“MIЯROR”
Mars Ice Rover Team
Mission Proposal
National Space Concepts Union
Potential Advance Concepts Kickoff Group
Raleigh, North Carolina
Den Baseda
James Burany
Richard Chapman (Lead)
Gary Martin
Kyle Murphy
Conrad Patton
Karoline Saunders
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0. Table Of Contents………………………………………………………………………..1
1-0. Stakeholder Expectations………………………………………………………..2
2-0. Martian Environment……………………………………………………………2
2-1. Rock and Crater Fields……………………………………………….....2
2-2. Permafrost Conditions………………………………………………......3
2-3. Ice Surfaces……………………………………………………………….3
2-4. Northern Ice Cap………………………………………………………...4
2-5. Atmospheric Conditions…………………………………………………5
3-0. Problem Statement and Mission Purpose………………………………………6
3-1. Problem Statement……………………………………………………….6
3-2. Prototype Demonstration………………………………………………..7
3-3. Mission Purpose and Goals……………………………………………...7
4-0. General Description of Operational Capability………………………………..7
4-1. System Type………………………………………………………………7
4-2. Conceptual Operations…………………………………………………..8
4-3. System Capabilities………………………………………………………8
4-3.1. Mars Ice Rover Capabilities…………………………………….8
4-3.2. Earth-based Rover Capabilities…………………………………8
4-4. General Description of Conceptual Delivery…………………………...9
5-0. Functional Flow Block Diagram of Conceptual Operations…………………..9
6-0. Vehicle Concepts…………………………………………………………………9
6-1. Treads……………………………………………………………………..9
6-2. Spiked Wheels……………………………………………………………9
6-3. Tri-wheeler……………………………………………………………...11
6-4. Legged “Walker” with Skiing Ability…………………………………11
6-5. Leg/Dish Sled Hybrid…………………………………………………..12
6-6. Vehicle Body…………………………………………………………….12
7-0. References……………………………………………………………………….13
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1. Stakeholder Expectations
As the Northern Ice Cap region of Mars is relatively unexplored, this area is of great
interest to the Agency Heads of the NCSU-PACK group. The environment and terrain in the area
of operation provides a set of unique challenges, which must be overcome. The stakeholders
shall receive a conceptual design of a rover to send to the Martian surface. This rover shall be
able to traverse a variety of terrains, such as sheet ice, permafrost and craters. Additionally, this
rover must be able to function in the often cold and windy environment of Mars. This will all be
accomplished by a system which can carry the weight of significant science experiments
(estimated at roughly 25-50kg, based on masses of previous rover-type missions). In addition to
the conceptual design provided to the Agency heads, an Earth-based proof-of-concept system
will be delivered to verify the practicality of the locomotion system.
2. Martian Environment
The Martian surface, especially around the northern ice cap, is a very hostile environment
to land a rover on. Research on this area is necessary to both successfully land and navigate over
this terrain. The 2011-2012 team which worked on this project did this research extensively, and
they documented it in their final CDR2. The following sections on the Martian surface terrain
summarize their findings.
2.1 Rock and Crater Fields
The Martian surface is covered with hundreds of thousands of craters, and they greatly
vary in size. The largest ones can reach over one hundred kilometers in diameter. These craters
are in no way evenly distributed along the surface, but it appears that their distribution is very
sparse in the far northern regions. This can be seen in Figure 1, which plots all of the known
craters on Mars that are 100 km in diameter or greater:
Figure 1: Martian Large Crater Distribution5
In addition, there is no distinguishable pattern to the size distribution of the craters, due to
the wind erosion and deposition. It should also be noted that most of these craters have depths
0.2 times the diameter, along with a rim height of 0.04 times the diameter3. With some craters
having a potential depth of over 24 kilometers including the rim, it is crucial that their locations
be known prior to deciding on a landing site. Landing inside one could very well lead to a very
early mission failure, so they should be avoided at all costs.
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2.2 Permafrost Conditions
Permafrost is a section of perennially frozen ground which has remained that way for two
or more years. It has not been extensively studied on the Martian surface, so this research mostly
focuses on permafrost sections on Earth. There are many different types of permafrost, and each
has its own distinct soil characteristics. The one thing they all have in common is an “active
layer”, which is the uppermost layer of the soil. This layer freezes and thaws each year with the
seasons. Permafrost has distinctive polygonal patterns along its surface, formed by ice wedges.
