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RF Wireless in Planetary Exploration and AIV

E W Pritchard

Systems Engineering & Assessment Ltd


Wireless Application Areas

Low Power Wireless SensorsRobust Networking

EMC AnalysesStructured (spacecraft)

demonstratorPlanetary demonstrator

Flight demonstrator?

CAN-BT Bridge & demoSpW-WiFi Bridge & demo

Wireless Test PortEMC Analyses


RF Wireless Outline Schedule

Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb

Jul 08LPPNS

Concept Review

EGSE/AIT Requirements& Preliminary Design

EGSE/AITDesign

Dec 08LPPNS PDR

EGSE/AIT CDR

Oct 08EGSE/AIT PDR

LPPNS Building Blocks, Requirements& Preliminary Design

ApplicationUse Cases

DemonstrationTest Environment

Mar 09LPPNS CDR

LPPNSDesign

EGSE/AITProcure/Build

Apr 09EGSE/AIT TRR

Oct 09EGSE/AIT AR

LPPNS DemonstratorDevelopment and Build

Sep 09LPPNS TRR

DemonstratorTests

Dec 09LPPNS TRB

EGSE/AITTest and Demonstration

2009 2010Today


Planetary Wireless

• The main purpose of wireless arrays in a planetary context is to extend the data gathering footprint

• This can be done using Rovers but they are transient devices providing a snapshot of different locations

• Some aspects of planetary investigations require long-term monitoring of separated locations for example:

– Seismology– Meteorology and Climatology

• It can be said that static systems benefit from dynamic monitoring but dynamic systems require long-term static monitoring


Seismology

• Seismology can be separated into deep and shallow investigations

• Deep seismology is the mapping of the gross structure of the planet, core, mantle, asthenosphere (if any) and lithosphere, and uses arrays with large separation.

• Arrays with close separation can be used to image fine shallow structure

• This is important for Mars in terms of determining possible sedimentary structures

• In a lunar context the volume of flood deposits in the mare can be assessed

• In any planetary scenario it is also important for shallow igneous structures such as plutons and magma chambers.


Seismic Wireless Arrays

S1

S3

S5

S7

S8

S4

S2

S6

L

R2

R1

R8

R7

R6

R5

R4

R3

4 km

L - LanderS1-S8 - Seismic StationsR1-R20- Relay Stations

R9

R10

R11

R12

R13

R14

R15

R16

R20

R17

R18

R19

• The point in seismic arrays is timing – on wired arrays we know how long it takes a pulse to go down a wire

• For large arrays on Earth we can keep to wires and tow them

• This is not an option on other planets where the seismic sources tend to be ad hoc (impacts, quakes)

• For extra-terrestrial arrays wireless has definite advantages but we must consider timing and time-tagging of data.

• Data rates are low long-term but high short term.


Possible Seismometer

UndeployedSeismic

Penetrator

DeployedSeismic

Penetrator

Solar Cells

Antenna

Seismometer,Wireless,Battery

3 - Axis MEMSAssembly

MUX

Microcontroller

Memory Access Control

Memory

Real Time Clock

Radio


Other Possible Uses

• Pressure / temperature / light sensors for microclimate (e.g. Martian dust devils)

• Chemical detectors to monitor atmospheric diffusion

• Relays and localisation of mini-rovers• Route markers in cave systems

Lander with DTE/Orbiter Link

Atmospheric Entry

Parachute descent

Aeroshell jettison andscatternet release

Lander deployment, minirovers released into

scatternet


Issues in Planetary Wireless

• Propagation is largely line of sight and horizon limited• Horizon distance:-

– Earth radius 6371km, tangent height to 4km 1.26m– Mars radius 3386km, tangent height to 4km 2.36m– Moon radius 1737km, tangent height to 4km 4.6m– Europa radius 1560km, tangent height to 4km 5.1m

• On Earth, the radio horizon is extended by atmospheric refraction and ionospheric reflection. This would not be the case on Moon, Mars.

• On Earth, GPS is available for localisation and timing. Elsewhere it may be necessary to use the array itself for this, or an external detection of array beacons.


Wireless In AIV

• Removing the wires between spacecraft and EGSE has many advantages.

– Enables pre-integration of instruments and subsystems over remote links (virtual spacecraft)

– Removes necessity for complex test harnesses and simplifies EGSE interfaces

– Reduces impact on test facilities such as vacuum chambers

– It is cleaner than wire!

Test Chamber

Three-Band Semi-Active Repeater

Band 1 Band 2 Band 3

Splitter

Combiner

Band 3

Band 2

Band 1


Wireless and biocontainment

• Sample return missions pose special problems for planetary protection

• It is easier to avoid contamination of samples and by samples if the facility is perforated as little as possible

• Using wireless links to the test piece and inductive links to power supplies avoids facility perforation by harnesses.

