In 1960, Philip Bono, a Space Vehicle Design Specialist with the Boeing Airplane Company, envisioned a manned Mars spacecraft which would outwardly have resembled the X-20A Dyna-Soar single-seat orbital glider that the company was developing for the U.S. Air Force at the time. Bono's Mars glider would, however, have been much larger than Dyna-Soar - large enough to hold an eight-man crew. The flat-bellied Mars glider would have measured a whopping 125 feet long and 95 feet across its delta wings.
Bono, in common with many Mars exploration enthusiasts of the early 1960s, optimistically targeted his expedition for the favorable 1971 Earth-Mars transfer opportunity, when the energy required to reach Mars would be at a minimum. Prior to launch, the forward section of Bono's glider would have been lowered into place atop its rear section on the launch pad. The rear section would have been mounted atop a living module which would in turn have rested upon a short central booster rocket stage. Six booster rockets would have surrounded and hidden the living module and short booster. Fully assembled and ready for launch, Bono's massive Mars launch stack would have stood 248 feet tall and weighed in at 8.3 million pounds.
On May 3, 1971, seven plug-nozzle engines in the base of the booster rocket would have ignited and powered up to provide a total of 10 million pounds of thrust (that is, 1.5 million pounds each). The plug-nozzle engine design would have done without large engine bells, reducing engine cooling requirements and booster mass. During first-stage operation, four of the outer boosters would have supplied propellants to all seven engines. The rocket would have climbed to 200,000 feet, where it would have cast off the four expended boosters, revealing the living module with its attached small rocket stage and the short central rocket booster stage. In the event of trouble during ascent, the eight-man crew would have blasted free in the glider's forward section.
The three remaining engines would have continued firing with the two remaining outboard boosters supplying all of their propellants. At 352,000 feet, the two boosters would have expended their propellants and detached. The short central booster would have continued firing until it placed the glider, living module, and small rocket stage on a trans-Mars trajectory, then would also have detached.
The astronauts would have crawled through a tunnel in the glider's tail into the 45-foot-long, 18-foot-diameter living module and deployed an inflatable 50-foot parabolic antenna for radio communication with Earth. They would have pointed the glider's nose - which would have contained a nuclear reactor for generating electricity - at the Sun. This would have placed the living module in shadow, and would have shielded the small rocket stage from solar heating. During the 259-day Mars voyage, the crew would have breathed a 40% oxygen/60% helium air mix, so would have sounded like Donald Duck.
On January 17, 1972, at the end of a 259-day Earth-Mars transfer, the crew would have strapped into the glider and separated it from the living module. The living module would have automatically discarded a 20,700-pound capsule containing human waste, then would have fired 20,000-pound-thrust Pratt & Whitney-built Centaur engines on its small rocket stage to slow down and enter Mars orbit. The waste capsule - the conical object between the living module and the glider in the image directly above - would have been permitted to strike Mars. Needless to say, this peculiar concept would have had few fans among scientists; it would certainly have introduced massive amounts of Earth bacteria into the martian environment, greatly complicating studies of martian biology.
The glider, meanwhile, would have carried the eight-man crew directly into the martian atmosphere. Bono's description of the glider's aerodynamic performance at Mars was based on an estimated martian surface air pressure about 8% of Earth's; the true figure is, however, less than 1% of Earth's surface pressure. The glider would have deployed a drag parachute to reduce speed. In the actual martian atmosphere, a single parachute of the size pictured above would not have been adequate. In addition, the glider's wing design would not have provided sufficient lift to enable effective gliding.
The Mars glider's pilot would have steered toward a level stretch of ochre desert. At an altitude of 2000 feet - which Bono declared was "adequate to clear the highest mountain of Mars," an assertion now known to be wildly inaccurate - three landing engines would have fired to slow it to a hover. The glider would then have lowered to the surface in a great cloud of yellow dust and sand and touched down on skids with its nose aimed 15° above the horizon.
During the "Mars Operational Phase," the eight Mars explorers would have set up a 20-foot-diameter inflatable living dome and relocated the glider's nuclear reactor several thousand feet away so that it could safely generate electricity for their encampment. During their 479-day conjunction-class Mars stay, the crew would have explored and moved equipment using a 4000-pound truck-like rover.
Near the end of their stay on Mars, the astronauts would have reconfigured their glider for launch from Mars by moving its landing engines so that they could serve as ascent engines and by returning the reactor to its place on the glider's nose. The glider's forward portion would then have blasted off using the aft portion as its launch pad. Its delta wings would have provided lift, reducing the amount of propellant and the size of the engines needed to attain Mars orbit. In the actual martian atmosphere, the combination would not have been adequate for flight to Mars orbit.
The glider forward section would have docked tail-first with the orbiting living module. Several of the astronauts would have spacewalked to link glider and living module and detach the empty torus-shaped propellant tanks on the living module's small rocket stage. The tanks would have been retained in Mars orbit after the Mars orbit insertion maneuver emptied them so that they could serve as meteoroid shielding protecting the expedition's Earth-return propellants.
The crew would have used the living module rocket stage to depart Mars orbit on October 21, 1973. Four months later (January 24, 1974), as the home planet shimmered invitingly ahead, the crew would have boarded the glider forward section, cast off the nuclear reactor and living module (these would have burned up in Earth's atmosphere), reentered directly, and glided to a triumphant desert landing on skids.
Reference:
"A Conceptual Design for a Manned Mars Vehicle," Philip Bono, Advances in the Astronautical Sciences, Vol. 7, pp. 25-42; paper presented at the Third Annual West Coast Meeting of the American Astronautical Society, Seattle, Washington, 4-5 August 1960.
