AVStar High Temporal and Spatial Resolution
Imaging from Geostationary Orbit
AstroVision International, Incorporated
Woodmont Road, Suite 210
Bethesda, MD 20814
Earth Imaging from Geostationary Earth Orbit (GEO) allows
frequent sampling of the environment within an observable
hemisphere. GEO Meteorological Satellites, have exploited this
advantage for over three decades. Visual imaging from these
satellites could be characterized as low in spatial and temporal
resolution. The absence of ‘true color’, and high
spatial and temporal resolution is partly due to the need to
optimize the METSAT’s ability to perform 24-hour multi-spectral
coverage of hemispheric cloud cover. Furthermore, providing
coverage in a variety of spectral bands, at nadir spatial resolution
of 1-4 km, provides a flood of data which must be transmitted
over limited telemetry bandwidth. The new US NOAA GOES-Next
series can resample limited areas at higher rates, however,
high resampling rates sacrifice full hemispheric coverage, and
the mode cannot be used. Transient phenomena occurring
at the smallest temporal scales, with significant environmental
impact are unobserved. The full benefit of GEO based imaging
is not realized. AstroVision International’s AVStar Earth
monitoring system is designed to overcome current limitations
of GEO Earth coverage by providing ‘ real time’
monitoring of changes to the Earth’s atmospheric, land
and marine environment at unprecedented spatial resolution.
AstroVision’s AVStar-1 is scheduled for launch in late
2003. This initial capabilities of the first of a globe girdling
constellation of five satellites will be discussed and the potential
benefits to society, science, commerce and education will be
. The AVStar commercial Earth monitoring satellite systems
being developed by AstroVision International, Inc. (AVII) of
Bethesda Maryland will deliver live, ‘true-eye’
color views of the Earth from Geostationary Earth Orbit (GEO)
at unprecedented temporal and spatial resolution for that altitude.
Eventually, five GEO AVStars, spaced at equal longitudinal intervals
around the globe will continuously monitor over 80% of the Earth
at sub-kilometer spatial resolution providing information for
news, weather, scientific and educational applications. Data
from the AVStar system will be immediate and relevant at a local
user level, by significantly improving severe weather detection
and warning capability, while becoming an important tool to
mitigate the effects of natural disasters and catastrophic events.
The commercial basis for AstroVision’s venture is the
fundamental recognition that a continuous source of new and
unique information is the ‘Holy Grail’ of the ‘Information
The first satellite, AVStar-1, is to be launched to its initial
GEO location over the equator at 90° West Longitude in late
2003. AVStar-1 will monitor North and South America awaiting
the launch of the upgraded AVStar-2, which will include an expanded
suite of sensors and will replace AVStar-1 at that location
a year later. The initial satellite will then be moved
to provide coverage to the mid-Pacific Ocean from 160° West
Longitude. Subsequent AVStar launches will occur at approximately
six-month intervals thereafter until each of the full system
of five satellites is operational.
While the Earth’s environment has been monitored from
GEO for more than three decades, the full advantage of that
position has yet to be realized. The AVStar system will be the
first designed to fully exploit the advantages of its GEO location.
Environmental Monitoring from Geostationary
The advantages of monitoring the Earth with instruments on
satellites in GEO have been recognized as early as Clarke’s
1945 seminal observations identifying the unique properties
of that orbital altitude1. From a circular
orbit at 35,765-km altitude a satellite’s speed matches
the Earth’s 24-hour rotation. For Earth-based observers
with a direct line of sight, a satellite in GEO appears to be
fixed at a point above the horizon. This makes GEO satellites
ideal stations for ‘point-to-point’ long-range communications
Reversing the observer’s perspective to view the Earth
from a GEO satellite reveals other advantages. The Earth itself
has no apparent motion, and the same area of the Earth’s
surface is continuously in view, 24 hours a day. From GEO altitude,
an observer’s line-of-sight horizon on the Earth’s
spherical surface subtends an angle about 81° as measured
from the satellite’s nadir point. Therefore GEO provides
a view of nearly an entire hemisphere of the Earth making it
very useful for wide area radio broadcast to the horizon. Furthermore,
with the same area always in view from GEO, the only changes
apparent in the scene will be due to processes occurring on
the surface or in the atmospheric above it. (although, within
about 5° of the horizon, the curvature of the Earth reduces
the practical utility of the view). Furthermore, any event occurring
within that vast geographical area can be viewed, recorded and
concurrently reported by line-of sight broadcast to anywhere
within the observable hemisphere.
