Lecture 7b/8 - Mars Flashcards
When do Mars’ great oppositions occur?
When Mars is closest to Earth
Every 7 oppositions (15-17 years)
What is Mars’ avg distance from the sun?
What is its orbital period?
1.5 AU (Closest at 1.38 AU, furthest at 1.67 AU)
687 days
What are the moons of Mars?
Phobos and Deimos
They appear to be small, captured asteroids
What were the theories of:
Angelo Secchi
Giovanni Schiaparelli
Percival Lowell
Secchi: Saw “canali” (canals) on Mars
Schiaparelli: Mistranslated canali into artificial channels to describe narrow linear markings
Lowell: Built an observatory to observe Mars and study its supposed Martian civilization because he thought he kept finding more channels
What did the Mariner 4 spacecraft find on Mars?
Many large craters
No canals and no signs of life
How was the landscape of Mars according to Viking 2?
Stones and boulders of various sizes
Frost on shaded side (either CO2 or water)
Orange skies
What is Mars’ atmosphere made of?
Mostly CO2
Some N2 and Ar
How much does Mars’ temperature and atmospheric pressure fluctuate?
Temp can fluctuate between 20C and -80C daily
Pressure fluctuates 30%
What happens to liquid water on Mars? Solid ice?
Liquid water freezes or evaporates
Solid ice turns directly into vapour
What happens in Martian winters and summers at each pole?
North pole: Long and cool summer, brief and mild winter
South pole: Brief and hot summer, long and frigid winter
The CO2 ice caps sublimate and condense depending on the season (but ice cap at North is permanent)
What are Martian polar ice caps made of? Why?
Water
Can’t be CO2 ice because it’s too weak; Would change to gas under expected pressures
What is the wind direction on Mars?
What are dust devils?
From one pole to other pole
Dust devils are caused by local heating of ground, common in summer
Since there is less air on Mars, the sky should be very dark blue. Why is it yellow-brown instead?
Dust scatters light and reflects the reddish colour of the ground
What is the Valles Mariners?
Huge canyon, showing signs of layered structure and water flows
Created by tectonic stresses - Mars may have shrunk when it cools, causing it to tear and form canyons
What are the volcanic crater regions on Mars?
Tharsis Bulge
Olympus Mons
What are Mars’ eons?
(From past to present)
Noachian: 4.6-3.8 bill years ago, Southern mountains, Tharsis
Hesperian: 3.8-1.0 bill years ago, Extensive lava plains
Amazonian: 1.0 bill years ago to present, Volcanic activity, Olympus Mons
What are the alternate eons of Mars?
Phyllocian: 4 Gyr ago, Alkaline water enviro (indicated by clay-rich phyllosilicate minerals), similar to Hadean
Theiikian: Intense volcanic activity, Sulfate minerals, Volcanic gases (SO2) in atmosphere
Siderikian: 3.5 Gyr to present, Absence of water, end of widespread volcanism, slow oxidation of iron-rich rocks by atmospheric peroxides, Mainly only shield volcano activity
What evidence shows that liquid surface water existed on Mars?
Old riverbeds
Indicated climate used to be warmer and atmospheric pressure higher for liquid water
What did Opportunity find on Mars?
Small rocks with layered structure, indentations and spheres showing water erosion
Where may have there been an ocean on Mars?
Northern hemisphere
Low elevation there and increased hydrogen content in that soul
What did the Phoenix Mars Lander find?
White substance on ground that disappears after 3 days
Shows signs of ice water that exists below surface
What happened to Mars as it cooled?
Since it’s smaller than Earth (less internal heat and radius), it cooled more rapidly
This caused the core to solidify and convection to stop (less vulcanism and magnetic field)
What kind of magnetic fields were found on Mars?
Localized, banded surface magnetic fields
How did solar wind strip away Mars’ H2O?
UV radiation dissociated H2O into H2 and O because there was no stratosphere to absorb UV
Because of low gravity, H2 evaporated into space
What happens to Mars’ rotation inclination?
It changes 0-60 degrees because of Jupiter’s gravity. Unlike Earth, it has no Moon to stabilize its axis.
Happens every 0.1-1 Myr.
What is a sign of climate change on Mars?
Edges if polar caps alternate between thick layers of ice and dust because of long intervals (0.1-1 Myr) of climate change
Result of axis inclination when larger because the seasons become more extreme
What was controversial about the Viking missions in 1976?
Collected soil sample on Mars that indicated sign of life but control sample showed that it was an error
Possibly from contamination of Earth cleaning products
In 2004, what was odd about the Mars Express detecting methane (CH4) in Mars’ atmosphere?
It was not from volcanoes because more SO2 should have been produced than CH4 but none have been detected yet
Maybe released from bacteria, comets or unknown surface reactions?
What is Curiosity’s mission? (2012)
What 5 things did it discover?
Analyzing terrain and Mount Sharp to look for environments where life could have been
1) Martian radiation at surface is not much worse than being on the ISS
2) Found evidence of ancient stream bed in Gale crater
3) Drilled samples of rocks that haven’t been contaminated or exposed to radiation
4) Spotted key chemicals for life in rock: S, N, H, O, Ph, C
5) Found 12 C in samples
Why is Mount Sharp a good place to look for life?
It’s inside a crater- Possibly caused by water putting pressure down to carve out land and eroding it
Water = Possible place for life
What was Perseverance and Ingenuity’s mission?
Perseverance: Collect samples from Jezero Crater
Ingenuity: Fly and track upcoming landscape (Rotors have to spin 1000x faster because atmosphere is thinner)
What was MAVEN’s (Mars Atmosphere and Volatile EvolutioN) mission? (2014)
Measure rate of Mars’ present-day atmospheric loss
Found H dissociating at fast rate and CO2 dissociating a bit slower because of solar wind from sun
What was MOM’s (Mars Orbiter Mission) mission? (2014)
- Explore Mars’ surface features
- Study atmosphere (methane and CO2)
- Study effects of solar wind/radiation
What was TGO’s (ExoMars Trace Gas Orbiter) mission? (2016)
Identify trace gases in Mars’ atmosphere (methane, water vapour, NO2)
Found to only make up of less than 1% of atmosphere
What is InSight’s mission? (2018)
Measures:
- Vibrations
- Thermal properties
- Uses radio communication to measure overall movement of Mars
- Record earthquakes, weather, and remnants of magnetic field
How can life be brought to and from Mars through contamination?
Earth extremophiles may be brought to Mars accidentally through equipment and vice versa
Meteorites might also bring life from Mars to Earth
How would we terraform Mars to be habitable?
1) Warm the atmosphere
(By producing greenhouse gases?)
2) Add liquid water
(Melt polar ice caps?)
3) Add ozone later to shield from solar UV radiation
(Split CO2 to release oxygen?)
4) Have more oxygen in atmosphere
(Bring photosynthesis bacteria and let them multiply?)
5) Screen against solar wind
