02 September 2015

Dyna-Soar's Martian Cousin (1960)

Dyna-Soar spaceplane. Image credit: U.S. Air Force
In 1960, Philip Bono, a Space Vehicle Design Specialist with the Boeing Airplane Company, envisioned a manned Mars spacecraft which outwardly resembled the X-20A Dyna-Soar single-seat orbital glider his company was at the time developing for the U.S. Air Force. Bono's Mars glider was, however, much larger than Dyna-Soar - large enough, in fact, to hold an eight-man "expeditionary force" and nearly 40 tons of supplies and equipment. The flat-bellied Mars glider measured a whopping 125 feet long and 95 feet across its delta wings.

Though Bono's Mars glider was impressively large, it was part of a Mars expedition plan that was in fact stripped-down and bare-bones by early 1960s standards. It lacked redundancy and provided few abort modes. For those familiar with Wernher von Braun's 1950s plans for Mars expeditions, some of which included 10 or more cargo and crew spacecraft, Bono's plan must have seemed daring, even reckless.

Bono himself acknowledged that his study did not "present the solution to many major problem areas." He nevertheless assured his readers that it was "restricted to the realm of practicality and reflect[ed] a moderate degree of conservatism."

A large crane hoists into place the forward section of Bono's Mars glider. Final assembly occurs on the launch pad. Image credit: Boeing Airplane Company
Prior to launch, the forward section of Bono's glider would be lowered into place atop its aft section on the launch pad. All assembly would take place on Earth. In the event of trouble during ascent, the crew would blast free in the glider's forward section. The glider aft section would be mounted atop a living module with an attached small rocket stage which in turn would rest upon a short central booster rocket.

Six tall outboard booster rockets would surround and hide the short booster, living module/rocket stage, and most of the aft section of the glider. Fully assembled, loaded with liquid hydrogen and liquid oxygen propellants, and ready for launch, Bono's massive Mars stack would stand 248 feet tall and weigh in at 4150 tons.

Abort: the forward section of the Mars glider (upper right) blasts free of a malfunctioning booster rocket during first-stage ascent. Image credit: Boeing Aircraft Company
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. On 3 May 1971, seven plug-nozzle engines - one per booster - would ignite and power up to generate a total of 10 million pounds of thrust. The advanced plug-nozzle engine design would do without large engine bells, in theory largely eliminating engine cooling requirements and reducing engine mass. The crew would feel a maximum acceleration equal to 5.6 times the pull of Earth's gravity during ascent.

During first-stage operation, four of the outboard boosters would supply propellants to all seven engines. The rocket would climb to an altitude of 200,000 feet, where it would cast off the four expended boosters. These would fall to Earth 60 nautical miles downrange of the launch site.

Bono's Mars spacecraft begins second-stage flight by casting off four outer boosters (lower left). Image credit: Boeing Aircraft Company 
The three remaining engines would continue firing with the two remaining outboard boosters supplying all of their propellants. At 352,000 feet, the two boosters would expend their propellants and detach. The short central booster would continue firing until it placed the glider, living module, and small rocket stage on a trans-Mars trajectory, then would expend its propellants and detach. The Mars spacecraft - two-part glider, living module, and small rocket stage - would have a mass of nearly 138 tons following Earth escape.

Safely on course for Mars, the astronauts would crawl through a tunnel in the glider's aft section to reach the 45-foot-long, 18-foot-diameter living module. They would deploy an inflatable 50-foot dish-shaped antenna for radio communication with Earth (the dish might have been a late addition to Bono's plan, for it is not depicted in any of the illustrations for this post). During the 259-day voyage to Mars, the crew would breathe a 40% oxygen/60% helium air mix, so in their radio reports to Earth they would sound like Donald Duck.