Patch Antenna

Bonded tohermeticallysealed RF-transparentwindow into

facility

Metal screened box to isolatefacility patch from EGSE

antenna (repeater inside box)

Monopole antenna to connectto EGSE computers


Wireless SpaceWire Demonstrator

• This part of the project is developing a wireless bridge to a Spacewire network

• The demonstrator is using a distributed SpaceWire based avionics system from another ESA project under development by SEA

• Bridge development is based on existing 4Links SpaceWire-EtherNet bridge.

• Communication is two-way over the network

As above

Power Supply

Power switchingand

Watchdog

Active Backplane

As above

Spare PCB slot

Processor 1

Processor 2

Mass Memory 1

Mass Memory 2

AtmelLEON2

16Gb RAM

ActelProASIC 3

FPGA

Atmel3 channel

SpaceWireASIC

ActelProASIC 3

FPGA

64Gb RAM

64Gb FLASH

Spare PCB slot

Spare PCB slot

Spare PCB slot

SpaceWire port

8 PortRouter

8 PortRouter

8 PortRouter

8 PortRouter

Demonstrator system rack

1 SpareSpaceWireport

1 SpareSpaceWireport

2 SpareSpaceWireports

2 SpareSpaceWireports

Mains powerin

MonitoringLEDs

Controlswitches

Boot PROM

Reconfigurationcontroller

LEON2debug port

SpaceWire port

4Links Spacewire Wireless Bridge

Control and Monitoring PC


Wireless CAN-BT demonstrator

• Under development at SSC, using PRISMA spacecraft model and bridge developed from existing CAN-USB developments

• The bridge forms a link to a replica bridge which permits analysis of spacecraft traffic but is not intended for module replacement.

THRUST

MICRO

CANCAN

CANCAN

CANCAN

CANCAN

CANCAN

CANCAN

CANCAN

ST-DPU-A

Telemetry

Telecmd

POWER

Spacecraftumbilical

Up / Down Conv erter

CA

N B

US

18 Heaters-A

22 Thermistors-A

TX-A

EXT powerCmd Pulses

HK-AHK-B

CA

N

CA

N

CA

N

EXT powerCmd Pulses

HK-AHK-B

CA

N

CA

N

CA

N

Power distribution

PCDU

UM

BIL

ICA

L

TM Umb1 PPS

SpW

CAN

FFRF_PPS TM Umb1 PPS

SpW

CAN

FFRF_PPS

Processor

TC-A

TC UmbTC-B

Cmd PulseRF Control

TX Block

SpW1SpW2SpW3

TM downlink

TC-A

TC UmbTC-B

Cmd PulseRF Control

TX Block

SpW1SpW2SpW3

TM downlink

Mass Mem

DHS

6 x Cat bed Heaters

6 x Valv es, HILV

LGA-1 (+X)

LGA-2 (-X)

CAN bus, nom/red

Spacecraft skin

CAN monitoring

connector

CAN BUS

ASMMRTU-A

CANCAN

PTCRTU-B

PTCRTU-A

DIPLEXER

DIPLEXER

6 x Cat bed Heaters

6 x Valv es, HILV

1 sec.

1 sec.

Serv ice connector

3 Quick nuts-A

PCU-A ARM

Battery 1 .. 5

S/A section 1..8

& Control

SU Core-A

RX-A

RX-B

TX-B

RWEL

RW-1

RW-2

RW-3

RW-4

ASMMRTU-B

GPTRTU-A

GPTRTU-B

ASERRTU-B

ASERRTU-A

ST-DPU-B

CHU-1

CHU-2

BME-1

BME-2

BME-3

BME-4

BME-5

LPSSPC-1

LPSSPC-8

LPSSPC-16

LPSSPC-34

POWER Unit

Therm-cpl

HILV Status

Therm-cpl

HPT

LPSSPC-40

Serial I/O-1

Serial I/O-2

JTAG

Solar array

PCU-B ARM

depl. 1-2

LV Sep. arm 1-3

TX-Block

CANCAN

CANCAN

GRWRTU-A

FF-RF

TC-unit / ScetTelemetry

SU Core-B

Service

Service

Sep./Depl.

