Quick access to medical treatment when-and where-it’s needed is an age-old problem for armies and disaster-relief organizations. An Oak Ridge, Tenn., startup called Tactical Medical Solutions is making a box the size of a large traveling trunk that can be popped open and expanded into an operating room ready for surgery in 30 minutes or less.

Setting up the portable M.A.S.H. unit is like putting up a tent. A frame is mounted on top of the box and used to expand the room to about 9 by 9 by 3 meters. The box itself serves as the structural center; it also stores medical equipment and supplies.

The prototype was developed at Oak Ridge National Laboratory and will be used first by the U. S. Marines. But Tactical Medical Solutions is also talking with civilian organizations, including the Red Cross, about deploying modified versions of its “E.R. in a box.”