Thus systems in GEO are able to monitor environmental changes
due to either natural processes or human activity, as they are
occurring. The GEO location allows observations over areas and
time periods that encompass the complete range of environmental
changes, including the most severe and rapidly evolving weather,
and the largest scale extra-tropical cyclonic disturbances.
Observations can be made of the most transient phenomena such
as volcanic eruptions, lightning activity and even meteoritic
events, as well as more slowly evolving events like flooding,
biomass burning, and land cover changes due to seasonal and
climatic effects. These observations have significant societal
and commercial value in a variety of applications.
The most obvious drawback to placing sensors in GEO, is the
low spatial resolution that must be endured to achieve hemisphere
scale coverage at even moderate sampling frequencies with telemetry
rates typically limited to a few megabits per second.
The parameters that must be traded to determine the temporal
and spatial coverage possible for a satellite based imaging
system are telemetry data capacity (including frequency and
bandwidth considerations), spatial and temporal resolution and
area coverage. For practical purposes, current GEO environmental
monitoring satellite design is not determined by a requirement
to observe all the terrestrial processes that occur and would
be visible from GEO. but rather is driven by specific phenomena
attributes that are traditionally judged to be most important
for making synoptic meteorological predictions. These include
observations of cloud cover, and measurements of atmospheric
water vapor content and temperatures. Moreover, until recently,
predictive models required the input of measurements made
over relatively coarse temporal (hourly samples) and spatial
(kilometer or larger) sampling grids. The temporal and
spatial capabilities of initial and current generations of GEO
satellite data are well suited to that relatively benign requirement.
Current GEO Systems Capabilities and Limitations
The first meteorological observations from GEO were made with
a panchromatic (black and white) scanning imaging system carried
aboard the first United States (US) Applications Technology
Satellite (ATS-1) launched by the National Aeronautics and Space
Administration (NASA) December 6, 1966. The experimental scanning
type imaging systems flown on the ATS series (which included
a short-lived color capability on ATS-3) led to two prototype
NASA Synchronous Meteorological Satellites (SMS) launched in
1974 and 1975. SMS-2 was followed by the first Geostationary
Operational Environmental Satellite (GOES) launched in 1975,
developed by NASA and, with all subsequent GOES systems, operated
by the US National Oceanic and Atmospheric Administration (NOAA).
Every meteorological satellite placed in GEO since ATS-1 has
employed some form of visible or infrared scanning imaging system.
In a scanning system, the instrument’s optically sensitive
element is periodically and repetitively moved in discrete horizontal
and vertical steps across a scene until the complete scene has
been digitally recorded as an image. The full disk defined by
the GEO horizon subtends about 17.4° or about 0.3 radians.
At the satellite’s equatorial nadir point, a one-kilometer
wide picture element subtends 28 microradians. A full
disk scene is thus comprised of nearly 11,000 such elements
at its widest point. (Satellites are not perfectly stable
platforms so the actual area viewed must be larger than 17.4°
to allow for drift and jitter). With optical elements sized
to view no more than a few kilometers at any one moment and
each step requiring about 50 microseconds for photon integration,
it may require a large fraction of an hour to build one complete
image of the Earth’s full disk.
For fixed telemetry band-width, spatial resolution performance
of a single imaging system can be traded with sampling frequency
to maintain a constant information flow-volume. Higher
resolution can be achieved by replacing a single scanning optical
element with a linear cluster of silicon optically sensitive
elements, (for visible wavelengths, known as ‘charge coupled
devices’ or more commonly as ‘CCD arrays’).
This latter approach incrementally increases the momentary data
‘through-put’ while reducing the total time required
to scan the entire scene. Finally, some of the latest
GEO MET-SATs can limit the extent of the scan coverage to enable
more frequent sampling of areas smaller than the full disk area.
The focus of current and past Earth observation from GEO has
been the monitoring of cloud-cover at visible and infrared wavelengths.
This emphasis has defined the required attributes of virtually
all GEO based instrumentation (excepting that highly classified
monitoring done for national security purposes).
