Mars Exploration

1
Mars Exploration

• Trey Smith
• November 9, 1999

2
Overview

• Mars Background
• Exploration Missions
• Focus on rovers
• CMU space activities
• Blue-sky plans for Mars

65 minutes, about 8 slides each
3
Mars Basics

• Most Earth-like planet (climate, geology)
• 6 millibar pressure of mostly CO2 at sea level
• Day length 24 h 37 m
• Inclination similar to Earths (Earth-like
  seasons)
• Orbit period 1 year 10 months

4
Geological Map
5
Mars Geology

• Northern hemisphere
• Mostly plains young, low altitude features
• Some are clearly volcanic, others attributed to
  sedimentation and action of sub-surface ice
• High points are volcanic plateaus of Tharsis
  (4000 km wide, 10 km high) and Elysium (2000 km
  wide, 5 km high)

6
Mars Geology

• Southern hemisphere
• Highlands similar to those on the moon, but
  craters are more eroded, and there are channels
  evidence of running water.
• Just south of the equator, the Valles Marineris
  (400 km long, up to 600 km wide and 7 km deep)
  dwarfs the Grand Canyon
• Impact basins Argyre (1800 km) and Hellas (900
  km)
• Poleward of 30 degrees south, heavier erosion
  seems to indicate large quantities of ice

7
Mars Geology

• Chaos terrain
• Jumble of broken blocks
• Leads into large dry valleys, interpreted as
  floodplains
• Linear features at ends lake shorelines?
• Lack mature drainage system features
• Floodplains were target of Viking 1 and
  Pathfinder
• Groundwater under extreme artesian pressure?
• Broken dams on large lakes?
• Other areas have small, more mature drainage
  basins
• Morphology of impact craters suggests ice
  everywhere at depths of a few hundred meters,
  closer to surface at poles

8
Climate History

• Erosion completely wiped out small craters and
  degraded others process stopped about 3.5 Gyr
  ago
• Liquid water requires high temperatures. CO2
  insufficient. CH4? NH3?
• Original water inventory estimated at 0.5 km over
  entire surface
• Isotopic studies suggest that up to 99 of
  Martian nitrogen, substantial CO2 and H2O went
  through nonthermal escape
• Some features younger than 3.5 Gyr (Elysium
  basin) have been attributed to shoreline wave
  action from a Northern ocean, but MGS found no
  such evidence
• In a few recent periods of high obliquity,
  conditions may have been warmer and wetter

9
Evidence for Life

• Requirements for Earth life water, certain
  organics, and an energy source
• Likely environments
• Groundwater energy source geothermal
• Ancient surface water
• Earth extremophile experts find bacteria
  everywhere they look on bare rocks in
  Antarctica, in Yellowstone hot springs, hundreds
  of meters down oil wells.
• Earth life evolved less than 2 Gyrs into its 4.6
  Gyr history, almost as soon as conditions made it
  possible
• Minority opinion says that Earth life first
  evolved deep underground using geothermal energy.
  Mars may have similar conditions
• Panspermia theory life evolved once and spread
  through meteorite exchange.
• Mars cooled sooner, could have had life first

10
ALH 48001 (August 1996)

• Classified as a SNC meteorite based on isotopic
  ratio of trapped gases
• Three lines of evidence suggest life
• PAHs
• Biominerals
• Shapes like nanobacteria
• Findings widely criticized
• Formation temperatures too high
• No known nanobacteria on Earth
• PAHs apparently resulted from post-impact
  contamination
• Nonetheless, gave NASA its current Mars mandate

11
Mars Missions

• Pre-Viking space-race days
• Viking and biology studies
• Eighties doldrums
• Current Mars mania

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Pre-Viking Missions

• Mariner 4 (July 1965)
• Five Soviet fly-by attempts failed, 1960-62
• Sister ship Mariner 3 failed on launch
• 22 pictures, 1 of the Martian surface
• Mariners 6 7 (July, August 1969)
• 400 pictures of southern hemisphere and equator
• Studies of polar caps, moons, climate
• Mariner 9 (May 1971)
• First US spacecraft to orbit another planet
• Discovered Mariner Valley, Tharsis volcanoes
• Mapped 100 of the surface and took high-res
  pictures of Marss moons

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Pre-Viking Missions

• Mars 2 3 (May 1971)
• Two orbiter/lander pairs
• Mars 3 First successful soft landing, but failed
  20 seconds later
• Both orbiters continued returning surface and
  atmosphere images into 1972
• Mars 4, 5, 6, 7 (July, August 1973)
• 4 5 were orbiters, 6 7 were landers
• Orbiters scout landing sites in advance
• Only Mars 5 meets mission objectives

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Viking 1 2 (1975)

• Two orbiter/lander pairs
• Viking 1 First US landing on Mars (July 20,
  1976)
• First took orbital images at 150-300 m resolution
  to select a landing site
• When the pictures came back, the ground crew
  thought the sky color was wrong and recalibrated.

