The document discusses the Mars Exploration Rover missions, specifically the Spirit and Opportunity rovers, detailing their design, operational challenges, and geological findings during their missions. Key aspects include the rovers' navigation systems, machine-terrain interactions, and the effects of soil composition on their performance. The presentation features graphs, images, and data related to the rovers' traverses and soil analysis on Mars.

1. The Spirit and Opportunity
Mars Exploration Rover
Missions
Ray Arvidson
Washington University in Saint Louis
Saint Christopher Lecture
17th International ISTVS Conference
9/19/11
1

2. Planetary Terramechanics
• Interaction of spacecraft systems with planetary
surfaces, e.g., during
– Hard landing (penetrometer)
– Soft landing (rockets, air bags, “sky crane”)
– Hopping (proposed Comet Hopper)
– Digging and sampling (Mars Phoenix Lander, MER-
Spirit and Opportunity)
– Drilling and sampling (Mars Science Laboratory
(Curiosity), Mars 2018 Sample Caching Rover)
– Roving (MER, MSL, Mars 2018 Sample Caching Rover)
2

3. Spirit and Opportunity Rovers
•Six wheel drive
with rigid wheels
•Outer four wheels
able to turn
•Rocker-bogie
suspension system
•Navigation and
hazard avoidance
systems
3

4. Machine-Terrain Interaction Design, Modeling, Testing, and Best Operational Practices
Must be Used to Avoid……..
Did not happen with either Spirit or Opportunity!

5. Spirit Rover
•Right front wheel
drive actuator
failed on sol 779
so subsequent drives
caused rotations
about that wheel
•Embedded in sands of
Troy after breaking
through soil crust
•Extrication stopped
Sol 2169 to prepare
for winter
•Last communication
March 2010 and
mission over May 2011
5

6. 6

7. Home Plate
Husband Hill
7

8. HiRISE View Spirit’s traverses entry to
Inner Basin to 3rd winter site
Home Plate
Mitcheltree Ridge
80 m wide
Tyrone
Low Ridge
Crossfield Slide
McCool Hill
Von Braun
Goddard
8

9. Spirit’s Traverses After Leaving Third Winter Site
9

10. Stapledon Nodular Rock Clast Close to Winter Site
72% SiO2
10

11. 11

12. Sulfate-rich Soils Excavated by Inoperative Right Front Wheel
30% SO3
12

13. Sol 1870 Navcam looking south showing Stratius and other features
The Troy Region as Seen on Sol 1870
13

14. Scamander crater 8 m wide and 25 cm deep
Rock Garden
14

15. Sandals
Stratius
15

16. 16

17. Olive tree
5 cm across
17

18. 18

19. Penina 3 (1.5 cm across)
19

20. Cyclops eye RAT Holes
Olive
branch
sites
20

21. “Breast Stroke” Maneuver Moves Spirit ~35 cm over last drives
21

22. Pancam
False color mosaic
after IDD and
extrication
efforts stopped
for winter
22

23. “Punch Line”
•Relatively insoluble
minerals concentrated
toward top of Troy
soil section with ferric sulfate
“lenses”
•Generate sulfates during
Inner Basin volcanic period
•Wind erosion and transport
mix sulfates and basaltic
materials, e.g., infilling Scamander
Crater
•On-going wetting (frosts,
snowpack) moves soluble
species down-section, without
complete re-equilibration
23

24. 24

25. Opportunity Rover
•Right front
wheel left rotated
~8 deg inward
when azimuthal
actuator failed
•Shoulder IDD
actuator failed so
driving uses
“fishing stow” and
have limited
deployment
work space
•Mini-TES no longer
responding
25

27. Purgatory
ripple
27

28. 28

29. After backing out of Purgatory Ripple
29

30. 30

31. Sol 2220 Ripple Slip of ~58% and sinkage of ~5 cm
31

32. 32

33. 33

34. Sol 2143 Ripple Crossing Simulation
34

35. Similar to observed
telemetry
35

36. 36

37. 37

38. Sol 2451 Backwards Downhill Drive Simulation
38

39. Similar to observed
telemetry
39

41. 41

46. 2.0 x100
1.8 Timmins ratio to Zn
GusevSoil Br
1.6 Adirondack
1.4 Marquette
Gibraltar
1.2
1.0 x10
logartihmic ratio
0.8 P S
change
Cl
0.6 K
0.4
Ti x2
Ca
0.2 Mn
Ni
0.0 x1
Fe
-0.2 Si
Na Al x0.5
-0.4 Mg
-0.6
-0.8 Cr
-1.0 x0.1
Oxide

47. HiRISE Image Opportunity

48. Sol 2709 Pancam Chester Lake
In-situ measurement target

49. Rock Abrasion Tool image acquired 9/11/11
Metal cable cover
From Twin Towers

50. Size Comparison
MARS SCIENCE
LABORATORY (MSL)
MARS
EXPLORATION
ROVER (MER)
MARS PATH
FINDER (MPF)
Rover Mass
10.6 kg 174.0 kg 975.0 kg