[Launch Alert] Vandenberg AFB Launch Schedule

Sat Feb 14 22:54:26 EST 2009

                             LAUNCH ALERT

                              Brian Webb
                    Ventura County, California
                        kd6nrp at earthlink.net
                    http://www.spacearchive.info

                             2009 February 14 (Saturday) 19:44 PST
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                   VANDENBERG AFB LAUNCH SCHEDULE
                       As of 2009 February 14

The following schedule lists rocket and missile launches from
Vandenberg AFB for the next six months. It is a composite of
unclassified information approved for public release from government,
industry, and other sources. This schedule is essentially accurate at
the time of publication, but may disagree with other sources. Details
on military launches are withheld until they are approved for public
release. For official information regarding Vandenberg AFB activities,
go to http://www.vandenberg.af.mil.

                   Launch
                 Time/Window
  Date            (PST/PDT)           Vehicle         Pad/Silo
--------       ---------------       ----------       --------

FEB 23         01:50-01:57           Taurus XL        576-E
Payload is the Orbiting Carbon Observatory (OCO) scientific satellite 

MAY 5          To be announced       Delta II         SLC-2W
Payload is the Missile Defense Agency's STSS ATRR 

JUL            ~09:12                Atlas V          SLC-3
Payload is the DMSP F18 military weather satellite. 

JUL            To be announced       Delta II         SLC-2W
Payload is the WorldView 2 commercial reconnaissance satellite

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The following feature discusses the Oribiting Carbon Observatory's
instrument. OCO is slated for launch from Vandenberg AFB later this
month. - Editor

     NASA MISSION MEETS THE CARBON DIOXIDE MEASUREMENT CHALLENGE
                Jet Propulsion Laboratory News Feature
                           2009 February 10

The challenge: very precisely measure carbon dioxide in Earth's
atmosphere all over the world, especially near Earth's surface.

For Orbiting Carbon Observatory Principal Investigator David Crisp of
NASA's Jet Propulsion Laboratory, Pasadena, Calif., and his team, the
logical solution was an Earth-orbiting spacecraft. But shopping for a
science instrument that could accomplish these objectives was no easy
task.

In this case, "shopping" meant finding the right technology to meet
the mission's demanding requirements. The observatory contains a
custom-built instrument designed to make what Deputy Principal
Investigator Charles Miller of JPL calls "the most difficult
atmospheric trace-gas measurement that's ever been made from space."
To put that measurement challenge into perspective, consider that all
of Earth's trace gases combined, including carbon dioxide, make up less
than one percent of Earth's atmosphere. In addition, carbon dioxide
levels vary by only about two percent from pole to pole. To
substantially increase our understanding of how carbon dioxide sources
(places where carbon dioxide is emitted) and sinks (places where it is
absorbed, or stored) are geographically distributed on regional scales
and study how their distribution changes over time, the new mission
needed to be able to resolve differences in atmospheric carbon dioxide
as small as 0.3 percent on regional scales every month. 

While one spaceborne instrument is already making carbon dioxide
measurements from space-the Atmospheric Infrared Sounder on NASA's Aqua
satellite-it sees the gas high up in the atmosphere, not near the
surface, where it is emitted and where some of it is absorbed into land
systems and the ocean. An instrument designed from the start to measure
carbon dioxide down to Earth's surface was clearly needed. 

Enter NASA's team of experts in atmospheric science, remote sensing
instrumentation and the optical properties of the atmosphere's
components.

The principle behind the observatory's measurement is relatively
simple. Carbon dioxide, like all molecules, has an affinity for
certain colors, or wavelengths, of light that have exactly the right
energy to make the molecule vibrate or rotate at specific frequencies.
A good analogy would be how a radio broadcasts sounds when it is tuned
to a specific channel. So, if you could shine a light through Earth's
atmosphere and see how the different colors that are sensitive to
carbon dioxide respond, you could use that information to calculate
how much carbon dioxide is present. Do this precisely enough and often
enough and it would be possible to see changes in carbon dioxide
levels over time-the key to identifying carbon dioxide sources and
sinks. 

The observatory uses the sun as its light source. To measure changes
in sunlight as it passes through the atmosphere, its instrument
incorporates a trio of high-resolution grating spectrometers, which
divide light from the sun into a very fine rainbow of colors called a
spectrum. They are known as grating spectrometers because they use a
grate, or grid, to partition light into different wavelengths.

"You can see a good example of how a grating spectrometer works by
looking at the back of a compact disc illuminated by a bright light,"
said Crisp. "The narrow circular tracks that record the information on
the disk are very effective at splitting light into different colors."

