinafter also referred to as “Swarm”) has been approved for implementation as the fifth Earth Explorer Mission.

The primary aim of the Swarm mission is to provide the best ever survey of the geomagnetic field and the first global representation of its variation on time scales from an hour to several years. The more challenging part, however, is to separate the contributions from the various sources. Swarm will simultaneously obtain a space-time characterisation of both the internal field sources in the Earth and the ionospheric-magnetospheric current systems.

The primary research objectives assigned to the mission are:

• studies of core dynamics, geodynamo processes, and core-mantle interaction,

• mapping of the lithospheric magnetisation and its geological interpretation,

• determination of the 3-D electrical conductivity of the mantle,

• investigation of electric currents flowing in the magnetosphere and ionosphere

In addition to the above sources, the ocean currents produce a contribution to the measured magnetic field. But the magnetic field is not only used as evidence of the evolution of the planet, it also exerts a very direct control on the dynamics of the ionised and neutral particles in the upper atmosphere, and possibly even has some influence on the lower atmosphere. This leads to the identification of the secondary research objectives of:

Analysis of the Swarm data will greatly improve existing and provide new models of the near-Eartmagnetic field of high resolution and authenticity compared to a single-satellite mission. Tprovide the prospect of investigating hitherto undetected features of the Earth’s interior.

The expected internal field characteristics at 400 km altitude based upon current knowledge are shown in Table 3-1. Also indicated are the types of measurements that are n


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Research

Objectives

Time

Range

Spatial

Range

Signal

Range

Signal at certain wavelength (wl)

Measurement

(B= magnetic)

Core dynamics and geodynamo processes

Static 3000 km to global

±65000 nT 0.8 nT @ 3000 km wl B-field vector, attitude and position

3 months to decades

2500 km to global

±200 nT/year 0.025 nT/3 months @ 2800 km wl

Lithospheric magnetisation

decades to static

300 km to 3000 km

±25 nT 0.8 nT @ 3000 km wl

0.009 nT @ 360 km wl

B-field vector, attitude and position

3-D mantle conductivity

1.5 hours to 11 years

300 km to global

±200 nT n.a (modeled as conductivity)


Ocean circulation

12 hours to 2 years

600 km to 10000 km

±5 nT 0.5 nT @ 10000 km wl

0.01 nT @ 600 km wl


Table 3-1: Internal Field Characteristics

In the Table 3-2 the expected signals of the external contributions are given. These values correspond to the same altitude.

Research

Objectives

Time

Range

Spatial

Range

Signal

Range

Measurement

(B= magnetic,

E= electric)

Ionosphere-magnetosphere current systems

0.1 sec to 11 years

10 sec to 3 months

1 km to global

10 km to global

B-field: ±1000 nT

E-field: ±0.2 V/m

Ion drift velocity: ±4000 m/s

B-field, E-field, and ion drift velocity vectors, attitude and position

Magnetic forcing of the upper atmosphere

10 sec to 2 years

10 sec to 3 months

200 km to global

Plasma density 1*108 m-3

to 5*1013 m-3

Air drag: 1*10-5 m s-2

Ion and electron temperature: 1000-100000 K

B-field and E-field vectors, ion and electron temperature and plasma density, attitude and position

Table 3-2: External Contributions


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After release from the launcher, a side-by-side flying lower pair of satellites at an initial altitude of about 450 km and a single higher satellite at about 530 km will form the Swarm constellation. The SWARM satellites will fly at near polar orbits in order to get a good global coverage.

The timing of the mission will also make it possible to take advantage of data recovered from previous missions to investigate changes, which occurred in the magnetic field over a full decade time scale.

3.1.2 The SWARM System

The system consists of the space segment and the ground segment. The space segment is composed of three identical satellites. Each satellite consists of a spacecraft and payload.

The payload of the Swarm satellite is defined as follows:

• Absolute Scalar Magnetometer (ASM)

• Vector Field Magnetometer (VFM)

• Electrical Field Instrument (EFI)

• Accelerometer (ACC)

• Laser Retro-Reflector (LRR)

• GPS Receiver (GPSR)

• Star Tracker (STR)

The y◊ d or procured under responsibility or EADS

◊ ments provided as Customer Furnished Instruments (CFI); they are the ASM and the

The othe

◊ The command and control ground segment provided by ESA.

d instruments is as following:

pa load to be incorporated in Swarm comprises two types of elements: Contractor Procured Instruments (CPI) developeAstrium; they are VFM, ACC, LRR, GPSR, STR

InstruEFI

r elements of the system are: ◊ The launcher, procured by ESA.

A short description of the embarke


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nd r obtaining the magnitude of the field with high accuracy an ASM is included in the payload.

n, ultra-high linearity and low noise easurements of the Earth's magnetic field vector components.

mperature and spacecraft potential. These parameters are used to calculate e local electric field.

FM axis orientation. This mechanical interface between STR and VFM is called Optical Bench B).

timing information.

with a ceiver, a common time scale can be

stablished for all the satellites and their instruments.

e and orbit control actuators, etc. he accelerometer will be embarked on an experimental status.

m and illustrates the process for the generation of level 1b scientific data as required by the users.

