Chp 11: Mars Flashcards
Do canals exist on the surface of Mars? Why were people excited about canals?
no, they don’t, people thought Martians created canals and were very smart to do so.
-“the proof by astronomical observations that conscious, intelligent human life exists upon the planet Mars.”
a.Is Mars smaller or larger than Earth?
Smaller, Mars is only slightly more than half the size of Earth
c. Is there a greenhouse effect on Mars?
No, The existing atmosphere is so thin that it cannot retain energy from the Sun.
a. Does Mars have satellites? Are they round? Why or why not?
two small satellites, Phobos and Deimos
- is shaped like a flattened loaf of bread
- the satellites are heavily cratered. Such cratering could have occurred while the objects were either still in the asteroid belt or in orbit around Mars
- In any case, the heavy battering has broken the satellites into irregular chunks of rock, and they cannot pull themselves into smooth spheres because their gravity is too weak to overcome the structural strength of the rock.
f. Are there seasons on Mars? Why or why not?
Yes, as Earth’s axis is tipped (now) 23.5°, that of Mars is tipped 25°, so both planets have seasons.
-As the northern and southern hemispheres turn alternately toward the Sun, seasonal changes are visible even through a small telescope.
g. Which is longer, a year or a day on Mars?
A year is longer.
-A day on Mars is nearly the same length as an Earth day - 24 hours and 40 minutes - and a martian year lasts 1.88 Earth years.
What are the names of the spacecraft that have explored Mars from its surface?
- Mars Curiosity (2011-present, USA)
- Mars Opportunity (2003-2018, USA)
a. What are Curiosity’s objectives and what kind of evidence might it look for? (Mars)
The primary objectives for Curiosity are:
- To investigate whether Mars could or has ever held microbial life.
- To explore the presence of water on Mars.
- To explore Martian climate.
- To explore Martian geology.
- sampling and analyzing soil and rocks
- Does Mars have an atmosphere?
i. What is the primary composition?
ii. Does it contain water?
Yes,
- 96% carbon dioxide , 2(2.7)% nitrogen, 2(1.6)% argon
- It contains miniscule traces of water vapour and oxygen
- its density at the surface of the planet - only 1% that of Earth’s atmosphere
How did the atmosphere of Mars form? Note similarities/differences to the formation (and characteristics) of atmospheres on Venus, Mercury and Earth.
- Volcanism on terrestrial planets typically releases carbon dioxide and water vapour plus other gases. Because Mars formed farther from the Sun, we might expect that it incorporated more volatiles than Earth when it formed.
- But Mars is smaller than Earth, so it has had less internal heat to drive geological activity, and we might suspect that it has not out-gassed (through volcanism) as much as Earth.
the implications of high versus low escape velocity to the atmospheric composition
- How much atmosphere a planet has depends on how rapidly it releases internal gas and how rapidly it loses gas from its atmosphere.
- The rate at which a planet loses gas depends on its mass and temperature. The more massive the planet, the stronger its gravitational attraction, thus the higher its escape velocity and the more difficult it is for gas atoms to leak into space.
- Mars has a mass less than 11% than that of Earth, and its escape velocity is only 5 km/s, less than half Earth’s. Thus, gas atoms can escape from it much more easily than they can escape from Earth.
How does the size of a planet affect the composition of its atmosphere? (e.g. compare a gas planet to a terrestrial planet, compare the different terrestrial planets). Pay attention to how planet size and cooling rates affects the core, the magnetosphere and loss of atmosphere.
-The thickness of a planet’s atmosphere depends on the planet’s gravity and the temperature of the atmosphere.
-A planet with weaker gravity does not have as strong a hold on the molecules that make up its atmosphere as a planet with stronger gravity. The gas molecules will be more likely to escape the planet’s gravity
The atmospheric characteristics of rocky and gas planets differ:
-The terrestrial planets in the solar system have atmospheres made up mostly of gases such as carbon dioxide, nitrogen and oxygen.
-The gas giants, on the other hand, consist mainly of lighter gases like hydrogen and helium.
