This article is about future unmanned spacecraft that are, literally, the size of a sewing needle, having a mass that is probably only a small fraction of gram.
FWIW: the first hypersonic aircraft (X36?) is only about 4 feet long.
Just a point of comparison that experimental vehicles traveling at extreme speeds need not carry cargo (much less people) nor be anything other than mind-jarringly small.
This concept brings with it a whole host of challenges that must be addressed: We'll need to develop a very, very tiny Crawler-Transporter to bring the ship out from the itsy-bitsy Vehicle Assemnly Building to the teeny-weeny launch pad. Then we'll have to construct a microscopic Mission Control facility to monitor the spacecraft throughout its mission. This is not going to be as easy as it sounds.