15
Viking Biology Experiments

• Pyrolitic Release (PR)
• Incubate soil in CO2/CO mixture tagged with C-14,
  pyrolize at 650 C collect and combust any
  organic compounds and search for tagged CO2/CO
• Labeled Release (LR)
• Incubate soil with C-14 tagged nutrient soup,
  look for evolved gases
• Gas exchange (GEX)
• Measures production and uptake of CO2, N2, CH4,
  H2, and O2 using gas chromatograph

16
Viking Biology

• Gilbert Levin, one of the investigators for the
  LR experiment, still believes life was found by
  Viking

17
After Viking

• Phobos 1 2 (July 1988)
• Largely European instruments
• US contributed DSN tracking
• Carried surface hoppers for Phobos
• Phobos 1 lost in transit, Phobos 2 lost just
  before Phobos rendezvous
• Mars Observer (September 1992)
• High-budget orbiter
• Lost contact just before orbit insertion
• Gamma ray spectrometer and other instruments
  flew/will fly on later missions
• Mars 96 (November 1996)
• European and US support
• Orbiter, 2 landers, 2 penetrators
• Crashed on Earth days after launch

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Better, Faster, Cheaper

• After Mars Observer, NASA space science effort is
  demoralized.
• Two new (on-going) series of missions are
  initiated
• New Millenium missions are test-beds for advanced
  technology
• Discovery missions have more conservative science
  objectives, this time with a cost cap
• ALH 48001 gives NASA a new mandate for Mars.
  Missions are now planned at every launch window
  until 2005

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Modern Mars Missions

• Mars Pathfinder
• Mars Global Surveyor (November 1996)
• Orbiter now returning highest resolution surface
  images to date (3 meters)
• Also carries thermal emission spectrometer
• Due to failed solar panel actuator aerobraking
  took a year longer than expected. Primary
  mapping didnt begin until March 1999
• Nozomi (July 1998)
• First Japanese interplanetary probe
• Orbiter to study atmosphere, plasma, dust,
  possible magnetic field
• Due to trajectory errors at Earth fly-by, Nozomi
  wont reach Mars until late 2003

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Modern Mars Missions

• Mars Surveyor 98
• Mars Climate Orbiter (Jan 1999)
• Intended to study Martian atmosphere
• Carried DS2 microprobes
• Impacted Mars due to software error in insertion
  burn September 23
• Mars Polar Lander (January 1999)
• Surface imager, robot arm, thermal and evolved
  gas analyzer
• Landing site is at the retreating edge of the ice
  cap
• Will land December 3

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Reaching the Moon Lunokhod

• Lunokhods 1 2 (November 1970, January 1973)
  were the first planetary rovers
• Teleoperated with echo time around 5 seconds
• Weighed in at 840 kg
• Operated for 10 km (5 months) and 37 km (4
  months)
• Engineering accomplishments
• Teleoperated control at lunar distances
• Toilet-bowl thermal strategy
• Drilling from a moving platform
• Solved antenna pointing issue (?)

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Reaching the Moon Apollo

• The Lunar Rover was first used on Apollo 15 (July
  1971)
• It weighed 462 lbs. empty
• Loaded, it could move 10-12 kph for about 50 km
  before exhausting its batteries
• Engineering accomplishments
• Wheels and suspension successfully adapted to
  regolith each wheel driven independently
• Guidance used an internal gyro and odometry to
  estimate relative positions, good to about 100
  meters

23
To Mars Pathfinder

• Launched Dec 1996, landed July 4, 1997. Operated
  for
• Engineering challenges
• 40 minute echo time, once-a-day operations
• Extremely limited power
• Rocky terrain
• Cold conditions
• Mobility sensors
• Stereo cameras dense stereo
• Laser light striper

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To Mars Pathfinder

• Information integration on the ground
• Registration of 3D meshes to form global terrain
  map
• Virtual Dashboard allowed operators to
  visualize command results
• Operated through command sequence from ground,
  but could adjust for obstacles
• Not only successful, but also extremely popular
• Mars 2001
• Orbiter carries GRS for elemental composition
• Lander will demonstrate ISRU propellant
  production with view to human missions
• Sojourner duplicate Marie Curie

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Mars Autonomy Athena

• 2003 and 2005 missions will form the two legs of
  a sample return (land in the same place)
• FIDO (Rocky 8) rover
• Sojourner-style steering and suspension
• 1 meter scale
• Stereo pairs pointing in all directions
• Can elevate a mast to get longer view
• Goal 100 meter traverse in one day of operations
• Cant reliably see the intervening terrain
  demands autonomy