Clouds in typical weather systems may move at 10-100 km/hour
with maximum velocities found in hurricanes, cyclones, and typhoons
on rare occasions exceeding 400km/hr. Thus wind driven
cloud movements may correspond to shifts of up to 50-200 picture
elements (pixels) between successive images of tropical storms
at a full disk resampling rate of twice per hour and spatial
resolution of 1 km. This is a large fraction of almost
any organized storm system, which frequently measure from 500
to 1,500 pixels in extent. Furthermore, the most severe
convective weather systems evolve at speeds that rival the resampling
rate of many GEO weather sensors obviating the use of current
satellite imagery for providing measurements of detailed cloud
dynamics. Perhaps most important, the opportunity is missed
to provide timely, local warning and damage mitigation information
for the destructive phenomena associated with severe convective
systems, such as tornadoes, hail, and microbursts. Recognizing
that clouds may move up to 7 ‘kilometer-sized’ pixels
in a minute, the need for higher sampling rates becomes evident.
It was, to some extent, to remedy this very shortcoming, that
the most recent generation of US NOAA GOES MET-SATs (GOES-Next)
introduced the capability to selectively limit the area scanned
at any point in the hemispheric field of regard, allowing more
rapid resampling of regions of particular interest. In practice,
this capability allows the two operational GOES platforms (GOES-East
and GOES-West at 75° and 135° West Longitudes respectively)
to sample a scene in one of three modes 2:
Routine Operations: provides coverage of the 48
contiguous United States (CONUS) with four (4) samples/hour,
the northern hemisphere nearly two times per hour and South
America sampled about once 45 minutes. The full
disk is observed once every three hours. This is the
usual mode in which the GOES are operated.
Rapid Scan Operations (RSO): provides coverage
of the Continental United States (CONUS) with eight
(8) samples/hour, the northern hemisphere with coverage about
once per hour and South America sampled about once an hour.
The full disk is observed once every three hours. GOES is
rarely operated in the RSO.
Super Rapid Scan Operations (SRSO): allows scenes
approximately 1,500-km square to be resampled once per minute.
As the area observed is increased, the sampling rate decrease
(an area the size of CONUS requires about 5 minutes to scan),
however, SRSO sacrifices coverage of all other areas and hence
has been used only in test operations. The few opportunities
to demonstrate SRSO have resulted in dramatic animations of
thunderstorms and hurricanes more than proving the worth of
observations at the higher sampling rates.
However, with SRSO mode unavailable for practical operations,
even the more modern GOES scan imaging system, is unable to
provide data that is sufficiently current or with adequate
resampling frequency, to totally exploit the full potential
of their GEO location. A scanning system requires a finite time
to create an image, so its data cannot be truly live and refresh
rates will be fundamentally limited by the time required to
complete a scan.
For the most violent weather processes this time lag can be
an important limitation of scanning systems. Furthermore, observations
of significant, but very transient phenomena that occur in sub-minute
time scales, (lightning and meteors) are missed entirely.
Clouds are efficient diffuse mirrors of solar radiation and
therefore naturally appear white with variations in brightness
seen as shades of gray. Color, enhancing the contrast and visibility
of the Earth’s surface background, may actually detract
from cloud contrast-visibility in a scene. This is one reason
why, although virtually all GEO MET-SATs are capable of multispectral
observations, they do not image the Earth in color. Adding color
at the same spatial resolution as a pixel Instantaneous Field
of View (IFOV) triples the digital volume of an image, which
burdens otherwise limited data telemetry bandwidth.
In the nearly 45 years since the first Russian Sputniks and
almost 35 years after the first environmental monitoring ATS
satellite in GEO, observations of the Earth from space at visible
wavelengths remain less complete in some ways than that done
during the exploration of the moon and planets. There
are, as yet, insufficient means to observe or study all the
processes that occur on or near the Earth’s surface and
influence life on the planet. The history of science confirms
that the human eye is an extremely effective research tool,
and instruments that might duplicate its spectral, spatial,
temporal and radiometric attributes would provide enormously
useful information. Planetary exploration missions place special
emphasis on the importance of including an electro-optical surrogate
human ‘eye’ in virtually every expedition.
The fact that instruments currently monitoring the Earth’s
environment are far less capable than a human eye in some critical
faculties ensures there will be gaps in our ability to observe
certain critical phenomena. Coverage of the Earth, at
visible wavelengths, including color during the day, and with
sufficient sensitivity to observe at night is typically performed
from spacecraft in low Earth orbit (LEO) where continuous monitoring
and a full disk perspective are unavailable. (ATS-3 and the
Apollo missions have provide the majority of the examples
of color Earth images beyond LEO.).
Without solar illumination, it is difficult to observe clouds
at night at visible wavelengths. Instruments with different
characteristics are required (such an instrument is carried
by the US military’s polar orbiting Defense Meteorology
Satellite Program (DMSP) spacecraft. Infrared scanning
imaging systems which measure scene temperatures now perform
the night imaging function for GEO satellites, albeit at coarser
temporal and spatial resolution.
