Paging Mr. Einstein...
"The paper claims that variations in radiation, temperature, and magnetic fields did not seem to limit the performance of the clock, making it suitable for operation in the extreme environment of space."
One presumes any effects of time dilation due to gravity or acceleration are not of concern here?
i.e. they only want an accurate time in the frame of reference of vessel it's on, rather than comparing it to earth's frame of reference?
Might have been interesting to at least mention a nod in that direction...