MARSIS Instrument Overview Andrea Cicchetti - Infocom Department - University of Rome “La...

MARSIS Instrument Overview

Andrea Cicchetti - Infocom Department - University of Rome “La Sapienza”

Mars Express Data WorkshopMars Express Data Workshop

ESAC, Villafranca del CastilloESAC, Villafranca del CastilloMadrid (Spain)Madrid (Spain)

MARSIS Instrument & Operation ConceptsMARSIS Instrument & Operation Concepts

9 -11 June 20089 -11 June 2008Andrea CicchettiAndrea Cicchetti

Raffaella Noschese, Marco Cartacci, Stefano GiuppiRaffaella Noschese, Marco Cartacci, Stefano Giuppi



Table Of ContentsTable Of Contents

1. MEX Orbital Configuration.2. MARSIS Working Range.3. Night Time Environment.4. Day Side Environment.5. Example of MARSIS Timeline.6. Main Instrument Parameters.7. MARSIS Block Diagrams .8. Tracking and Acquisition Concepts.9. Doppler Processing.10.Raw Data Collection (Flash Memory Utility)11.Global Coverage per Band achieved until

29/Feb/0812.Phobos Observation Criteria and latest Results.13.Overview of the Support Tools



1 MEX Orbital Configuration1 MEX Orbital Configuration

Mars Express was Mars Express was successfully launched on successfully launched on 2 June 2003 from 2 June 2003 from Baikonur, Kazakhstan, by Baikonur, Kazakhstan, by a Russian Soyuz rocket.a Russian Soyuz rocket.

Following a cruise of Following a cruise of almost 7 months, the SC almost 7 months, the SC was captured into orbit was captured into orbit on 25 December 2003 on 25 December 2003 and soon established a and soon established a highly elliptical polar highly elliptical polar orbit with a closest orbit with a closest approach to the surface approach to the surface of about 300 Km and a of about 300 Km and a period of about 6.65 hperiod of about 6.65 h

Periapsis ~ 300Km

Apoapsis~ 10.000Km

N

w

ORBIT 5851

Event UTC PERI2008 JUL 23 03:37:24

MEX Orbital Plane

Mars

MARSIS MARSIS Working Slot Working Slot



2 MARSIS Working Range2 MARSIS Working Range

~ 300Km

SC Altitude

Mars

~ 1200Km

~ 900Km

AIS AIS

5 min 5 min

Sub Surface Sounding Modes or AIS

30 min

MARS Pericenter



3. Night time Environment3. Night time Environment

H2O Deposit

~ 5 Km

MARS Surface

MARS Sub Surface

~130 Km

Soft Ionosphere Layer

1.8 MHz3.0 MHz

Good Penetration Capabilities

Dipole antenna

Monopole antenna



4. Day time Environment4. Day time Environment

H2O Deposit

~ 1-2 Km

MARS Surface

MARS Sub Surface

4.0 MHz5.0 MHz

Dipole antenna

Monopole antenna

80 ~130 Km

Strong Ionosphere Layer

Acceptable Penetration Capabilities

The lowest Bands (1.8 and 3.0 MHz)Will be completely reflected by the Ionosphere layer



In the deep day side it is not possible to use the lowest radar bandsdue to the upper ionosphere layer that will completely reflects the MARSIS Signals.

Mars Surface

Orbit 4628 (11/Aug/07)

295.7 Km

Upper Ionosphere Layer in the day side

150 Km

145.7 Km

4.1 Ionosphere Reflection proprieties in the day side

Band 1 (1.8 MHz)



5 Example of MARSIS Timeline5 Example of MARSIS Timeline

SC [SEA]/Altitude

AIS

Time Off Peri [min]

-15°

SS3B1/B2

SS3B2/B3

SS3B3/B4

AISAIS

0°

35°

-20.0 -15.0 0.0 15.0 20.0

~1200 Km ~1200 Km

~ 900 Km ~900 Km

~ 300 Km

Day Side



6 Main instrument Parameters6 Main instrument Parameters

Sub Surface Sounding ParametersSub Surface Sounding Parameters

Centre Frequencies:Centre Frequencies:Band 1 Band 1 1.8 MHz 1.8 MHzBand 2 Band 2 3.0 MHz 3.0 MHzBand 3 Band 3 4.0 MHz 4.0 MHzBand 4 Band 4 5.0 MHz 5.0 MHz