As described above, a major consequence of the scanning imager
design used in GEO MET-SATs, is the inability to observe the
occurrence of many known phenomena that significantly impact
human lives. The improved understanding of these phenomena that
GEO observations would yield are impossible with current systems.
Moreover, it is believed that severe weather cloud dynamics
may have correlated, recognizable and predictable behavior that
provides an advance signal of the onset and locale of the most
The anticipated benefits to global society and the commercial
value of observing these phenomena spurred the design and development
of AstroVision International’s AVStar commercial remote
sensing system, using alternative technologies that fulfill
the potential of Earth environmental monitoring from GEO.
AVStar System Description
Whatever their insufficiency, GEO MET-SATs have proven that
GEO platforms are a source of valuable environmental news and
weather information, in addition to their obvious scientific
and educational applications. The full utility and commercial
market for live, high-frequency, hemispheric scale environmental
monitoring from GEO has been estimated (by AVII supported market
studies) to be sufficient to support development of a totally
commercial, global remote sensing system in GEO. The AVStar
Earth monitoring system is designed to provide live hemispheric
coverage from a suite of cameras aboard each of 5 satellites
spaced at roughly equal longitudinal intervals around the globe.
Development of the AVStar commercial GEO Earth monitoring
system was facilitated by exploiting enabling technologies developed
for interplanetary class exploration. In particular, the
launch energy and endurance requirements, of planetary science
missions put a premium on the use of small, highly stable spacecraft
with high reliability and long life. These spacecraft
are much less expensive then the larger MET-SATs currently in
use. The fact that small satellites may be launched to
GEO as a secondary payloads results in further savings.
The requirements for interplanetary instruments are equally
stringent in ways that make them ideal for GEO Earth monitoring
from a small platform. Volume, mass and power requirements
have motivated electronics miniaturization and the use of advanced
technology optical elements that mimic the attributes of the
human eye. During the last two decades, the use of Megapixel
CCD FPA technology has become common in planetary space missions.
Megapixel CCD FPAs can form a color image of a large two-dimensional
area in microseconds. The exposure times can be varied
allowing a vary wide dynamic range that includes solar to lunar
levels of illumination. The advantage inherent in upgrading
planetary-type cameras to incorporate recently developed multi-megapixel
CCD arrays is an obvious and natural evolution of CCD technology.
The result is digital cameras able to instantaneously image
a very large area at reasonable spatial resolution with resampling
rates exceeding a frame per second
AVStar imaging instruments are primarily designed to monitor
a wide variety of phenomena, with relatively equal emphasis
on surface and atmospheric processes. AVStar imaging system
performance requirements were determined by the spectral, radiometric,
spatial and temporal attributes required to sense specific phenomena.
Radiometric characterization of the AVStar first generation
instruments will allow only ‘first order’ estimates
of image radiometry with subsequent systems subjected to a more
Information products will be developed from a standard instrumentation
package. All imaging systems will use multi-megapixel
CCD focal plane arrays (FPA) capable of variable exposure times
and sampling a full scene approximately once every second. The
basic camera suite for the first two satellites will include:
One wide, 18° circular field-of-view Red-Green-Blue
(RGB) camera system providing modest 5.5-km nadir spatial
resolution color images of the Earth’s full disk; and
Two identical narrow, 1.64° square field-of-view steerable
RGB camera systems providing 500-meter nadir resolution.
One of these high-resolution systems will be tasked to point
toward and track events of particular interest (e.g. hurricanes),
while the second will perform regular scans of either CONUS
or the Earth’s full disk to provide periodic high-resolution
updates over these larger areas. A mosaic of the full
disk, comprised of about 140 high-resolution narrow field
camera images can be created in less than three minutes, while
a mosaic of CONUS can be created in about 15 seconds.
One steerable panchromatic ‘low-light’ imaging
system for night observations having the same ‘field-of-view’
and spatial resolution as the narrow field RGB systems.
This camera’s primary purpose is to record night urban
illumination and transient light sources such as lightning
and meteorite activity, but it will also be sufficiently sensitive
to detect lunar illuminated clouds at night.
One multispectral camera system identical to the low-light
camera except the FPA will include a layer containing ten
(10) adjacent narrow band-pass filters. Each scene recorded
will be divided into ten 1.64° x .164° spectral regions.