Absolute Scalar Magnetometer

The Absolute Scalar Magnetometer (ASM) provides the ability of performing an in-flight calibration of the vector magnetometer, to maintain absolute accuracy in a multi-year geomagnetic field mission the ability of performing an in-flight calibration of the vector magnetometer is needed. For this purpose afo

Vector Field Magnetometer

The Vector Field Magnetometer (VFM) accomplishes high precisiom

Electrical Field Instrument

The Electric Field Instrument (EFI) makes in-situ measurements of the ion distribution and its moments. Key parameters that can be determined by this instrument are ion arrival angle, drift velocity, ion density, teth

Star Tracker (STR) Assembly

The Star Tracker assembly shall deliver 3 axis highly accurate attitude data, whose performances accuracy is compatible with the level 1 B product performances requirements The STR shall be mounted together with the VFM on a rigid mechanical interface to get the required precise knowledge of the V(O

GPS Receiver

The GPS receiver will provide autonomous and real time satellite positioning andPrecise orbit determination will be computed during post processing on ground.

By using the precise timing information contained in each navigation solution in combination synchronisation pulse delivered every second by the ree

Accelerometer

An accelerometer (ACC) takes measurements of the non-gravitational accelerations acting on the spacecraft caused by air density, solar wind, Earth albedo, attitudT

Laser Retro Reflector

The LRR shall allow precise range measurements from ground based satellite laser ranging stations.

The figure below gives an overview on the main elements of the SWARM syste


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The SWARM constellation with a pair of satellites at lower altitude and the third one at higher altitude is shown, interfacing with the GPS system and a Laser Range Station for precise attitude and orbit determination.

The ground station for Telemetry and Telecommand (TT&C) is used for the reception of the scientific raw data (level 0) delivered by the payload instruments.

In order to establish the required data quality, correction factors derived from on-ground calibration of the instruments prior to launch and from flight calibration during in-orbit commissioning and nominal operations have to be taken into account. The scientific raw data and the correction factors are merged in the level 1b processor resulting in a scientific data stream of level 1b quality.

Figure 3-1: Functional breakdown of the SWARM system, including the major data flows (General Information Only !)

3.1.3 SWARM Configuration

The mission goal of SWARM has a number of implications for the system and satellite design and the overall operational concept. Most important requirements for the satellite design are related to magnetic cleanliness, avoidance of satellite charging, precise attitude and orbit determination and control, accurate information on location and time of scientific data collection (datation), instrument performance, accommodation and calibration, favourable ballistic properties and sufficient delta-V resources.

The constellation keeping and orbit maintenance - in particular for the lower pair of satellites - has strong influence on the Attitude and Orbit Control sensors and safe mode concepts.


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The given operational and ground segment interface requirements demand a high degree of on-board autonomy and single satellite reliability. For the operational phase an “off-line“ control concept has to be established to implement the requirement for a single scientific data dump per day and per satellite.

There are very strict requirements for the payload instruments regarding their accommodation, align-ment and stability, in particular for the magnetometers, the Absolute Scalar Magnetometer (ASM) and the Vector Field Magnetometer (VFM) and also for the Star Tracker (STR) assembly providing reference data for the measurement of the magnetic field direction. All these instruments are accommodated on the magnetometer boom. The VFM and STR require a high precision and high stability co-alignment as an assembly on an optical bench due to their strong influence on the scientific data quality.

The key design features are summarized in the figure below.

Figure 3-2: SWARM S/C Configuration (General Information Only !)

The figure provides side, top and cross-sectional views of the satellite configuration with deployed boom. The overall length of the satellite amounts to almost 9.5 m.


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Figure 3-3: SWARM S/C Overall Dimensions (General Information Only !)

All three satellites shall be launched in a single launch configuration considering launchers such as Vega and other suitable launch vehicles.

This imposes restrictions on dimensions and mass of the satellites and impacts the launch separation and orbit injection strategies.

The three-satellite single launch configuration is shown for Rockot, Vega and Dnepr which are all candidate launchers for SWARM.

Figure 3-4: Three-Satellite Single Launch Configuration (General Information Only !)

The nominal origin of the Satellite Reference Frame (XS , YS , ZS ) shall be on the interface plane separating the satellite and the launcher.


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Satellite +X axis, direction of travel • Origin located on outer surface of

lower panel, LVA is +ve X

Satellite +Z axis in Nadir direction • Origin located on outer surface of

Nadir panel

Satellite Y axis, complements RH rule • Origin located at centre of Nadir

panel

The origin description given here is for information, only. Detailed, exact location of the Spacecraft Reference Frame can be found in the respective I/F drawings.

Figure 3-5: Spacecraft Reference System

3.2 Flight Operations

The SWARM satellites will be operated by ESOC using the appropriate ground segment for TT&C and data reception while the ESRIN facility will be in charge of processing, archiving and distributing the scientific data to the users.

After launch, the spacecraft will be manoeuvred to their initial orbits. The pair on lower orbit of 450 km, called SWARM A and B, will be maintained in their relative configuration during mission life. The orbit may decay down to an altitude of 300 km at End of Life. In contrast, the orbit of SWARM C may decay freely from the initial height of 530 km. However, its orbit will always be higher than SWARM A and B.


