A worker prepares to connect a crane to the interstage adapter at the mobile service tower at Space Launch Complex 2 on Vandenberg Air Force Base.

A worker prepares to connect a crane to the interstage adapter, or ISA, for NASA's Orbiting Carbon Observatory-2 mission, or OCO-2, at the mobile service tower at Space Launch Complex 2 on Vandenberg Air Force Base in California.

OCO-2 is scheduled to launch into a polar Earth orbit aboard a United Launch Alliance Delta II 7320-10C rocket in July. The ISA is the interface between the Delta II first and second stages. The second stage engine fits within the ISA. Once in orbit, OCO-2 will collect precise global measurements of carbon dioxide in the Earth's atmosphere and provide scientists with a better idea of the chemical compound's impacts on climate change. Scientists will analyze this data to improve our understanding of the natural processes and human activities that regulate the abundance and distribution of this important atmospheric gas. To learn more about OCO-2, visit http://oco.jpl.nasa.gov. Photo credit: NASA/Randy Beaudoin