Science a-54 – Life as a Planetary Phenomenon (Spring 2008) Section 6: Mars Week All image credits: nasa/esa today
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Science A-54 – Life as a Planetary Phenomenon (Spring 2008) Section 6: Mars Week      
  
All image credits: NASA/ESA Today:
1. A Brief History of Mars Exploration First Flyby Missions: Mariner 3-4 1964, M3 failed on launch. M4 became the first flyby of another planet. Mariner 6-7 1969, Proved there were no canals or cities. First close-ups of south pole.
Mariner 8 1971, Orbiter, failed Mariner 9 1971, First planet orbiter, discovered Olympus Mons & Vallis Marineris Viking 1 1976, Orbiter Viking 2 Orbiter Viking 1 Lander Viking 2 Lander
11 failed attempts before first success (Mars 2 Orbiter, 1971) Followed by 4 more orbiter failures, 2 more orbiters successes (10 days of data) 2 lander failures, then 1 capsule landed (150 seconds of data). Last attempt was in 1996. Currently planning a sample return mission from Mars' moon Phobos-Grunt in late 2011 or early 2012.
Mars Climate Orbiter 1998, Burned up in atmosphere upon arrival Mars 96 Russian, launcher failed, fell to Earth Mars Global Surveyor 1996, First major orbiter in 20 years The Modern Mars Golden Age Mars Pathfinder First airbag landing, first rover Mars Polar Lander 1999 Crashed Mars Exploration Rover 1 Spirit, Gusev Crater, planned for 90 day mission, currently over 2267 days, geology mission Mars Exploration Rover 2 Opportunity, Meridiani Planum Mars 2001 Odyssey High Resolution, mineral mapping Mars Express Europe’s first orbiter, Super Hi res. plus color and 3D. Beagle Lander Crashed (British) Deep Space 2 Penetrators Crashed/Lost Mars Reconnaissance Orbiter Ultra high resolution Mars Phoenix Lander Polar Lander Dedux, landed May 25, 2008, confirmed water-ice on mars, showed soil is alkaline (pH 8-9) Missions Largely Underway Mars Science Laboratory Lands via Sky Crane. Size of Mini, 60% built, scheduled Oct 14, 2011. Will assess whether Mars ever was or is habitable, able to support microbial life! Mars Trace Gas Mission Scheduled for 2016, orbiter to map sources of methane and choose Exomars landing site ExoMars Europe’s planned rover, Mobile Viking-like experiments, faced horrible budget cuts, launch delayed 7 years to 2018 with a much reduced science mission. Mission: to search for biosignatures. Missions In Planning Stages: Mars Atmosphere and Volatile EvolutioN (MAVEN), expected launch 2013 Mars Sample Return, possible launch 2018, return 2020-2022 Mars Deep Drill, unknown launch, nominally 2018 Mars Astrobiology Field Laboratory – unknown launch Notable Non-Mars Missions Galileo Orbited Jupiter for many years. Stunning moon images. Bad antenna Cassini Last of NASA's huge flagships. Currently flawlessly orbiting Saturn. NEAR Orbited & landed on an asteroid (although never designed to land!) Hayabusa Attempting the first sample return from beyond the moon Rosetta Enroute to orbit and land on a comet Deep Impact Probed the subsurface of a comet (now exoplanet hunting!) DAWN Enroute to orbit the two large asteroids Juno and Ceres New Horizons aka the Pluto Express. Flys by Pluto-Charon system in 2014 MESSENGER Enroute to orbit Mercury for the first time. Kepler Hoping to detect the first Earth-like planet
Juno Jupiter Polar Orbiter 2011 Neptune Orbiter - cancelled Venus Balloon OSIRIS-Rex - U.S. Asteroid Sample Return Europa Orbiter - cancelled Europa Lander – cancelled Europa Jupiter Space mission – 2020 joint NASA and ESA 2. Spacecraft Design Basics 1. The Essential Components Multiple radiation hardened computers Power sources (Solar, Nuclear, Batteries) Communications (Dish Antenna & Low Gain Antenna (as fail-safe)) Fuel/Tanks/Engines Payload