These wedges exert pressures on the surrounding soil, thus forming ridges. An example of this
thawing permafrost with polygonal structuring can be seen below, in Figure 2:
Figure 2: Thawing Permafrost19
Among the different types of permafrost, the variations occur below the active layer. In
some areas, ice-bonded sections occur immediately below the active layer. In this case, the active
layer is usually quite thin, ranging between two centimeters and one meter, with the massive ice
sheet underneath. In some cases there is a dry permafrost region between the active and icebonded regions4. This dry permafrost has very low water content, and is characterized as being
non-cohesive. This is the form which our rover will most likely encounter on the Martian
surface2. These conditions are most similar to what can be found in Antarctica, in the ice-free
surface regions. The upper ten to twenty five centimeters consist of a sandy layer of soil, which
is not very stable12. Our rover will have to be able to traverse over this sandy layer, encountering
soil shifts of a few centimeters that can occur at any point.
2.3 Ice Surfaces
The northern ice cap of Mars is not as well studied as the lower altitude regions of the
planet, but the Viking orbiters did perform a thermal mapping on it. These studies revealed that
the makeup of the northern ice cap is made up of mostly water ice and sediment14. There are also
seasonal deposits of carbon dioxide when the temperature reaches low enough7. It is about a
quarter of the size of Antarctica, with a maximum thickness of three kilometers. The deposits can
range from a few to hundreds of meters high7,14.
The Mars Global Surveyor used an altimeter to study the surface of the ice cap, revealing
sublimation depressions along the surface7. These altitude changes are shown in Figure 3:
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Figure 3: Northern Ice Cap Altitude Distribution14
This varying terrain can pose large problems for a rover, but the data also revealed that
the terrain remains fairly consistent along each ridge. The structuring of the northern ice cap is
different from anything found on Earth, mostly from the lower density, temperature, and pressure
on Mars. This causes the creep deformation of the ice as well as the cracks to be smaller, and the
compressive strength of the ice is increased. It was found, with substantial evidence, that the
closest comparable conditions on Earth to the Martian northern ice cap are found in the
Antarctic.6
2.4 Northern Ice Cap
During the northern pole’s winter season, carbon dioxide present in the atmosphere
condenses into dry ice. Up to one hundred centimeters of dry ice can condense from the
atmosphere during this time period. This creates a major problem for any rovers deployed in the
area during this season as experienced by the Phoenix rover. The University of Arizona
estimated that as much as nineteen centimeters of dry ice accumulated on the top of the rover,
adding a calculated weight of about one hundred pounds. This eventually crushed and broke off
the rover’s solar panels taking it out of commission17.
Another major concern of the northern ice cap is the extreme winds that occur during the
transition period between the winter and summer season. As summer approaches and
temperatures begin to rise at the northern region, the dry ice begins to sublime. This sudden
change in atmospheric pressure and temperature causes huge gusts of wind that can reach speeds
of up to three hundred kilometers per hour. Since the density of the air of Mars’ atmosphere is
less than that of Earth’s these winds will not be as strong as on Earth but should still be kept in
mind in designing the rover.
A final hazardous concern in the ice cap region is the carbon dioxide geysers. These
geysers form and erupt on the surface of the polar ice cap region as pockets of carbon dioxide
gas begin to form underground because of uneven sublimation of the dry ice during the start of
the summer season. These geysers have only been observed on the southern pole but should still
be considered as similar conditions exist on the northern ice cap.
Planning to start the landing mission for the end of the transition period between the
winter and summer seasons would be ideal as it would avoid all of the environmental hazards of
the winter season while maximizing the available time period to conduct scientific research
during the summer.
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2.5 Atmospheric Conditions
Carbon Dioxide is the primary component of the Martian atmosphere making up 96.8
percent of the atmospheric mass. There are trace amounts of other gases that make up the air on
earth as well as shown in Table 1 below.