The full scene can be sampled at each spectral band by steering
the camera system through ten discrete 0.164° steps on
an axis orthogonal to the filter long dimension. The ten spectral
bands range from the near ultraviolet (NUV) at about 0.35-nm.
to the near infrared, (NIR) at about 0.94-nm.
In addition to these five systems, the second satellite will
carry a lightning detection system that will operate both day
and night and a multi-band thermal imager to measure surface
and cloud temperatures and water vapor content. While a separate
low light system is carried specifically for night observations,
the exposure times for all the systems are variable and should
provide all systems with some night imaging capability.
Among the spectral bands sensed by the AVStar multispectral system,
NUV and blue wavelength information is not currently obtained
from GEO, and may be important for atmospheric aerosol and ozone
measurements with practical application to climate studies
and volcanic plume tracking for air traffic threat mitigation.
NUV wavelengths are not well suited to monitoring surface processes
(due to low intensity of solar illumination, and atmospheric ozone
absorption), but blue wavelengths allow the determination of true
surface color containing valuable information for the marine agriculture
industry. Infrared image information in a variety of useful
bands is already provided around the clock from meteorology satellites,
in LEO and GEO. Improved temporal and spatial resolution visible
and infrared Earth coverage would be helpful to better serve existing
markets for weather satellite imagery, and a source of high quality
data products for new emerging markets for climate information
products. For example, the telecast image quality from all cameras
is superior to, but compatible with, high definition television
(HDTV) standards and particularly suitable to serve the needs
of the broadcast and cable television media.
Phenomena observable from AVStar systems that are not currently
well observed by GEO systems includes a variety of natural terrestrial,
celestial and human activities: Amplifying references or satellite
observation example are cited,
Cloud Spatial Structural Scales and Motion Especially
rapidly evolving storm systems.(GOES SRSO)
Volcanic Eruptions and Plumes: Typically occurring about
weekly around the globe3. Explosive eruptions may
eject material at near sonic velocities causing large plumes
to quickly expand and become visible from GEO within seconds.
At stratospheric altitudes, the plume will be carried by prevailing
winds at up to 200-kph. AVStar monitoring may be the
first and best coverage available for major daylight volcanic
eruptions; especially in remote areas. Volcanic plume detection
and tracking may be a great boon to air traffic safety. (GOES)
Biomass Burning and burn scars can be detected and climatic
impact monitored 4
Flooding: measuring cloud precipitable water content and
post-flood impact analysis.(GOES)
Lightning: Observed from space, both cloud-to-ground and
intra-cloud lightning are detectable. Flash rates
of the latter, not easily observed by ground systems, have
been correlated with the advent of severe weather 5,
6 .GEO-based detection is a means to provide advance
warning of destructive severe weather outbreaks.(DMSP)
Urban Illumination; a means of monitoring urban sprawl
and environmental impact 7,8
Meteors (declassified US Defense Department documents
reveal satellite sensors detected 136 meteoritic atmospheric
impacts over 17 years with an explosive yield in excess of
1 kiloton 9
Terrestrial-Color Spatial and Temporal Variability
bi-monthly limb transits of the Moon10 (with
the lunar surface observed at about 5-km resolution by AVStar
narrow field cameras) (GOES)
Solar Eclipses with the Moon’s shadow moving at
about 1,500-km/hr across the face of the Earth. (GOES)
In addition to live coverage of geophysical phenomena AVStar
cameras will also be able to observe features related or due
to human activities on the planet. These include:
Space Shuttle launch and re-entry (GOES)
Maritime wakes due to the movement of large maritime vessels11
Industrial smoke plumes and aircraft contrails (GOES)
Large explosions (GOES and METEOSAT)
During the past four years, AstroVision has worked with
NASA’s Commercial Remote Sensing Program Office at Stennis
Space Center in Mississippi to create visualizations of AVStar-1
image products and Earth coverage. These simulated products,
based on imagery from the NOAA GOES satellite series are dynamic
animations processed to include a natural ‘true-eye’
color Earth surface background and to demonstrate the higher spatial
resolution and sampling rates possible with AVStar coverage.
