Meter is a unit of linear measure. If you want to use meter for area, you have to say “square meters” (or meter2 or m2). I tend to presume that scientific types know this. Now look at this sentence:
With a total collection area of 73,000 square meters (roughly 20 square acres), the NAIC stood as the largest single-aperture telescope on the planet from the date of its completion in 1963 to 2016 when China completed its FAST telescope.
Apparently the writer doesn’t know English units! Acre is already a unit of area; you wouldn’t say “square square meters,” would you?
PS—I put the hyphen in “single-aperture” because it’s a compound adjective; a topic for another post.