Bandwidth = 1.0 MHz Bandwidth = 1.0 MHz δδ= 150m (free space depth resolution) = 150m (free space depth resolution) Transmit pulse Length = 250 usTransmit pulse Length = 250 usPRF = 127.267 Hz (Pulse Repetition Frequency)PRF = 127.267 Hz (Pulse Repetition Frequency)Receive Window Size = 350us Receive Window Size = 350us Sounder Dynamic Range = 40 to 50 dBSounder Dynamic Range = 40 to 50 dB

Surface Sounding Altitude Range = 250 to 900 KmSurface Sounding Altitude Range = 250 to 900 Km

Ionospheric Sounding ParametersIonospheric Sounding Parameters Maximum Altitude = 1200 KmMaximum Altitude = 1200 Km

Frequency Range = 0.1 to 5.5 MHzFrequency Range = 0.1 to 5.5 MHz

δδ= 15 Km= 15 Km

Bandwidth = 10 KHzBandwidth = 10 KHz

Transmit Pulse Length = 91.43 usTransmit Pulse Length = 91.43 us

Minimum Frequency Step = 10.937 HzMinimum Frequency Step = 10.937 Hz

Repetition Period = 7.38sRepetition Period = 7.38s

Dipole Antenna element length = 20 mDipole Antenna element length = 20 mMonopole Antenna length = 7 mMonopole Antenna length = 7 m

Total Mass = 20 KgTotal Mass = 20 KgDC Operation Power = 60 WDC Operation Power = 60 W



7 MARSIS Block Diagram7 MARSIS Block Diagram

MARSIS Consist ofMARSIS Consist of : :

1.1. A sounder channel containing a programmable signal generatorA sounder channel containing a programmable signal generator2.2. a surface cancellation channela surface cancellation channel3.3. a dual channel data processora dual channel data processor4.4. a power and control subsystem which controls all the sounder functionsa power and control subsystem which controls all the sounder functions

A/D Converters A/D Converters Operate at a Sampling frequency of 2.8 MHz (8 bit) Operate at a Sampling frequency of 2.8 MHz (8 bit)

PowerPowerAndAnd

ControlControl

ProcessorProcessor

S/CS/C

TransmitterTransmitter

ReceiverReceiver

SignalSignalGeneratorGenerator

Analog toAnalog toDigitalDigital

ConverterConverter

11

ReceiverReceiverAnalog toAnalog to

DigitalDigitalConverterConverter

22

33

44

MonopoleMonopole

DipoleDipole I/QI/QSynthesisSynthesis

I/QI/QSynthesisSynthesis



7.1 Subsurface Sounding Processing Functionalities

IonosphericIonosphericCalibrationCalibration

TrackingTracking AcquisitionAcquisitionPassive Passive

IonosphericIonosphericSoundingSounding

Range & DopplerRange & DopplerProcessingProcessing

Range & DopplerRange & DopplerProcessingProcessing

Data Data PresummingPresumming

TimingTimingSystemSystem

From I/Q Synthesis



7.2 Subsurface Sounding Mode SS1 (2 Frequencies – 2 Antennas – 1 Doppler Filter)

Rx Dipole Ch

RX1

RX2

450 us

t [us]

Trigger

Tx Phase

TX1

TX2

250 us 250 us

450 us

t [us]

Two frequencies operation: Two frequencies operation:

four echoes are received, two from Dipole four echoes are received, two from Dipole channel and two from Monopole channel. channel and two from Monopole channel.

Echoes are processed to synthesize a Echoes are processed to synthesize a single Doppler filter. single Doppler filter.

Complex data for each of the four Complex data for each of the four synthesized Doppler filters, before range synthesized Doppler filters, before range compression, are transferred in the compression, are transferred in the science source packet data format.science source packet data format.

This mode allows coherent clutter This mode allows coherent clutter cancellation on two frequency bands by cancellation on two frequency bands by means of dual antenna clutter cancellation means of dual antenna clutter cancellation ground processing.ground processing.

Rx Monopole Ch

RX1

RX2

450 us

t [us]

Trigger



7.3 Subsurface Sounding Mode SS2 (2 Frequencies- 1 Antenna (dipole) – Onboard Multi-look)

Rx Dipole Ch

RX1

RX2

450 us

t [us]

Trigger

Tx Phase

TX1

TX2

250 us 250 us

450 us

t [us]


two echoes are received, two from Dipole two echoes are received, two from Dipole channel. channel.

