1. Mars Express Data Workshop ESAC, Villafranca del Castillo
Madrid (Spain)
MARSIS Instrument & Operation Concepts
9 -11 June 2008
Andrea Cicchetti
Raffaella Noschese, Marco Cartacci, Stefano Giuppi

2. Table Of Contents MEX Orbital Configuration. MARSIS Working Range.
Night Time Environment.
Day Side Environment.
Example of MARSIS Timeline.
Main Instrument Parameters.
MARSIS Block Diagrams .
Tracking and Acquisition Concepts.
Doppler Processing.
Raw Data Collection (Flash Memory Utility)
Global Coverage per Band achieved until 29/Feb/08
Phobos Observation Criteria and latest Results.
Overview of the Support Tools

3. 1 MEX Orbital Configuration
Periapsis
~ 300Km
Apoapsis
~ Km N w
ORBIT 5851
Event UTC PERI
2008 JUL 23 03:37:24
MEX
Orbital Plane
Mars
Mars Express was successfully launched on 2 June 2003 from Baikonur, Kazakhstan, by a Russian Soyuz rocket.
Following a cruise of almost 7 months, the SC was captured into orbit on 25 December 2003 and soon established a highly elliptical polar orbit with a closest approach to the surface of about 300 Km and a period of about 6.65 h
MARSIS
Working Slot

4. Sub Surface Sounding Modes or AIS
2 MARSIS Working Range
~ 300Km
SC Altitude
Mars
~ 1200Km
~ 900Km
AIS
5 min
Sub Surface Sounding Modes or AIS
30 min
MARS Pericenter

5. 3. Night time Environment
H2O Deposit
~ 5 Km
MARS Surface
MARS Sub Surface
~130 Km
Soft Ionosphere Layer
1.8 MHz
3.0 MHz
Good Penetration
Capabilities 
Dipole antenna
Monopole antenna

6. Acceptable Penetration
4. Day time Environment
H2O Deposit
~ 1-2 Km
MARS Surface
MARS Sub Surface
4.0 MHz
5.0 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

7. Upper Ionosphere Layer in the day side
4.1 Ionosphere Reflection proprieties in the day side
In the deep day side it is not possible to use the lowest radar bands
due to the upper ionosphere layer that will completely reflects the MARSIS
Signals.
Band 1 (1.8 MHz)
Mars Surface
Orbit 4628 (11/Aug/07)
295.7 Km
150 Km
Upper Ionosphere Layer in the day side
145.7 Km

8. 5 Example of MARSIS Timeline
SC [SEA]/Altitude
AIS
Time Off Peri
[min]
-15°
SS3
B1/B2
B2/B3
B3/B4 0°
35°
~1200 Km
~ 900 Km
~900 Km
~ 300 Km
Day Side

9. 6 Main instrument Parameters
Sub Surface Sounding Parameters
Centre Frequencies:
Band 1  1.8 MHz
Band 2  3.0 MHz
Band 3  4.0 MHz
Band 4  5.0 MHz
Bandwidth = 1.0 MHz
δ= 150m (free space depth resolution)
Transmit pulse Length = 250 us
PRF = Hz (Pulse Repetition Frequency)
Receive Window Size = 350us
Sounder Dynamic Range = 40 to 50 dB
Surface Sounding Altitude Range = 250 to 900 Km
Ionospheric Sounding Parameters
Maximum Altitude = 1200 Km
Frequency Range = 0.1 to 5.5 MHz
δ= 15 Km
Bandwidth = 10 KHz
Transmit Pulse Length = us
Minimum Frequency Step = Hz
Repetition Period = 7.38s
Dipole Antenna element length = 20 m
Monopole Antenna length = 7 m
Total Mass = 20 Kg
DC Operation Power = 60 W

