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Determining surface characteristics at candidate MSL landing sites using THEMIS high-resolution orbital thermal inertia data. Robin Fergason Philip Christensen MSL Landing Site Selection Workshop May 31, 2006. Thermal Inertia Background. Used to infer a particle size of the surface layer

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

Robin Fergason

Philip Christensen

MSL Landing Site Selection Workshop

May 31, 2006


Thermal inertia background
Thermal Inertia Background sites using THEMIS high-resolution orbital thermal inertia data

  • Used 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


Ares Valles sites using THEMIS high-resolution orbital thermal inertia data

Exposed Bedrock

6.4 N

Nili Patera

9.5 N

Christensen et al., 2003a; 2005

Rogers et al., 2005

3.4 km

3.5 km

5.9 N

8.7 N

66.9 E

67.6 E

341.3 E

341.6 E

800

260

950

190

THEMIS-derived thermal inertia overlain onto THEMIS visible


Hebes Chasma Interior Layered Deposits sites using THEMIS high-resolution orbital thermal inertia data

TI: 125-145

TI: 190-245

TI: 275-360

TI: 290-420

125

615

800 m

Fergason et al., submitted

V10052001


Thermal inertia background1

I = ( sites using THEMIS high-resolution orbital thermal inertia dataρkc)1/2

ρ – bulk density

k – conductivity

c – specific heat

Thermal inertia measures a material’s resistance to change in temperature

Thermal Inertia Background


Themis derived thermal inertia
THEMIS-derived thermal inertia sites using THEMIS high-resolution orbital thermal inertia data

  • Use thermal model developed by H. H. Kieffer

    • Ls, latitude, local time from spacecraft ephemeris

    • TES-derived albedo (8ppd)

    • MOLA-derived elevations (128 epd)

    • TES-derived dust opacity (2 ppd) every 30° Ls

  • Radiance at 12.57 μm (Band 9) is converted to brightness temperature, correcting for drift and wobble of the spacecraft

  • Interpolate upon a 7-D look-up table


Themis derived thermal inertia uncertainties
THEMIS-derived Thermal Inertia Uncertainties sites using THEMIS high-resolution orbital thermal inertia data

  • Uncertainties 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 tes
Comparison with TES sites using THEMIS high-resolution orbital thermal inertia data

TES

40 N

40 S

180 E

180 E

THEMIS

40 N

40 S

180 E

180 E

Fergason et al., submitted

25

600


Comparison of Mini-TES and THEMIS sites using THEMIS high-resolution orbital thermal inertia dataThermal Inertia

250

430

Fergason et al., 2006


Landing site characterization
Landing Site Characterization sites using THEMIS high-resolution orbital thermal inertia data

  • Identify regions of very high or very low thermal inertia

    • TI > 400 likely has rocky surface [Nowicki, 2006]

    • TI < 100 is likely dusty and not drivable

  • Evaluate surface properties of the candidate landing sites

  • Predicted surface temperature for the primary mission

    • Rover design temperature limits: 145 - 310 K

    • Maximum diurnal temperature range: 145 K


Opportunity THEMIS Temperature Mosaic - 2003 sites using THEMIS high-resolution orbital thermal inertia data


Opportunity THEMIS Temperature Mosaic - 2006 sites using THEMIS high-resolution orbital thermal inertia data


26.8 N sites using THEMIS high-resolution orbital thermal inertia data

26.3 N

62.6 E

63.2 E

175

570

Fergason et al., submitted


THEMIS Day and Night IR sites using THEMIS high-resolution orbital thermal inertia data


Predicting surface temperature

Thermal inertia is derived from THEMIS image sites using THEMIS high-resolution orbital thermal inertia data

The 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

Predicting Surface Temperature


Asu will provide
ASU Will Provide sites using THEMIS high-resolution orbital thermal inertia data

  • Interpretations 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 provide1
ASU Will Provide sites using THEMIS high-resolution orbital thermal inertia data

  • Individual 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 temperatures

    • Derive maximum diurnal temperature range


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