The buggers could probably see about the same spectrum of light as human beings, and there was artificial lighting in their ships and ground installations.
There are no more uses of "spectrum" in the book.
Show samples from other sources
That a man pleasured could so easily resolve himself to the whole spectrum of acts, indifferent and murderous and humane, and choose with such arbitrary will what he shall have to remember forever and forever.
Chang-rae Lee -- A Gesture Life
His appreciation of growing things became more subtle, turned within a more limited spectrum and gradually Lalla’s visits tapered away.