1. Mapping Engineering Constraints from Orbit to the Surface Or How to Certify a Landing Site Matt Golombek Jet Propulsion Laboratory

2. How to Certify a Landing Site on Mars? Selecting landing site critical decision If the spacecraft doesn’t land safely there is nothing to show for the effort (and money) –Mission success rests on safe site (including all science) –Fate of a spacecraft (hundreds millions of dollars) Must learn everything possible about the site It is one thing to write a science paper about some topic, it is something else entirely to risk an entire mission on the interpretation Engineering Constraints - Derive from s/c and EDL Address Engineering Constraints with Remote Sensing Data –Mapping Engineering Constraints to Atmosphere and Surface - Better do this, better can select safe site

3. Outline PERSPECTIVE MER EXAMPLES –Possible Sites –Data Used to Evaluate Sites –How the Data was Used –How Site was Certified –Assessment of Landing Site Predictions EXPECTATIONS FOR MSL –Data Sets –Addition of MRO Data –Certification Process

4. VL1 MPF Meridiani VL2 Gusev Landing Sites on Mars

5. Golombek’s Perspective Viking - "The blind leading the blind" –Predictions of the surface were incorrect, but the atmosphere was within specifications –Most importantly they both landed successfully Pathfinder - "Take your best shot" –Little new data since Viking Mission, but much greater appreciation of how VL1 and 2 landing surfaces relate to Viking Orbital data –Clear Earth analog near mouth of catastrophic outflow channel –Surface and atmospheric predictions were correct MER - "Never has so much data been acquired of and so much work done on 4 small spots on Mars" –An unprecedented explosion of information from MGS and Odyssey resulted in the best imaged, best studied 4 spots in the history of Mars exploration –The major engineering concerns were addressed by data and scientific and engineering analyses suggested the sites were safe –Data allowed detailed exposition of testable scientific hypotheses at the sites - became template for surface operations –Surface and atmospheric predictions (wrt safety) were correct

6. Preliminary MER Engineering Constraints ATMOSPHERE - ELEVATION –Must be <-1.3 km [wrt MOLA geoid] for Parachute –Atmospheric Column Density, Low-Altitude Winds <20 m/s LATITUDE 5°N TO 15°S for MER-A and 15°N to 5°S for MER-B –Solar Power, Temperature, Sub-Solar Latitude; 37° Lander Separation –Ellipse Size and Orientation, Lat. Dep. – Varied w/simulations SURFACE SLOPES <6° RMS (<15°) –Mesa Failure Scenario; Radar Spoof; Lander Bounce/Roll; Rover Deploy; Power; Later <2° at 1 km; <5° at 100 m; <15° at 3-10 m ROCKS – 0.5 m High for Landing –Athena Rover Trafficability - Total Rock Abundance of <20% –Athena Wants Rocks – It is a Rock Mission DUST –Must Have Radar Reflective Surface – Descent Altimeter –Load Bearing and Trafficable Surface –Reduce Lifetime, Coat Solar Panels, Rocks & Instruments

7. VL1 MPF Meridiani Isidis Elysium VL2 Gusev Landing Sites on Mars 15°N 15°S

8. Data Used to Evaluate Landing Sites Viking Images - 230 m/pixel MDIM (Base Map) MOLA –Definitive Elevation, geoid, atmospheric pressure wrt geopotential –Definitive Slopes at 1 km Scale –Pulse Spread - RMS Relief at ~100 m Scale –100 m Roughness & Slope from Relief 3 km to 300 m Extrapolated via Hurst Exponent (Self Affine) –Shaded Relief Maps Thermophysical Properties –IRTM Thermal Inertia, Fine Component, Rocks, Albedo [~1°] –TES Thermal Inertia & Albedo [3 km], Surface Temperature –Dust Cover Index - TES Thermal Inertia and Particle Size –THEMIS - Thermal Images [100 m], Surface Temperature

