7: Mars

What high priority science topics about Mars are addressable by Meteorites?

• How water could have been brought to earth (panspermia)

• internal or surface structure

• age dating

What high priority science topics about Mars are addressable by Rovers?

• habitability through subsurface exploration

• drill down ice to look

What high priority science topics about Mars are addressable by Orbiters?

• differences between earth and mars atmosphere

• whole mars atmosphere column

• alignment of mars magnetic minerals (magnetosphere in past?)

What has been brought back by Mars Sample Return?

• igneous and sedimentary rocks by NASA perserverance rover

• alkali rich igneous rocks - different to meteorite collection

• carbonates - signs of microbial life?

Which country is next going tot collect Mars samples?

China with Tianwen 3 in 2028

• 500g material

• drill and scoop

What are the names of Mars’ moons?

1. Phobos: closest to planet in SS (~600km)

2. Deimos

Likely captured asteroids

Phobos 1 mission

• 1988

• expected communication failed to occur and the spacecraft failed to operate

Phobos 2 mission

• July 12 1988

• investigated mars surface and atmos

• returned 37 images

Phobos-Grunt Mission

• russian mission, 8 Nov 2011

• sample return mission

• communications lost - failed

• programming error

MMX Mission

• JAXA sample return mission 2026

• 2 possible landing and sample collections

• ~10g samples collected and return - 2029

Describes Mars’ structure vs earth

• chemically and isotopically distinct

• formed in different part of solar system to other terrestrials

• could be stranded planetary embryo

• remained much further from sun than earth

• differentiated after formation

• rocky exterior - iron rich interior

• has atmosphere

  

Mars and Magnetic field

• does not currently have one

• could have in the past if core was molten

Describe mars interior

• complicated layered mantle comp

• minerals similar to those of interior earth

• partial melting of different melting = volcanoes

• inferred from chem structure of martian meteorites

  

Describe Mars’ crustal make-up

1. Primary

• southern highlands - modified by impacts

2. Secondary

• Volcanic eruption centres - single plate planet

• mostly secondary#

3. tertiary

• water lain deposits

• volcano-sediment interaction

• glacial products

What is the Mars Geological timescale

1. Noarchian

2. Hesperian

3. Amazonian

What occured in the Hesperian period?

Early volcanism, little impact cratering

What occured in the amazonian?

small scale volcanism, impact cratering, large scale resurfacing due to aeolian wind processes, tectonics etc.

What happened most recently in Mars timescale?

oxidation of surface, red colour, Fe

What area of Mars’ surface is youngest?

• northern hemisphere is youngest

• based on counting crater impacts

  

Hellas Planitia

• crater in southern hemisphere

• over 6km deeo and 2000km in diameter

• formed 3.8-4.1Ga

• Could have been lake or small sea in past

  

What is the Mars dichotomy?

• the two hemispheres geology differ in elevation by 1-3km

• NORTH: amazonian in age

• Northern lowlands: 32km crust thickness

• Southern highlands: 58km crust thickness

• could a large impact have stripped the northern hemisphere? Good place for water stability

What is the age range of Mars Volcanic features?

• Noachian (>3.7Ga) to late Amazonian (<500Mya)

Olympus Mons

• largest mountain in solar system

• 24km high, 500km diameter

• most recent eruption 25Mya

Tharsis region

• huge bulge on surface, 4000km across and 10km high

• no tectonics to move things around

• sustains large vol of melt

• tharsis used to be in North - so much volcanism that it has driven mars to rotate on its axes and move tharsis towards the equator

  

Tholi

• dome-shaped edifices that are much steeper and larger than Tharsis shields

• central calderas large in proportion to base diameters

• densite of impact craters reveal they are older than large shields

Igneous features of Vallis Marineras

• old intrusive mafic dykes

• not only lavas erupted in volcanos but also magmas stored in mars’ crust as magma chambers or dyke systems

past volcanism on mars and the corresponding meteor types

1. effusive volcanism: shergottites and nakhlites

2. intrusive magmatism: chassignites, ALHA 84001, orthopyroxene

3. pyroclastic material (?): black beauty meteorite

which earth rock types have been found on mars?

What is the Valles Marineris Formation?

• system of canyons 400km long and 2-7km wide

• crust stretched, faulted noamrlly, valley floor drops relative to surroundings

• modification by landslides and erosion

  

Analysis of Valles Marineris Formation

• largest canyon in SS

• equitorial

• formed in rift faults like the East African Rift valley - made bigger by erosion and collapsing of rift walls

• floor may be lake bed sediments, retaining palaeobiological

• valley systems feed water into valley floor

What evidence is there for Mars Quakes?

• avalanches on northern polar scarps of Mars

Evidence for fluvial processes on Mars?

• flash flood evidence

• river systems/valley networks

• island creation

• deposition of river deposits - delta deposits

• mineralogical evidence of water - hematite Fe2O3 - opportunity rover 2023

• hematite blueberries - hydroxyl material

• sedimentary rocks in fluvial environment

what do hematite blueberries look like?

Time for sedimentation on Mars

Evidence for recent liquid water on mars?

slipe lines, could be related to seasonal releases of volatiles in walls of impact craters

Why is there no water now on Mars?

• due to changes in p/T ratios over time

• mars exists at a triple junction point o f3 domains on graph shown

• ice sublimates

• thin atmosphere

  

What temperature is Mars’ atmosphere?

• avg temp: -63C

• max temp: 20C

• min temp: -140C

What makes up Mars’ atmosphere?

• CO2: 95.3%

• N2: 2.7%

• Ar: 1.6%

• O2: 0.13%

• H2O: 0.03%

• Ne: 0.00025%

What triggers dust storms?

• solar heating of surface heats the air above the surface, causing a temp gradient - cooler pulled downwards

• wind lifts dust

• dust heats up

• most storms are localised - only few are global

What features do dust storms form on mars?

• Yardangs: wind-abraided ridge found in desert environments - few impact craters - erosion still occuring

• Dust devils

Mars environment human implications

• dust is an abrasive material

• surface radiation

• mars quakes

• long spaceflight duration (18 months)

Where have organics been found on mars?

• found by Viking

• found at Gale Crater by Curiosity rover

what evidence is there for past microbial activity on mars?

• ALH 84001 meteorite

• contained magnetite, carbonite minerals

• possible evidence of fossilised microbes - debated

What scientific equiptment was on the viking lander?

• two 360 degree cameras

• sampler arm up to 30cm

• temp, wind, pressure

• seismometer

• x-ray spectrometer

what was the aim of Viking

experiment to see if bugs in martian sediment were producing carbon that could be tracked as a tracer for respiration - produce carbon that could be detected by a gas spectrometer

What were the results of the Viking experiment?

1. Gas exchange: O2 emitted by both steralised and unsteralised - no life present within soil

2. pyrolitic release: both produced no evidence of C14 so no life

3. label release: steralised samples DID produce radioactive carbon (life?). when more nutrients were added it gave less amounts of carbon - not predicted