Download 8sept03_notes - World of Teaching

Surface Exploration of Mars: Past & Future
• Martian Meteorites
• Martian Moons
• Martian Surface Exploration
The Viking Landers (early 80s)
Pathfinder (1997)
Current Surface Explorers (three en route!)
Future of Martian Exploration (“astrobiology”)
• Review of Mars
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Martian Meteorites
Martian data
without going
there!
What are these “meteorites”? Unusual rocks found in Antarctica
How did they get to Earth?
An impact on Mars (crater size: 10-100 km) ejected
part of the Martian surface
How do we know these meteorites are from Mars?
Chemical composition does not match usual meteorites
Only 1.3 billion yrs old (most asteroid-type meteorites
MUCH older); Higher content of volatile substances
Why aren’t they orange – the color of Mars surface?
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Has to do with how the rocks weathered
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Solar System - C. C. Lang
What DO they tell us?
-Physical processes on Mars
Crust/core developed early in Solar System
Volcanism until < 1 Billion Years ago
- Chemical composition
Different than normal asteroid (meteorite) comp.
Interaction with water
Martian atmosphere composition
What DON’T they tell us?
- Location of origin (on Mars – which part of surface?)
- Enough about Mars’ water & atmosphere
- Need to actually RETURN ROCKS from Mars!!
Case Study: Martian Rock ALH84001
Mass = 1.9 kg
Igneous Rock
Discovered in Antarctica (easier to find) 1984
Formed on Mars 4.5 Billion yr ago
Ejected ~16 Million yr ago
Landed ~13,000 yr ago
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Controversial – microbial presence in meteorites??
Close up views reveal structure similar to Earth microbes?
Globules of carbonate minerals (the
yellow-orange grains) are scattered along
cracks in this small chip of ALH 84001.
The rims contain iron oxides (including magnetite)
and iron sulfides--incompatible minerals that on
Earth would suggest microbial action
Astrobiology: exciting field of research – study of origin of life in the solar system,universe
- LIFE IS UBIQUITOUS in the universe – we just haven’t found it
- LIFE IS A SPECIAL
quirk
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Solar System
- C. of
C. nature
Lang and timing – very very rare! 4
Martian Moons
 Two moons: Deimos, Phobos
Small (~20km) irregularly
shaped
 Orbit Mars in 8hr, 30hr
 Probably captured asteroids
Deimos
Comparison: Asteroid Eros
Phobos (20 km x Solar
27 km)
System - C. C. Lang
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(33 km x 13 km)
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Risks of Solar System Missions
PROS for Space Missions
 Closest views of the planets
that are possible
 Access to wavelengths that are
unavailable on the ground
 Atmospheric effects gone – get
clearer views than on Earth
 Development of sophisticated
tech. and research
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CONS for Space Missions
+ Can not fix/test equipment as easily
+ Large risk with rocket launch
+ Much much more costly! (although
more costly for manned than
unmanned)
+ Lifetime is usually shorter
+ Upgrades much more difficult
Solar System - +
C. C.Risks
Lang
from UV radiation, cosmic 6rays
Viking Landers 1 and 2
• Viking 1 launched in August of 1975, Viking 2 launched in Sept. 1975
• Vikings arrived at Mars in June, August of 1976
• Orbiter + Lander – Orbiters alone weighed close to a ½ ton each –
very expensive launch/rocket equipment !!
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Solar System - C. C. Lang
- these days NASA’s mantra: “Faster Better Cheaper”
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Viking Lander Images of Mars’ Surface
• landing site chosen from Orbiter images – two different regions in Northern Lowlands
• revealed that the surface of Mars was littered with jagged rocks and fine dust everywhere
• rocks were probably result of crater-forming impact (“ejecta”)
• rocks resemble lava-rocks on Earth – lava flows broken up by impacts
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Viking Landers: Search for Life on Mars
• Science Instruments:
- chem lab to explore reactions of
Mars rock with water (none
detected)
- scoop arm with magnet – found
that the soil was IRON-rich
• confined to study only one part of
Martian surface – its landing site
• inspired NASA to propose for
missions with MOVING surface
vehicles – Pathfinder 1997!
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Mars has a very thin atmosphere and no magnetosphere.
If humans populated the Martian surface, what environmental
problems will they be concerned about?
(1) Global Warming
(2) Solar flare particles and ultraviolet radiation
(3) Nitrogen poisoning
(4) Lead contamination from volcanoes
(5) Magnetic anomalies in the interior causing brain
disorders
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Mars Pathfinder Mission – landed on Mars 4 July 1997
Demonstration mission for
“Faster Better Cheaper”
NASA mantra
• used lightweight airbags
to land
• small, efficient robotic
vehicle
• 10x as many images as
previous missions (computers)
• landed 500 miles from
Vikings – flood plain area
(volcanic rocks with silicon)
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Panoramic View from Mars’ Pathfinder’s Sojourner Rover
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ATHENA: MARS EXPLORATION ROVERS
Opportunity & Spirit (or MER A and MER B)
• Launched in June
and July of 2003
Rover
• arrival at Mars –
January 2004
• Each Rover weighs
180 kg, is ~5 ft high
• surface exploration:
travels 100m per day
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ATHENA: MARS EXPLORATION ROVER
Mars Rover Entry
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Sequence
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cartoon of the “airbag” landing of the Mars Exploration Rovers on surface
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Choosing a site to land on Mars
Can not just land anywhere – need to consider the safety of the vessel!
- previous missions have landed in the northern lowlands
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Mars Landing Considerations
• terrain
- altitude (impossible climbs, falls)
- slopes (use too much energy)
- rockiness (protect airbags)
• solar panel heating – keep rover operable
• dust
- solar panels clear
- RAT tool works more in thick dust
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Science Objectives of the MER mission
• Characterize a variety of rocks and soils that hold clues to past water activity
– i.e. try to identify carbonates (indicate water-volcano cycles)
• Distribution and composition of minerals, rocks, and soils near sites
• Determine geologic processes have shaped the local terrain
• Perform "ground truth" –
calibration and validation –
of surface observations made
by Mars orbiter instruments.
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Mars Exploration Rover: Science Instruments
Pancam- Stereo camera
IR Spectrometer - rock
composition
X-ray Spectrometer - soil
and rock chemistry
RAT - rock abrasion tool
Microscopic imager (search
for fossils?)
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Landing Sites on Mars: 1. Gusev Crater - morphological
- 15 degrees South of Mars’ equator
- large crater feature with several ‘channels’ leading into it
- water may have pooled in crater during first 2 billion years
“channel”
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Landing Sites on Mars: 2. Meridiani Planum - mineralogical
- 2 degrees South of Mars’ equator
- other side of planet from Landing Site 1
- place where hematite has been found (rust-like mineral) –
it is a former dried lake bed
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indicates that
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Mars Express – European Effort
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MARS EXPRESS
• Launched June 2003
• Radar instrument
(MARSIS) built at
University of Iowa
(Prof. D. Gurnett, P.I.)
• other instruments,
including a small rover
called “Beagle 2”
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MARS EXPRESS: Radar Experiment
• Radar reflection signal of
water is very different from rock
• Echoes can differentiate
between rock and ice or water
• Radar transmitter operates at
1-2 MHz and penetrates ground
to several km depth
• Probably cannot distinguish
between CO2 and H20.
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Mars Surface Exploration – the Future!
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Mars Surface Exploration – the Future!
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Future Mars Exploration: “Scout Missions”
• lightweight/efficient ballons
• fleet of small aircraft to explore Mars
• develop new technology
• also SAMPLE RETURNS
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Martian Outpost: 2030
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