9. Rocks –Abundance from IRTM Spectral Differencing; % Rocks >0.1- 0.15 m Diameter Covering Surface –Model Size-Frequency Distributions; Potentially Hazardous Rocks; Comparison to Test Platform Rock Distributions –Boulders Visible in MOC Images MOC and THEMIS Imaging Data –MOC Images at 1.5-6 m/pixel; Nadir MOLA Shots along image –THEMIS Visible Images at 18 m/pixel Stereogrammetry & Photoclinometry –10 m and 3 m DEMs (Digital Elevation Models); Slopes Radar Reflectivity and Roughness (RMS Slope) –X (3.5 cm)- and S (12.6 cm)-Band: Goldstone & Arecibo –Reflectivity –Specular and Diffuse Scattering Data Used to Evaluate Landing Sites

11. GUSEV CRATER Clear Morphologic Evidence for Water High Preservation Potential of Environment in Deposited Sediments

12. GUSEV

13. Gusev Crater Lake Sediments Cratered Surface - No Layers Obvious Etched Terrain Dark Streaks Dusty 2 km

14. Meridiani Planum (Hematite) Site (MER - B)

15. TERRA MERIDIANI Smoothest, Flattest Place in Equatorial Mars

16. MERIDIANI

17. Meridiani Bright Dunes Dark Surface Unit Bright Underlying Unit

18. Golombek et al., 2003

19. General Landing Site Predictions Broad predictions [Golombek et al., 2003] –Safe for Landing –Trafficable for Rover Meridiani –Completely Unlike other Landing Sites, Very Few Rocks, very little dust –Dark Gray Plain of Sand and Granules with Discontinuous Outcrops of Bright Units that Surface from Beneath Gusev –Similar to VL Landing Sites, Less Rocky and Moderately Dusty –Dust Devil Tracks in THEMIS Images (would be exception)

20. Predictions

21. Broadly Similar to VL Sites Dusty, Moderately Rocky Spirit Landing Site - Gusev Crater

22. How Well Did Remote Sensing Data Predict Surface? All Predictions Correct –Thermal Inertia, Rock Abundance, Albedo –Elevation, Slope (1 km, 100 m, 5 m), Roughness –Important Because Use landing sites as “ground truth” for orbital data Essential for selecting & validating landing sites for future missions Correctly interpret surfaces, kinds of materials globally present on Mars Use Similar Method for MSL Landing Sites Golombek et al., 2005

23. THERMOPHYSICAL PROPERTIES Surface Characteristics Thermal Inertia - –Resistance of Surface Materials to Change in Temperature –Dependent on Particle Size or Cohesion –Is the Surface Load Bearing/Competent? –How Much Dust/Rocks? –Surface Characteristics

24. TES Thermal Inertia Putzig et al., 2005 Albedo Dust Cover Index Ruff and Christensen, 2002

25. Putzig et al. 2005 TES Global Albedo vs Thermal Inertia Meridiani-B Gusev-C A - Dust B - Dark C - Dusty, Crusty, Rocky 78% Mars

26. THERMAL INERTIA Meridiani - Bulk Thermal Inertia (I) ~200 SI units –Predicted to be Sand 0.2 mm Gusev ~300 Si Units TES/THEMIS Observations Similar to MiniTES Predicted to be Competent and Load Bearing Cemented Soils/Duricrust, Sand and Granules No Thick Deposits of Cohesionless Dust No Special Risk to Landing or Roving Golombek et al., 1997

27. THEMIS Thermal Inertia Over THEMIS Visible (18 m/pixel) Landing Site in Low Inertia Plains - 285 Legacy Pan Partway up Ejecta - 290 Bonneville on Crater Rim - 330 Golombek et al., 2005 Fergason et al., 2006

28. ROCKS Surface Characteristics Thermal Inertia - –Rock Abundance –Size-Frequency Models –Probability Impact Boulder Fields - –Rock Abundance Comparison to Test Surfaces - –Airbag Capabilities