The end of second-stage operation: the remaining pair of outboard boosters exhaust their propellants and separate, leaving to the short central booster the task of placing the glider, living module, and small rocket stage on course for Mars. This image displays the plug-nozzle engines unobscured by exhaust - they are the cones at the bottoms of the two boosters (lower left and lower center). Image credit: Boeing Aircraft Company
Its job done, the short central booster stage shuts down and fires thrusters to separate from the Mars spacecraft. Image credit: Boeing Aircraft Company
On 17 January 1972, at the end of a 259-day Earth-Mars transfer, the crew would strap into the glider and separate it from the living module. They would discard a 10.4-ton capsule containing human waste accumulated during the voyage to Mars. The small rocket stage, meanwhile, would ignite its four 20,000-pound-thrust Pratt & Whitney-built Centaur engines to slow itself and the living module so that Mars's gravity could capture them into orbit.

After deploying the antenna, the crew would point the glider's nose - which would contain a nuclear reactor for generating the Mars expedition's electricity - at the Sun. This would place the living module in shadow, and would shield the liquid hydrogen/liquid oxygen propellants in the small rocket stage from solar heating. Bono assumed that no course corrections would be necessary so that his spacecraft could maintain its nose-toward-Sun attitude throughout the journey to Mars.

17 January 1972: Arrival at Mars. The unpiloted living module (left) ignites its small rocket stage to slow down so Mars's gravity can capture it into Mars orbit while the glider bearing the crew enters Mars's atmosphere directly. Image credit: Boeing Aircraft Company
The waste capsule - the skinny conical object between the living module and the glider in the image directly above - would strike Mars. Needless to say, this peculiar concept would likely have had few fans among scientists; it would certainly have introduced massive amounts of Earth bacteria into the martian environment, greatly complicating studies of any native martian biosphere that might exist.

The glider, meanwhile, would carry the eight-man crew directly into Mars's atmosphere with no stop in orbit. If conditions on Mars were not suitable for an immediate landing - for example, if a planet-wide dust storm were raging - then the crew would have no way of aborting atmosphere entry and descent to the martian surface. (Such a storm did in fact occur in late 1971, though by January 1972 it had mostly abated.)

The Mars glider casts off its drag parachute as it steers toward a smooth area of martian desert. Image credit: Boeing Aircraft Company
Vertical descent and touchdown. The artist depicts Mars as smooth and dusty, with no obvious rocks on its surface. Image credit: Boeing Aircraft Company
As it descended past 3000 feet of altitude, the glider would deploy a 42-foot-diameter drag parachute to reduce speed. The Mars glider pilot would steer his craft toward a level stretch of ochre desert. At an altitude of 2000 feet - which Bono declared (wrongly, as it turns out) was "adequate to clear the highest mountain of Mars" - three landing engines with a combined thrust of 60,000 pounds would ignite to slow it to a hover. The glider would then lower vertically to the surface in a billowing cloud of yellow dust and sand and touch down on skids with its nose aimed 15° above the horizon. At touchdown, the Mars glider would have a mass of 70.4 tons.

Bono's description of the glider's aerodynamic performance was based on an estimated martian surface air pressure equal to about 8% of Earth's. The true value is, however, less than 1% of Earth's surface pressure. In the actual martian atmosphere, a single 42-foot parachute would not be adequate to slow the heavy glider's descent. In addition, the glider's wing design would not produce sufficient lift to enable effective gliding. In short, Bono's glider would reach the surface while still moving at supersonic speed. Some call this "lithobraking."

Mars Outpost: members of the eight-man crew lower the glider's nose-mounted nuclear reactor onto the expedition truck. In the background (right) stand radio antenna masts and the inflatable dome-shaped shelter. Image credit: Boeing Aircraft Company
During the 479-day "Mars Operational Phase," the eight Mars explorers would set up a 20-foot-diameter, 2000-pound inflatable living dome and relocate the glider's nuclear reactor several thousand feet away so that it could safely generate electricity for their encampment. The crew would have at their disposal about 4.2 tons of scientific gear. They would explore and move equipment using a truck-like two-ton rover.

