Founded in 1999, XCOR Aerospace is a California company which specializes in the design and production of high reliability and low cost rocket engines.
Recently, their collaboration with NASA and ATK to develop methane-oxygen engines has been particularly successful, resulting in the successful construction and test-firing of their XR5M15 engine designed for spacecraft main propulsion.
The XR5M15 is one of XCOR's most recent engine designs and their most powerful design to date, with a rated thrust of 7500 lbf (33.4 kN).
The engine is being developed as a partnership between XCOR and ATK for NASA as part of the Vision for Space Exploration. It is intended to provide propulsion for return flights from the Moon and Mars, as well as for in-space maneuvering. The design builds upon their smaller XR3M9 LOX/methane engine, and reuses elements from many of their other designs.
As it is fueled by methane and LOX, it has a great deal of potential use for proposed Mars missions due to the possibility of producing methane on the Martian surface from locally available materials.