29. Rock Abundance on Mars IRTM Thermal Differencing 1° x 1° Pixels Mode is 8% N. Plains Are Rocky Christensen, 1986

30. Rock Abundance Rocks - IRTM Orbit (±5%) –Gusev 7-8% ellipse, 7% pixel –Meridiani 5% ellipse, Few% pixel Measured at Surface –Spirit 4% at Land Site >0.1 m Diameter –5% & 30% Towards Rim Bonneville –Size-Frequency Distribution Similar to Model D>0.1 m –Meridiani Outcrops are Rocks –Consistent Few % Surface Coverage –Now Sampled Full Spectrum of Rock Abundance Surfaces on Mars Safe for Landing Benign for Roving Golombek et al., 2005

31. Bulk I Versus Rock Abundance For Lines of Constant Fine Component I for Effective I Rock of 2100 (dashed lines) & 1300 (solid lines) - 20% Possible Rock Abundance Change Golombek et al. [2003] For Bulk Inertia and Derived Effective Inertia of the Rock Population Can Derive Fine Component Thermal Inertia Golombek et al., 2003

32. Gusev Boulder Fields 100 m Golombek et al., 2003

33. Identified Gusev Boulder Fields GUSEV ELLIPSE Boulder Fields Outside Ellipse Inside Ellipse Boulder Field Size

34. Boulder Size-Frequency Distributions Boulder Fields Rare –~0.1% of MOC Image –Low Sun >38° Plotted Max Subareas –Ave, Min 2-10 x Lower Extreme Distributions –Steep Slope, Exponential Decay –Similar to Model Dist. ~1% Surface Covered by 3- 10 m Diameter Boulders Can’t See Boulders at 3 Landing Sites, 20% –If Can’t See, <20% Rock Abundance Formal Probability Analysis –0.2-2% Chance Impacting Boulder in Boulder Field Golombek et al., 2003

35. Airbag Drop Test Platform 60° Dipping Platform at Plum Brook Largest Vacuum Chamber in World Fully Inflated Airbags Around Full Scale Lander Bungee Chord Pulls Lander to Impact Velocities Airbags Impact First at Edge Between Tetrahedrons & Then Rotates to Face

36. ELEVATION MOLA Topography & Geoid Excellent for Landing Site Evaluation Spirit located at 14.5692°S, 175.4729°E at -1940 m Tracking Results, 14.5718921°S, 175.47848°E; Radial Elevation 3392.2997±0.001742 km Geoid of Closest MOLA point -14.56903°S175.47075°E, 3394.2367 km, minus elevation, 3392.2967 km, Difference of 3 m, within uncertainty Opportunity located at 1.9462°S, 354.4734°E at –1385 m Tracking Results 1.9482823S, 354.47417°E; Radial Elevation 3394.1482±0.0004683 km Geoid of Closest MOLA point -1.94539°S, 354.48697°E, 3395.5351 km minus elevation is 3394.14816 km, which is within 0.04 m Actually do not know exactly where any particular MOLA elevation shot is to ±300 m, so uncertainties in map tie and ability to read elevation from map overwhelm comparison

37. Atmosphere Models Limb Profiles Binned Nadir Profiles Limb Mean Profile Nadir Mean Profile Baseline Profile Surface T, P and wind time series –VL1, VL2, MPL) Remote soundings of T profiles –TES ·Almost 3 Mars years ·~10 km vertical resolution ·Inaccurate near the surface –Viking IRTM –Radio Occultations –Mariner 9 IRIS Kass et al., 2003

38. Meridiani Planum ~ 1pm LTST East-West cross section vertical wind Strong convection narrow upwellings broad downwellings hexagonal pattern Extends ~ 5 km vertically Modest horizontal winds ~4 m/s average random directions Peak upward velocity ~ 6.5 m/s Peak downward velocity ~3.5 m/s Rafkin et al., 2003

39. Mesoscale Wind Model Results 3-D dynamical atmospheric models Model meteorological phenomena at the 2 to 200 km scale Track pressure, temperature, and wind vectors Kass et al., 2003

