NASA team demonstrates greenhouse gas-measuring instrument

‘Science on a Shoestring’

Credit: Lawrence Livermore Laboratory, LLNL-PHOTO-753023

Online — A novel instrument that has already proven its mettle on field campaigns will attempt to measure atmospheric greenhouse gases from an occultation-viewing, low-Earth-orbiting CubeSat mission called Mini-Carb early next year—marking the first time this type of instrument has flown in space.

Emily Wilson, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is teaming with the Lawrence Livermore National Laboratory, or LLNL, to fly a smaller, more rugged version of her patented mini-Laser Heterodyne Radiometer, or mini-LHR, on an LLNL-built CubeSat platform early next year.

Wilson has demonstrated the ground-based mini-LHR during several field campaigns in Alaska, the Amazon River Basin, and the Royal Observatory in Edinburgh, Scotland, among other locations. Highly portable, the mini-LHR is comprised of commercially available components and literally can go anywhere to gather measurements.

Although NASA is currently measuring carbon dioxide from space, the agency has never flown a laser heterodyne radiometer to do the job.

Laser heterodyne radiometers were adapted from radio receiver technology. In this variation, the concentrations of greenhouse gases are found by measuring their absorption of infrared sunlight.

Each absorption signal is mixed with laser light in a fast photoreceiver within the instrument and the resulting signal is detected at an easier-to-process radio frequency.

While this is similar to other absorption techniques, such as those used in the Orbiting Carbon Observatory-2, laser heterodyne radiometry offers higher spectral resolution as well as improved signal-to-noise levels due to the internal mixing of sunlight with laser light, Wilson explained.

Other advantages are that the mini-LHR is more compact and includes no moving parts, Wilson added.

Furthermore, the instrument can measure three greenhouse gases: in addition to carbon dioxide, her instrument can simultaneously measure water vapor and methane in Earth’s atmospheric limb.

“And comparatively speaking, the instrument cost a small fraction to build compared with more traditional, non-CubeSat instruments,” Wilson said. “This is the epitome of science on a shoestring.”

Flight Aboard New CubeSat Bus

About the size of a toaster, the flight version of her instrument will fly as the only payload on LLNL’s new, 11-pound 6U CubeSat bus known as the CNGB—short for CubeSat Next Generation Bus. The CubeSat Office at the National Reconnaissance Office originated the CNGB concept, funding researchers at LLNL, the Naval Postgraduate School, and the Space Dynamics Laboratory to develop a government-owned nano-satellite architecture that could support a broad range of missions. Mini-Carb is the first mission to do so.

Read more at: https://phys.org/news/2018-08-nasa-team-science-shoestring-greenhouse.html

Provided by: NASA’s Goddard Space Flight Center (http://www.nasa.gov/centers/goddard/home/index.html)