Performance modelling of miniaturized flash-imaging lidars for future Mars exploration missions

International Conference on Space Optics 7-10 October 2014 / Tenerife, Spain Performance modelling of miniaturized flash-imaging lidars for future Mars exploration missions Alexandre Pollini 1, Jacques Haesler 1, Valentin Mitev 1, João Pereira do Carmo 2, 1 CSEM, Switzerland; 2 ESA-ESTEC, The Netherlands

Motivation Support of 3D vision in the GN&C system during key spacecraft s proximity phases: i) soft Landing; ii) Rendez-vous and Docking between a Sample Canister (SC) and an orbiter spacecraft; iii) Rover Navigation. Reference: http://exploration.esa.int/mars/44969- images-videos-archive/ Copyright 2014 CSEM ICSO2014, Paper 66403 Page 2

Background ESTEC Contract No. 4000103730/11/NL/EM «MILS: Miniature Imaging LiDAR System, Phase 1» - Objectives: Study of novelty detection and scanning technologies for imaging lidar; EBB preliminary design The results from the Study of novelty detection and scanning technologies for imaging lidar are reported in companion poster presentation at ICSO 2014: Paper 66409: «Evaluation of novel technologies for the miniaturization of flash Imaging lidar», CSEM, Switzerland. FBK, Italy, LZH, Germany, Astrium EADS, France, ESA-ESTEC, The Netherlands) Selected ranging method, system architecture and detection technology: Direct TOF, flash lidar, SPAD array (TCSPC) Copyright 2014 CSEM ICSO2014, Paper 66403 Page 4

Study logic [AD1]: MILS mass and power budget: [AD1]: Environmental and measurement conditions For what we need the performance modelling Inputs and logic Figure of merit TDBB results: Model verification Numerical performance model «Result» for the measurement specs (2) Selection of Subsystem specifications (3) Selection of Operation modes New selection and Trade-off compliant with the requirements in [AD1]: noncompliant with the requirements in [AD1]: Output to EBB preliminary design, (2) and (3) Copyright 2014 CSEM ICSO2014, Paper 66403 Page 5

Analytical model Signals and noise 2 r 1 A p N s ( r) E L K T K R exp 2 atm( r') dr' E ph 2r 2 0 0 t 2 r gate A cr p N atm ( r) E L K T K R ( r)exp 2 atm( r') dr' E ph r 2 4 0 0 1 N SK 2 R A p B F tgate(cos )(cos ) bg E ph N s, cc N sd, 1 sra ( r) E L K T K R E ph ( 2 ) 2 0r 1 ( ) sd A cc r E L K T K R Eph r 4 Copyright 2014 CSEM ICSO2014, Paper 66403 Page 6

Analytical model Single photon detection probabilities in Poisson distribution 1 PD( signal"0") * PD( "0" ) PD( signal"1") noise PD( noise"0") ( Ntotal_ n( r)) exp( Ntotal_ k n ( r)) / 0! PD( noise"1") 1 PD( noise"0") PD( signal"0") ( N ( )) k s r exp( N s ( r))/ 0! SNR( signal) p( signal"1")* p( signal"1")* NLP p( signal"0) p( total _ noise"1")* p( total _ noise"0") Range error (statistical) R ( r) c L 2 2 1.2 SNR( r) 2 c spad 2( NDC( r)) 2 c c 2 Copyright 2014 CSEM ICSO2014, Paper 66403 Page 7

Analytical model Is the model correct? see in companion poster presentation 66409 «Evaluation of novel technologies for the miniaturization of flash Imaging lidar» Copyright 2014 CSEM ICSO2014, Paper 66403 Page 8

Landing - Rendezvous and docking - Rover Same SPAD array, general requirement 1024x1024 pixels, microlens array 3 different lasers Laser Specifications Landing RVD RN Laser Type Q-switched, Micropulsed, Diode laser, gainswitched single pulse Nd:YAG Wavelength 532nm 532nm 635nm Pulse repetition rate 1Hz 25KHz 1MHz /80MHz Pulse energy Mars: >3mJ >3mJ 125nJ Moon: >12mJ Pulse duration <1ns <1ns <70ps consumed power 30W 22.5W 11.25W Copyright 2014 CSEM ICSO2014, Paper 66403 Page 9

Landing Main challenge: Fast descent, histogram of arrivals not from the multiple laser pulses but from the multitude of pixels in a single laser pulse, pixel binning 20m/s 175m/s 20m/s 45m/s Copyright 2014 CSEM ICSO2014, Paper 66403 Page 10

220 mm International Conference on Space Optics / 7-10 October 2014 / Tenerife, Spain Landing Preliminary design Total mass (without PSU): < 7kg Total power consumption: <40W 160 mm Copyright 2014 CSEM ICSO2014, Paper 66403 Page 12

Rendezvous and Docking max 6 000m min 1m Acquisition mode and tracking mode, Slow scanning with MOEMS «Traditional» TCSPC, micropulse high PRR laser since the SC is into one pixel footprint, pixel binning at very close range Step-wise variation of the number of laser pulses in one measurement Step-wise variation of the laser beam divergence in final tracking phase Pixel binning at very close range Copyright 2014 CSEM ICSO2014, Paper 66403 Page 13

RVD Results from numerical performance evaluation Trade-offs: Statistical range accuracy vs uncertainty due to the finite integration time Steps due to the step-wise variation of the integration time (number of pulses) and laser beam divergence Angular resolution vs range accuracy Copyright 2014 CSEM ICSO2014, Paper 66403 Page 14

156 mm International Conference on Space Optics / 7-10 October 2014 / Tenerife, Spain Rendezvous and Docking Preliminary design Total mass (without PSU): < 6kg Total power consumption: <30W 250 mm Copyright 2014 CSEM ICSO2014, Paper 66403 Page 15

Rover Navigation Results from numerical performance evaluation Trade-offs: Angular resolution vs range accuracy Burst mode and pixel binning needed for range over ~50m Copyright 2014 CSEM ICSO2014, Paper 66403 Page 17

120 mm International Conference on Space Optics / 7-10 October 2014 / Tenerife, Spain Rover Navigation Preliminary design Total mass (without PSU): < 1.5kg Total power consumption: <15W 150 mm Copyright 2014 CSEM ICSO2014, Paper 66403 Page 18

Conclusion Readiness for EBB development for any of the applications: Landing, RVD, RN Critical technology developments needed: - Large SPAD array, intermediate steps possible - Lasers: efficiency, pulse duration, space qualification - Compact and lightweight optics - MOEMS (needed only for RVD) Copyright 2014 CSEM ICSO2014, Paper 66403 Page 19

Thank you for your attention! With acknowledgments to: - ESTEC Contract No. 4000103730/11/NL/EM «Miniature Imaging LiDAR System, Phase 1» - and to the partners in this project: FBK (It), LZH (Ge), ASTRIUM EADS (Fr) Contact: valentin.mitev@csem.ch