If that is its mission the answer is "small payloads" since the carrying capacity of the thing would be quite limited with its 2.1 x 1.2 m [1] payload bay. That

If that is its mission the answer is "small payloads" since the carrying capacity of the thing would be quite limited with its 2.1 x 1.2 m [1] payload bay. That leaves little room for the grappling arm or other mechanism needed to pluck a satellite out of its orbit. I suspect it does not retrieve payloads but takes them up and down again. Which payloads? Good question. Experimental sensors meant for inclusion in next-generation reconnaissance satellites maybe? [1] https://web.archive.org/web/20150321121050/http://www.boeing.com/boeing/defense-space/ic/sis/x37b_otv/x37b_otv.page https://web.archive.org/web/20150321121050/http://www.boeing...