7: Mars Missions

how many martian meteorites have been identified?

~145

What are the 5 witnessed falls of martian meteorites? plus years

1. Nakhla, Egypt 1911

2. Chassigny, France, 1815

3. Shergotty, India, 1865 - basaltic

4. Zagami, Nigeria, 1962 - largest (~18kg)

5. Tissint, Morocco, 2011

   

What is the classification for martian meteorites?

• All are igneous rocks and cumulates

• ages range from 150-600Ma

Groups

1. Shergottites (~134) - basaltic, iherzolitic

2. nakhlites (12) - clinopyroxene

3. Chassignites (3) - dunite

4. ALH84001 (1) - orthopyroxene

5. polymict/regolith breccia (1) - basaltic breccia, impact melt breccia

   

What is Alan Hills ALH 84001?

Mars meteorite:

• 1.931kg

• found in Allan Hills icefield in antarctica 1984

• identified as martian in 1994

• comp: orthopyroxene - distinct from the snc groups

• igneous

• 4.5ga

  

What was the controversy surrounding life on mars?

• 1996 paper: suggested carbonate globules in ALH 84001 had biogenic origin

• evidence deemed insufficient

• recently: nitrogen containing organic molecules found

What is NWA 7034?

Martian meteorite:

• morocco 2012

• comp: Al, Ca and Fe

How do we know if a meteorite is from mars?

1983: gasses in ETT 79001 found to match atmospheric measurements taken by viking mission on Mars

What do Martian meteorites tell us about mars?

1. ancient volcanism/magmatism

2. evidence for past water:

• Nakhlites - hydrated phyllosilicate clays

• ALH 84001 - carbonate globules

3. possible indicators of past life

4. timing of impacts - ejection ages compared with known crater ages

5. soil (regolith) composition

6. mineral makeup, age, chemistry

describe the pre-space age telescope observations

From earth:

• mottled surface

• dark regions vary over time

• polar ice caps change with seasons

Historical mapping

• Giovanni Schiaparelli (1888)

• Percival Lowell (1895)

What is the scientific motivation for mars exploration?

1. geological and climatic history

2. comparative planetology - model for early earth

3. habitability assessment

What are the names of the first Mars missions?

Mariner

Mariner 4

• 1965

• first successful flyby

• data: 21 images, ~1% surface

• finding: heavily cratered surface

• 250km sections

  

Mariner 6 & 7

• 1969

• dual flyby

• 200 photographs returned

• wide and narrow angle cameras

• studied southern hemisphere

• discovered: craters, plains, huge impact structures

Mariner 9

1971

Discovered:

1. Olympus Mons

• 630km diameter

• 25km height

• 100x vol of Mauna Loa

2. Valles Marineris

• vast canyon system

• dwarfs earths grand canyon

3. Nirgal Vallis

• 575km long, 5-6km wide

• has tributaries

• resembles drainage channels formed by water

4. Sand dunes

5. Polar ice caps

• permanent H2O ice caps at both poles

• seasonal CO2 that sublimes

Why is mars NOT similar to the moon and mercury?

• not just craters, impact melts and lava flows

• complex geology: volcanoes, valleys, river-like channels, wind-driven features, dynamic polar caps

• similar to earth

Soviet Mars program

Mars 2 and 3 1971

• first orbiter and soft lander

• arrived during greatest martian dust storm recorded

• secret rovers

remained secret

small vehicles on side - movement by skis, carried penetrometers and densitometers

Viking Mission

• two identical missions with orbiter and lander

• Viking 1: July 20, Chryse Planitia

• Viking 2: September 3, utopia Planitia

• analysis of surface and atmosphere

• high res mapping: whole surface at 150-300m, selected areas at 8m

What instrumentation was present on the Viking landers

Environmental modelling:

• 2 360 degree cameras

• meteorological sensors: temp, wind direction/speed, pressure

• seismometer

Sample analysis:

• robotic sampler arm (30cm)

• x-ray spectrometer

• gas chromatograph mass spectrometer

Biology experiments:

• gas exchange, labelled release and pyrolytic release experiments to detect biosignatures

Name some notable post-viking mars exploration missions (1990s-2020s)

• Mars Global Surveyor (NASA) - detailed mapping

• Mars Pathfinder (NASA, 1997) - first rover (Sojourner)

• Mars Odyssey (NASA) - orbital surveying

• Mars Express (ESA) - European orbiter

• Mars Reconnaissance Orbiter (NASA) - high-resolution imaging

• Phoenix Mars Lander (NASA) - polar region studies

• MAVEN (NASA) - atmospheric studies

• Mars Science Laboratory/Curiosity (NASA)

• InSight (NASA) - seismology

• Mars Orbiter Mission (India) - first Asian Mars mission

• Perseverance (NASA, 2020)

• Tianwen-1 (China) - orbiter, lander, and rover

Mars Pathfinder

• 1997

• airbag landing system - protective

• sojourner rover: first wheeled vehicle on another planet, small, provided scale of surroundings, colour images

  

Mars climate orbiter

• 1999

• FAILED

• navigation error due to unit conversion mistake

  

Mars Polar Lander

• 1999

• FAILED

• premature engine shutdown - struck at high velocity

Beagle 2

• 2003

• FAILED

• solar panels not fully deployed

• ESA Mars express mission

What are the two Mars Exploration Rovers?

Spirit and Opportunity, 2004-2018

Spirit Rover

Landed: Gusev Crater

Findings:

• lack of expected lake sediments - lava flows instead

• later: water evidence in si rich dust

• bonneville impact crater

• columbia hills

• soil chemistry - salt rich, carbonate, habitable envs, silica rich soils

• meteorites: asteroid fragments

• lost in 2010

Opportunity Rover

• designed for 90 days, lasted 04-18

• Victoria crater

What was the camera technology on both mars rovers (2004-2018)?

Pancam technique:

• black and white CCd instruments

• 13 rotating filter wheels

• multiple images of same scene with different wavelengths

• first colour image from Spirit

Phoenix Mars lander

2008 - Polar Regions

• TEGA (thermal and evolved gas analyser): heated soil samples, analysed gases, confirmed presence of water ice

• Major: confirmation of water ice below surface, ‘snow white’ trench exposed bright subsurface material

  

Curiosity Rover

• 2012 - present

• Gale Crater

• travelled 7km

• objective: traverse to Mount Sharp

  

Why is the Gale Crater important?

• filled with younger sedimentary layers

• fine-grained sediments and mudstones

• clay minerals

• RIVER DELTAS AND LAKE DEPOSITS = WET SYSTEMS

• DRAMATIC CLIMATE CHANGE

Evidence of ancient water;

• rounded pebbles in conglomerates

• poorly sorted

• formed by flash floods

• similar to terrestrial alluvial deposits

  

evidence for wind-blown deposits;

• STIMSON FORMATION in gale crater

• cross bedded sandstones

• simple dune structures

• dry, arid

• evidence of aeolian wind processes

  

Evidence for ancient lake environment:

• chemical analysis of mudstones

• clays and magnetite

• moderate ph and low salinity = habitable for microbial life

• likely persisted for extended periods

InSight Lander

• 2018-2022

• goal: study mars interior structure - deploy seismometer

• Instrumentation: seismic package, heat flow probe

• challenges: long delays, ~150m overspend - vacuum seal issues with seismometer

• acheivments: detected marsquakes, data on interior structure

ExoMars program

• 2016-present

• trace gas orbiter

• goals: ATMOSPHERE

• investigate methane sources

• Schiaparelli test lander: entry, descent and landing technology - crashed

ExoMars Rosalind Franklin Rover

• 2022

• landed: Oxia Planum

• 2m drill

• accessed subsurface: below radiation, water ice may be stable, organic material preservation

• search for biosignatures

Perseverance Rover Mission

• 2020

• Jezero Crater

• ancient river delta, fed into crater lake (3.5Ga)

• well preserved sedimentary deposits