Getting in and out of the Luk could be problematic. The Russians had somehow determined that just about anyone—or at least anyone capable of meeting the physical standards of the cosmonaut program—could force their body through a hole forty centimeters in diameter. Accordingly, each Luk included a flange—a forty-centimeter ring of fiberglass with bolt holes spaced around its periphery. All the layers of plastic converged on it, further enhancing its onionlike appearance. This became the onion’s cut-off stem. To keep the air from rushing out through that forty-centimeter hole, it was equipped with a stout diaphragm of much thicker plastic that could be put into place after the cosmonaut had climbed inside.