26
Mars Autonomy at CMU

• Three year NASA program started last fall
• Studying software needed for 100 m scale traverse
  with a FIDO-like rover
• Two-prong approach
• Local obstacle avoidance reactive controller to
  dodge rocks
• Global path planning slower planning of optimal
  path to goal using current information

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Mars Autonomy at CMU

• First reduce stereo data to grid of goodness and
  certainty
• Local obstacle avoidance
• For each steering arc, integrate goodness and
  certainty of cells along the arc to get a score
• Global path planning
• Uses D (dynamic A) algorithm
• Scores a steering arc based on the path cost from
  the end of an arc to the goal
• Optimistically assumes uncertain areas are
  traversable
• Both modules vote/veto to determine executed
  command

28
Space Initiative at CMU RI

• Icebreaker Discovery proposal to be submitted in
  March (for launch 2003)
• Lunar Prospector has detected hydrogen
  concentrations at the lunar poles
• The best explanation is ice in permanently
  shadowed regions like craters
• Icebreaker would travel in and out of permadark,
  verifying the presence of ice and assaying
  quantity, distribution

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Space Initiative at CMU RI

• Sky Worker
• Nine month NASA grant from space solar power
  program (demonstration in April 2000)
• Implementing a scaled-down prototype assembly,
  inspection and maintenance robot
• The prototype has 3 arms, walks hand over hand

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Space Initiative at CMU RI

• Robotic Antarctic Meteorite Search
• 3 year NASA program, ends spring 2000
• Attempts to autonomously find the next ALH 48001.
  Final field test in December
• Visually identifies rocks and classifies them as
  meteor/non-meteor with a magnetometer
• Demonstrates teleoperation, endurance, autonomy
  capabilities needed for Icebreaker
• Uses local obstacle avoidance module similar to
  that of Mars Autonomy

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CMU Astrophysics Projects

• Sloan Digital Sky Survey study
• Looking for patterns in huge deep-sky image
  databases
• Viper Telescope
• Assembled in August in Antarctica
• 2 meter IR telescope resolves 0.1 arc-second
  features in cosmic background
• Also measures velocities of nearby galaxies
  relative to background, providing independent
  measure of H0

32
Blue-Sky Plans for Mars

• NASA has no long-term plan for human exploration.
• From the HEDS web site Currently, NASA's efforts
  in human space flight are focused on the Space
  Shuttle and International Space Station Programs.
  Both of these programs are important to the
  development of a capability for human exploration
  beyond low-Earth orbit.

33
1997 Reference Mission

• NASA bowed to pressure from engineers both within
  and outside its ranks to create a mission design
  which cut costs and extended mission times using
  ISRU
• Based largely on Robert Zubrins Mars Direct
• 4 launch mission
• Unfueled Mars Ascent Vehicle
• Earth Return Vehicle
• Nuclear reactor powered propellant plant
• Two years later, with all the pre-launched
  components verified, astronauts take a fast (6
  month) transfer orbit to Mars

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1997 Reference Mission

• Propellant plant uses water and Mars atmosphere
  2H20 CO2 - CH4 O2
• Obstacles to development
• No full-scale CH4/O2 thrusters
• A new HLLV is needed to launch each component
• Long-term effects of reduced gravity, radiation
  still not well understood (though probably not as
  dangerous as NASA would have us think)
• Overall, this is a very big mission and not on
  NASAs political agenda right now

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Cheap Launches

• The raw energy costs of launch from a planetary
  surface (Earth included) are on the order of per pound
• Heres why it currently costs so much more
• Rocket equation you need to carry your launch
  vehicle and fuel, which wastes energy
• With expendables or high-maintenance reusable
  hardware, the bulk of the cost is in the launch
  vehicle assembly and maintenance
• Since each vehicle has never flown before, the
  risks are higher, leading to high insurance costs

36
Mars Beanstalk

• How do you get around all of these problems?
• Dont launch the launcher
• On the moon you can use a mass driver
• On Mars, you use a beanstalk
• Part is above the geosynchronous orbit level,
  balances the part below. Zero energy cost to
  stay in orbit
• Now launch is just riding an elevator
• An Earth beanstalk would require exotic materials
  like buckytubes to handle the enormous tension
• Lower Mars gravity allows current construction
  technology to suffice.
• In the future, Mars may be a supply station for
  asteroid colonies

37
Terraforming

• Making other planets more Earth-like
• Mars is probably the best candidate
• Bring cometary water (greenhouse gas)
• Darken the surface with engineered lichens
• First habitable areas are deep in impact basins
• Engineered plants can survive unprotected well
  before humans
• Mars land area approximately equal to Earths