As the Orbiting Carbon Observatory satellite circles the globe, the
telescope on its instrument captures sunlight reflected by the surface
below-light that has traveled from the sun, down through Earth's
atmosphere and back up again to space. It sends the light to the three
spectrometers, each of which looks at a different range of colors and
breaks that spectral range down even further into more than 1,000
discrete colors. Two of the three spectral ranges that the
spectrometers target are sensitive to carbon dioxide, and one responds
to molecular oxygen. 

The resulting spectra look something like bar codes, with dark lines
showing where carbon dioxide or oxygen have absorbed specific colors.
"By measuring the fraction of the light that has been absorbed in each
of these dark lines, we can count the number of carbon dioxide or
oxygen molecules in the atmosphere," said Crisp. 

Three separate digital detectors, one for each spectrometer, record a
spectrum three times each second as the observatory flies above
Earth's surface. Fast exposures are essential because the spacecraft
moves at more than four miles per second along its orbit track. "We
don't want long exposures that could include clouds as well as clear
sky within individual exposures," says Crisp. "We also want to take
the data fast and get more clear views to the surface." 

While similar to the digital detectors in an ordinary camera, the
observatory's detectors take advantage of advances from the world of
astronomy to achieve the greatest possible sensitivity. "These
detectors were originally developed to measure objects that are faint,
fuzzy and far-away," said Crisp. "Here, we use them to measure very
fine details in the spectrum of sunlight reflected from Earth." 

The three spectral ranges measured by the observatory's spectrometers
are in the near-infrared part of the electromagnetic spectrum,
invisible to the human eye. Each provides a critical piece of
information. One provides precise information about changes in the
amount of carbon dioxide present in the atmosphere, while the others
show just how much of the atmosphere is being measured. "We need all
three of these measurements to do the job," said Crisp. 

One spectral range absorbs carbon dioxide relatively weakly, but it
measures carbon dioxide the most precisely, especially near Earth's
surface. 

The second spectral range absorbs carbon dioxide much more strongly,
so much so that almost all of the light in this part of the spectrum
is absorbed completely as it traverses the atmosphere. Adding more
carbon dioxide produces little additional absorption, so this
wavelength is less useful for showing changes in carbon dioxide
amounts. However, it does provide needed information about the pathway
the light has taken. It helps determine whether the observatory is
looking at light coming up all the way from the surface, or if clouds
or aerosols, such as particles of smog or smoke, have gotten in the
way and reflected the light back to space before it can be absorbed by
carbon dioxide. 

The third spectral range shows how much oxygen is present in the
light's pathway, another way to determine how much atmosphere the
light has passed through. 

"Oxygen makes up about 21 percent of the atmosphere," explained Crisp.
"Because we know the concentration, we know how much sunlight it
should absorb over any particular surface elevation. If the sunlight
penetrates all the way to sea level before it is reflected back to the
spacecraft, it will produce more absorption than if it penetrates only
to the top of a mountain or to the top of a cloud before it is
reflected to space. We can even use measurements of the oxygen
absorption to infer the surface pressure differences associated with
elevation changes as small as 100 feet. We can also detect scattering
by very thin clouds or hazes that reflect less than one percent of
light back to space. These precise measurements of the atmospheric
optical path are essential for accurate carbon dioxide measurements." 

The high-resolution grating spectrometers and the digital detectors
make it possible to make these measurements from a space-based
instrument, according to Crisp. 

Another technological challenge for the mission was designing the
instrument to meet the strict size and energy requirements of an
Earth-orbiting spacecraft. 

"One of the most challenging aspects of the mission was not inventing
components, but fitting a big instrument into a small spacecraft about
the size of a phone booth and designing it to use very little power,"
said JPL's Randy Pollock, the mission's instrument systems engineer.
The observatory's instrument uses only about 100 watts of electricity,
while the entire spacecraft uses only 400-500 watts, about half the
amount used by most microwave ovens. 

Once received back on Earth, the observatory's data will be analyzed
to yield estimates of the carbon dioxide concentration over Earth's
sunlit hemisphere at spatial resolutions as small as one square mile
using complex mathematical algorithms. Scientists will then analyze
these carbon dioxide estimates using global transport models similar
to those used for weather prediction to quantify carbon dioxide
sources and sinks.

"Carbon dioxide is the primary human-produced greenhouse gas and,
therefore, the primary human-caused driver of global warming," said
Crisp. "To estimate the rate of global warming, we have to understand
the processes controlling the buildup of carbon dioxide in Earth's
atmosphere. Global, space-based monitoring systems like the Orbiting
Carbon Observatory are essential tools for this task. The technology
we validate on this mission will be used to develop future carbon
dioxide monitoring missions." 

For more information on the Orbiting Carbon Observatory, visit:
http://www.nasa.gov/oco . 

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