AstroVision has exploited
the recent advent of computer models able to simulate the “true-eye”
color of the Earth. AVII worked with ARC Science Simulations,
of Loveland, Colorado, using their “Face of the Earth”
model to add color to existing GOES visible images by creating
an overlay of the GOES “white” cloud layer on a
model “true-eye” color Earth. Such purely
synthetic models can not reproduce actual day-to-day changes
in surface color and so do not obviate the need for “true-eye”
color observations and are certainly not a substitute for live
Earth coverage. High spatial resolution is simulated by extrapolating
from the nearly 2-to-1 over-sampling in the horizontal scan
direction of GOES imagery.
narrow field camera high temporal coverage was simulated by
interpolating from GOES SRSO image sequences at one-minute image
these colorful animations cannot be included in a static, black-and-white
print format of this paper.
1. AVStar Wide Field Camera view of Earth’s full disk
from 90° West longitude.
The view of the Earth from
AVStar-1’s GEO position at 90° West longitude is shown
in figure 1, a ‘gray-scale’ mosaic of the
Earth’s full disk recorded by GOES 8 and 9 on August 2,
1996. Luis is inserted near Puerto Rico interior to the narrow
field camera coverage white outline.
The field of view of the two narrow field cameras is depicted
in figure 2 from an image of Hurricane Luis recorded by GOES-9
September 6, 1995.
The United States Department of Commerce licenses domestic US
companies planning to engage in space based remote sensing of
Earth for commercial purposes. AstroVision International
was granted its initial license for one Earth monitoring satellite
at 90° West Longitude in 1995. A recent (2000) amendment
to that original license authorized AVII to operate two satellites
with significantly enhanced capability at 90° and 160°
Figure 2. Narrow Field Camera area of regard with hurricane.
Also in 2000, the US Federal Communications Commission (FCC),
which authorizes ‘space-to-ground’ telecommunications
for Earth Exploration Satellites in the X-Band, has authorized
AVII the use of 160MHz of bandwidth between 8.075 and 8.375-Ghz.
This corresponds to a data rate of 320-Mbps, sufficient for each
AVStar to deliver uncompressed frame-per-second imagery of the
Earth’s day side from each of the three RGB cameras and
data from the multispectral instrument..
In November of 2000, AVII selected Malin Space Science Systems
to build imaging systems to be carried aboard the first two
AVStars. In March of 2001, AVII selected Ball Aerospace
of Boulder, CO, to build the initial two satellites. The
design of these satellites will be based upon the Ball BCP-2000
Instruments and satellites are under construction with the
launch of AVStar 1 scheduled for third quarter 2003. Earth
coverage should become available within a month after launch.
AVStar data is being purchased by NASA to support the development
of improved severe weather detection, tracking and warning under
the auspices of its Earth Science Enterprise program during
the first two years of AVStar operation. Ground station
and image processing and distribution facilities are currently
planned to be located in proximity to the John C. Stennis Space
Center in Mississippi.
Clarke, A.C., Wireless World, October 1945, pages 305-308
GOES I-M Data Book, Space Systems Loral, DRL 101-8, Revision
1, 31 August 1996.
Simkin, T., Terrestrial Volcanism in Space and Time, Annual
Reviews of Earth and Planetary Science, 21, p. 427-452, 1993.
Levine, J.S., W.R. Coffer III, D.R. Cahoon, Jr., E.L.
Winstead, Biomass Burning, A Driver for Global Change, Environmental
Science and Technology, 29, no. 3, p. 121A-125A, 1995.
Boccippio, D.J., K.L.Cummins, H.J. Christian, S.J. Goodman,
Combined Satellite and Surface- Based estimation of the intracloud-Cloud-to-Ground
Lightning Ratio over the Continental United States, Monthly
Weather Review, 19, 108-122, January 2001.
Christian, H.J., R.J. Blakeslee, and S.J. Goodman, The
Detection of Lightning from Geostationary Orbit, J. of Geophysical
Research, 94, no. D11, p. 13,329-13,337, 1989.
Beatty, J.K., Impacts Revealed, Sky & Telescope,
Elvidge, C.D., K.E. Baugh, E.A. Kihm, H.W. Kroehl and
E.R. Davis, Mapping City Lights with Nighttime data from the
DMSP Operational Line Scan System, Photogrammetric Engineering
and Remote sensing, 63, pp 727-734, June 1997.
Sullivan, W.T. A 10-km Resolution Image of the Entire
Night-time Earth Based on Cloud-Free Satellite Photographs
of the 400 –1100-nm Band, J. Remote Sensing, 10, pp.
Landecker, P.B., Lunar Surface as Viewed from GOES, Monthly
Weather Review, 112, pp2122-2125, October, 1984.
Howard, W.E. and O.K. Garriott, Can You See Ships from
Space?, Proceedings of the naval Institute, pp 89-94, December,
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