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Mars Exploration. Trey Smith November 9, 1999. Overview. Mars Background Exploration Missions Focus on rovers CMU space activities Blue-sky plans for Mars. 65 minutes, about 8 slides each. Mars Basics. Most Earth-like planet (climate, geology)

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mars exploration

Mars Exploration

Trey Smith

November 9, 1999

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

65 minutes, about 8 slides each

mars basics
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 Earth’s (Earth-like seasons)
  • Orbit period 1 year 10 months
mars geology
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)
mars geology1
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
mars geology2
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
climate history
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
evidence for life
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
alh 48001 august 1996
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
mars missions
Mars Missions
  • Pre-Viking space-race days
  • Viking and biology studies
  • Eighties doldrums
  • Current Mars mania
pre viking missions
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 Mars’s moons
pre viking missions1
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
viking 1 2 1975
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.
viking biology experiments
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
viking biology
Viking Biology
  • Gilbert Levin, one of the investigators for the LR experiment, still believes life was found by Viking
after viking
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
better faster cheaper
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
modern mars missions
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 didn’t 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 won’t reach Mars until late 2003
modern mars missions1
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
reaching the moon lunokhod
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 (?)
reaching the moon apollo
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
to mars pathfinder
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
to mars pathfinder1
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
mars autonomy athena
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
  • Can’t reliably see the intervening terrain – demands autonomy
mars autonomy at cmu
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
mars autonomy at cmu1
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
space initiative at cmu ri
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
space initiative at cmu ri1
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
space initiative at cmu ri2
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
cmu astrophysics projects
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
blue sky plans for mars
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.
1997 reference mission
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 Zubrin’s “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
1997 reference mission1
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 NASA’s political agenda right now
cheap launches
Cheap Launches
  • The raw energy costs of launch from a planetary surface (Earth included) are on the order of < $1 per pound
  • Here’s 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
mars beanstalk
Mars Beanstalk
  • How do you get around all of these problems?
  • Don’t 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
terraforming
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 Earth’s