Satellite Tracking of Endangered Species
Running Head: SATELLITE TRACKING
Satellite Tracking of Endangered Species
By
Perry T. Patterson
Submitted to
Dr. William Hartman, Ph.D
Nova Southeastern University
Graduate School of Computer and Information Sciences
Master of Management Information Systems
MMIS 653 - Telecommunications and Computer Networks
Spring 2004
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Satellite Tracking of Endangered Species
Table of Contents
Introduction
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Statement of the Problem
.………………………………….……….…
Technological Overview
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Organizations
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3
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Transmitter Technology
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Basic Elements of Transmitters
.………………………….……….…
Batteries and Alternate Power Supplies
.………………….……….…
Installation (Tagging) of the Transmitters .………………….……….…
Environmental Obstacles
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Satellite and Tracking Technology
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Satellite Basics
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The Doppler Effect ……………………….………………….……….…
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Conclusion
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References
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Ground Segment
Ethical Considerations
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Satellite Tracking of Endangered Species
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Introduction
Statement of the Problem
Through hunting, large scale commercial fishing and territorial encroachment, many
species of animals have become endangered over the last century, including whales, dolphins,
birds and other animals. People are working hard to help save some of these creatures, but we
must learn more about their activities and migration. The tracking of the animals by satellites is
now a popular method for monitoring the animals. According to Daniel Mulcahy of the Alaska
Biological Science Center, "the days of doing biology by sitting on a rock with a pair of
binoculars are over,” (Bogo, 1999).
Many obstacles exist for tracking of the animals. The transmitters must be protected
from the elements, must be small and light and have a long lasting battery or alternative power
source. Transmission to moving satellites is also difficult and must be well managed. Finally,
the ethics of tagging the animals is important in analyzing if the short term pain is acceptable in
light of long term benefits.
Technological Overview
The technology for tracking of endangered species is fairly simple in concept, but it relies
on some very sophisticated technology. Animals are tagged with transmitters that communicate
with satellites that relay information to ground stations that record and distribute the data. While
the relay may seem simple, it could not exist without the telecommunications satellites and
technology to create small transmitters requiring minimal power that can be easily and safely
attached to the animals.
Satellites moving in space in a polar orbit are used for receiving data. The satellites
rotate over the earth approximately every 102 minutes, placing objects in view for periods of
eight to fifteen minutes from three to fourteen times per day, per satellite. Tagged animals near
the equator have as little as 24 minutes when their data can be transmitted, while animals near
the Polar Regions can have as much as 210 minutes per satellite (Service Argos, Inc., 1998).
Organizations
Service Argos, Inc. is an organization dedicated to monitoring environmental data from
moving objects carrying transmitters. Argos was formed in the 1970s under a Memorandum of
Understanding between NASA, the French Space Agency (CNES) and the National Oceanic and
Atmospheric Administration. The Argos system is managed by a French company, CLS
(Collecte Localisation Satellites) which also has North American Subsidiaries included in the
project. There are also a multitude of companies involved in the development and
manufacturing of the equipment used in the tracking process (Service Argos, Inc., 2004).
Users of the technology include many environment groups looking to help in the
management and preservation of endangered species. Many organizations specialize in one
species or type of species such as the Santa Cruz Predatory Bird Research Group (SCPBRG) and
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the Caribbean Conservation Corporation & Sea Turtle Survival League (CCCSTSL).
Organizations typically focus their efforts on specific animals or groups of animals to improve
their effectiveness. Through the efforts of SCPBRG, which utilizes satellite tracking
mechanisms, the numbers of the peregrine falcon were increased enough to be removed from the
federal endangered species list (Santa Cruz Predatory Bird Research Group, 2004).
Transmitter Technology
Basic Elements of Transmitters
To track an endangered species, transmitters are required to send a signal with basic
information about the specimen. Argos calls these Platform Transmitter Terminals (PTTs). The
PTTs are attached to the specimens (the platform) and must be sized appropriately, some as light
as 15 grams and the size of a matchbox. The device for a migrating bird will not be the same as
for a polar bear (Service Argos, Inc., 2004).
Most PTTs transmit without acknowledgement or request from the Satellites, indicating
they are a simplex transmission. Transmissions are repeated every 45 to 200 seconds to increase
the likelihood of a received signal. The transmissions are at a frequency of 401.65 MHz, which
is altered upon receipt by the “Doppler Effect”. Message lengths are up to 32 bytes and take up
to 96 milliseconds for a single transmission of data. The PTTs are powered by batteries, solar
power or some other external source (Service Argos, Inc., 1998).