VBS1

CAMERA

TC TeleCommand unitTCRTU Thermal control Remote Terminal Unit

GRWRTU Gyro & Reaction Wheel RTU

PCU Pyro Control Unit

ABBREVIATIONS

PCDU Power Control & Distribution Unit

BME Battery Management ElectronicsCHU Camera Head Unit (Startracker)

ST-DPU Start tracker Data Handling Unit

ARS Angular Rate Sensor

SP Solar Precense detector

D-GPS

D-GPS

18 Heaters-B

22 Thermistors-B

3 Quick nuts-B

+28V

+28V

HYBRID

GRWRTU-B

GPTRTU Green Propellant Thruster Remote Terminal Unit

LGA Low Gain Antenna

D-GPS Differential GPSFF-RF Formation Flying RF

ISL-RF Inter Satellite Link RF

SS-A

X Y Z

MM A

MM B

SS-BSP1..6

SP1..6MT

Accelerometers

SPARE

AGC 0-5V

2 channels

ISL-RF

ISL-RF

AGC 0-5V

THRUST

MICRO

SS Solar (angular) Sensor

1, 2, 3, 4, 5

AR

S1

AR

S2

AR

S3

AR

S4

AR

S5

RWEL Reaction Wheel ElectronicRW Reaction Wheel

MM Magnetometer

ASMMRTU Accelerometer, Sun Sensor, MagnTorquer & Magnetometer RTU

UpLink RX-AUpLink RX-B

MTRTU-A

MTRTU-BCAN

CAN

SPARE

HYBRID

AGC 0-5V

AGC 0-5V

2 channels

8 x Ev ents

8 x Ev ents

ASERRTU Asynchronous Serial RTU

PTCRTU "Pyro" and Thermal Control RTU

TM Umb1 PPS

SpW

CAN

FFRF_PPS TM Umb1 PPS

SpW

CAN

FFRF_PPS

Processor

TC-A

TC Umb

TC-B

Cmd PulseRF Control

TX Block

SpW1SpW2SpW3

TM downlink

TC-A

TC Umb

TC-B

Cmd PulseRF Control

TX Block

SpW1SpW2SpW3

TM downlink

Mass MemTC-unit / ScetTelemetry

Sep./Depl.

biphase

decoder

biphase

decoder

VBS2

FFRF_PPS

FFRF_PPS

CA

N B

US


LPPNS Concept

• Wireless Sensor Networking– Spacecraft/Planetary applications– IEEE802.15.4 wireless nodes

• Available Technologies– IEEE802.15.4 MAC/Baseband IP CORE– TinyOS based micro-controller

• More efficient than ZIGBEE• Terrestrial heritage

– LEON3 core

• Digital and Mixed signalASIC for FM

– FPGA & commercialradio for DM/EQM

• Demonstration system in design applicable to target application areas.

Sensortransducer

Data Captureand CollateM

UX

ADCWireless

protocol stack

MediaAccess

Layer logicRadio

Real Time Clock and subsystem power control

Front-End Leon3FT

ASIC

UART DSUMem IF

868MHzPHY

2.4 GHz

868.3 MHz20 Kbps channel

Channel 0 Channels 1-10

Channels 11-26

2.4835 GHz

928 MHz902 MHz

5 MHz

2 MHz

2.4 GHz PHY

40 Kbps channels

250 Kbps channels

915MHz

PHY

868MHzPHY

2.4 GHz

868.3 MHz20 Kbps channel

Channel 0 Channels 1-10

Channels 11-26

2.4835 GHz

928 MHz902 MHz

5 MHz

2 MHz

2.4 GHz PHY

40 Kbps channels

250 Kbps channels

915MHz

PHY


LPPNS Development and Demonstration

LPPNS Development produces 16 off

modules, of which 4 are environmentally

characterised.

Planetary DemonstratorSpacecraft Demonstrator

Demo Modules(16 off)

Characterisation(4 modules)

COTS DevModel

Demonstration& Test System

RadiationThermalVibration

Launcher environment will be extrapolated from spacecraft mock-up test results of a structured

environment


LPPNS Intra Spacecraft Demonstrator

• Example of a structured space application• Uses 16 off LPPNS modules• Launcher application similar context but tailored to special launcher structural

and data handling needs.

DTS computer

Remote Nodes Primarily RFDs Optionally FFDs

DHS Node FFD Optionally PA+LNA

Structured Applications


Planetary Demonstrator

• Will use 16 off LPPNS modules in use cases still to be determined• Will assess issues and solutions in wireless uses on planetary surfaces,

particularly propagation, timing and localisation• Sensors are unlikely to be representative but throughput will be based on

planetary models for seismology, climatology, etc.• The performance of the nodes will be scaled so that the restricted area

available does not give unrealistic impressions of real-world scenarios

DTS computer

Remote Nodes Primarily RFDs Optionally FFDs

Concentrator Node FFD Optionally PA+LNA Optionally NB radio

Planetary Applications


Programme Conclusions

• ESA funded technology development programme progressing the exploitation of wireless network technologies for broad range of space applications.

• Development of 16 off wireless modules during 2009 with supporting wireless test environment. Demonstration in representative environments:

– Spacecraft mock-up.– Planetary mock-up.

• Environmental testing of wireless modules (including thermal and radiation):– Provides guide for further development to FM modules– Characterises demonstration modules to support possible flight demonstrations.

• Parallel civil activities ensure coherence and compliance with emerging standards.

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