Posted on by Ken Kremer

NASA’s Carbon Dioxide Greenhouse Gas Observatory Captures ‘First Light’ at Head of International ‘A-Train’ of Earth Science Satellites

OCO-2 leads the international Afternoon Constellation, or A-Train, of Earth-observing satellites as shown in this artist's concept. Japan’s Global Change Observation Mission - Water (GCOM-W1) satellite and NASA’s Aqua, CALIPSO, CloudSat and Aura satellites follow. Credit: NASA

NASA’s first spacecraft dedicated to studying Earth’s atmospheric climate changing carbon dioxide (CO2) levels and its carbon cycle has reached its final observing orbit and taken its first science measurements as the leader of the world’s first constellation of Earth science satellites known as the International “A-Train.”

The Orbiting Carbon Observatory-2 (OCO-2) is a research satellite tasked with collecting the first global measurements of atmospheric carbon dioxide (CO2) – the leading human-produced greenhouse gas and the principal human-produced driver of climate change.

The ‘first light’ measurements were conducted on Aug. 6 as the observatory flew over central Papua New Guinea and confirmed the health of the science instrument. See graphic below.

NASA's OCO-2 spacecraft collected "first light” data Aug. 6 over New Guinea. OCO-2’s spectrometers recorded the bar code-like spectra, or chemical signatures, of molecular oxygen or carbon dioxide in the atmosphere. The backdrop is a simulation of carbon dioxide created from GEOS-5 model data. Credit: NASA/JPL-Caltech/NASA GSFC
NASA’s OCO-2 spacecraft collected “first light” data Aug. 6 over New Guinea. OCO-2’s spectrometers recorded the bar code-like spectra, or chemical signatures, of molecular oxygen or carbon dioxide in the atmosphere. The backdrop is a simulation of carbon dioxide created from GEOS-5 model data. Credit:
NASA/JPL-Caltech/NASA GSFC

Before the measurements could begin, mission controllers had to cool the observatory’s three-spectrometer instrument to its operating temperatures.

“The spectrometer’s optical components must be cooled to near 21 degrees Fahrenheit (minus 6 degrees Celsius) to bring them into focus and limit the amount of heat they radiate. The instrument’s detectors must be even cooler, near minus 243 degrees Fahrenheit (minus 153 degrees Celsius), to maximize their sensitivity,” according to a NASA statement.

The team still has to complete a significant amount of calibration work before the observatory is declared fully operational.

OCO-2 was launched just over a month ago during a spectacular nighttime blastoff on July 2, 2014, from Vandenberg Air Force Base, California, atop a the venerable United Launch Alliance Delta II rocket.

OCO-2 arrived at its final 438-mile (705-kilometer) altitude, near-polar orbit on Aug. 3 at the head of the international A-Train following a series of propulsive burns during July. Engineers also performed a thorough checkout of all of OCO-2’s systems to ensure they were functioning properly.

“The initial data from OCO-2 appear exactly as expected — the spectral lines are well resolved, sharp and deep,” said OCO-2 chief architect and calibration lead Randy Pollock of JPL, in a statement.

“We still have a lot of work to do to go from having a working instrument to having a well-calibrated and scientifically useful instrument, but this was an important milestone on this journey.”

Artist's rendering of NASA's Orbiting Carbon Observatory (OCO)-2, one of five new NASA Earth science missions set to launch in 2014, and one of three managed by JPL. Credit: NASA-JPL/Caltech
Artist’s rendering of NASA’s Orbiting Carbon Observatory (OCO)-2, one of five new NASA Earth science missions set to launch in 2014, and one of three managed by JPL. Credit: NASA-JPL/Caltech

OCO-2 now leads the A-Train constellation, comprising five other international Earth orbiting monitoring satellites that constitute the world’s first formation-flying “super observatory” that collects an unprecedented quantity of nearly simultaneous climate and weather measurements.

Scientists will use the huge quantities of data to record the health of Earth’s atmosphere and surface environment as never before possible.

OCO-2 is followed in orbit by the Japanese GCOM-W1 satellite, and then by NASA’s Aqua, CALIPSO, CloudSat and Aura spacecraft, respectively. All six satellites fly over the same point on Earth within 16 minutes of each other. OCO-2 currently crosses the equator at 1:36 p.m. local time.

OCO-2 poster. Credit: ULA/NASA
OCO-2 poster. Credit: ULA/NASA

The 999 pound (454 kilogram) observatory is the size of a phone booth.

OCO-2 is equipped with a single science instrument consisting of three high-resolution, near-infrared spectrometers fed by a common telescope. It will collect global measurements of atmospheric CO2 to provide scientists with a better idea of how CO2 impacts climate change and is responsible for Earth’s warming.

During a minimum two-year mission the $467.7 million OCO-2 will take near global measurements to locate the sources and storage places, or ‘sinks’, for atmospheric carbon dioxide, which is a critical component of the planet’s carbon cycle.

OCO-2 was built by Orbital Sciences as a replacement for the original OCO which was destroyed during the failed launch of a Taurus XL rocket from Vandenberg back in February 2009 when the payload fairing failed to open properly and the spacecraft plunged into the ocean.

The OCO-2 mission will provide a global picture of the human and natural sources of carbon dioxide, as well as their “sinks,” the natural ocean and land processes by which carbon dioxide is pulled out of Earth’s atmosphere and stored, according to NASA.