Information transmitted varies depending on the types of animal being tracked. The
Caribbean Conservation Corp & Sea Turtle Survival League tracks items such as water
temperature, number of dives for a measured time period and length of the dives. The location
of the transmission is also recorded to determine the migratory patterns (Caribbean Conservation
Corporation & Sea Turtle Survival League, 2003).
Software analyzes the position of the Satellite and the received frequency to determine
the longitude and latitude of the PTT. The technology is based on the Doppler Effect. As
satellites approach a PTT, the received frequency is shifted higher. As a satellite moves away
from a PTT, the received frequency is shifted downward. This information, combined with
measurements of time between transmissions, allows the systems to determine the location of the
PTTs (Service Argos, Inc., 1998).
Batteries and Alternate Power Supplies
The transmitters are only useful if they have power to continue transmitting. A great
effort is made to maximize the length of time that the PTTs will function. Most of the PTTs send
very weak signals, relying on the strong receivers of the low-earth orbit satellites. Some PTTs
are built with enough intelligence so they can turn on and off their transmitters based on logic of
the satellite orbits and latitude of the species to be tracked. This may be less beneficial
depending on how far a particular animal can travel (Service Argos, Inc, 1998).
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Creative methods of power generation also come into play. Some transmitters are built
with solar collectors. A group of students in Japan had a project to track whales and to make it
as cheap as possible using commonly available technology. One of their goals was to have a
transmitter with an extensive life and with no power constraints. The students invented a “whale
generator”. Electricity was generated from the movement of a small propeller attached to the
PTT placed on the whales (Washida, 2003).
Installation (Tagging) of the Transmitters
As with any computer hardware, equipment must be installed. For a desk top computer,
that may be as simple as plugging everything together, connecting to a network port in the wall
and the process is complete. That is not the case for the installation of transmitters on animals.
The process known as tagging can be difficult and potentially harmful to the animals.
To install a transmitter on a whale or dolphin is quite a challenge. For a study in New
Zealand, hector dolphins are trapped and pulled out of the water for a surgical procedure that can
take up to 30 minutes. A hole is drilled in the dorsal fin and bolts are inserted to hold the tag.
There are some that feel this method of tagging is cruel and harmful to the animals (Whale and
Dolphin Conservation Society, 2004).
Tracking of many animals is not as invasive and easier to perform. Tagging of sea turtles
is done by attaching a transmitter to the shell using environmentally safe glues. Little backpacks
containing the transmitters are mounted on the peregrine falcon. For mammals such as polar
bears, caribou and moose, collars are attached. In general, researchers work hard to install the
devices in a way to minimize the harm to the animals. For caribou, typically only females are
collared as the male’s neck grows extensively during rutting season making the collars harmful
to the animals (Space for Species, 2004).
Environmental Obstacles
Unlike a PC sitting on a desk, the equipment used in tracking of endangered species
experiences some unique obstacles. One certainly is battery life that was previously discussed,
as there is no place to plug in a turtle when she is out at sea. Other issues are related to how the
elements treat the transmitters and the transmissions.
When a typical computer is connected to a network, it is always connected. Certainly,
users may have to dial-in via a modem, but that is a pretty straight forward process.
Transmission for sea creatures can only happen when they come to the surface, as the devices
can not transmit through water (Space for Species, 2004). Sensors must know when the animals
have come up and transmit at that time. This poses a challenge in the calculation to determine
the location of the creatures. Many animals stay on the surface for only a few minutes at a time,
and it takes from three to five minutes of transmissions for the systems to accurately determine
the locations (Caribbean Conservation Corporation & Sea Turtle Survival, 2004).
Erosion is another problem for transmitters. The transmitters for the leatherback turtle
are attached differently than most turtles, as their shells are not hard and they are glue resistant.
Satellite Tracking of Endangered Species
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They wear a harness similar to a belt and suspenders. However, the salt water corrodes the metal
links and the harness falls away (Space for Species, 2004). Since turtles also come to shore to
lay eggs, the transmitters can be damaged by rocks and corals where they nest (One Ocean
Organization, n.d.). Other dangers include weather, in-breed fighting and predators, things a
laptop or office computer rarely experience.
Satellite and Tracking Technology
Satellite basics
The Service Argos instruments are on board Polar Orbiting Environmental Satellites
(POES) managed by the National Oceanic and Atmospheric Administration (NOAA).
Transmission from the Platform Transmitter Terminals (PTTs) are received and relayed to
ground stations in real time. The transmissions are also stored on tape and transmitted to three
main ground stations which are located in Wallops Island, Virginia, Fairbanks, Alaska and
Lannion, France (Service Argos, Inc., 1998).