The behavior of carbon dioxide is extremely important when considering a Mars mission
as it is the primary makeup of the atmosphere. The phase diagram in Figure 4 shows that under
standard Earth pressure conditions, carbon dioxide only exist as a solid or a gas. Since the
atmospheric pressure on Mars is less than 1% than that of Earth’s, the gas will only exist as a
solid below -130 C (142 K). This means that the carbon dioxide will deposit as a solid during the
winter season on the northern poles when temperatures fall below the average temperature of 150
K and sublime during the summer season when temperatures can reach 223 K7.
Table 1: Composition of Martian Atmosphere by Mass8
Gas
Percent (Mass)
Carbon Dioxide (CO2)
96.8
Nitrogen (N2)
1.7
Argon (Ar)
1.4
Oxygen (O2)
0.1
Carbon Monoxide (CO)
0.04
Neon (Ne)
1.1 ppm
Krypton (Kr)
0.6 ppm
Xenon (Xe)
0.2 ppm
Figure 4: Phase Diagram for Carbon Dioxide18
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Table 2 summarizes the average surface conditions of Mars as well as some specific
cases that are characteristic of the northern ice caps. The lower atmospheric density means that
any aerodynamic effects and wind forces will be substantially lower compared to those found on
Earth. The main weather related aspect that is more extreme on Mars than on Earth is the
extreme low temperatures. The only comparable temperatures at the northern ice cap occur
during the summer season when the temperature can rise to 223 K which is similar to the
conditions characteristic of the Antarctic7. A final concern that is directly related to the weather
of Mars is dust storms. Fortunately, these storms occur less frequently at the northern ice caps
and are less severe when they do. The gusts during the dust storms can reach up to twenty meters
per second but is not necessarily a concern since the air density is very low as stated before.
However, the possible damage and erosion from the dust particles should be considered.
Table 2: Mars Atmospheric Data1
Mars Atmospheric Conditions
Surface Atmospheric Density
Summer
Fall
Surface Wind Speed
Dust Storm
Sublimation Transition
2 m/s Wind
Dynamic Pressure
10 m/s Wind
83 m/s Wind
Surface Atmospheric Pressure
Diurnal Temp Range
Ice Cap Winter Temp
0.0155 kg/m3
2 – 7 m/s
5 – 10 m/s
17 – 30 m/s
Up to 83 m/s
0.03 N/m2
0.8 N/m2
53.39 N/m2
636 N/m2
184 – 242 K
< 150 K
3. Problem Statement and Mission Purpose
3.1 Problem Statement
Design, build and test a novel vehicle for the exploration of the northern polar ice cap of
Mars, with the ability to overcome terrain and environmental hazards characteristic to the region
such as craters, sheets of ice, permafrost, high winds, low temperatures and radiation.
Additionally, the creation of a testing ground for Martian ground-based rovers must be
constructed to implement a sustainable testing area, as well as to perform an accurate and
meaningful evaluation.
3.2 Prototype Demonstration
In order to prove that the concepts used in the Mars Ice Rover design will be successful, an
Earth-based prototype will be constructed and tested. Since funding and time are both limited,
the main concepts to be demonstrated will be those used in the locomotion of the rover. It is the
intent of the design to provide a robust and efficient design for the locomotion of the rover since
it will need to be able to overcome a broad set of terrain types. In order to effectively
demonstrate the effectiveness of the locomotive concepts used in the rover design, a Martian
terrain testing ground will be constructed and used to test a prototype.
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3.3 Mission Purpose and Goals
The purpose of developing and sending the Mars Ice Rover is to perform scientific
research in the unexplored areas near the north Martian pole since relatively little is known about
the region. It is NASA’s exploration strategy to “Follow the Water” in the search for the
possibility of life on Mars, past or present13. It is for this reason that the polar ice cap regions
need further exploration. The Phoenix rover mission confirmed that there is permafrost in the
northern polar region of Mars and that “H2O ice and vapor constantly interacted with the soil”9.
This means that there is water frozen in the soil leaving reason to speculate that there may be
larger quantities of water trapped underneath the permafrost. Therefore, it is of interest to send a
rover capable of traveling across the ice and permafrost that can use ground penetrating radar to
survey and map the geological features underneath the permafrost. This could lead to the finding
of subsurface water, liquid or frozen. Underground crevices are another potential discovery that
could point to the past presence of flowing water on Mars. The rover will have a secondary
mission of obtaining and analyzing an ice sample from the permanent ice cap in order to
determine its exact composition. This mission will be accomplished by designing a prototype
rover capable of landing and traveling through the ice cap region while surveying the permafrost
and taking and analyzing any scientifically relevant samples.
