This study describes a satellite limb sounding technique that uses 2.1 and 4.7 THz spectrometers to retrieve atomic oxygen density and temperature profiles in the upper mesosphere and lower thermosphere. The analyses include a realistic simulation of instrument sensitivity, orbital sampling, oxygen emission, and inversion algorithm, as an end-to-end evaluation for a potential spaceborne mission in the future.

The paper is generally well organized and easy to follow. Some minor English and style issues may need to be fixed before publication.

Comment:

Is the line width (sigma) in Eq.4 same as the shape parameter in Eq.6?

If not, please use a different symbol.

All simulations are from pencil-beam calculations. What would be the impact from antenna beam patterns, say 10 km field of view, on the simulated results and conclusions?

There are a number of single-sentence paragraphs. Not sure what is their purpose? If they are a key statement/point to make, the authors need to provide the supporting materials to help the reader better understand the claim. If they are a supporting sentence, the authors may consider to group them into the related paragraph.