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• attitude acquisition phase, including:

◊ delivery of power from the solar array

• ase, in which contingency manoeuvres for initial collision avoidance can be performed

3.3.2 Commissioning Phase

rument operational parameters

• platform functional checkout, in which the satellite basic functions and health are verified;

• instruments switch on and funtional check-out to verify their health;

• SWARM initial performance characterisation / calibration;

In-orbit verification of level 1b performances and performance stability.

3.3 Mission Phases

3.3.1 Launch and Early Orbit Phase (LEOP)

The LEOP will include the following events, starting at the switchover from ground-supplied power to the satellite internal batteries:

• internally powered pre-launch phase, during the count-down;

• launch phase, from the launch until separation of the satellite from the launcher

• satellite collision avoidance at the separation of the satellites from the launcher

• initial switch-on, in which communication is established between the On-Board Computer (OBC) and other satellite subsystems being off during launch/ascent

◊ rate reduction

◊ attitude acquisition

◊ any appendage deployment

orbit correction ph

During the Commissioning Phase the overall satellite, including the instruments, will be brought into afully operational state. Relevant adjustments may be made to the instor software to optimise performance. Specific activities may include:

• Initial formation and constallation establishment;

• Ground Segment data acquisition, processing and final commissioning;

•


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• S/C Manoeuvres for data calibration

• maintenance in case it is necessary from initial altitude down to 300 km or lower at the end of life

3.3.4 End-of-life Phase

• strated that it will burn up during re-entry in the atmosphere and does not pose any hazard, or

• de-orbiting shall commence and a controlled re-entry in the atmosphere shall be allowed

3.3.3 Operational Phase

During the Operational Phase the three spacecraft will operate nominally. Specific activities may include:

• Nominal operation where the instruments operate continuously or perform internal characterisation and calibration measurements which are needed to achieve the specified performance.

• Processing of raw data and production of Level 1B data with data acquisition, processing, archiving and data product distribution

• Orbit control, to maintain the selected orbit of each Swarm satellites

• Constellation maintenance between the lower satellites and the upper one

Free decay or a combination of free decay and altitude

During the End-of life Phase, the satellites will:

dispose all remaining fuel, if it can be demon


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4. TERMS AND DEFINITIONS

The terms and definitions listed hereunder will be used throughout the Swarm documentation.

4.1 Company Designations

The Agency or ESA

European Space Agency being the customer for the Swarm programme.

EADS Astrium GmbH (EAD)

Prime contractor of the Swarm space segment including the related ground segment as far as defined in the contract.

EADS Astrium Ltd. (EAU)

Sub-contractor to EAD providing major parts of the space segment and related ground segment.

Sub-Contractor

Any other sub-contractor to EAD or EAU being a member of the Swarm industrial team.

4.2 General System Designations

Mission is defined as the whole entity of the project comprising the space segment and the ground segment.

The space segment, synonymous with satellite or spacecraft, comprises all hardware and software to be placed into Earth orbit with the exception of the launch vehicle. The satellite (spacecraft) is composed of the platform and the payload.

The Swarm space-segment comprises the three satellites, designated Swarm A, Swarm B and Swarm C.

The payload is defined as the set of all the instruments embarked on the satellite (spacecraft) used for the acquisition of scientific data and in case of dual use for acquisition of scientific data and for provision of satellite (spacecraft) attitude and orbit control data.

The Swarm payload comprises the Vector Feed-back Magnetometer (VFM) and Star Tracker (STR) assembled together on the Optical Bench, Absolute Scalar Magnetometer (ASM), Electrical Field Instrument (EFI), Accelerometer (ACC), GPS Receiver (GPSR) and Laser Retro-reflector (LRR).

The platform is defined as the set of all equipment of the satellite providing the necessary services for the payload.

The Swarm platform comprises the Structure, Boom, Electrical Power Sub-System (EPS), On-Board Computer (OBC), S-Band TT&C (SBS), Attitude and Orbit Control Sub-System (1) (2), Cold Gas Propulsion Sub-System (CGPS) (1) and Thermal Control Sub-System (1).


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The instrument is a composite of one or more units for measuring specific physical/chemical properties/effects for scientific purposes and in case of dual use in addition for provision of attitude and orbit control data, e.g. STR comprising STR Head, STR Baffle, STR Electronics and STR Harness or ASM Electronics and ASM Sensor.

The equipment is a composite of one or more units for providing specific services to the payload, e.g. OBC or CGPS Tank, CGPS Valves, CGPS Pressure Regulators, CGPS Thrusters and CGPS Pipework.

A unit is a single box providing a specific function, e.g. STR Electronics, S-Band Antenna, CGPS Pressure Regulator.

(1), Although the term sub-system is used in the designation due to common practice Swarm is following a two step approach, i.e. system level and equipment/instrument level, only.

(2), The AOCS makes use of a number of instruments following the dual use approach.

4.3 Reference Frames

4.3.1 International Celestial Reference Frame (ICRF)

The ICRF is a Cartesian inertial reference frame based on the precise coordinates of

extragalactic radio sources. The origin of the frame is the Earth’s center of mass. The x-axis is

pointing towards the Vernal Equinox at J2000.0.The z-axis is the vertical on the Mean

Equator at J2000.0, pointing North. The y-axis completes a right-hand system.

