Introduced herein are the design, systems integration, and performance analysis of an exotic magnetohydrodynamic (MHD) slipstream accelerator engine for a single‐occupant “Mercury” lightcraft. This ultra‐energetic, laser‐boosted vehicle is designed to ride a ‘tractor beam’ into space, transmitted from a future orbital network of satellite solar power stations. The lightcraft’s airbreathing combined‐cycle engine employs a rotary pulsed detonation thruster mode for lift‐off & landing, and an MHD slipstream accelerator mode at hypersonic speeds. The latter engine transforms the transatmospheric acceleration path into a virtual electromagnetic ‘mass‐driver’ channel; the hypersonic momentum exchange process (with the atmosphere) enables engine specific impulses in the range of 6000 to 16,000 seconds, and propellant mass fractions as low as 10&percent;. The single‐stage‐to‐orbit, highly reusable lightcraft can accelerate at 3 Gs into low Earth orbit with its throttle just barely beyond ‘idle’ power, or virtually ‘disappear’ at 30 G’s and beyond. The objective of this advanced lightcraft design is to lay the technological foundations for a safe, very low cost (e.g., 1000X below chemical rockets) air and space transportation for human life in the mid‐21stCentury — a system that will be completely ‘green’ and independent of Earth’s limited fossil fuel reserves. © 2004 American Institute of Physics