3.4 Travel Route/Timeline Specifics
The landing site for the rover will be in the same vicinity of the Phoenix rover that landed
in May, 2008 at 68.22oN, 234.25oE9. Once the rover has landed on the permafrost it will begin
mapping the surrounding terrain’s subsurface geology. The mission will take place during the
summer season of the Northern Hemisphere of Mars leaving the rover about 300 days before the
return of winter weather conditions. The rover will travel north, across permafrost terrain,
towards the permanent ice cap layer while continuing to carry out its mission. The ice cap has a
rough diameter of 1000 kilometers during the summer season15. Using Google Mars it is
determined that the rover will be traveling nearly 800 kilometers from its landing site to the edge
of the ice cap. This should take approximately 80 days if the rover averages just 13 kilometers a
day. Upon reaching the ice cap, the rover will take and analyze an ice sample to determine its
exact composition allowing for a good approximation for the total water locked in the ice cap.
The remaining mission time will be used to continue mapping the terrain surrounding the
permanent portion of the northern ice cap in search of subsurface water sources.
4. General Description of Operational Capability16
4.1 System Type
The Mars Ice Rover will consist of a compact rover capable of traversing adverse
environmental terrain and prepared for withstanding various harsh weather
conditions. It will be an automated system for conducting research on specified
Martian aspects.
The Earth-based Rover prototype will be a budget and time-constrained project
yielding a general visualization and functionality of the Mars Ice Rover. Emphasis
will be given upon traversing terrain rather than instrumentation.
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4.2 Conceptual Operations
The Mars Ice Rover will have the capability of navigating tough and harsh terrain in
different seasonal conditions on Mars. This includes permafrost, ice, dirt, craters, and other
Martian obstacles encountered from the proposed landing site to the Northern Polar Ice Cap.
Various tests conducted with on-board instrumentation will be executed along the trip, as well as
upon the arrival to the destination of the Ice Cap. Potential instrumentation and tests could
include: penetrometer (strength and moisture of Martian soil and ice), gas chromatographer-mass
spectrometry (determine chemical makeup of atmosphere, ice, gas sublimations), accelerometer
(for navigational purposes), pyrolyzer (for atmospheric composition), amongst others. The data
will be sent back to the orbiting satellite (when in range) from three separate antennae, each set
of data twice redundant (cf. Cassini-Huygens Channel A failure, consequential Doppler
experimental data loss)11. The Rover will be sustainable long enough for a complete Martian
seasonal cycle as to conduct experimentation during different weather climates.
The Earth-based prototype will exhibit simplified terrain navigation features of the Mars
Ice Rover. The navigational ability will include: 360 degree movement as well as azimuthal and
nadiral capabilities, rotation, stability, swiftness of movement, and others. Due to monetary and
time constraints, mechanical and instrumental minutiae must be negated.
4.3 System Capabilities
4.3.1 Mars Ice Rover Capabilities
(a) Safely deploy from orbital insertion and landing. This includes: heat
shielding, parachute, drogue parachute, heat shield and parachute detachment,
impact, and initial start-up.
(b) Accurately land within a designated landing area zone. Major requirement of
the landing zone is proximity to the Northern Ice Cap.
(c) Autonomously traverse various terrain types with two primary sections: Ice
Cap and Rocky.
(d) Conduct research and send data back to orbiting satellite, to be relayed to
Earth-based observatories.
(e) Self-sustained power for assigned duration of mission.
Potential Additional Requirements:
(a) Survive Martian seasonal cycle while combating large climate fluctuations for
long duration mission.
(b) Sustained power or seasonal shut-down/reboot of power system for long
duration mission.
4.3.2 Earth-based Rover Capabilities
(a) Remotely demonstrate terrain navigation features.
(b) Self-sustained via power supply.
