X-42 Pop-Up Upper Stage
X -42 "Pop-Up Upper Stage" ( Pop -up school) is the name of a still undisclosed space project of the U.S. military. Specifications and photos of the program have not been published and therefore not much is known about it. It is believed that this is a re-ignitable liquid driven rocket upper stage (hydrogen peroxide JP- Jet Fuel ), which can carry a payload of 1800 kg into orbit.