Echoes from the Monopole channel are not Echoes from the Monopole channel are not processed, while echoes from the Dipole processed, while echoes from the Dipole channel are processed to provide a channel are processed to provide a Multilooked information for a single Doppler Multilooked information for a single Doppler filter using parallel synthesis of five Doppler filter using parallel synthesis of five Doppler filters on board. filters on board.

The power detected samples for each of the The power detected samples for each of the two multilooked Doppler filters synthesized two multilooked Doppler filters synthesized are transferred in the science source packet are transferred in the science source packet data format.data format.

Rx Monopole Ch

t [us]

No signals processed from MonopoleChannel



7.4 Subsurface Sounding Mode SS3

Rx Dipole Ch

RX1

RX2

450 us

t [us]

Trigger

Tx Phase

TX1

TX2

250 us 250 us

450 us

t [us]


This mode allows downlink, for each frame, This mode allows downlink, for each frame, of the I and Q data of three Doppler filters of the I and Q data of three Doppler filters collected on the dipole antenna channel at collected on the dipole antenna channel at two frequencies. two frequencies.

Range processing is performed on the Range processing is performed on the ground.ground.

Rx Monopole Ch

t [us]

No signals processed from MonopoleChannel

99.99 % Of the data have been 99.99 % Of the data have been collected with this modalitycollected with this modality



7.5 Subsurface Sounding Mode SS5

Single frequency operation: Single frequency operation:

two echoes are received, one from the two echoes are received, one from the Dipole and one from the Monopole. Dipole and one from the Monopole.

Echoes are actually pre-summed over Echoes are actually pre-summed over groups of four to increase the Signal to groups of four to increase the Signal to Noise Ratio. Noise Ratio.

Pre-summed Echoes are processed to Pre-summed Echoes are processed to synthesize three central Doppler filters for synthesize three central Doppler filters for each channel. each channel.

Complex data of the six synthesized Complex data of the six synthesized Doppler filters before range compression, Doppler filters before range compression, are transferred in the science source packet are transferred in the science source packet data format.data format.

This mode uses a short pulse waveform to reduce This mode uses a short pulse waveform to reduce the impact of uncontrolled sidelobes on deep the impact of uncontrolled sidelobes on deep subsurface reflectionssubsurface reflections

Tx Phase

TX1

30 us

t [us]

TX2

TX3

TX4

Rx Dipole Ch

t [us]

TriggerTX1

TX2

TX3

TX4

Rx Monopole Ch

t [us]

TriggerTX1

TX2

TX3

TX4



TransmitterTransmitter

ReceiverReceiver A/DA/D BufferBuffer AzimuthAzimuthCompressionCompression

RangeRangeCompressionCompression

&&IonosphereIonosphere

CompensationCompensation

LoL LogicLoL Logic

Acquisition ModalityAcquisition Modality

Tracking Lost

Preset TrkH = 674Km

Set by the User

Trig ~ 4493 us“ Calculated by MARSIS”

AGC TrackingAGC Tracking Range TrackingRange Tracking

Preset Trk ?Preset Trk ?yes not

Mars

8 Tracking & Acquisition Concepts8 Tracking & Acquisition Concepts



8.1 Timing of Tracking and Acquisition

NPNNPN Rx Gate Acq.Rx Gate Acq.

1400 us36

5.7

1 u

s

91

.43

us

1000 us

Rx_Trig_AcqPassive Ionosphere Gate

ACQ Band = 200 KHz

Acquisition Timing

Tx F1Tx F1

350 us 91

.43

us

25

0 u

s

Rx_Dist_F1Passive Ionosphere Gate

TRK Band = 1.0 MHz

Tracking Timing (SS3)

Tx F2Tx F2

Rx Gate F1Rx Gate F1 Rx Gate F2Rx Gate F2

350 us

25

0 u

s

450 us

Rx_Dist_F2



8.2 Tracking Initialization Overview (Worse Case)MARSIS starts to operate

Ionosphere Layer Ionosphere Layer 100 us is the maximum delay in the day 100 us is the maximum delay in the day

H = 400 Km 2666.7 us

Rx Phase

Time [us]

