1. Geology of the Moon, Mercury, and Mars

2. How the maria formed
A very large impact fractures the crust and creates ringed mountains
Structure is called an “impact basin”
Low viscosity lava flows up through the cracks and fills the basin
This happened after the period of late heavy bombardment, so there are relatively few craters in the maria

3. Mare Orientale is a textbook example of an impact basin
Very little lava flooded Orientale because it happened late – it was probably the last large impact basin to form.
(Compare to Mare Imbrium)
Ringed mountains
Flat mare
(few craters)
Mare Orientale

4. Interestingly, the far side of the Moon has no large maria
The near-side has many large maria
The crust is thicker on the far side, and so impacts are much less likely to fracture it down to molten material
But why is it thicker there? We don’t know.

5. The Moon also has interesting features called “rilles”
They’re all over, but we’re going to visit one here

6. This is “Hadley Rille”
Mount Hadley
Apollo 15 landing site

7. Here the Apollo 15 lunar rover is parked next to Hadley Rille
1200 ft deep in this area, ~ 80 miles long
“Sinuous Rilles” are lava tubes that ran dry and collapsed, leaving a winding valley

8. On which side of the Moon is the crust the thickest?
A) The far side
B) The near side
C) They are equally thick
D) We have no way of knowing

9. On which side of the Moon are maria more prevalent?
A) The far side
B) The near side
C) They are equally prevalent on both sides

10. The surface of the Moon is covered by loose, powdery material called regolith.
It is the product of constant bombardment from micrometeorites.
It has very different properties from the “soil” of Earth:
Very dry and sharp edged
Electrostatically charged, so it clings to everything

11. 2 – 4 mm sample of lunar regolith NOTE the glass spherules

12. Microscopic regolith sample
Note the sharp edges

13. Astronauts inside the lunar lander after an EVA were coated with it
Gene Cernan, Apollo 17
This stuff gets into everything, and raises serious technical problems!

14. Mercury shows similar features, though no large maria
Notice that in many areas, like this one, the impact craters are not as closely packed as in the lunar highlands
But more so than in the lunar maria.
This suggests that this area was covered by lava flows late in the heavy bombardment era

15. Lobate scarps on Mercury
This is a form of tectonics we do not see on any other terrestrial planet

16. Rank these surfaces from oldest to youngest:
B) 1, 3, 2
C) 2, 3, 1
D) 2, 1, 3
E) 3, 2, 1 1 3 2

17. Percival Lowell and Mars
1879 Giovanni Schiaparelli reported linear features on Mars
He called them “canali”, Italian for “channels”
1895 Percival Lowell published maps of “canals” on Mars
H. G. Wells War of the Worlds (Radio broadcast was 1938, Oct. 30)
Ray Bradbury The Martian Chronicles
NASA’s Mariner 4 spacecraft: No Martians

18. A current map of Mars
Volcanism
Tectonics

19. Valles Marineris

20. ~85,000’
29,029’
33,500’

21. Evidence of water on Mars 1

22. Evidence of water on Mars 2
Mars rovers have found many examples of minerals that are known to form only in the presence of liquid water

23. Evidence of water on Mars 3
Here gypsum fills a crack in Martian rock.
The gypsum was deposited by water flowing through the cracks in the rock.

24. Evidence of water on Mars …
Evidence of recent (last million years or so) water erosion on a crater wall

25. Evidence that liquid water occasionally flows on today’s Mars
Released in summer 2015…
Evidence that liquid water occasionally flows on today’s Mars
(just below the surface)

26. Recurring Slope Lineae (RSL)
They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons.
Scientists discovered hydrated salts in these lines.
On Earth these salts are known to lower the freezing point of liquids to as low as -94º F
The RSL are “likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.”

27. Astro-Cash Cab!
Jesse K.
Emily
Amanuel JC
Katy

28. 1) Matching:
A) Regolith _____
B) Impact basin _____
C) Sinuous rille _____
1) Collapsed lava tube
2) A large, ringed area indicating a very large impact event
3) Loose, powdery material on the lunar surface

29. 2) Put these 3 things in age order, from youngest to oldest:
The mare
The crater
The rille

30. 3) What is this feature on the surface of Mercury called?

31. 4) On which planet will you find the largest volcano in the solar system?