The Douglas ASTRO: An Air Force Launcher

douglas-astro

The ASTRO, as pictured in the September 3, 1962 issue of Missiles and Rockets. Image artist unknown and copyright status uncertain, but believed to be in the public domain. Via the Internet Archive.

What it was: A lifting body craft proposed to the USAF by Douglas Aircraft. It would initially be used as a suborbital trainer then, after up-scaling and being paired with a second lifting body in an unusual nose-to-tail arrangement, evolve into a fully reusable vehicle with a nine-tonne payload capacity to LEO.

Details: In late 1962, the USAF was on the cusp of deciding how it would go forward with its plans to put military men in space. The X-15 had made its first flight mid-year, and the X-20 program was ramping up. Doubts about the latter were getting stronger, though, and would ultimately result in the Air Force deciding to work on the Manned Orbiting Laboratory instead.

It was at this point that an article was published in the now-defunct Missiles and Rockets magazine outlining a proposal from Douglas Aircraft that was supposedly being evaluated by the USAF. What it outlined was a two-part development program that would check the usual laundry list of military applications for space as perceived in the early 1960s.

The core of the ASTRO (Advanced Spacecraft Truck/Trainer/Transport Reusable Orbiter) was the answer to a question the USAF had proposed to North American Aviation and Douglas, as well as Boeing, Vought, and Republic: how to train pilots for the X-20 on actual flights prior to the X-20 being built. North American had come back with what they called the STX-15, which was a way of reconfiguring an X-15 to have the projected flight characteristics of an X-20 (except for, of course, the highest speed and orbital parts). The Phase I of Douglas’ ASTRO was their significantly more ambitious counter to the NAA proposal.

astro-schematic

A schematic of the ASTRO’s A2 vehicle, which would be both independent for suborbital hops, or be boosted to the point that it could be lifted into orbit by a derivative of the same vehicle. Note the booster nose’s ghostly presence at the far right of the image. Same source as previous. Click for a larger view.

Unfettered by the previously existing X-15, Douglas wanted to build a completely new craft dubbed A2, which would be capable of suborbital hops of about 5000 miles (8000 kilometers) after taking off from a runway under the impetus of a J-2 engine, the same rocket engine used by the Saturn V’s second and third stages. Pilots would get their space training, the USAF would have themselves a reusable vehicle with intercontinental range which could carry ten people, or a similar amount of payload. Two RL-10s, as used on the Centaur, would provide a little extra oomph.

Phase II was where Douglas diverged from the question being asked. Take the A2, modify it so that it only carried one crew and two extra J-2 engines, then stick it nose to bumper on the end of another A2 built to the Phase I spec. Turn it 90 degrees and launch it vertically, with the two separating from each other at altitude and speed (both unspecified). The sole crew member aboard the booster would glide back to Earth, while the uppermost A2 would ignite its engines, hopefully after allowing a bit of distance to build from the booster, and carry on into orbit. Douglas projected two crew and about a tonne of cargo to LEO in this configuration.

Phase III scaled up the booster, now dubbed B, and equipped it with two J-2s and one M-1, a never-built LH2/LOX engine that dwarfed even the F-1 engines used on the Saturn V’s main stage. Also launched vertically, this would be the ultimate version of the craft.

The full, two-stage Phase III vehicle was to have been 159 feet long (48.5 meters) and while mass was not mentioned the propellant capacity of the stages (165,000 pounds for the A2 and 594,000 pounds for the B) are—this suggests a total loaded vehicle mass at launch of about 380 to 400 tonnes. Total payload, as mentioned previously, was about nine tonnes, including crew, and there’s a sign that Douglas was nervous about this: the article specifically mentions wanting to launch due east from the Equator, which is an odd thing to be suggesting in 1962, well after the US had committed to launching from the continental USA.

If built, the program was expected to run from 1964 to 1970, with the first flight of the Phase III craft at the end of that period.

What happened to make it fail: It’s difficult to fit the ASTRO into the chronology of the X-20. Phase I appears to have been an attempt to come up with a “Gemini” for the X-20’s “Apollo”, giving the USAF the capability of sending pilots on long suborbital jaunts to train them for the environment they’d encounter when aboard the fully orbital X-20. Phase III would then have been a follow-up to the X-20, increasing crew capacity and payload over that craft.

If this is the case, then, it explains why the ASTRO never went anywhere. The craft made its sole notable public appearance in September of 1962, and American Secretary of Defense Robert McNamara was definitely thinking about cancelling the X-20 no later than March 1963—and possibly earlier. When the X-20 was stopped, then ASTRO would go with it. This is particularly true if one assumes, as seems likely, that the USAF was never very warm about the idea at all, and that it primarily existed as a pitch from Douglas leaked through Missiles and Rockets magazine to drum up support. There’s essentially no reports or discussion of ASTRO post-dating the magazine’s unveil.