40. Atmospheric Profile & Winds Atmospheric Model VL1 (adj. elev.), TES T Profiles & MGCM Weather (D. Kass) Density Derived from Deceleration Profile & Aeroshell Properties Derived Temperature Profile –Within 5K Spirit, warm below 15 km, cool above –Within 15K Opportunity Profile within 1 standard deviation (low) bounds of atmospheric model –Overestimated mean density by 8% uncertainties below 5 km Winds Appear within Expectations based on Mesoscale Models –Gusev Greater Horizontal Winds –Both Experienced Updrafts Golombek et al., 2005

41. TES Albedo Versus Thermal Inertia Adjusted Meridiani Ellipse to Minimize Cold Nighttime Temperatures

42. SLOPES Surface Characteristics 1 km Slopes - <2° To Reduce Continuous Role 100 m Slopes - <5° To Prevent Radar Spoofing 5 m Slopes - <15° To Reduce Airbag Bounce & Spinup

43. MERIDIANI Bidirectional Anderson et al., 2003

44. Elysium 1.2 km Slope Bidirectional Slope Anderson et al., 2003

45. Meridiani 100 m Slope 100 m Slope Derived from Allen Variation/Hurst Exponent Haldemann et al. MOLA Pulse Spread 150 m Scale Roughness Garvin Anderson et al., 2003

46. 1 km and 100 m Statistics SiteMeridianiGusevElysiumIsidisVL1VL2MPF 1.2 km Bi-Dir. Slope°,Mean ±s.d., RMS, n 0.15±0.18 0.26 680 0.20±0.44 0.49 679 0.48±0.55 0.73 934 0.19±0.24 0.30 782 0.27±1.020.28±0.280.30±1.07 1.2 km A-Dir. Slope°,Mean ±s.d., RMS, n 0.24±0.47 0.53 208 0.19±0.29 0.34 277 0.41±0.29 0.51 361 0.14±0.10 0.17 315 0.32±1.010.27±0.190.25±0.68 Pulse Width, m [G]slopecor Mean ±s.d., RMS, n 0.75±0.24 0.8 1152 1.42±0.44 1.5 1340 1.10±0.4 1.1 1366 1.10±0.35 1.2 1140 Pulse Width, m not slopecor [N] Mean±s.d., n 0.8±0.9 531 1.5±1.3 101 1.9±2.8 478 5.1±1.8 8 2.1±3.7 3640 1.1±0.4 921 2.0±3.6 2742 Pulse Width, m [N] Mean±s.d., n 0.8±0.8 544 1.1±1.0 296 1.5±1.7 5879 1.8±2.8 7078 1.7±2.9 535 1.1±0.4 921 2.0±4.1 1755 Self affine 100 m Allen dev, m RMS slope° 3.4 1.9 5.8 3.3 4.0 2.3 2.6 1.5 1.8 1.0 5.0 2.9 Golombek et al., 2003

47. Gusev 10 m DEM Kirk et al., 2003

48. 5 m Slopes SiteMeridianiGusevElysiumIsidisVL1VL2MPF MOC Stereo or PC RMS Adirectional slope° 2-44-173-53-95 Meridiani Smoothest –RMS Slopes Very Low Elysium Next Smoothest –RMS Slopes Comparable to MPF Isidis Slightly Rougher –Has Rougher Terrains in Ellipse Gusev is the Roughest –Has Roughest Terrains in Ellipse MOC Stereo - 10 m, PC-Photoclinometry generally ~3 m; Corrected to 5 m Kirk et al., 2003

