Measuring sunlight reflected off the Earth's surface by employing a diffraction grating to separate the inbound light energy into a spectrum of multiple component colors (Orbiting Carbon Observatory).

Aura instruments enable daily global observations of Earth's atmospheric ozone layer, air quality, and key climate parameters (Tropospheric Emission Spectrometer - TES).

To the naked eye, our atmosphere looks clear much of the time, or filled with clouds, or somewhere in between. When not obstructed by clouds, sunlight and starlight appear to pass through our atmosphere pretty much unimpeded in the blur of colors we call "light."

With instruments that divide this "light" very finely into its individual components of color and shade, the picture begins to look much more complex. Some wavelengths are strongly absorbed, so not much light gets through, while wavelengths nearby pass through the atmosphere with little attenuation. This fine spectral structure of absorption, throughout the ultraviolet, visible and infrared portions of the electromagnetic spectrum, is diagnostic of the many chemical species present in our atmosphere, or in any other atmosphere, such as at Mars, Jupiter, or Titan.

Different spectrometers are used to divide light finely into its spectral components, and to accurately "read" absorption and transmission "lines" in the electromagnetic spectrum of transmitted or reflected sunlight. As examples, the Orbiting Carbon Observatory (OCO) Spectrometer is being built to very accurately measure the heat-absorbing gas carbon dioxide in Earth's atmosphere. The Tropospheric Emission Spectrometer (TES), launched in 2004 aboard NASA's Aura Earth Observing System spacecraft, measures ozone and a variety of trace molecules down to very low concentrations.

People at JPL and JPL's subcontractors have built a variety of optical spectrometers for atmospheric measurements, based on which a large body of scientific work has been published on an astonishing variety of topics.

Orbiting Carbon Observatory (OCO)

February 24, 2009 - NASA's Orbiting Carbon Observatory satellite failed to reach orbit after its 1:55 a.m. PST liftoff Tuesday from California's Vandenberg Air Force Base.

Preliminary indications are that the fairing on the Taurus XL launch vehicle failed to separate. The fairing is a clamshell structure that encapsulates the satellite as it travels through the atmosphere.

A Mishap Investigation Board will be immediately convened to determine the cause of the launch failure.