Mass-produced rocket engines no larger than a fingernail may one day lift payloads cheaply into orbit. MIT aerospace engineer Adam London is etching a microrocket motor just 3 millimeters thick and 1.5 cetimeters across into a silicon wafer. Thanks to microscale physics of the sort that allows ants to haul potato chips, the rocket-on-a-chip should pro-vide 20 times as much thrust per unit weight as the space shuttle's main engine.

London plans first ignition this winter. Burning gaseous methane fuel and oxygen, he hopes to generate 15 newtons of thrust. A chip-top turbo-pump under development at MIT could pressurize the liquid propellants in a second-gen-eration prototype, says Alan Epstein, head of MIT's Gas Tur-bine Laboratory.