At least two satellites are in a near polar, sun-synchronous orbit at any one time, with six
currently in service simultaneously (Service Argos, Inc., 2004). A satellite in a near polar orbit
is traveling a path that takes it over the north and south poles. These satellites pass over the earth
approximately every 102 minutes. Deborah J. Shaw, Director, Dept. of User Services for
Service Argos, Inc. (personal communications, June 4, 2004) states with sun-synchronous orbits,
“the satellite passes the same location at the same time every day; it's really the same local solar
time (which could change on our clocks).” This allows for logic management for when
transmitters may be automatically turned on and off.
As the satellites pass over the earth, their viewing space is a circle approximately 5,000
kilometers in diameter (Service Argos, Inc., 1998). To understand how this works, picture a
small flashlight circling over a basketball. At any point in time, the light from the flashlight is
only on a portion of the ball. In this same manner, a satellite sees only a portion of the earth at
any point in time. Now imagine the basketball making a slow rotation on its access, and you can
see that the light points to different parts of the ball. In this manner, the satellites are pointing to
different parts of the earth as it rotates below.
Another interesting thing is that the parts of the earth near the poles are viewed more
often than those near the equator. The poles are viewed completely on each of the approximately
fourteen daily orbits per satellite. The points on the equator are viewed half as many times, as
each side of the earth is seen once per orbit. The time that the satellite is able to view a portion
of earth is from 8 to fifteen minutes per orbit (Service Argos, Inc., 1998).
It is important that the Satellites move in a well regulated speed, in order to ensure that
various portions of the earth are viewed daily and for proper calculations when determining the
location of the observed objects. Fixed objects on earth transmit powerful signals that are used
to help ground station personnel calculate the relative position of the satellites. Orbitography
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Processing technology is used to determine if the satellites are staying in their proper orbits and
adjustments are made as necessary (Service Argos, Inc., 1998).
The Doppler Effect
Satellites do not see the PTTs on the ground but are simply receiving signals. For
researchers to properly study the endangered species, it is important not just to have facts such as
length of dive, water temperature and such, but to be able to know where each specimen is
located. Scientists need a way to determine where the object is located on earth for the studies to
be of any great meaning. Fortunately, scientists can rely on a finding by Christian Doppler first
publicized in 1842, a finding that has come to be known as the Doppler Effect (Russell, 2003).
In layman’s terms, think of a horn as it comes towards you in a moving car or train. As
the car comes towards you, the pitch seems high. As the car or train passes by, suddenly the
pitch seems low. In reality, the pitch of the horn did not change at all. This perceived change in
pitch, or frequency, is the Doppler Effect. Doppler’s theory states that the relative frequency of a
wave (whether it be sound, light, radio or other electromagnetic waves) is related to the actual
frequency in relation to the speed of movement of observing object, the source object and the
speed of the transmitted waves (Russell, 2003).
The Doppler formula can be written as rf = af ( (ws + vo) / (ws+vs) ) where rf is the
relative frequency, af is the actual frequency, ws is the wave speed, vo is the velocity of the
observing object and vs is the velocity of the source object (Russell, 2003). With constants of
wave speed, actual frequency, velocity of the satellite (observing object) and potential speeds of
the source object, the relative frequency of the transmission can be used to determine the
distance and direction of the objects. It can not be determined in just one transmission, but the
multiple of transmissions received in an average ten minute viewing cycle are typically enough
to determine with fairly decent accuracy the position of the PTTs (System Argos, Inc., 1998).
Ground Segment
The final piece in the process of satellite tracking is the ground segment. Ms. Shaw,
Director, Dept. of User Services (personal communications, June 4, 2004) from Service Argos,
Inc. described the ground segment.
The ground segment is really broken into three parts: the receiving stations, the
processing centers and the NOAA satellite offices. The receiving stations and the NOAA
satellite office sends the data directly to our processing centers, here in Maryland, USA
and in Toulouse, France. It's at the processing centers where we do the quality assurance
and the location calculations.
There are three main processing stations for gathering data, as previously discussed.
These stations receive downloads from the satellites of recorded transmissions when the satellites
are in range. This ensures all transmission are received and processed (Service Argos, Inc.). Ms.
Shaw states that Service Argos, Inc. has “38 regional stations for receiving real-time data. We
Satellite Tracking of Endangered Species
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continue to improve this coverage by adding more stations.” The three main processing stations
also act as regional, real-time receivers of data.
The data received is recorded and validated. As with any network, the data must be
validated. The managers must check the data from the transmission noting the PTT
identification code, validating the location calculations and other data collected. Conceptually
this is a quality assurance process and data at times may be rejected. Transmissions are even
graded, depending on how many are received in a small period of time and the quality of the
data.