The ICRF is the Earth Centered Inertial (ECI) reference system employed in the Swarm

mission.

This reference system is used for the attitude quaternion output from the Star Tracker.

4.3.2 International Terrestrial Reference Frame (ITRF)

The ITRF is an Earth-fixed Cartesian system.

The origin of the frame is the Earth's center of mass.

The x-axis points towards the IERS Reference Meridian.

The z-axis points to the Reference North Pole.

The y-axis completes a right-handed system.

The ITRF is the Earth Centered Earth Fixed (ECEF) reference system employed in the

Swarm mission.

This reference system is used for the orbit model, the input models and the GPSR model.


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4.3.3 North-East-Centre (NEC) Frame

The NEC frame is a local instrument frame with the origin in the geometric center of the instrument. The radial component points from the center of the instrument towards the center of the Earth (defined in ITRF). The north (N) and east (E) components point from the center of the instrument towards north and east, i.e. along the local tangent of the meridian, respectively, the parallel, of the sphere (defined in ITRF) with radius from the center of the Earth to the center of the instrument.

Mathematical formulation outside the poles:

)(

)]100[()]100[(

CEN

CCE

Pos

PosC

T

T

ITRF

ITRF

×=

××

=

−=

Mathematical formulation at the poles :

)(

]010[

CEN

E

Pos

PosC

T

ITRF

ITRF

×=

=

−=

4.3.4 Orbit Reference Frame (ORF)

The Orbit Reference Frame (ORF) is defined as follows:

Origin: centre of mass of the spacecraft

+Z-axis towards nadir (centre of the earth)

+Y-axis perpendicular to the orbit plane, positive towards negative orbit normal

+X-axis completes the right-handed reference frame (in the flight direction)

Mathematical formulation :

)(

)(

)(

XZY

VelPos

VelPosX

Pos

PosZ

ICRFICRF

ICRFICRF

ICRF

ICRF

×=

×

×=

=

The orientation and location of the orbit reference frame is described with respect to. the ICRF by the

classical orbit parameters:

• Longitude of the ascending node (also called RAAN)

• Inclination


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ee

Semi major axis

Terminal

ceive cated sections "Receive" is as seen from

smit ns "Transmit" is as seen

UTC

an solar day. For most practical purposes, UTC is r time at the prime meridian (0° longitude) such that

on average the Sun is overhead within 0.9 seconds of 12:00:00 UTC on the

TAI

cycles of radiation corresponding to the transition between two hyperfine levels of the ground state of cesium 133. TAI is a constant and continuous time scale wit a zero reference time of zero hours on 1st January 1958.

• Argument of perig

• True anomaly

• Eccentricity

•

4.4 Engineering Packet Terminal: All instruments supporting high level S-PUS based packet communication

with the OBC.

Non-Packet All instruments supporting low leve based raw data communication with the

OBC

If not explained explicitely in the dediRethe Instrument point of view. Therefore Receive means the data-flow from the OBC towards the Instrument

If not explained explicitely in the dedicated sectioTranfrom the Instrument point of view. Therefore Transmit means the data-flow from the Instrument towards the OBC

Coordinated Universal Time (UTC). UTC is maintained by the Bureau International des Poids et Mesures (BIPM) and follows TAI exactly except for an integral number of leap seconds which are introduced to comply with the international agreement that UTC is kept within 0.9 seconds of UT1. Leap seconds are inserted on the advice of the International Earth Rotation Service (IERS) nominally up to twice yearly, during the last minute of the day of June 30 and December 31. In exceptional cases it is also possible to introduce them during the last minute of the day of March 31 and September 30 (although so far this has never been done). On the day when an adjustment is made the last minute of the day will have either 59 or 61 seconds. UTC is the modern successor of Greenwich Mean Time, GMT, which was used when the unit of time was the meequivalent to mean sola

meridian of Greenwich.

International Atomic Time (TAI) is calculated by the Bureau International des Poids et Mesures (BIPM) from the readings of more than 200 atomic clocks located in metrology institutes and observatories in over 30 countries around the world. TAI is made available every month in the BIPM Circular T. It is estimated that TAI does not lose or gain with respect to an imaginary perfect clock by more than about one tenth of a microsecond (10-7 seconds) per year. Its fundamental unit is exactly one Systeme International (SI) second at mean sea level where the SI second is defined as the duration of 9,192,631,770


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ed to a UTC zero time-point defined as midnight on the night of January 5 1980 / morning of January 6 1980. GPST

StartUp S/W p S/W is considered to be that piece of software executed after a

cold/warm start initially before the control is handed over to the application

old Start A cold start is considered to be the (Re-)Start after SWITCH ON a

SWITCHED OFF instrument

arm Start Warm start is considered tobe the (Re-)Start of the processor by pulsing the

elemetry Telemetry is considered to be a collection of data (normally received by the

Telecommand

ne exception: A time packet send out of the OBC and received by the instrument. This time-packet is used to timestamping and

Correlation: tween two clocks such that it

is possible to determine the value of one clock from the value of the other clock (i.e. to determine f(tclk2) where tclk1= f(tclk2)).

ynchronisation: To synchronise means to set two clocks to have one and the same value (i.e. tclk1=tclk2) at a given instant;

4.5 Software

S/W running on the on-board computer, other P/F

computer. This , AOCS S/W, Thermal Control S/W, CESS S/W and OBCP’s.

prises the OBC StartUp SW and OBC API SW

the boot process of the OBC.