250 us

400 Km 2666.7 us

Extra delay

350 us

150 us

Chirp Length

50 us Lost

MEX Orbit

h~7.5 Km50us

Hellas Planitia (minimum depression)Mars Topography

Range PolynomialCoefficients



8.3 (Timeline) Example of the Tracking effect

SS3B3/B2OST 4

SC [SEA]/Altitude

AISOST 7

Time Off Peri [min]

SS3B4/B3OST 3

AISOST 0

12°

-18.0 -13.0 -7.5 -1.5 13.0 18.0

761 Km

SS3B2/B1OST 5

5°

478 Km

-5°

314 Km

763 Km

-23°

Orbit 1885 – 4/July-2005“ First Routine Orbit”

Fake SS2

“Tx Slow Power UP”-No Science-

Fake SS3(15”/30”)

“Band inversionBefore each

AIS”B1/B2

-No Science-



8.4 (Level 2 data) Example of the Tracking effect

OST 3 (B4) OST 4 (B3) OST 5 (B2)

Trigger Offset

Trigger Compensated“L2 Product from PSA”

Tracking Lost“Low SNR”



8.5 (Level 2 data) Example of the Tracking effect

Tracking lost due to the low SNR rate.



9 Doppler Processing9 Doppler Processing

DPL

Range

Along Track

HDPL 22

Where:H SC altitudeδ Range Resolution (150m)

MEXFly direction

δH

9.1 Observation GeometryRange

Along Track

Cross Track

DPL

MEXFly direction

Main ContributionFrom the

Mars Surface

Dipole Antenna

Monopole Antenna



9.2 Doppler Processing

Range

Along Track

Cross Track

DPL

MEXFly direction


Mars Surface

Dipole Antenna

Monopole Antenna

Data AcquisitionData Acquisition

Range

Along Track

Cross Track

DPL

MEXFly direction


Mars Surface

Dipole Antenna

Monopole Antenna

IncreasedAzimuth

Resolution

On Board Doppler ProcessingOn Board Doppler Processing



10. Raw Data Collection (Flash Memory Utility)10. Raw Data Collection (Flash Memory Utility)

Orbit 3990Start Lat=12.4NP-60 (Time Off Pericenter)

SS3B3/B2

SS3B4/B3

SEA=0°

-120 S 0.0 S-300 S

Raw Data Start Acq.

On Board On Board ProcessingProcessing

Raw DataCollection

Flash Memory

SC

In

terf

ace

SC

In

terf

ace

DipoleAntenna

Flash Memory Blocks Diagram

Science AreaOf Interest



11. Global Coverage achieved until 29/Feb/0811. Global Coverage achieved until 29/Feb/08

MARSIS MARSIS OperationOperation

Centre Centre Main ArchiveMain Archive

All FramesAll FramesSNRSNR

Evaluation Evaluation SWSW

GlobalGlobalCoverageCoverage

Sub ArchiveSub Archive

OptimumOptimumFramesFrames

18 dBGeneric Fr……

Generic OST Line Ch1

Generic Fr……

Generic OST Line Ch2

Generic Frame, SNR ~ 18 dBFrame Selection within an OST line



11.1 Band 2 Global Coverage



12. Phobos Observation Criteria and latest Results12. Phobos Observation Criteria and latest Results

Orbit number: 5851

Time Period2008 JUL 23 04:50:51

Minimum Flyby distance:

93 km !!MEX

Orbital Plane

Closest Approach“ Phobos Data Take”

Mars

PhobosOrbital Plane

Phobos

Periapsis ~ 300Km

Apoapsis~ 10.000Km

ApproachEncounter

Departure



Protection Zone

Range [Km]

Offset Time [us]

0 1600-1600

240

~ 93

Working Zone Working Zone

With the standard on board configuration it is not possible the Phobos detection

12.1 Limitation of the Standard Onboard Configuration



12.2 Timing of the Standard on board configuration

Tx Phase

TX1

TX2

250 us 250 us

450 us

700 us

Time [us]

Rx Phase

Time [us]

SW limitation

1600 us

1600+50 us us 240+7.5 KmRX1

RX2

RX1 RX2

50us of margin (7.5 Km)



Tx Phase

TX1

TX2

250 us 250 us

450 us

700 us

Time [us]

Rx Phase

Time [us]

SW limitation

1600 us

RX1

RX2

RX1 RX2

240 Km

12.3.1 Reduction of the SW limitation “First level of range extension”

1550 us

247.5Km 240Km.