2. Objectives and the instruments chosen to meet those objectives Science Missions and Engineering Missions Using Proven Technology Redundancy 3. Cost Hardware Cost Operations Cost "Faster, Better, Cheaper" "Budget, Schedule, Quality: Pick two." Both Pathfinder & the movie Waterworld cost ~250M$ (2005 USD) 4. Always trade-offs: Very tight instrument mass restrictions (mass overruns cascade!) Orbiters vs. landers For landers: mobility vs. a stationary platform 5. Choice of landing sites Safety vs. interest 6. Gradual evolution of missions from one to the next: Pathfinder-MER-MSL-MSR 3. Example Missions Viking: 1. Launched: 1975 2. Twin missions, each with an orbiter and a lander. 3. Landing sites: Chryse Planitia (22.48° N, 49.97° W and Utopia Planitia (47.97° N, 225.74° W) 4. Orbiter: Mass: 2,325 kilograms (5,125 pounds) with fuel Power: nuclear Objective: High resolution surface mapping Science instruments: High-resolution camera, atmospheric water-vapor mapper, surface heat mapper, occultation experiment 5. Lander:
a. CCD stereo color cameras b. Soil sampler c. Apparatus for gas exchange experiment, pyrolysis (color assimilation) experiment, labeled release experiment ; coupled gas chromatograph/mass spectrometer d. Seismometer (measures abundance of heavy elements) e. Temperature and Wind sensors f. X-ray fluorescence spectrometer 6. Cost: $1 billion 1975 dollars (roughly $4 billion in 2010 dollars) 7. Fun fact: Carl Sagan provoked his Viking colleagues into using valuable payload space for a camera by pointing out that their microbial experiments might miss larger life forms, like Martian polar bears Mars Pathfinder Lander: 1. Launched: 1996 2. One rover, named Sojourner (11.5 kg) 3. Objectives: To demonstrate rover technology and provide geochemical measurements to groundtruth orbital data. 4. Power: solar 5. Landing site: downstream from the mouth of a giant catastrophic outflow channel (Ares Vallis) 6. Cost: $266 million in 1996 dollars, including mission operations (ca $370 million in 2010 dollars) Mars Exploration Rovers (MER): 1. Launched: 2003 2. Objective: Geological exploration, with particular emphasis on the question of past water on Mars. 3. Landing sites: Gusev crater (interpreted as possible ancient lake) and Meridiani Planum (hematite) 4. Two rovers a. Mass: 185 kg b. Power: Solar (100 watts to drive) 5. Cost: $850 million (~1 billion in 2010 dollars) for the pair
2. One rovers 3. Landing Site: To be determined 4. To expand the exploration program begun by MER; designed for long term (> 2 Earth years) operation, and at least 55 km of travel 5. Mission Goals: 1. Determine the nature and inventory of organic carbon compounds. 2. Inventory the chemical building blocks of life as we know it: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. 3. Identify features that may represent the effects of biological processes. 4. Investigate the chemical, isotopic, and mineralogical composition of the Martian surface and near-surface geological materials. 5. Interpret the processes that have formed and modified rocks and soils. 6. Assess long-timescale (i.e., 4-billion-year) Martian atmospheric evolution processes. 7. Determine present state, distribution, and cycling of water and carbon dioxide. 8. Characterize the broad spectrum of surface radiation, including galactic radiation, cosmic radiation, solar proton events and secondary neutrons. 6. Mass: est. 900 Kg (9 feet in length) 7. Cost: est. $2.3 billion
2. Orbiter (success) and Lander (failed) 3. Objectives: The Orbiter was designed to provide unprecedented scope and resolution in the imaging and geochemical analysis of the martian surface; it will: image the entire surface at high resolution (10 meters/pixel) and selected areas at super resolution (2 meters/pixel); produce a map of the mineral composition of the surface at 100 meter resolution; map the composition of the atmosphere and determine its global circulation; determine the structure of the sub-surface to a depth of a few kilometers; determine the effect of the atmosphere on the surface; determine the interaction of the atmosphere with the solar wind. The lander, Beagle II, carried a suite of life detection instruments, but apparently crash-landed into Mars 4. Mass: 113 kg orbiter payload and 60 kg lander 5. Power: Solar 6. Cost: 300 million euros ($471 in 2010 dollars)