GPS Time: GPS Time (GPST) is referenc increments with TAI.

The StartU

software

C

Wreset line of the processor.

TOBC from the Instrument.

Telecommand is considered to be a request to execute an activity on the instrument side. It is send out by the OBC and received and executed on the Instrument. There is o

timesynchronisation.

To correlate means to establish a relationship be

S

On-Board Software (OBSW)

All S/W installed on-board the S/C, i.e. all equipment and the instruments.

On-Board Computer S/W (OBC SW)

All application S/W incl. the real-time operating system running on the on-board includes D/H S/W

OBC Basic S/W

The OBC Basic SW com

OBC Start-Up S/W

S/W performing


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he OBC’s Application Programming Interface Software, i.e. the drivers.

/W is separated from the OBC SW, although hysically it is one S/W once installed on the OBC.

racterisation/Calibration

e ration is based on characterisation measurements preferably performed on

round before launch.

which are

sed ilities built into the instrument (internal calibration) or on external

ources (external calibration).

4.7 Magnetic Field Sources

tic field sources to be determined as mission goal:

core

sediments in the crust and upper mantle,

ing in the ionosphere and magnetosphere,

lectric currents flowing in the solid Earth and the oceans caused by induction effects

OBC API SW

T

Note: As the OBC Basic S/W is provided by the OBC H/W sub-contractor, it is a Product Tree item related to the OBC H/W. Therefore, the OBC Basic Sp

4.6 ChaCalibration

Calibration is the procedure for converting the instrument measurement output data into the required physical units. After calibration, the output data must be within a known tolerance, consistent with all performance requirements, everywhere around the orbit, over the dynamic range and over the lifetimof the instrument. Calibg

Characterisation

Characterisation is the direct measurement, or analytical derivation from measurements, of a set of technical and functional parameters, over a given range of conditions (e.g. temperature),necessary for the instrument calibration, ground processor initialisation and verification.

Characterisation is performed before launch on-ground. Additional in-flight characterisation is necessary at least for those parameters which may have varied since on-ground characterisation or for which on-ground measurements have not been possible. In-flight characterisation may be baeither on data derived from facs

Natural magne

CORE FIELD

Geodynamo in the Earth

LITHOSPHERIC FIELD

Magnetised rocks and

EXTERNAL FIELDS

Electric currents flow

INDUCED FIELDS

E


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5. MODELS

5.1 Simple E-field distribution model For the simulation of the EFI performance only the two electric field components perpendicular to the magnetic field are of interest. The following definition is thus limited to the transverse components Eψ, (lying in the magnetic meridian plane and pointing outward) and E3, (perpendicular to the magnetic meridian plane and pointing eastward). The average electric field in the MFA system The E-field components Eψ and E3 depend on latitude α: Latitude range Eψ E3

poleward of |α|=75° +20 mV/m sin(T) -20 mV/m cos(T) Equatorward of |α|=75° -120 mV/m e-(75° – |α|) /12° sin(T) -1 mV/m cos(T)

where α is geographic latitude in degree, and T is local time in radians.

The average electric field in the NEC system Eψ and E3 are transformed to Er, Eθ and Eφ according to

( )( )

3

3

2 2

sin

cos sin cos

sin cos sin ,

/ 2 /

,

atan

atan2

r

r

E E

E E E

E E E

B B B

B B

ψ

θ ψ

φ ψ

θ φ

φ θ

β

γ γ β

γ β γ

β π

γ

= +

= + −

= − +

= + +

= −

The effect of small-scale fluctuations For the representation of the small-scale fluctuations individual series of random numbers (centred) should be added to all components, having amplitudes of 20% of the average magnitudes. Hermann Lühr (GFZ) and Nils Olsen (DSRI), October 2004


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Appendix: Coordinate System used for the Electric Field Model For the simulation of the electric field the Mean-Field-Aligned (MFA) system is used. The MFA is a local system related to the mean magnetic field, as characterised by recent magnetic field models (e.g., IGRF). Its origin is in the centre of the respective instrument (e.g., EFI). In the proposed model only the electric field components perpendicular to the magnetic field are of interest. The definition of the transverse components is: Eψ, (lying in the magnetic meridian plane and pointing outward) and E3, (perpendicular to the magnetic meridian plane and pointing eastward – denoted as Eφ in the following Figure). The parallel component, E|| , is identically zero.


