You know...when I was a kid in middle school (when dinosaurs roamed the EARTH <img src="/images/icons/wink.gif" /> ) we had a kid named Boynton who had some...er, ah..."intestinal problems." We were pretty gung ho about rockets, etc., though this was before SputnikI. We thought that a methane/oxygen rocket would be a good thing, and that one way to obtain the methane was to feed this kid beans and EXLAX! Voila! Boynton Drive!<br /><br />Sorry, just couldn't resist! <img src="/images/icons/laugh.gif" /> <br /><br />In actual fact, in the 1970's, as part of a university engineering project, I did some very preliminary research on the use of methane/oxygen engines, using garbage-generated methane. A 1 lbf laboratory rocket was actually successfully fired using methane generated off a municipal sewage treatment plant! The methane was collected over water, to avoid mixing with any oxygen ahead of time, cooled to liquid form, and allowed to warm back to the gaseous state, pressurized, in a small lab "bottle". The pressure vessel was then connected to the rocket system, as was an GO2 tank, and fired. Excellent results, though the Isp was lower because of the presence of trace gases, such as water vaopr, ethane, etc.<br /><br />Perhaps DOD will do what NASA doesn't have the budget for.<br /><br />Ad Luna! Ad Ares! Ad Astra!