10. 7 MARSIS Block Diagram S/C 1 4 3 2 MARSIS Consist of : Power And
Control
Processor
S/C
Transmitter
Receiver
Signal
Generator
Analog to
Digital
Converter 1 2 3 4
Monopole
Dipole
I/Q
Synthesis
MARSIS Consist of :
A sounder channel containing a programmable signal generator
a surface cancellation channel
a dual channel data processor
a power and control subsystem which controls all the sounder functions
A/D Converters  Operate at a Sampling frequency of 2.8 MHz (8 bit)

11. 7.1 Subsurface Sounding Processing Functionalities
Ionospheric
Calibration
Tracking
Acquisition
Passive
Sounding
Range & Doppler
Processing
Data
Presumming
Timing
System
From I/Q Synthesis

12. 7.2 Subsurface Sounding Mode SS1 (2 Frequencies – 2 Antennas – 1 Doppler Filter)
Tx Phase TX 1 2
250 us
450 us
t [us]
Two frequencies operation:
four echoes are received, two from Dipole
channel and two from Monopole channel.
Echoes are processed to synthesize a
single Doppler filter.
Complex data for each of the four
synthesized Doppler filters, before range
compression, are transferred in the
science source packet data format.
This mode allows coherent clutter
cancellation on two frequency bands by
means of dual antenna clutter cancellation
ground processing.
Rx Dipole Ch RX 1 2
450 us
t [us]
Trigger
Rx Monopole Ch RX 1 2
450 us
t [us]
Trigger

13. No signals processed from Monopole
7.3 Subsurface Sounding Mode SS2 (2 Frequencies- 1 Antenna (dipole) – Onboard Multi-look)
Tx Phase TX 1 2
250 us
450 us
t [us]
Two frequencies operation:
two echoes are received, two from Dipole channel.
Echoes from the Monopole channel are not processed, while echoes from the Dipole channel are processed to provide a Multilooked information for a single Doppler filter using parallel synthesis of five Doppler filters on board.
The power detected samples for each of the two multilooked Doppler filters synthesized are transferred in the science source packet data format.
Rx Dipole Ch RX 1 2
450 us
t [us]
Trigger
Rx Monopole Ch
t [us]
No signals processed from Monopole
Channel

14. 99.99 % Of the data have been collected with this modality
7.4 Subsurface Sounding Mode SS3
Tx Phase TX 1 2
250 us
450 us
t [us]
Two frequencies operation:
This mode allows downlink, for each frame, of the I and Q data of three Doppler filters collected on the dipole antenna channel at two frequencies.
Range processing is performed on the ground.
Rx Dipole Ch RX 1 2
450 us
t [us]
Trigger
99.99 % Of the data have been collected with this modality
Rx Monopole Ch
t [us]
No signals processed from Monopole
Channel

15. 7.5 Subsurface Sounding Mode SS5
Tx Phase TX 1
30 us
t [us] 2 3 4
Single frequency operation:
two echoes are received, one from the Dipole and one from the Monopole.
Echoes are actually pre-summed over groups of four to increase the Signal to Noise Ratio.
Pre-summed Echoes are processed to synthesize three central Doppler filters for each channel.
Complex data of the six synthesized Doppler filters before range compression, are transferred in the science source packet data format.
This mode uses a short pulse waveform to reduce the impact of uncontrolled sidelobes on deep subsurface reflections
Rx Dipole Ch
t [us]
Trigger TX 1 2 3 4
Rx Monopole Ch
t [us]
Trigger TX 1 2 3 4

16. “ Calculated by MARSIS”
8 Tracking & Acquisition Concepts
Mars
Transmitter
Acquisition Modality
Range
Compression
&
Ionosphere
Compensation
Azimuth
Compression
Receiver
A/D
Buffer
Preset Trk
H = 674Km
Set by the User
Trig ~ 4493 us
“ Calculated by MARSIS”
AGC Tracking
Range Tracking
LoL Logic
Tracking Lost
Preset Trk ?
yes
not

17. 8.1 Timing of Tracking and Acquisition
NPN
Rx Gate Acq.
1400 us us
91.43 us
1000 us
Rx_Trig_Acq
Passive Ionosphere Gate
ACQ Band = 200 KHz
Acquisition Timing
Tx F1
350 us
91.43 us
250 us
Rx_Dist_F1
Passive Ionosphere Gate
TRK Band = 1.0 MHz
Tracking Timing (SS3)
Tx F2
Rx Gate F1
Rx Gate F2
450 us
Rx_Dist_F2