Here’s a NASA description of how OCO-2 collects measurements.

As OCO-2 flies over Earth’s sunlit hemisphere, each spectrometer collects a “frame” three times each second, for a total of about 9,000 frames from each orbit. Each frame is divided into eight spectra, or chemical signatures, that record the amount of molecular oxygen or carbon dioxide over adjacent ground footprints. Each footprint is about 1.3 miles (2.25 kilometers) long and a few hundred yards (meters) wide. When displayed as an image, the eight spectra appear like bar codes — bright bands of light broken by sharp dark lines. The dark lines indicate absorption by molecular oxygen or carbon dioxide.

It will record around 100,000 precise individual CO2 measurements around the worlds entire sunlit hemisphere every day and help determine its source and fate in an effort to understand how human activities impact climate change and how we can mitigate its effects.

OCO-2 mission description. Credit: NASA
OCO-2 mission description. Credit: NASA

At the dawn of the Industrial Revolution, there were about 280 parts per million (ppm) of carbon dioxide in Earth’s atmosphere. As of today the CO2 level has risen to about 400 parts per million, which is the most in at least 800,000 years, says NASA.

OCO-2 is the second of NASA’s five new Earth science missions planned to launch in 2014 and is designed to operate for at least two years during its primary mission. It follows the successful blastoff of the joint NASA/JAXA Global Precipitation Measurement (GPM) Core Observatory satellite on Feb 27.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

The Orbiting Carbon Observatory-2, NASA's first mission dedicated to studying carbon dioxide in Earth's atmosphere, lifts off from Vandenberg Air Force Base, California, at 2:56 a.m. Pacific Time, July 2, 2014 on a Delta II rocket. The two-year mission will help scientists unravel key mysteries about carbon dioxide. Credit: NASA/Bill Ingalls
The Orbiting Carbon Observatory-2, NASA’s first mission dedicated to studying carbon dioxide in Earth’s atmosphere, lifts off from Vandenberg Air Force Base, California, at 2:56 a.m. Pacific Time, July 2, 2014 on a Delta II rocket. The two-year mission will help scientists unravel key mysteries about carbon dioxide. Credit: NASA/Bill Ingalls
Posted on by Tammy Plotner

Earth’s “Missing Energy”

Clouds play a vital role in Earth's energy balance, cooling or warming Earth's surface depending on their type. This painting, "Cumulus Congestus," by JPL's Graeme Stephens, principal investigator of NASA's CloudSat mission, depicts cumulus clouds, which transport energy away from Earth's surface. Image credit: Graeme Stephens

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Like many of us, Earth works on a budget – an energy budget. However, this energy isn’t the type that powers our automobiles or electric lights. It’s the energy that empowers our living planet. When it comes to input and output, the Earth is a huge throughput system. The most massive source of incoming energy is solar radiation, with geothermal and tidal energy completing the circle. All of these forms of energy are converted to heat and re-radiated into space. In 2010, scientists at the National Center for Atmospheric Research in Boulder, Colorado publicized a study taken from satellite observations which stated there were certain variances between Earth’s heat and ocean heating. What they found was “missing energy” in our planet’s system. Why did this energy seem to be disappearing? The research group began wondering if perhaps there was a problem with the method of recording energy as absorbed from the Sun and its emission back to space.

This was a question that needed an answer. Enter an international team of atmospheric scientists and oceanographers, led by Norman Loeb of NASA’s Langley Research Center in Hampton, Virginia, and including Graeme Stephens of NASA’s Jet Propulsion Laboratory in Pasadena, California. It was their mission to account for the missing energy. Armed with 10 years of data from NASA Langley’s orbiting Clouds and the Earth’s Radiant Energy System Experiment (CERES) instruments, the team set out to record the radiation balance located at the apex of Earth’s atmosphere and how it changed with time. Supplied with the CERES data, they then combined it with estimates of oceanic heat content as recorded by three separate sensors. Their findings showed that both satellite and physical measurements of the ocean’s energy agreed with one another once observational uncertainties were added to the equation. Their work was summarized in a NASA-led study published January 22 in the journal Nature Geosciences,

“One of the things we wanted to do was a more rigorous analysis of the uncertainties. When we did that, we found the conclusion of missing energy in the system isn’t really supported by the data.” said Loeb. “Our data shows that Earth has been accumulating heat in the ocean at a rate of half a watt per square meter (10.8 square feet), with no sign of a decline. This extra energy will eventually find its way back into the atmosphere and increase temperatures on Earth.”

For the most part, scientists concur that around 90% of extra heat created by the greenhouse gas effect is being stored in Earth’s oceans. If it follows the laws of thermodynamics and is released back into the atmosphere, “a half-watt per square meter accumulation of heat could increase global temperatures by 0.3 or more degrees centigrade or 0.54 degree Fahrenheit”. As Loeb explained, these observations show the need to employ several different measuring systems over time and the findings underline the imperative need to continually update how Earth’s energy flows are recorded.

The newly published work came from the science team at the National Center for Atmospheric Research and other authors of the paper are from the University of Hawaii, the Pacific Marine Environmental Laboratory in Seattle, the University of Reading United Kingdom and the University of Miami. Their study mapped inconsistencies between satellite information on Earth’s heat balance between the years of 2004 and 2009 and included information on the rate of oceanic heating taken from the upper 700 meters of the surface. They said the inconsistencies were evidence of “missing energy.”

Original Story Source: JPL News Release.