NASA has selected a proposal from the Smithsonian Astrophysical Observatory in Cambridge, Mass., to build the first space-based instrument to monitor air pollutants across North American hourly during daytime. The $90 million instrument – to be completed in 2017 – will be a hosted payload on a commercial satellite in geosynchronous earth orbit (GEO).

"NASA is excited to make this initial step into using commercially available space on geostationary communication satellites to engage in cutting edge science," said John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate in Washington. "We expect to see significant advances in air quality research with TEMPO. The vantage point of geostationary orbit offers the potential for many new opportunities in other areas of Earth system science."

Tropospheric Emissions: Monitoring of Pollution (TEMPO) will for the first time make accurate observations of atmospheric pollution concentrations of ozone, nitrogen dioxide, sulfur dioxide, formaldehyde and aerosols with high resolution and frequency over North America.

The TEMPO team of researchers and private industry has extensive experience in measuring the components of air quality from low-Earth orbit. Chief researcher Kelly Chance is on the science teams of the Ozone Monitoring Instrument, now in orbit on NASA's Aura satellite, boasting supporting partnerships with Ball Aerospace and Technologies, NASA's Langley Research Center and Goddard Space Flight Center and the U.S. Environmental Protection Agency, as well as several U.S. Universities and research organizations.

Building the instrument is only half the battle. TEMPO is expected to have one completed by September 2017 that NASA will seek to put on an appropriate satellite headed to GEO, most likely a communications satellite. The agency expects "numerous" satellites to be available for hosting in 2017, so it should be able to work out a good deal with a provider to get its secondary payload onboard.

Once in orbit, TEMPO will observe Earth's atmosphere in ultraviolet and visible wavelengths to determine concentrations of many key atmospheric pollutants.  From a geostationary perch, observations can be made several times a day when North America is facing the sun. Current Earth observation satellites, such as NASA's "A-Train," get one observation a day from low earth orbit. Other space agencies are planning similar geo-based observations over Europe and Asia, enabling a constellation of geostationary air quality satellites.

NASA plans to make other calls for proposals using instrumentation either on smaller missions or as hosted payloads. Being able to "ride share" aboard a commercial satellite is a win-win, allowing NASA to save money since it doesn't have to build and launch a dedicated satellite while a commercial operator can pick up some extra money to defray the cost of a larger satellite project.