They are still in the process of mapping: https://earth.jpl.nasa.gov/emit/mission/destination/

I posted the original NASA article a few days ago, which has better info than this Smithsonian article: https://news.ycombinator.com/item?id=33349999

Note that the map they produce will be of surface properties (like mineral composition), not methane.

The surface properties are the main intermediate product on the way to the climate-related overall goal (https://earth.jpl.nasa.gov/emit/science/objectives/). Namely, does the dust lofted from these deserts heat or cool the Earth?

Yeah, let's name these super-emitters!