Can water escape Mars’ atmosphere? How is it lost? Was there ever liquid water on the surface?
- The current atmospheric pressure is too low to keep it from boiling away to vapour
- there was, we find enough enrichment of deuterium to say that Mars once had really abundant liquid water supplies – enough for large oceans.
- perchlorates found
What evidence do we have for weather, storms or wind on the surface of Mars?
- Winds on Mars can produce dust storms that envelope the entire planet or tiny ‘dust devils’.
- Martian dust storms have been seen, proving the existence of Martian dust transport.
We have not found liquid water on Mars, but what evidence do we have that there is/was water on Mars?
- we found enough enrichment of deuterium to say that Mars once had really abundant liquid water supplies – enough for large oceans.
- Chemical analysis shows that the magma from which the rocks solidified must have contained up to 1.8% water
Where does water currently exist on Mars?
- Ice in caps at north and south poles.
- Ice as permafrost just below surface.
- Water chemically bound to other elements in the structures of minerals and rocks.
- Tiny amounts of water vapour which, during local winter, forms frost and thin temporary ice deposits.
Compare plate tectonics on Mars, Earth and Venus
- Mars is a one-plate planet (similar to Venus), and includes some of the largest volcanoes in the Solar System.
- Earth is broken into moving plates like those that create the topography
Why does Mars surface lack the regolith seen on the Moon?
- These are lava plains fractured by meteorite impacts, but they don’t look much like those on the surface of the Moon.
- The atmosphere of Mars, though thin, protects the surface from the blast of micrometeorites that grinds Moon rocks to dust.
- Also, the martian dust storms may sweep fine dust away from some areas and leave larger rocks exposed.
Why are there few craters on the northern lowlands (how does this compare to areas on Venus that lack craters?)
- northern lowlands are smooth and so remarkably free of craters that the lowlands must have been resurfaced roughly a billion years ago.
- the northern lowlands may once have been filled by an ocean of liquid water
- On Venus, volcanic floods filled the northern lowlands and buried the craters there.
Give examples of surface features that tell us something about the crust of Mars
- The largest volcano in the Solar System is Olympus Mons on Mars
- Olympus Mons is much larger than Mauna Loa but has not sunk into the crust of Mars, which is evidence that the crust of Mars is much thicker than the crust of Earth.
What does the mineralogy of Martian soils tell us about the environment (sulphates, iron oxides, blueberries)
- Evaporite salts, sulfates, and carbonates tend to bond surface dust into duricrust, shows water has played a role in the martian mineral chemistry,
- red beds, arid (dry) regions with intermittent supplies of moisture produce the red iron oxide minerals
- blueberries, they are iron oxide (the mineral hematite) formed into spherules by gentle rolling water.
- Compare the Martian core to the other terrestrial planets:
a. Is the core molten?
b. Is the core metal?
c. Is there a magnetic field?
- Mars’ core is liquid
- iron core
- The magnetosphere of Mars is far simpler and less extensive than that of the Earth.
Mars has some of the largest volcanoes in the solar system – in general how are they formed?
long ago, eruptions built enormous volcanoes and piles of thick ash.
What are the 4 stages of developmental history of Mars?`
- Differentiation: the planet seems to have differentiated into a core, mantle, and crust. There are no obvious traces of plate tectonics such as folded mountain ranges. Mars lacks a magnetic field, so its core cannot contain much molten iron.
- Cratering: the crust of Mars was battered during the heavy bombardment as the last of the debris in the young Solar System was swept up.
- Flooding: included flooding by great lava flows that smoothed some regions. The evidence that the flooding stage included not only volcanic magma but also water seems quite impressive. As atmospheric gases leaked into space, the surface temperature fell, and what water remained became trapped in the soil as permafrost. Mars became a frozen world.
- The crust of Mars is now too thick to be active. The planet has lost much of its internal heat, and now it lacks much of a molten core, as evidenced by the lack of a planet-wide magnetic field. Although the crust was
stressed by rising magma, it is too thick for plate tectonics.
