>a Utopia with no rat problem
N817NA, a DC-8, is one of NASA's Flying Laboratories.
They can install all kinds of instruments on boards & measure all kinds of things.
Could be SAR, Temperature, Humidity, magnetics … anything.
Check N-number in any flight data page (flighradar24, adsbexchange etc), and you'll see them flying these kind of patterns all the time.
Cheers, m8!