The Orbiting Carbon Observatory (OCO) was a NASA satellite mission intended to provide global space-based observations of atmospheric carbon dioxide (CO2). The original spacecraft was lost in a launch failure on 24 February 2009, when the payload fairing of the Taurus rocket which was carrying it failed to separate during ascent. The added mass of the fairing prevented the satellite from reaching orbit. It subsequently re-entered the atmosphere and crashed into the Indian Ocean near Antarctica. The replacement satellite, Orbiting Carbon Observatory-2, was launched 2 July 2014 aboard a Delta II rocket. The Orbiting Carbon Observatory-3, a stand-alone payload built from the spare OCO-2 flight instrument, was installed on the International Space Station's Kibō Exposed Facility in May 2019.
Mission description OCO's measurements are designed to be accurate enough to show for the first time the geographic distribution of carbon dioxide sources and sinks on a regional scale. The data is planned to improve the understanding of the global carbon cycle, the natural processes and human activities that influence the abundance and distribution of the greenhouse gas. This improved understanding is expected to enable more reliable forecasts of future changes in the abundance and distribution of carbon dioxide in the atmosphere and the effect that these changes may have on Earth's climate.
The OCO spacecraft was provided by Orbital Sciences Corporation. During its two-year mission, OCO will fly in a near polar orbit which enables the instrument to observe most of Earth's surface at least once every sixteen days. It is intended to fly in loose formation with a series of other Earth-orbiting satellites known as the Earth Observing System Afternoon Constellation, or the A-train. This coordinated flight formation was intended to enable researchers to correlate OCO data with data acquired by other instruments on other spacecraft. In particular, Earth scientists would like to compare OCO data with nearly simultaneous measurements acquired by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's Aqua satellite and ground-based data from the Total Carbon Column Observing Network (TCCON). Alignment with the A-train demands a particularly short launch window of 30 seconds. The original cost of the mission was US$280 million. It was sponsored by NASA's Earth System Science Pathfinder Program. NASA's Jet Propulsion Laboratory in Pasadena, California, manages OCO for NASA's Science Mission Directorate.
Technology The satellite will carry a single instrument designed to make the most precise measurements of atmospheric carbon dioxide ever made from space. The instrument consists of three parallel, high-resolution spectrometers, integrated into a common structure and fed by a common telescope. The spectrometers will make simultaneous measurements of the carbon dioxide and molecular oxygen absorption of sunlight reflected off the same location on Earth's surface when viewed in the near-infrared part of the electromagnetic spectrum, invisible to the human eye. As sunlight passes through Earth's atmosphere and is reflected from Earth's surface, molecules of atmospheric gases absorb very specific colors of light. If the light is divided into a rainbow of colors, called a spectrum, the specific colors absorbed by each gas appear as dark lines. Different gases absorb different colors, so the pattern of absorption lines provides a telltale spectral "fingerprint" for that molecule. OCO's spectrometers were designed to detect these molecular fingerprints. Each of the three spectrometers was tuned to measure the absorption in a specific range of colors. Each of these ranges includes dozens of dark absorption lines produced by either carbon dioxide or molecular oxygen. The amount of light absorbed in each spectral line increases with the number of molecules along the optical path. OCO's spectrometers measure the fraction of the light absorbed in each of these lines with very high precision. This information was then to be analyzed to determine the number of molecules along the path between the top of the atmosphere and the surface. If the amount of carbon dioxide varies from place to place, the amount of absorption will also vary. To resolve these variations, the observatory's instrument will record an image of the spectrum produced by each spectrometer three times every second as the satellite flies over the surface at more than four miles per second. This information would then be transmitted to the ground, where carbon dioxide concentrations would be retrieved in four separate footprints for each image collected. These spatially varying carbon dioxide concentration estimates would then be analyzed using global transport models, like those used for weather prediction, to infer the locations of carbon dioxide sources and sinks. The OCO instrument was developed by Hamilton Sundstrand Sensor Systems in Pomona, California, and the Jet Propulsion Laboratory.
Original launch
The satellite was originally launched from Vandenberg Air Force Base in California on a dedicated Taurus XL rocket. However, the payload fairing—a clam shell-shaped covering that protects the satellite during launch—apparently failed to separate from the spacecraft. "We have not had a successful launch tonight and will not be able to have a successful OCO mission", NASA commentator George Diller said.
Date: 24 February 2009, 09:55:31 UTC Launch Vehicle: Orbital Sciences, Taurus-XL Launch Site: Vandenberg Air Force Base, Launch Complex 576-E A payload fairing is a clamshell-shaped cover that encloses and protects a payload on the pad and during early flight. Fairings are a standard component of expendable launch vehicles, and are always jettisoned as soon as possible after a rocket has climbed high enough for heating from air friction to no longer risk damaging the payload. The Taurus XL's fairing was intended to separate several seconds after stage 2 ignition. Its extra mass was not a significant factor during the flight of the larger lower stages, but kept the relatively small stage 3 from adding enough velocity to reach orbit. 17 minutes after liftoff the payload fell into the ocean near Antarctica. NASA investigators later determined the cause for the launch failure to be faulty materials provided by aluminum manufacturer Sapa Profiles.
Re-flight
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