Workers monitor the Delta II second stage for NASA's Orbiting Carbon Observatory 2 mission or OCO-2.

Workers monitor the Delta II second stage for NASA's Orbiting Carbon Observatory-2 mission, or OCO-2, as it is lowered into position for mating with the rocket's first stage in the mobile service tower at Space Launch Complex 2 on Vandenberg Air Force Base in California.

OCO-2 is scheduled to launch aboard a United Launch Alliance Delta II rocket in July. The rocket's second stage will insert OCO-2 into a polar Earth 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