2. Orbiter 3. Objectives: mapping surface topography, mineralogy, and magnetic properties; also monitors weather phenomena (dust storms, etc.) 4. Power: Solar (980 watts) 5. Mass: 1,031 Kg of hardware, with about an equal mass (at launch) of propellant)
4  . Lego Robotics Mars Rovers
You are not building this, but here’s an example: Objective: Learn what it’s like to be an engineer; this is more important than a working robot. Build a pair of simple Mars Rover analogs that can drive around the section room's "U" shape of conference tables: autonomously, dodging random obstacles, and without falling off! Intro to Lego Robotics: NXT MicroController USB or Bluetooth link to a desktop computer 5 demo programs Advanced programs are downlinked from a desktop machine. 4 Input Channels for Sensors (1,2,3,4); in order from left to right in the picture below Touch Sensor – sends a signal when getting pushed in Microphone – records sound levels Light Sensor – records red light levels Ultrasonic Sensor – detects distance 3 Output Channels (A,B,C) For 3 Servo Motors. A servo motor is just a motor that can be commanded to a specific number of rotations, not just a given power level)
  
Many pieces are able to connect between two of these types of connections. Many strange/special elements to turn corners: building a three-dimensional structure is often the hardest part
Team 1: Tracks Team 2: Wheels
Left Bumper Right Bumper Ultrasonic “cliff” sensor Back “cliff” sensor Add NXT brick to Chassis Integrate all the components Testing, testing, testing Everyone should have a good opportunity to participate. You can have managers and subcontractors or some other organization.
1 full Lego NXT Robotics Kit for each team. 1 set of spare parts to share between teams. 3 touch sensors, 1 ultrasonic sensor for each team Plenty of cables
Writing the computer program to run your robot is as difficult and time-consuming as building, sometimes more so. The program we have written does the following: [ Constantly drive unless something happens to the three forward sensors (left/right bumper and ultrasonic). If a bump is detected, stop and move backwards (turning away from the obstacle). If a cliff is detected (by detecting a distance greater than ~6 inches), stop and move backwards (also turning away). As the robot moves backwards, it will check for the back touch sensor: if it is undepressed, it will stop moving backwards. ] The algorithm in the square brackets is constantly repeated until the program is turned off. For the program to work this is how the NXT brick needs to be wired: A – left motor B – right motor 1 – left touch sensor (bumper) 2 – right touch sensor (bumper) 3 – back touch sensor (back cliff sensor) 4 – ultrasonic sensor (forward cliff sensor) Note that the chassis is oriented so that the motor connectors are in the back. The front sensors must be placed on the other side. BUILDING
Tips: “Perfect is the enemy of good enough”: your robot won’t be perfect, it just needs to be good enough to fulfill the objective. Use the right tool for the right job. Everything takes longer than you think it will. The last step, full system testing, is the most important and will take a long time. Keep in mind space for cable connections NXT box mounting to the chassis need not be perfect. Just good enough to drive! Think about placing at your forward bumpers various distances ahead of the wheels. Think about your where to place your ultrasonic sensor (above/below forward/behind the bumpers) Think about hitting a wall straight on as well as at and angle Think about approaching a cliff at a sharp angle as well as head on. Test your individual parts and then test them all together. If they fail, redesign them. Iterate. Though functional robots work quite well, you should always be ready to catch your robot. Negotiating between teams for scare parts? Industrial Espionage? Please help clean up your robots. What did you learn about being an engineer? |