18. 8.2 Tracking Initialization Overview (Worse Case)
MARSIS starts to operate
Ionosphere Layer  100 us is the maximum delay in the day
H = 400 Km  us
Rx Phase
Time [us]
250 us
400 Km  us
Extra delay
350 us
150 us
Chirp Length
50 us Lost
MEX Orbit
h~7.5 Km
50us
Hellas Planitia (minimum depression)
Mars Topography
Range Polynomial
Coefficients

19. 8.3 (Timeline) Example of the Tracking effect
SS3
B3/B2
OST 4
SC [SEA]/Altitude
AIS
OST 7
Time Off Peri
[min]
B4/B3
OST 3
OST 0
12°
761 Km
B2/B1
OST 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 inversion
Before each AIS”
B1/B2

20. 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”

21. 8.5 (Level 2 data) Example of the Tracking effect
Tracking lost due to the low SNR rate.

22. 9 Doppler Processing 9.1 Observation Geometry Range Range MEX
DPL
Range
Along Track
Where:
H  SC altitude
δ  Range Resolution (150m)
MEX
Fly direction δ H
Range
Along Track
Cross Track
DPL
MEX
Fly direction
Main Contribution
From the
Mars Surface
Dipole Antenna
Monopole Antenna

23. On Board Doppler Processing
Range
Along Track
Cross Track
DPL
MEX
Fly direction
Main Contribution
From the
Mars Surface
Dipole Antenna
Monopole Antenna
Data Acquisition
Range
Along Track
Cross Track
DPL
MEX
Fly direction
Main Contribution
From the
Mars Surface
Dipole Antenna
Monopole Antenna
Increased
Azimuth
Resolution
On Board Doppler Processing

24. 10. Raw Data Collection (Flash Memory Utility)
SS3
B3/B2
B4/B3
SEA=0°
-120 S
0.0 S
-300 S
Raw Data Start Acq.
Orbit 3990
Start Lat=12.4N
P-60 (Time Off Pericenter)
Science Area
Of Interest
On Board
Processing
Raw Data
Collection
Flash Memory
SC Interface
Dipole
Antenna
Flash Memory Blocks Diagram

25. 11. Global Coverage achieved until 29/Feb/08
MARSIS
Operation
Centre
Main Archive
All Frames
SNR
Evaluation SW
Global
Coverage
Sub Archive
Optimum
Frames
Generic Fr …
Generic OST Line Ch1
Generic OST Line Ch2
18 dB
Frame Selection within an OST line
Generic Frame, SNR ~ 18 dB

26. 11.1 Band 2 Global Coverage

27. 11.2 Band 2 Global Coverage

28. 11.3 Band 3 Global Coverage

29. 11.4 Band 4 Global Coverage

30. Minimum Flyby distance:
12. Phobos Observation Criteria and latest Results
MEX
Orbital Plane
Closest Approach
“ Phobos Data Take”
Mars
Phobos
Periapsis
~ 300Km
Apoapsis
~ Km
Encounter
Approach
Departure
Orbit number: 5851
Time Period
2008 JUL 23 04:50:51
Minimum Flyby distance:
93 km !!

31. 12.1 Limitation of the Standard Onboard Configuration
Protection Zone
Range [Km]
Offset Time [us]
1600
-1600
240
~ 93
Working Zone
With the standard on board configuration it is not possible the Phobos detection

32. 12.2 Timing of the Standard on board configuration
Tx Phase TX 1 2
250 us
450 us
700 us
Time [us] RX 1 2
RX1
RX2
50us of margin (7.5 Km)
Rx Phase
Time [us]
SW limitation
1600 us
us us  Km