The ground crews are also responsible for monitoring the orbits of the satellites and the
systems that combine the reading to determine the locations of the PTTs. Validated and graded
information is then made available to contracted parties for use in the studies. Information is
disseminated in more standard formats such as faxing, e-mail and data base downloading.
Ethical Considerations
Satellite tagging of animals has proved to be a great way for learning about endangered
species and helping increase the populations of some species. However, there is some
controversy regarding the tagging of animals. Captain Paul Watson, founder of the Sea
Shepherd Conservation Society, expresses concern over the tagging of gray whales. "The cases
we've observed have demonstrated that tagging is an over and over again process that causes
undue harassment of animals for very little result," (Bogo, 1999).
Organizations such as the SCPBRG have come to rely heavily on satellite tracking and
speak highly of the benefits. In the past, large numbers of birds had to be banded in the hopes
that a few would be caught again for noting the new locations. With newer, lightweight
transmitters the birds can be tagged and there is no need to have any additional invasive activity
to gather a wealth of information. The group has used devises “on eagles for many years without
any indication of harm or discomfort” (Santa Cruz Predatory Bird Research Group, 2004).
The safety of animals is critical to the researches responsible for tagging of endangered
species. Andrew Read is an associate professor at Duke University's Marine Laboratory. When
discussing tagging of the harbour porpoises Mr. Read stated “If what we're doing affects [an
animal's] behavior, then our work is meaningless”. Some people believe other approaches to
monitoring should be used but Mr. Read points out that "When dealing with highly mobile
animals that cross international boundaries and travel thousands of miles, there's simply no other
way of getting this kind of info,” (Bogo, 1999).
Conclusion
Satellite tracking of endangered species is built on some very basic concepts but depends on very
sophisticated technology. Transmitters must be made small, light and long lasting to minimize
harm to the creatures and increase the information available. Sophisticated satellites are required
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to receive and relay the information received, even though the signals are simplistic (and
simplex) in form. It takes a great amount of technology to manage the satellites and to calculate
the location of the tagged animals. From formulas utilizing the Doppler Effect to Orbitography
Processing, it takes a great deal of technology to manage the simple task.
As with any project, one must weigh the pros and cons of the application. With satellite
tracking of endangered species, people must work to ensure the creatures are treated in a humane
manner, working for the greater good of the species. It is not pleasant to learn how dolphins
have transmitters installed in their dorsal fins, but it is even more unpleasant to learn of the
demise of so many animals.
J. Nichols, a researcher that managed the first project to track the migration of loggerhead
sea turtles, noted “Everyone's trying to improve and work toward least-invasive methods”.
Daniel Mulcahy, wildlife veterinarian with the Alaska Biological Science Center, when
discussing the ethics of tagging stated “if it was a perfect world, none of us would have to do
anything,” (Bogo, 1999).
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References
Bogo, J. (1999, May). Conservation tag … you’re it, E: The Environmental Magazine.
Retrieved May 27, 2004 from
http://articles.findarticles.com/p/articles/mi_m1594/is_3_10/ai_54623296
Caribbean Conservation Corporation & Sea Turtle Survival League (2003). How tracking sea
turtles by satellite works. Retrieved May 2, 2004 from http://cccturtle.org/satintro.htm.
One Ocean Organization. (n.d.). Satellite tracking our turtles. Retrieved May 29, 2004 from
http://www.oneocean.org/ambassadors/track_a_turtle/satellite/.
Russell, D. (2003, May 7). The Doppler Effect and Sonic Booms, Kettering University.
Retrieved May 29, 2004 from
http://www.gmi.edu/~drussell/Demos/doppler/doppler.html.
Santa Cruz Predatory Bird Research Group. (2004). Home Page. Retrieved May 23, 2004 from
http://www2.ucsc.edu/scpbrg/.
Service Argos, Inc. (1998). Basic description of the Argos system. Retrieved May 2, 2004 from
http://www.argosinc.com/documents/sysdesc.pdf.
Service Argos, Inc. (2004). System Overview. Retrieved May 25, 2004 from
http://www.argosinc.com/system_overview.htm
Space for Species. (2004, March 18) Satellite Telemetry. Retrieved May 29, 2004 from
http://www.spaceforspecies.ca/space_tech/satellite_telemetry.htm.
Washida, T. (2003, Feb-Mar). Japanese amateur whale ecology observation satellite launched,
The Orbiter. Retrieved April 26, 2004 from http://www.sspi.org/orbiter/FebMar03/views2.html.
Whale and Dolphin Conservation Society. (2004, March 8). Tagging of endangered dolphins a testing issue. Retrieved May 2, 2004 from
http://www.wdcs.org/dan/publishing.nsf/allweb/9F48025ED941DB5980256E510038899
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