Robin Fergason Philip Christensen MSL Landing Site Selection Workshop May 31, 2006

Determining surface characteristics at candidate MSL landing sites using THEMIS high-resolution orbital thermal inertia data

Robin FergasonPhilip Christensen

MSL Landing Site Selection WorkshopMay 31, 2006

Thermal Inertia BackgroundUsed to infer a particle size of the surface layer

Helps to identify features, their location and extent on the surface, and their particle size

Detect exposed bedrock and dust

Exposed Bedrock80026067.6 ENili Patera66.9 E8.7 N9.5 NAres VallesRogers et al., 2005Christensen et al., 2003a; 2005950190341.6 E341.3 E5.9 N6.4 N3.4 km3.5 kmTHEMIS-derived thermal inertia overlain onto THEMIS visible

Hebes Chasma Interior Layered DepositsV10052001800 mTI: 190-245TI: 275-360TI: 290-420TI: 125-145125615Fergason et al., submitted

Thermal Inertia BackgroundI = (kc)1/2 bulk density k conductivity c specific heatThermal inertia measures a materials resistance to change in temperature

THEMIS-derived thermal inertiaUse thermal model developed by H. H. KiefferLs, latitude, local time from spacecraft ephemerisTES-derived albedo (8ppd)MOLA-derived elevations (128 epd)TES-derived dust opacity (2 ppd) every 30 LsRadiance at 12.57 m (Band 9) is converted to brightness temperature, correcting for drift and wobble of the spacecraftInterpolate upon a 7-D look-up table

THEMIS-derived Thermal Inertia UncertaintiesUncertainties are primarily due to: (1) instrument calibration (2) uncertainties in model input parameters (3) thermal model uncertainties

Variations in thermal inertia within a single image are accurate and represent differences in the physical properties of the surface

Comparison with TES25600180 E40 S40 N180 E180 E40 S40 N180 ETHEMISTES Fergason et al., submitted

Comparison of Mini-TES and THEMISThermal InertiaFergason et al., 2006250430

Chart2

168.16280

157.09300

192.93330

150.12305

197.5175290

136.43225315

216.638350

487.788390

668.1165

1206.98

436.476

336.216

351.142

205.595

196.736

363.331

235.513

257.435

227.187

220.189

164.327

294.06

275.998

284.769

759.402

352.24

178.753

240.203

276.633

338.538

176.183

Mini-TES Thermal Inertia

THEMIS Thermal Inertia

Spirit - Gusev Landing Site Number

Thermal Inertia

THEMIS and Mini-TES Thermal Inertia

Sheet1

Gusev Plains Traverse

Comparing THEMIS and Mini-TES thermal inertia data results

THEMIS Thermal InertiaMini-TES Thermal InertiaMini-TESTHEMIS

SolAvg SolAve SiteFeatureAvg THEMIS thermal inertiaAvg Mini-TES thermal inertiaAlbedo - 0.25Albedo - 0.22Albedo - 0.22 - minus the outlying high values to calculate an appropriate standard deviation

Albedo 0.25Alb 0.22siteSolinertiainertia

1-50254plains280140173325133.71168.16280168.16

51-615612transition between plains and Bonneville crater300190134437124.62157.09284157.09

61-897520Bonneville ejecta330380774744161.49192.93288192.93

90-1009526transition between plains and Bonneville crater305300301946125.952150.12292150.12

101-12311236Lahonton Crater2901852441050146.677197.5175296173.1635197.5175

124-13312848plains315195196115282.13136.43225300136.43225

138-15014456plains3503103071261185.56216.638310133.845216.638

150-15815464near Colombia hills3902402641362419.42487.788320487.788

1565697.01668.1165330436.476

RMS between THEMIS and MT24891206.981206.98321.7263.8658055556774.47336.216

2590315436.476313.4358.177225351.142

2691286.22336.216305205.595

2799304.56351.142302.5301.9266666667196.736

28101176.25205.595300363.331

29102167.465196.736297.5235.513

31106313.82363.331295257.435

33109202.17235.513292.5227.187

36112217.12257.435290220.189

39118183.54227.187295164.327

42122186.25220.189300243.7122857143294.06

44124129.42164.327305275.998

46125294.06294.06310284.769

48128239.5275.998315352.24

50130121.94284.769326.6196.23178.753

55143567.46759.402338.2240.203

57145300.95352.24350276.633

59147152.72178.753363.3338.538

61149207.967240.203376.6307.27425176.183

64153239.112276.633390

71189293.93338.538

73191147.75176.183293.8536190476263.7846666667

6170.926

314.6031693548313.3551724138

218.72087890789.0118269262

RSS

Bonneville to CH RSS:319.5983309972Mini-TESBonneville to CH RSS:

331.9487912314THEMIS

12.3504602342

Sheet1

Mini-TES Thermal Inertia

THEMIS Thermal Inertia

Spirit - Gusev Landing Site Sol Number

Thermal Inertia

THEMIS and Mini-TES Thermal Inertia

Sheet2

Mini-TES Thermal Inertia

THEMIS Thermal Inertia

Spirit - Gusev Landing Site Number

Thermal Inertia

THEMIS and Mini-TES Thermal Inertia

Sheet3

Landing Site CharacterizationIdentify regions of very high or very low thermal inertiaTI > 400 likely has rocky surface [Nowicki, 2006]TI < 100 is likely dusty and not drivableEvaluate surface properties of the candidate landing sitesPredicted surface temperature for the primary missionRover design temperature limits: 145 - 310 KMaximum diurnal temperature range: 145 K

Opportunity THEMIS Temperature Mosaic - 2003

Opportunity THEMIS Temperature Mosaic - 2006

63.2 E57017526.8 N26.3 N62.6 EFergason et al., submitted

THEMIS Day and Night IR

Predicting Surface TemperatureThermal inertia is derived from THEMIS imageThe derived thermal inertia value is then used to calculate the surface temperature for a given local time and season

Can predict the minimum surface kinetic temperature during the primary mission

ASU Will ProvideInterpretations of THEMIS and TES thermal inertia data for all candidate landing sites

Thermal inertia mosaics of candidate landing site regions (100 m)Relative thermal inertia values

ASU Will ProvideIndividual thermal inertia images of specific areas of interest (100 m)Thermal inertia values of specific morphologies

Predicted temperature maps of candidate landing site regions (100 m)Predict range of temperaturesDerive maximum diurnal temperature range