49. SLOPE 1.2 km Scale Slopes Lowest at Meridiani [0.15°& 0.24°; 0.3°] and Lower at Gusev [0.2° and 0.19°; 0.5°] than at VL or MPF 100 m 100 m Slope Lowest at Meridiani [1.9°; 0.7°] and Lower at Gusev [3.3°; 1.4°] than at VL1 (comparable to VL2) or MPF 5 m RMS Slope (MOC DEM) Lowest at Meridiani and Lower at Gusev than at MPF [2° & 4°]; 1.4° & 2.5° Consistent with Extraordinarily Smooth and Flat Surface at Meridiani (smoothest, flattest place investigated) and Reasonably Smooth & Flat Surface at Gusev RMS Slopes from Rover Traverse Telemetry

50. RADAR Surface Characteristics Is the Surface Radar Reflective? Reflectivity >0.02 –Will the Descent Radar Altimeter Function Correctly? Does the Surface Have a Reasonable Bulk Density? –Is the Surface Load Bearing? Safe for Landing & Roving Surface Roughness –RMS Slope <6°

51. Landing Site Radar Properties Landing Site WavelengthReflectivity 1,  0 rms slope 1,  rms Source Meridiani3.5 cm 0.05  0.011.3  0.4  GSSR track: 1.83  S, May 3, 2001. 3.5 cm 0.05  0.011.2  0.4  GSSR track: 1.82  S, May 5, 2001. Gusev 12.6 cm 0.025  0.0151.4  0.2  GSSR track: 14.59  S, Sep. 10,1971 3.5 cm 0.04  0.024.7  1.6  Average GSSR data unit Hch 2. Isidis3.5 cm 0.02  0.013.8  0.7  GSSR track: 5.11  N, Jan. 21, 1993. 3.5 cm 0.03  0.013.3  0.5  GSSR track: 4.86  N, Jan. 23, 1993. 3.5 cm 0.03  0.014.0  1.0  GSSR track: 3.60  N, Jun. 17, 2001. Elysium3.5 cm 0.05  0.033.0  1.1  Average GSSR data unit Hr 2. 1 Quasi-specular scattering reflectivity,  0, as derived from a Hagfors scattering model fit, is the square of the Fresnel normal reflection coefficient, while the Hagfors-derived rms slope,  rms, is considered to apply to a length-scale in the range from 10x to 100x the wavelength. 2 Unit Hch is ‘Older channel material’, and unit Hr is ‘Ridged plains material’, as mapped by Greeley and Guest [1997]. Haldemann et al.

52. Radar Reflectivity Engineering Constraint Reflectivity >0.02 Implies Bulk Density >700kg/m 3 Meridiani (0.05) –~1500 kg/m 3 Gusev (0.04) ~1200 kg/m 3 Similar to Bulk Densities of Soils Traversed by Pathfinder Rover Should Pose No Problems to Landing or Roving Golombek et al., 1997

53. Radar RMS Slope RMS Slopes Low at Meridiani; Higher at Gusev Compare Favorably w/ Rover Traverse 1.4° & 2.5° at 5 m RMS Slopes No Rougher than VL1 & MPF, both 3° at 3 m –Gusev smoother at 12.6 cm No Unusual Diffuse Scattering Radar Consistent with MOC DEMs –Meridiani Smoothest, Followed by and Gusev Safe for Landing & Roving SiteMeridian i GusevElysiumIsidisVL1VL2MPF MOC Stereo/PC 5 m RMS slope° 2-44-173-53-95 3.5 cm Radar RMS slope° 12.6 cm Radar 1.3±0.44.7±1.6 1.4±0.2 3.0±1.13.3±0.54.7±1.82.0±0.34.5±1. 8

54. Meridiani RMS Slope versus Baseline Kirk et al., 2003 * MOLA 1.2 Bi * * * Allan 100 m * Radar RMS **

55. Gusev RMS Slope versus Baseline * MOLA 1.2 Bi * Allan 100 m * Radar RMS * * * * Kirk et al., 2003

56. Example Hazard Map: Gusev Etched TerrainHeavily Cratered TerrainCratered Plains Golombek et al., 2003

57. Digital Terrains Derived from MOC images Terrains developed by Randy Kirk Cratered Plains Heavily Cratered Terrain Etched Terrain