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6. ABBREVIATIONS

A ABCL As-built Configuration List AC Alternating Current ACC Accelerometer Instrument ACK Acknowledge ACSYS Arctic Climate System Study ACT Attitude Control Thruster AD Applicable Document ADC Analogue to Digital Converter ADD Architectural Design Document ADR Architectural Design Review ADU Acquisition Data Unit AFT Abbreviated Functional Test AGC Automatic Gain Control AIT Assembly Integration and Test AIV Assembly, Integration and Verification AN Analysis ANX Ascending Node Crossing AOCS Attitude and Orbit Control Subsystem AOS Acquisition of Signal AOS AOCS Offline Simulator AP Automated Procedure (Control File, Test Software) API Application Programming Interface APID Application Process ID (Field in TM/TC packets) AR Acceptance Review ASC Advanced Star Camera ASIC Application Specific Integrated Circuit ASM Absolute Scalar Magnetometer ATP Authorisation to Proceed B BB Bread Board model BC Bus Controller (Mil-Bus) BER Bit Error Rate BHD Battery Handling Device BM Balance Mass BNF Backus-Naur Form BOL Begin of Life bps bits per second BPSK Binary Phase Shift Keying BW Bandwidth C C&C Command and Control CAB Change Appeal Board CAD Computer Aided Design CADU Channel Access Data Unit CBCP Current Baseline Cost Plan CBS Cost Breakdown Structure CCB Change Control Board


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CCN Contract Change Note CCS Command and Control Subsystem CCSDS Consultative Committee for Space Data Systems CDR Critical Design Review CESS Coarse Earth Sun Sensor CETeF Co-ordinated European Test Facilities CFE Customer Furnished Equipment CFI Customer Furnished Instrument CFRP Carbon Fibre Reinforced Plastic CGS Core (Columbus) Ground System CGPS Cold Gas Propulsion System CIDL Configured Items Data List CIL Critical Items List CLCW Command Link Control Word CLIVAR Climate Variability and Predictability Program CLTU Command Link Transmission Unit CM Configuration Management CMD Command COG Centre of Gravity COP Command Operation Procedure COT Central Onboard Time COTS Commercial Of The Shelf CPDU Command Pulse Distribution Unit CPI Contractor Procured Instruments CPM Coarse Pointing Mode CPT Comprehensive Performance Test CPU Central Processor Unit CPV Common Pressure Vessels CR Change Request CRB Change Review Board CRC Cyclic Redundancy Check CRP (Flight) Contingency Recovery Procedures CS Contract Structure CTE Coefficient of Thermal Expansion CTU Central Terminal Unit (of the OBC) CUC CCSDS Unsegmented Time Code CVCDU Coded VCDU D DAC Digital to Analogue Converter DAPB Data Acquisition and Processing Block dB deci Bel dBc dB related to centre frequency dBm dB related to 1 mW DBMS Data Base Management System DC Direct Current DCG Document Contents Guideline DCL Declared Components List DCN Document Change Note DCR Document Change Request DDD Detailed Design Document DEM Digital Elevation Model DFH Data Field Header DIL Deliverable Item List


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DMA Direct Memory Access (or Defense Mapping Agency) DML Declared Materials List DMS Document Management System DNSC Danish National Space Center DOD Depth of Discharge DPL Declared Processes List DPU Digital Processing Unit DR(B) Delivery Review (Board) DRD Documents Requirements Description DRL Documents Requirements List DSPG Distributed Star Point Grounding DSU Data Switching Unit DTC [US] Department of Trade Control E EBB Elegant Bread Board model ECMWF European Centre for Medium-term Weather Forecasting ECP Engineering Change Proposal ECSS European Co operation for Space Standardisation EDAC Error Detection and Correction EEE Electronic, Electrical and Electromagnetic parts EEPROM Electrically Erasable Programmable Read Only Memory EFIS ESA Financial and Invoicing System EGSE Electrical Ground Support Equipment EICD Electrical Interface Control Document EID Error or Event Identifier EIDP End Item Data Package EIRP Effective Isotropic Radiated Power EFI Electrical Field Instrument EFILP Electrical Field Instrument Langmuir Probe EM Engineering Model EMC Electromagnetic Compatibility EMI Electromagnetic Interference EOEP Earth Observation Envelope Program EOL End of Life EOPP Earth Observation Preparatory Program EPC Electrical Power Conditioner EPS Electrical Power Subsystem EQM Engineering Qualification Model EQSR Equipment Qualification Status Review eRTB Extended Real-Time Testbed ESD Electro Static Discharge ESA European Space Agency ESO European Southern Observatory ESOC European Space Operations Centre ESTEC European Space Technology Centre ET Ephemeris Time. F FA Functional Analysis FAR Flight Acceptance Review FCL Fold Back Current Limiter FCP Flight Control Procedures FDIR Failure Detection Isolation & Recovery FEC Forward Error Correction


