HONOLULU — A NASA Earth science hosted payload mission to study the planet’s carbon cycle has been confirmed for development, although exactly when and how it will fly have yet to be determined.

NASA Administrator Jim Bridenstine announced in a Dec. 28 tweet that the GeoCarb mission had passed its confirmation review. “The innovative GeoCarb measurements of CO2 and methane and its novel technology implementation hosted on a commercial spacecraft are a priority for me and NASA,” he said.

NASA spokesman Steve Cole said Jan. 3 that the confirmation review, which cleared the mission to proceed into Phase C of development, set a cost cap of $172.7 million for GeoCarb. The instrument, being built by Lockheed Martin, will be ready for launch in 2022.

NASA selected GeoCarb, led by Berrien Moore of the University of Oklahoma, in December 2016 as part of its Earth Venture Mission line of competitively selected small Earth science missions. GeoCarb is a hosted payload that will be included on a commercial communications satellite operating in geostationary orbit over the Americas.

At the time of the selection of GeoCarb, and in subsequent announcements, NASA said GeoCarb will be hosted on a satellite through an agreement with SES Government Solutions, the arm of Luxembourg-based satellite operator SES that does business with U.S. government agencies. Cole said an agreement with SES on when GeoCarb will be launched will be made later this year.

Once launched, GeoCarb will be able to monitor carbon dioxide, carbon monoxide and methane concentrations in the atmosphere over most of North and South America. The measurements will help scientists better understand how carbon is exchanged between the atmosphere, oceans and land masses with much better temporal resolution than is possible with polar-orbiting satellites.

A program of low-cost Earth science missions like GeoCarb was one of the recommendations of the 2007 decadal survey in Earth sciences. NASA is now working to implement recommendations of the latest decadal survey in the Earth sciences, published in early 2018.

In a separate Dec. 28 tweet, Bridenstine said he was instructing Thomas Zurbuchen, associate administrator for science, to “develop a comprehensive strategy to implement the 2017 Earth Science Decadal.”

That comment took some in the field by surprise, since that decadal report was released two years ago and NASA had previously indicated it would work to implement the recommendations of the decadal. “The 2017 Earth Science Decadal strategy is well on its way and the designated observables architecture studies have been in motion for over a year,” Sandra Cauffman, acting director of the Earth science division at NASA, said in a Dec. 28 tweet.

Cole confirmed Jan. 3 that NASA had already started studies on the best ways to implement the decadal survey, which, rather than recommending specific missions, instead identified “designated observables,” or Earth science phenomena that could be studied by spacecraft in some way. He said that, by the end of fiscal year 2020 or early in fiscal year 2021, those studies will conclude with architectures for measuring those observables. Studies associated with other aspects of the decadal survey “are well underway,” he added.