58. Landing Simulation Model 3 Stage Monte Carlo Simulation –Most Sophisticated Landing Simulation Known –500-2000 Trails/Site 6 DOF Entry to Parachute –Entry, Ballistic Descent, Atmosphere Variations 18 DOF Parachute to First Bounce –Multibody Sim, Parachute, Winds, Retrorockets 3 DOF Bouncing to Roll Stop –Hazard Terrain Unit (DEM), Rocks –Extrapolated from DEM to Ellipse via Hazard Map 3 Most Important Factors-Combined –Low-Altitude Horizontal Winds - Add Horizontal Velocity –Lander Scale Slopes - Airbag Bounce, Spinup –Rocks - Airbag Rip, Abrasion, Stroke Out

59. Meridinai - Smooth, Flat Plain Backshell 450 m Away; 1 m High Dust and Rock Free Dark Surface-Dust Free Granule Lag Surface Ripples Low Albedo ~0.1

60. Relatively Dust Free; Albedo 0.195 Very Low Relief at 1 km, 100 m, Moderate at 10 m Spirit Landing Site - Gusev Crater

61. Dust Devil Tracks Albedo Difference between Bright (0.26) and Dark Areas (0.19) Pancam Albedo Matches Orbital Albedo

62. Mars Pathfinder Landing Site Relatively Dusty, Albedo 0.22 Relatively High Relief at 1 km, 100 m, 10 m

63. Relatively Dusty, Albedo 0.23 Low Relief at 1 km, 100 m, 10 m Viking Lander 2

64. Viking Lander 1 Relatively Dusty, Albedo 0.25 Relatively Higher Relief at 1 km, 100 m, 10 m

65. Viking Lander 1 Relatively Dusty - Note Drift Material Relatively Higher Relief at 1 km, 100 m, 10 m

66. MER Results Accurately Predicted Important Safety Characteristics of Both Landing Sites –Ambiguity in Science of Landing Site Major Engineering Constraints Addressed by Data and EDL Tested Against Parameters Indicating Sites Safe Now Have 5 “Ground Truth” Sites to Compare with Remote Sensing Data –Span Many Important Likely Safe Surfaces * Future Efforts to Select Safe Landing Sites are Likely to be Successful

67. Putzig et al. 2005 TES Global Albedo vs Thermal Inertia Meridiani-B Gusev-C A - Dust B - Dark C - Dusty, Crusty, Rocky 78% Mars

68. Expectations for MSL Avalanche of New MRO Data Extensive Data Since MER: Odyssey MEx PP is a “Feature” of Site Selection Extensive Investigation of Sites Thorough Evaluation of Engineering Constraints - Extensive Testing Comprehensive Simulations to Assess Risk and Safety of Sites Selection will Balance Science and Safety

69. Odyssey and Mars Express Data to Evaluate Landing Sites THEMIS Thermal Inertia –Calibrated Global I –Variations 100 m scale HRSC Stereo 10 m/pixel –Improved Slopes at 100 m scale –HRSC High Resolution ~2 m/pixel Omega Multispectral Data –Composition and Mineralogy

70. MRO Data of Landing Sites HiRISE - 30 cm/pixel, 6 km wide –Repeat Coverage Stereo - Slopes at m scale –Boulders/Rocks/Outcrops CTX - 6 m/pixel, 30 km wide –Repeat Coverage Stereo - Slopes at 10 m scale –Morphology at Intermediate Scale CRISM - 20 m/pixel, 11 km wide –Repeat Coverage Stereo - Slopes at 100 m scale –Mineralogy, Compositional Information; 512 bands 0.4-4  m All Images Co-Located or Nested –Multiple Resolution Same Location and Lighting –New Data Sets Take Time to Calibrate/Interpret MARCI - Global Weather Maps MCS - Mars Climate Sounder –Thermal Temperature Sounder-Profiles/5 km –Daily Global Weather Challenge is Assimilate New Data and Extract Useful Science and Safety Information on Landing Sites in Timely Manner