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4.4 General Description of Conceptual Delivery
The Mars Ice Rover package will be delivered to Mars from an Earth-based
rocket payload. It must arrive via a decided orbit or orbital maneuver. The conceptual
orbital design must consist of a variety of factors including: calculative factors, missioncritical issues (radiation shielding, low temperatures), and entry into the Martian
atmosphere. The Mars Ice Rover package must also perform a safe landing upon the
Martian surface from the satellite as well as have the capability to send back transferred
data from the Rover on the surface.
5. Functional Flow Block Diagram (FFBD) of Concept of Operations (ConOps)
TOP LEVEL
1.0
2.0
Launch
3.0
Earth Orbit
4.0
Transfer
5.0
Mars Orbit
EDL
De-orbit burn
to Martian
atmosphere
7.0
Deployment
Mars Surface
Operation
8.0
Closeout
SECOND LEVEL (7.0 - Mars Surface Operation)
SECOND LEVEL (5.0 - EDL)
5.1
6.0
5.2
5.3
5.4
Deceleration
Burn
Heat Shield
Function and
Jettison
Parachute
Deployment
5.5
Landing
System
Initiation
7.1
7.2
7.3
Establish
Ground Path
Using Onboard
Pictures/Video
Follow Ground
Path,
Reconfigure if
Needed
Execute
Science Mission
7.4
Shutdown
6. Vehicle Concepts
6.1 Treaded Tires
Figure 5: Rover with “Snowmobile” Treaded Tire System
Treaded tires, as used on the rear portion of snowmobiles and construction vehicles, have
promise for use as a locomotion system for this particular rover. The dimples on the tread grip
very well on a variety of surfaces, and if made out of a favorable material may even grip sheets
of ice. Such systems have had significant testing and research, making this a leading candidate
for a potential design.
6.2 Spiked Wheels
If standard rover wheels with treads are to be used, a major design consideration is to
prevent rover slippage on the ice. One solution is to install spikes into the tires. Preferably, these
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spikes would be retractable to facilitate movement on rocky surfaces. When the rover’s sensors
indicate ice or permafrost, these spikes could be remotely deployed. The spikes would be hinged
and be designed with a tab which would allow it to rotate when a force is applied. This force
could be applied by inflating a gas-filled bladder, which has been used for similar spikedeploying tires on earth10. Similarly, the spikes could be retracted by deflating the bladder.
However, this concept requires the rover to be heavy enough to drive the spikes deep enough
into the ice to prevent slippage.
A more complicated version of this concept includes a rounded spike. Each spike has
three sides to facilitate glacial entry, and will also allow any icy remnants to slide off the spike
when exiting the ice: this concept has been used in ice axes. The spikes will be in between each
tread in parallel pairs. An air-bladder system will allow for the spikes to be deployed when icy
surroundings are recorded. This concept intends to use both air and gravity to deploy the spikes:
by adding a weight far away from the hinge and maximizing moment, the spikes should swing
out as the tires rotate them closer to the ground. This eases the rover’s ability to traverse hilly
Martian terrain. Illustrations of these concepts are shown below.
Figure 6: Spiked Wheels with Deployment Options
The below is a similar design which uses a hollow wheel in an attempt to accommodate various
types of terrain.
Figure 7: Hollow Wheel Design with Spikes
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6.3 Tri-wheel
Wheels in this configuration can rotate around their own axes as well as revolve around a
central axis. This allows them to both run along flat surfaces as well as climb step-like obstacles,
such as rock faces or small boulders.
Figure 8: Tri-wheel Rolling/Stepping Rover
6.4 Legged Walker
A legged walker design provides excellent ground clearance at the cost of requiring a
more developed stability and control system. Though relatively untested, it is an exciting new
concept, being able to climb a wide variety of inclines and traverse very rocky plains. In
addition, this design exhibits legs which lower the rover to a pair of skis on the bottom of the
body. This allows it to slide on ice sheets, while still controlled by its legs.
Figure 9: Legged Walked with Lowering Body and Skis
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6.5 Leg/Dish Sled Hybrid
An extension of the skiing legged rover, the entire body of this design is the same shape
as a dish-style sled. This allows the rover to walk in a legged configuration and slide on ice after
lowering itself.