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FEE Front End Equipment FFT Fast Fourier Transform FGM Flux-Gate Magnetometer FGSE Fluidic Ground Support Equipment FID Failure Identifier / Failure Code FIFO First In, First Out FM Flight Model FMD Feed Module FMECA Failure Modes Effects & Criticality Analysis FOM Flight Operations Manual FOP Flight Operations Procedure FOV Field of View FPE Fill and Pressurisation Equipment FPGA Field Programmable Gate Array FPM Fine Pointing Mode FPT Full Performance Test FS Flight Spare FTP File Transfer Protocol FVV Fill & Vent Valve G G/S Ground Station GCM Global Circulation Model GDIR General Design and Interface Requirements GDR Geophysical Data Record GDU Generation Data Unit GDW Geographical Distribution of Work GFZ Geo-Forschungszentrum Potsdam GHA Ground Handling Adapter GMFE Generic Modular Front End GMM Geometrical Mathematical Model GPPS GPSR PPS GPS Global Positioning System GPSR GPS Receiver GPSRA GPS Receiver Antenna GPSRE GPS Receiver Electronics GPSRH GPS Receiver Harness GSE Ground Support Equipment H H/W Hardware HA Hazard Analysis HCI Human Computer Interface (-> MMI) HDRM Hold Down Release Mechanism HITL Hardware in the Loop HK House-Keeping HLD Horizontal Lifting Device HP Heat Pipe HPA High Power Amplifier HPC High Priority Command HPF High Pressure Filter HPL High Power Load HPLV High Pressure Latch Valve HPT High Pressure Transducer HPTM High Priority Telemetry


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I I/F Interface IABG Industrie-Anlagen-Betriebs-Gesellschaft (test facilities) IAG International Association of Geodesy IAU International Astronomical Union ICD Interface Control Document ICRF International Terrestrial Reference Frame ID Identifier ie id est IERS International Earth Rotation Service IGBP International Geosphere-Biosphere Program IGN Institute Geographic National of France INS Inspection IOS Industrial Organisation Structure IP Internet Protocol IRD Interface Requirements Document IRD Interface Requirements Drawing IRM IERS Reference Meridian IRP IERS Reference Pole ISP Instrument Source Packet IST Integrated System Test ITAR International Traffic in Arms Regulations ITRF International Terrestrial Reference Frame. ITT Invitation to Tender ITU International Telecommunications Union J JD Julian Day JGM-3 Joint Geopotential Model, version 3 K kbps 1.024 Bits per second (210 bps) KIP Key Inspection Point L LA Launcher Adapter LAN Local Area Network LCL Latching Current Limiter LEOP Launch and Early Orbit Phase LFM Linear Frequency Modulation LHCP Left Handed Circular Polarisation LHA Local Hour of Ascending Node LI Lead Investigator LLI Long Lead Item LLM Lower Level MGSE LOL Limit of Liability LOS Line of Sight or Loss of Signal LPF Low Pressure Filter LPS Launch Power Supply LPT Low Pressure Transducer LRR Laser Retro Reflector LSB Least Significant Bit LV Latch Valve M MAP Multiplexer Access Point Mbps 1.048.576 Bits per second (220 bps)


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MCE Monitoring and Control Equipment MD Mechanical Dummy MDVE Model based Development and Verification Environment MET Mission Elapsed Time MGSE Mechanical Ground Support Equipment MID Memory Identifier MIP Mandatory Inspection Point MJD Modified Julian Day MLI Multi-Layer Insulation MLST Mean Local Solar Time MMI Man-Machine Interface (-> HCI) MMU Mass Memory Unit MoI Moment of Inertia MPA Mass Property Adapter MPR Monthly Progress Report MPCB Materials & Processes Control Board MPP Milestone Payments Plan MPPT Maximum Power Point Tracker MRB Materials Review Board (formal NCR board) MRD Mission Requirement Document MRR Manufacturing Release Review MSB Most Significant Bit MSIS Mass Spectrometer, Incoherent Scatter atmospheric model MTBF Mean Time between Failure MTL Mission Timeline MTQ Magnetic Torquer N NA Not Applicable NAK Not-Acknowledge NCR Non Conformance Report NDIU Network Data Interchange Unit NEA Non Explosive Actuator NEC North-East-Center-Frame NEOS National Earth Orientation Service NPIT Nadir Panel Integration Trolley NPLD Nadir Panel Lifting Device NRB Non-Conformance Review Board NRZ Non Return to Zero NSSDC National Space Science Data Centre NT Not to be tracked NTP Network Time Protocol O OB Optical Bench OBC On-board Computer OBC Sim On-board Computer Simulator for SVF OBC On-board Computer OBCP Original Baseline Cost Plan OBCP On Board Control Procedures OBRT On Board Reference Time OBS Original Breakdown Structure OBT On Board Time OCM Orbit Control Mode OCT Orbit Control Thruster


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OCOE Overall Check-Out Environment OCT Orbit Control Thruster OGSE Optical Ground Support Equipment OOP Onboard Orbit Propagator ORF Orbit Reference Frame OTS Off-the-Shelf P P/F Platform P/L Payload PA Product Assurance PAD Part Approval Document PCB Parts Control Board PCB Printed Circuit Board PCDU Power Control and Distribution Unit PCM Pulse Code Modulation PCR Preliminary Concept Review PCU Power Control Unit PDF Portable Document Format PDR Preliminary Design Review PDT Payload Data Transmission PDU Power Distribution Unit PFM Proto-Flight Model PID Process ID (sub-field of APID) PLL Phase Lock Loop PLM Payload Module PLOP Physical Link Operation Procedure PM Processor Module PMP Project Management Plan PMP Parts, Materials, and Processes POD Precise Orbit Determination PPL Preferred Parts List PPS Pulse Per Second PR Pressure Regulator PRF Pulse Repetition Frequency PROM Programmable Read Only Memory PSA Parts Stress Analysis PSK Phase Shift Keying PSS Procedures, Specifications and Standards PT Product Tree PT Pressure Transducer PTD Packet Telecommand Decoder PUS Packet Utilisation Standard Q OCM Orbit Control Mode QM Qualification Model QPL Qualified Parts List QPSK Quadratic Phase Shift Keying QR Qualification Review QSR Quality Summary Report R RAM Random Access Memory RCS Reaction Control System RCMC RCS Feed Modul Container