Near the end of their stay on Mars, the astronauts would reconfigure their glider for launch by moving its landing engines so that they could serve as ascent engines and by returning the reactor to its place on its nose. They would also anchor the aft section of the glider to the surface using stakes and cables. The glider's forward section would then blast off at a 15° angle using the aft portion as its launch pad.

Liftoff from Mars: the forward part of Bono's Mars glider begins the climb to Mars orbit. Image credit: Boeing Aircraft Company
Bono wrote that his Mars glider's delta wings would provide lift, greatly reducing the quantity of propellant and the size of the engines it would need to attain Mars orbit. In the actual martian atmosphere, however, the glider he described would not reach orbit before it expended its propellants.

The crew would dock the glider forward section tail-first with the waiting living module which would have loitered in Mars orbit throughout their surface stay. Several astronauts would spacewalk to join together the 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 after the Mars orbit capture maneuver emptied them so that they could protect the small rocket stage and the precious Earth-return propellants it contained from meteoroid punctures.

Members of Bono's Mars crew cast off empty torus-shaped propellant tanks on the small rocket stage (upper right) attached to the aft end of the living module (center) in preparation for Mars orbit departure. Image credit: Boeing Aircraft Company
The forward section of Bono's Mars glider separates from the living module ahead of Earth atmosphere reentry. Image credit: Boeing Aircraft Company
24 January 1974: the forward section of Bono's Mars glider returns to Earth. Image credit: Boeing Aircraft Company
The crew would use the living module rocket stage to depart Mars orbit on 21 October 1973, then would discard it. Four months later (24 January 1974), as the home planet shimmered invitingly ahead, the crew would board the glider forward section once more and cast off the nuclear reactor and living module (they would burn up in Earth's atmosphere). Bono's glider, its weight reduced to just 15 tons, would then reenter Earth's atmosphere directly 997 days after launch and glide to a triumphant desert landing on skids.


"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

More Information

Space Race: The Notorious 1962 Proposal to Launch an Astronaut on a One-Way Trip to the Moon

A Forgotten Pioneer of Mars Resource Utilization (1962-1963)

A 1964 Proposal for a Small Lifting-Body Shuttle with "Staged Reentry"

NASA Marshall's 1966 NERVA-Electric Piloted Mars Mission


  1. The optimism of this scenario is fascinating... Where is the propellant needed for return to Earth?
    Also, I wonder what a "plug-nozzle engine" can be, and how it can "do without large engine bells" ?

  2. Optimism or madness? :-) I mention in several places that the small rocket stage attached to the living module - the same stage that slows the living module so it can capture into Mars orbit - boosts the living module and glider forward section out of Mars orbit toward Earth. As for the plug-nozzle engine, it's something Bono really liked. The fifth image from the top (the two outer boosters separate) shows the conical plug-nozzle engines best. Exhaust comes out around the upper part of the cone and the plume changes shape as the rocket climbs, expanding away from the cone as atmospheric pressure decreases. In theory this is really efficient, but in practice there are problems.

    I'm not an expert on the technology. As far as I know, no plug-nozzle engine has ever flown. They tend to be heavier, not lighter, than conventional bell-type engines. If I'm not mistaken, the plume can do unexpected things. In short, plug-nozzles haven't developed the way that Bono hoped they would.


  3. The plug-nozzle engine has it sources in the 1940s. The Junkers Jumo 004 was the first jet-engine in mass production and served as the propulsion system for the Messerschmitt Me 262, the first operational jet fighter aircraft. More than 1,400 were build in Nazi Germany during WWII. Remember here only the nozzle is important.

    The more advanced aerospike engine was tested in the 1990s for a Space Shuttle replacement, the X-33. When funding was decreased to the X-33 project there were still some more tests done by the company Aerospike Engines.

    I don't know what type of engines was in Bono's mind, the quality of the pictures is too bad, but I'm pretty sure it's the nozzle design from the 1940s.