33. 12.3 Techniques to reduce the instrument Protection Zone
Reduction of the SW limitation “First level of range extension”
Tx Phase TX 1 2
250 us
450 us
700 us
Time [us]
247.5Km  240Km.
7.5Km less !!
SW limitation
Rx Phase RX 1 2
RX1
RX2
240 Km
Time [us]
1550 us
1600 us

34. 12.3.2 Ambiguity Technique “Second Level of Range Extension”
Tx Phase
250 us
250 us TX 1 TX 2
Time [us]
450 us
700 us
450 us
67.5 Km
Rx Phase
SW limitation
RX1
RX2 RX 1 2
Time [us]
1550 us

35. 12.3.2.1 Timing of the ambiguity Technique
Tx Phase
250 us
250 us
240Km  157.5Km.
82.5 Km less !! TX 1 TX 2
Time [us]
450 us
700 us
SW limitation
1550 us
Rx Phase RX 1 2
RX1
RX2
450 us
1150 us
157.5 Km
Time [us]

36. 12.3.3 Margin back in the game (50+125us) “ Third level of range extension”
Tx Phase
250 us
250 us
157.5Km  Km.
7.5Km+3.75Km=11.25 Km less !! TX 1 TX 2
Time [us]
450 us
700 us
247.5Km  Km.
Km less !!
SW limitation
1550 us
Rx Phase
RX1
RX2
975 us Km RX 1 2
450 us
125 us

37. 12.4 Overview of the Reduced Protection Zone
Range [Km]
Offset Time [us]
1600
-1600
240
~ 93
Working Zone
975
-975
146

38. 12.5 Consolidated Timeline and prediction of the results
CAL
Low
Power
TX Slow
Power Up
PREO
STBY
Medi
POST
SS3
B3/B3
36”
AIS
2m0”
1m57”
-75
-39 39 75
195
315
-177
-279
-399
-699
235 Km
146 Km
~ 93
Range [Km]
Offset Time [us]
Total Number Frames = = 72
Total Number of echoes = = 6480

39. 12.6 Latest Phobos flyby results 07/Oct/2007
Display of the generic echo
MEX Fly direction
SNR÷20dB

40. Overview of the
Matlab Support Tools

41. 13 Overview Of the Support Tools
13.1 Support Tool “Basic Level”
Get File
Read Header
fields
Read Scientific
Data
Linear/dB
Conversion
Write Outputs
Files
Display
Plots
FRM_SS3_TRK_CMP_RDR_1885.DAT
Output Files

42. 13.1.1 Basic Level Tool “Main Output”
Generic Frame
Science Data
Header Data 1 94 95
607
94 Elements
512 Elements

43. 13.2 Support Tool “Advanced Level”
Get File
Read Header
fields
Read Scientific
Data
FRM_SS3_TRK_CMP_RDR_1885.DAT
LineardB
Noise
Evaluation
dB Linear
Multi
Look
Write
Outputs
Files
Display
Plots
Output Files

44. 13.2.1 Advanced Level Tool “Noise Attenuation Concepts”
350us
t [us]
Pwr [dB]
Noise Estimation
Slot
350us
t [us]
Pwr [dB]
Noise Level
350us
t [us]
Pwr [dB]
Noise Level
Noise Attenuation
Pwr [dB]
350us
t [us]
350us
t [us]
Pwr [dB]
Noise Estimation
Slot
Shift back
of the peak

45. 13.2.2 Advanced Level Tool “Main Output”
Multi Look Representation
The filters (-1,0,+1) collapse in one
Radargram (multi look)

46. 13.2.3 Advanced Level Tool “ Radargram without the Noise attenuation, Noise_Att=1”

47. 13.2.4 Advanced Level Tool “ Radargram with Noise attenuation, Noise_Att=0.8”

48. 13.2.5 Advanced Level Tool “Single frame visualization, without noise attenuation”

49. 13.2.6 Advanced Level Tool “Single frame visualization, with noise attenuation”

50. 13.2.7 Advanced Level Tool “ Radargram without any range offset”

51. 13.2.8 Advanced Level Tool “ Radargram shifted of 100us down”