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Gullies on Mars. Mars is the fourth planet from the Sun

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Gullies on Mars. Mars is the fourth planet from the Sun, referred as the red planet ... Mars rovers have excavated on the surface and collected samples to study ... – PowerPoint PPT presentation

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Title: Gullies on Mars. Mars is the fourth planet from the Sun


1
Designing Optical Probe for Regolith Analysis
  • Presented by
  • Obadiah Kegege
  • Advisor Dr. Larry Roe, PE
  • Arkansas Center for Space
  • and Planetary Science
  • University of Arkansas
  • July 2007

2
Outline
  • Introduction
  • Approach
  • Experimental Equipment
  • Preliminary Results
  • Summary and Conclusion

3
Introduction
  • Mars is the fourth planet from the Sun, referred
    as the red planet
  • Martian atmosphere is composed primarily of
    carbon dioxide with small amounts of other gases
  • The surface temperatures range from -140
    C (-220 F) to 20 C (68 F)
  • Evidence of features resembling gullies,
    riverbeds, and erosions suggest that water or
    some fluid existed on the surface
  • Mars rovers have excavated on the surface and
    collected samples to study regolith - disturbs
    the sedimentary layering which hinders
    exploration and full information extraction
  • This work focuses on designing an optimum system
    for sampling Martian regolith - explore Mars
    without disturbing sedimentary layering.

Channel/riverbed on Mars
Gullies on Mars
4
Approach
  • First, we experimentally investigate the force
    required to insert different dimensions of
    sampling spikes into regolith
  • Next, use the optimum dimensions and design the
    shaft/penetrator with linear array of near-IR
    illuminators within a spectral range of 0.5 to 5
    µm
  • Real-time mineralogical and chemical profiling as
    a function of depth for undisturbed sediments.
  • This proposed system shall be applicable to any
    surface that has regolith or icy properties
    including Moon and asteroids.

Mars rover (Figure obtained from 1 )
Probe to be pushed below the surface by rovers
with minimum force
5
Approach
Overview of simple probe
  • The regolith resistance to probe
    penetration can be expressed as
  • where

Total force acting on the probe (tip sleeve)
Probe surface area (tip sleeve )
6
Experimental Equipment
  • We have two measurement setups
  • constant velocity system
  • constant force system

Regolith Two different types of regolith have
been used in these experiments JSC Mars-1
feldspar, Ti-magnetite, with minor olivine,
pyroxene and glass JSC Mars-2 45 clay, 45
basalt, 10 iron oxide
Constant velocity penetration test
Constant force penetration test
7
Experimental Equipment
  • To create relationship between regolith strength
    and depth
  • (1) Velocity Mode
  • Electric actuator pushes the probe down at
    certain speed to a designated depth and stops
    there
  • At each depth level, the load cell will read the
    regolith strength (penetration force)
  • (2) Constant Force Mode
  • Pneumatic actuator pushes the probe down at
    certain constant force until balanced by the
    resistance strength from the regolith.
  • The LVDT will measure the penetrating depth
  • Computer program will measure the time between
    depth intervals

8
Preliminary Results Constant Velocity
  • It takes 210 N to insert a 19.05 mm cylindrical
    spike to 152 mm into JSC Mars-1
  • 79 N to insert a 12.70 mm cylindrical spike into
    JSC Mars-1
  • 6 N removing 19.05 mm spike
  • 3 N removing 12.70 mm spike
  • It takes about 1/10 of the force applied in JSC
    Mars-1 to insert the same spikes into JSC Mars-2.

9
Preliminary Results Constant Velocity
  • 19.05 mm diameter spike
  • 19 degrees tip angle 313N
  • 12 degrees tip angle 130N
  • 12.70 mm diameter spike
  • 19 degrees tip angle 145N
  • 12 degrees tip angle 123N
  • Reducing the spike tip angle reduces the
    penetration force for both 19.05 mm and 12.70 mm
    spikes.

10
Preliminary Results - Constant Force
JSC Mars-1 Data
Spirit/Opportunity rover on NASA's Mars mission
weigh 1800 N (397 lb)
JSC Mars-2 Data
11
Summary and Conclusion
  • Preliminary penetration force experiments show
    that regolith resistance is dependent on regolith
    texture/composition
  • Possible to characterize the layering of
    undisturbed regolith by measured strength at
    different depths
  • The mechanical penetration of the probe will
    characterize regolith strength versus depth, and
    the near IR illuminators (under design by R.
    Pilgrim) would obtain mineralogical composition
    at each depth.
  • The ultimate goal is to design and build a
    simple, low cost, light weight, low power
    regolith sampling probe

12
Future Work
  • Collaboration and experiments using the simulated
    Martian environmental chamber to facilitate the
    development of a real-time autonomous regolith
    sampling sensor system.
  • Acknowledgements
  • I would like to acknowledge support from Space
    Center grant and faculties in the Arkansas Center
    for Space and Planetary Sciences

13
References
  • Rick Ulrich, Derek Sears, Matt Leftwich, Larry
    Roe, Vincent Chevrier, Walter Graupner, Fiber
    Optic Spectral Array on a Regolith Probe for
    Surface and Sub-Surface Mineralogical Profiling
    Optical Probe for Regolith Analysis, Arkansas
    Center for Space Planetary Sciences, University
    of Arkansas, June 2006
  • Peter M. Cao, Ernest L. Hall, Soil sampling
    sensor system on a mobile robot, Proceedings of
    SPIE, Intelligent Robots and Computer Vision XXI
    Algorithms, Techniques, and Active Vision, pp.
    304-310, October 2003
  • Jeffrey E. Herrick, Tim L. Jones, "A dynamic
    cone penetrometer for measuring soil penetration
    resistance", Soil Science Society of America
    Journal 661320-1324 , 2002
  • Bradley D.A, Seward D.W., Developing real-time
    autonomous excavation-the LUCIE story,
    Proceedings of the 34th IEEE Conference on
    Decision and Control, 1995
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