Emily Wilson developed a miniaturized laser heterodyne radiometer (mini-LHR) to measure the emissions of carbon dioxide and methane from melting permafrost. Wilson’s technology will be one of several NASA instruments sent to Alaska in June to analyze trace gases in the region’s atmosphere.
NASA Tech Briefs: Can you describe the mini-LHR?
Emily Wilson: It’s a portable laser heterodyne radiometer that measures carbon dioxide (CO2) and methane in the atmosphere column, which is roughly the first seven kilometers from the surface up. We’re using sunlight as the light source, and we’re mixing this with laser light to get a better signal. We use the laser to scan across an absorption feature. How deep the peak is for the absorption signal is proportional to the concentration in the atmosphere. We can measure other gases, too. We can definitely do water vapor. Carbon monoxide is also something we’re working on.
NTB: Why is it important to measure permafrost?
Wilson: There is likely a significant amount of methane stored in permafrost. As the global mean temperature rises by a few degrees, the permafrost starts to melt and then all these stores of methane get released. You can possibly have an amplified effect, which is kind of frightening.
NTB: What have you learned so far?
Wilson: There aren’t many instruments measuring CO2 and methane in the atmospheric column. The network isn’t dense enough, and they are not necessarily located in places where you see large emissions, like near cities.
We’ve partnered with AERONET [NASA Goddard’s AErosol RObotic Network]. They have 500 instruments globally, and we can target the ones that are important to climate change: carbon dioxide and methane.
NTB: What are the objectives of the June project?
Wilson: We have several different instruments. One of them is ground-penetrating radar that will measure the depth of the permafrost, and the water level at the different permafrost sites. Another team member will measure methane and CO2 on a horizontal path. We will try to connect the emissions on these sites to satellite imagery of the sites.
NTB: What is most exciting aspect of this technology?
Wilson: It’s low-cost, and NASA could lead the biggest network of ground instruments that measure CO2 and methane. Right now, the only way you get a global measurement is with a satellite. That costs millions of dollars, and then you maybe only get a lifetime of a few years. A ground instrument can conceivably go on indefinitely. A longterm, continuous measurement is key; to change laws, that’s what the modelers need.