7.5Km less !!

12.3 Techniques to reduce the instrument Protection Zone



Tx Phase

TX1

TX2

250 us 250 us

450 us

700 us

Time [us]

Rx Phase

Time [us]

SW limitation

1550 us

RX1

RX2

RX1 RX2

450 us67.5 Km

12.3.2 Ambiguity Technique “Second Level of Range Extension”



Tx Phase

TX1

TX2

250 us 250 us

450 us

700 us

Time [us]

Rx Phase

Time [us]

SW limitation

1550 us

1150 us157.5 Km

240Km 157.5Km.

82.5 Km less !!

RX1

RX2

RX1 RX2

450 us

12.3.2.1 Timing of the ambiguity Technique



Tx Phase

TX1

TX2

250 us 250 us

450 us

700 us

Time [us]

Rx Phase

RX1

RX2

RX1 RX2

975 us146.25 Km

157.5Km 146.25Km. 7.5Km+3.75Km=11.25 Km

less !!

247.5Km 146.25Km.

101.25 Km less !!SW limitation

1550 us

450 us125 us

12.3.3 Margin back in the game (50+125us) “ Third level of range extension”



Protection Zone

Range [Km]

Offset Time [us]

0 1600-1600

240

~ 93

Working Zone Working Zone

975-975

146

12.4 Overview of the Reduced Protection Zone



Total Number Frames = 36+36 = 72Total Number of echoes = 3240 + 3240 = 6480

Offset Time [us]

CALLow

Power

TX Slow Power Up

PREOSTBY

CALMedi

Power POST

0

SS3B3/B336”

SS3B3/B336” AIS

2m0”AIS

1m57”

-75 -39 39 75 195 315-177

-279

-399

-699

235 Km

146 Km

~ 93

Range [Km]

12.5 Consolidated Timeline and prediction of the results



Display of the generic echo

MEX Fly directio

n

SNR÷20dB

12.6 Latest Phobos flyby results 07/Oct/2007



Overview of the Matlab Support Tools



13 Overview Of the Support Tools13 Overview Of the Support Tools

13.1 Support Tool “Basic Level”

Get FileGet FileRead HeaderRead Header

fieldsfieldsRead Scientific Read Scientific

DataData

Linear/dBLinear/dBConversionConversion

Write OutputsWrite OutputsFilesFiles

Display Display PlotsPlots

FRM_SS3_TRK_CMP_RDR_1885.DAT

Output Files



13.1.1 Basic Level Tool “Main Output”

Science DataScience Data

Header DataHeader Data

11

9494

9595

607607

94 Elements

512 Elements

Generic Frame



Get FileGet FileRead HeaderRead Header

fieldsfieldsRead Scientific Read Scientific

DataData

FRM_SS3_TRK_CMP_RDR_1885.DAT

LinearLineardBdB NoiseNoiseEvaluationEvaluation

dBdB Linear LinearMultiMultiLookLookLinearLineardBdB

Write Write OutputsOutputs

FilesFiles

Display Display PlotsPlots

Output Files

13.2 Support Tool “Advanced Level”



13.2.1 Advanced Level Tool “Noise Attenuation Concepts”

350us

t [us]

Pwr [dB]

350us

t [us]

Pwr [dB]

Noise Level

Noise EstimationSlot

Pwr [dB]

350us

t [us]

Shift back of the peak

350us

t [us]

Pwr [dB]

Noise Level

Noise Attenuation

350us

t [us]

Pwr [dB] Noise EstimationSlot



13.2.2 Advanced Level Tool “Main Output”

The filters (-1,0,+1) collapse in oneRadargram (multi look)

Multi Look Representation



13.2.3 Advanced Level Tool “ Radargram without the Noise attenuation, Noise_Att=1”



13.2.4 Advanced Level Tool “ Radargram with Noise attenuation, Noise_Att=0.8”



13.2.5 Advanced Level Tool “Single frame visualization, without noise attenuation”



13.2.6 Advanced Level Tool “Single frame visualization, with noise attenuation”



13.2.7 Advanced Level Tool “ Radargram without any range offset”



13.2.8 Advanced Level Tool “ Radargram shifted of 100us down”

MARSIS Instrument Overview Andrea Cicchetti - Infocom Department - University of Rome “La...

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