Figure 10: Dish Sled Rover with Legs
6.6 Vehicle Body
Body configurations are not a main concern of this project; however, it is critical that
there be some system for the Martian rover which will be able to withstand the environmental
effects. These will include but will not be limited to” multiple, sturdy antenna arrays; strong side
paneling at an angle to mitigate wind effects; and a platform which will allow instruments to be
attached and functional. A concept of such a design is shown below.
Figure 11: Vehicle Body Concept
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7. References
1
Antol, Jeffery, et al. "Low Cost Mars Surface Exploration: the Mars Tumbleweed." NASA/TM
212411(2003): Print.
2
Bernard, A., Desai, P., Frisbey, M., Garg, A., Pauli, J. “Critical Design Review, Team Mars-Ice.”
(2012).
3
Bernard, D. and Golombek, M.“Crater and Rock Hazard Modeling for Mars Landing.” AIAA
2011-4697 (2001). Print.
4
Campbell, I. B. and Claridge, G. G. C. (2006), Permafrost properties, patterns and processes in
the Transantarctic Mountains region. Permafrost and Periglacial Processes, 17: 215–232. doi:
10.1002/ppp.557
5
Caplinger, Mike. “Determining the age of surfaces on Mars.” Malin Space Science Systems.
February 1994. Web 9 September 2012. <http://www.msss.com/http/ps/age2.html>.
6
Cockell, Charles S. "Martian Polar Expeditions: Problems and Solutions." Acta Astronautica
49.12 (2001): 693-706. Print.
7
Cockell, Charles S. "The Uses of Martian Ice." Interdisciplinary Science Reviews 29.4 (2004):
395-406. Print.
8
Colvin, James E., Landis, Geoffrey A. "Effect of Inert Propellant Injection on Mars Ascent
Vehicle Performance." American Astronautical Society-The Case for Mars V 93.840 (2000):
215-239. Print.
9
“H2O at the Phoenix Landing Site.” ScieneMag.org. July 2009. Web. August 2012.
<http://www.sciencemag.org/content/325/5936/58.full?ijkey=9ZTMoi3Mylweg&keytype=ref&s
iteid=sci#F1>
10
Hanlon, M. (2007, March 15). New Tire with Retractable Studs. Retrieved from
http://www.gizmag.com/go/6989/
11
Lorenz, Ralph, and Jacqueline Mitton. "Chapter 5: Landing on Titan: The Plan for
HUYGENS." Titan Unveiled. New Jersey: Princeton University Press, 2008. 135-138. Print.
12
Margesin, Rosa. Permafrost Soils. Berlin: Springer-Verlag Berlin Heidelberg, 2009. Print.
13
“The Mars Exploration Program.” NASA. October 2011. Web. August 2012.
<http://www.nasa.gov/mission_pages/msl/news/msl20120829.html>
14
Masse, M., et al. "Martian Polar and Circum-polar Sulfate-bearing Deposits: Sublimation Tills
Derived from the North Polar Cap." Icarus 209(2010): 434-451.
13
15
“Northern Ice Cap of Mars.” NASA. 26 May 2010. Web. August 2012.
<http://www.nasa.gov/mission_pages/MRO/multimedia/pia13163.html>
16
"Operational Requirements." Mitre. The Mitre Corporation, 03 May 2012. Web. 10 Sept. 2012.
<http://www.mitre.org/work/systems_engineering/guide/se_lifecycle_building_blocks/concept_d
evelopment/operational_requirements.html>.
17
"Phoenix Mars Lander Is Silent, New Image Shows Damage." Phoenix Mars Mission. NASA
and The University Of Arizona, 24 May 2010. Web. Sept. & Oct. 2011.
<http://phoenix.lpl.arizona.edu/05_25_10_pr.php>.
18
Shakhashiri. "Chemical of the Week, Carbon Dioxide, CO2." General Chemistry. Scifi Fun, 6
Feb. 2008. Web.
19
"Thawing Permafrost Could Release Vast Amounts of Carbon and Accelerate Climate Change
by the end of this Century « Berkeley Lab News Center." Berkeley Lab News Center. N.p., n.d.
Web. 8 Sept. 2012. <http://newscenter.lbl.gov/news-releases/2011/08/22/permafrost/>.
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