    Nevertheless I believe the aerospike could be the the future for launches into Earth orbit. The X-33 concept as a SSTO (Single Stage To Orbit) plane was crappy, but the engines wasn't. This engine combined with Bono's booster concept (using all engines but only a few tanks in the beginning) would resemble the greatest heavy launch vehicle I can imagine.

    Some links:
    Plug-nozzle: https://en.wikipedia.org/wiki/Plug_nozzle
    Junkers Jumo 004: https://en.wikipedia.org/wiki/Junkers_Jumo_004
    Messerschmitt Me 262: https://en.wikipedia.org/wiki/Messerschmitt_Me_262
    Aerospike engine: https://en.wikipedia.org/wiki/Aerospike_engine

  4. You know, when I was a youngster I built a model of the Me 262 from a kit. I wondered why the engines were the way they were. As I stated, I don't know much about this technology, except that it has been proposed for flight for many decades but has never actually made it off the ground. When that sort of thing happens, I tend to be a little suspicious. If a technology is ground-breaking, then why hasn't it broken ground? Of course, I'm savvy enough to know that good technology sometimes runs afoul of all manner of non-technical obstacles. Nuclear-Electric Propulsion is probably a good example.


  5. Really enjoyed reading this. I have seen the illustrations of this Mars expedition proposal appear singly without much explanation in several books but this is the first time that I ever saw all the pieces fit together. It's pretty amazing how people like Phillip Bono could imagine these epic expeditions to Mars when so little was actually known about Mars much less the Moon. Heck you can go to the Moon how hard could it be? Just figure out more of the details once your there I love the illustrations of the time that make Mars appear to have canals too.
    As I recall one of the early shuttle proposals used a short very wide booster rocket that was to encorporate some kind of plug-nozzle technology related to some of Bono's designs for gigantic SSTO rockets. He certainly was a man with amazing ideas.

  6. Thanks for the kind words. I try to stay with schemes that are more or less realistic, but this one is so much fun I had to include it. I apologize that not all the images are as clear as they should be - I had to scan a copy xeroxed from microfiche. Still, I think if one studies the images carefully a lot of details pop out.

    I think the Shuttle proposal was Chrysler's SERV booster, which would have been used with the little MURP space plane and various cargo canisters with and without upper stages. Bono's Single-Stage To Orbit concepts were a little different from SERV, but the idea was generally the same. I plan to write about SERV, but I'm doing some research first into similar designs that preceded it. I already have papers on Bono's ROMBUS and ICARUS, the latter being a suborbital transport. Among other things, Bono envisioned using ICARUS to launch troops to trouble spots around the world in an hour or so.


  7. I am amazed at the optimism in Bono's proposal, not just for the technology but for the human factors as well. Eight people living together in a 20 ft diameter dome for over a year?

    Any idea what propellants he proposed to use? I would imagine hypergolics but the illustrated tankage seems a tad undersized for fuels with a mediocre ISP...

  8. I added a few more details from Bono's paper. Bono assumed that Centaur development would enable NASA to tame liquid hydrogen and liquid oxygen propellants - which it eventually did, though not without challenges - so he used them in his booster rockets and the small rocket stage attached to the living module.


  9. Using helium oxygen mix would not work. Helium is such a small molecule that containment is very difficult and requires 10^-10 testing. To contain it would hugely increase the cost and weight of the spacecraft for very little gain. By the time they reached Mars it should be gone. Nitrogen is 1.251 grams/liter at sea level pressure. Helium is 0.1785 grams/liter. This would save some kilograms of weight of inert gas. Neon might be practical for a tiny bit of weight saving at 0.8999 grams per liter.

  10. Helium was used as buffer gas in diving suits, deep-sea submarines, and undersea habitats in the 1950s and 1960s (and perhaps earlier/later - I do not know). I suspect that that is what Bono was thinking of when he proposed it for his Mars mission.



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