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RD Reference Document RDM Rate Damping Mode RF Radio Frequency RFC Radio Frequency Compatibility RFD Request for Deviation RFI Radio Frequency Interference RFU Radio Frequency Unit RFW Request for Waiver RHCP Right Hand Circular Polarisation RID Report Identifier or RID Review Item Discrepancy RM Reconfiguration Module RMS Root Mean Square ROD Review of Design RoHS Restriction of the use of certain Hazardous Substances ROM Read Only Memory ROM Rough Order of Magnitude RS Reed-Solomon R-S Reed-Solomon encoding RSS Return Signal Simulator RSS Root Sum of Squares RT Remote Terminal (Mil-Bus) RTB Real-Time Testbed RTS Real Time Simulator RU Remote Unit (of the OBC) RV Relief Valve RX Receiver S S/C Spacecraft S/S Subsystem S/W Software S/A Solar Array SALD Solar Array Lifting Device SAPS Solar Array Power Simulator SAR Synthetic Aperture Radar SAS Special Application Software or SAS Solar Array Simulator SBM Standy Mode SBT Satellite Binary Time SCC Stress Corrosion Cracking SCOE Special Check-Out Equipment SDB Satellite Data Base SDE Software Development Environment SDR Sensor Data Record SDR System Design Review SEL Single Event Latch-up SEU Single Event Upset SFT System Functional Test SGM Safeguard Memory (in the CDMU) SHD Structure Handling Device SHLD Satellite Horizontal Lifting Device SI International System of Units SID Structure Identifier


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SimFE Simulation Front-End SK Spare Kit SLR Satellite Laser Ranging SM Structural Model SMDB Satellite Mission Database SMF Software Maintenance Facility SMPT Satellite Multi Purpose Trolley SMTP Simple Mail Transfer Protocol SOL Switch-Off Line SOW Statement of Work SPAP S/W Product Assurance Plan SPARS S/W Product Assurance Requirements for Sub-co’s SPF Single Point Failure SPICE Spacecraft & Instrument Check-Out Environment SPPS System PPS S-PUS SWARM Packet Utilisation Standard SRD System Requirements Document SRR System (or Software) Requirements Review SR-SDB SWARM Satellite Reference TM/TC Database (multi-satellite) SSP Sub Satellite Point SSPA Solid State Power Amplifier STA Shaker Test Adapter STB Satellite Testbed STC Satellite Transport Container STM Structural/Thermal Model STR Star Tracker STRB Star Tracker Baffle STRE Star Tracker Electronics STRH Star Tracker Harness STRS Star Tracker Sensor Head SUM Software Users Manual SVF Software Verification Facility SVLD Satellite Vertical Lifting Device SVT System Validation Test SWT S-Band Switch T TAA Technical Assistance Agreement TAI International Atomic Time TB/TV Thermal Balance, Thermal Vacuum TBC To be confirmed TBD To be defined TBW To be Worded TC Telecommand TCP Transmission Control Protocol TCS Thermal Control Subsystem TCXO Temperature Compensated Crystal Oscillator TEB Tender Evaluation Board TES Test Execution System TFG Transfer Frame Generator TM Telemetry TMM Thermal Mathematical Model TP Test Port TR(B) Test Review (Board)


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TRP Temperature Reference Point TRR Test Readiness Review TRSP Transponder TSW Transistor Switch TTC Telemetry, Telecommand and Control TTC Tracking, Telemetry & Command TV Thermal Vacuum TVTA Thermal Vacuum Test Adapter TWT Travelling Wave Tube TWTA TWT Amplifier TX Transmitter U UART Universal Asynchronous Receiver Transmitter UHD Unit Handling Device ULS Upward Looking Sonar UQPSK Unbalanced Quadrature Phase Shift Keying URD User Requirements Document URL Universal Resource Location USO Ultra Stable Oscillator UT1 Universal Time UT1 UTC Universal Time Co-ordinated V VC Virtual Channel VCD Verification Control Document VCDU Virtual Channel Data Unit VCID Virtual Channel Identifier VCO Voltage Controlled Oscillator VFM Vector Field Magnetometer VLD Vertical Lifting Device VSS Vertical Support Stand W w/o without WBS Work Breakdown Structure WCA Worst Case Analysis WCRP World Climate Research Program WEEE Waste of Electrical and Electronic Equipment WG Wave Guide WG(S) Wave Guide (Switch) WGS-84 World Geodetic System 1984 WOCE World Ocean Circulation Experiment WP(D) Work Package (Description) WPF Working Platform X Y Z