What was necessary for it to succeed: It’s not easy to see a way forward for this one. X-20 was dead in the water less than six months later (eventually being formally cancelled in December 1963), and the payload capacity of even the Phase III ASTRO was marginal for what would have been an expensive program. There’s also the issue of Douglas vastly exceeding the question posed by the USAF—it’s unclear that there was any interest on the part of the Air Force in anything other than Phase I. This in turn defeated the purpose of building a fully operational craft for pilot training.

Sources

“Air Force Studies Space Trainer”, Missile and Rockets. September 3, 1962.

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“Big G”: Getting to Orbit Post-Apollo

big-g-schematic

A schematic of one Big G configuration. The original Gemini capsule can be seen on the left, while everything from the passenger compartment on to the right was new. The adapter on the far right was designed to allow yet another cargo module, space lab, or habitation/life3 support module depending on the mission. Public domain image from a short briefing document given to NASA in December 1967. Click for a larger view.

What it was: A 1967 proposal by McDonnell Douglas to build a new Gemini spacecraft with an extra module attached to its aft end. This would be the craft for flying astronauts to and supplying the proposed space stations—both civilian and military—that were to follow the Apollo landings. It would have been able to deliver twelve people (ten on top of the pilot and co-pilot of the original Gemini) and 2500 kilograms of cargo to low Earth orbit; with an optional extension module it could have taken 27,300 kilograms.

Details: NASA was well into post-Apollo planning by 1967 and at that early stage it was far from settled that they were going to go for a spaceplane as their next major spacecraft. Even if they did go for one, some (including Wernher von Braun) felt that an interim system was needed until what was slowly turning into the Space Shuttle was ready. Basic research on lifting bodies was still underway and while landing on land was already considered desirable, at the time NASA’s chief spacecraft designer Max Faget favoured doing so with a ballistic capsule using a device that the agency had been working on for years: a Rogallo parawing to brake its descent.

big-g-and-third-module

A clear view of the third, cylindrical module which would have been used for some Big G missions. Public domain image dating to 1969 via the NASA publication SP-4011 Skylab: A Chronology.

While there had been discussions about using the parawing with an Apollo capsule, the Gemini had the advantage in that it was the one where that program had begun; it had progressed as far as manned drop tests—Jack Swigert of “Houston, we’ve had a problem here” fame started his career as an astronaut flying a Gemini mockup under a parawing. McDonnell Douglas then sweetened the pot by reconfiguring their Gemini B so that it had the same base diameter as an Apollo capsule (making it simple to attach to a Saturn rocket) while giving twice the cargo capacity of its competitor. A modification of the Apollo CSM had studied in the years prior to Big G, and the so-called MODAP could match this increase, and even go beyond it with external cargo capsules—but then this is where the Big G’s cylindrical extension module came in and blew the Apollo derivative out of the water.

The Gemini B had begun as a logistics craft for the USAF’s Manned Orbiting Laboratory that, for the purposes of this discussion, had one important difference from the regular Gemini. It needed to be able to dock to the MOL and the most reasonable way to do so was at its aft end. This necessitated cutting a hatch into the capsule’s heat shield. While this looked like a dangerous strategy on the surface, it was proven to work and it became possible to attach other things to the Gemini B’s underside. For the basic Big G this was a truncated cone that increased the base diameter of the new craft to match that of the Apollo spacecraft, making it easier to mate it with Apollo hardware—and not just rockets. While they preferred their own cylindrical module for the third module that made a regular Big G into the nearly thirty-ton large cargo craft, McDonnell Douglas also came up with a side proposal to use Apollo Service Modules in that slot if NASA so desired.

The Big G was designed to be launched by one of three rockets. In its smallest configuration, it would be lofted by a Titan IIIM, a man-rated version of the Titan III which the USAF had started working on as a rocket for the Dyna-Soar program and then moved over to the MOL when Dyna-Soar was cancelled. This was the least powerful of the three alternatives, and would have been able to launch only the basic Big G. For one with the full complement of extra modules the choices were one of two Saturn variants that NASA was interested in building, either the Saturn INT-11 (the first stage of a Saturn V with four of the strap-on boosters used for the Titan IIIM) or the Saturn INT-20 (which would have consisted of a Saturn V’s third stage directly mated to the same rocket’s first stage).

As Big G was proposed not long after the Apollo 1 fire, it was designed to use an oxygen and helium mixture for its atmosphere, a difference from the pure oxygen of the original Geminis. The interior of the craft was also heavily reworked, with all of its systems upgraded and improved from the original’s. After all, as successful as it had been the previously flown Gemini had been only the second model of spacecraft flown by the United States.

When launched the Big G could have flown directly to a space station of short resupply or astronaut delivery-or-return missions. Alternatively the third module could be adapted to be a mini space lab, or a life support and habitation module capable of stretching the flight to 45 days; when the Big G was first being discussed, the then-record longest spaceflight of 13 days, 8 hours, 35 minutes had been achieved in an original model Gemini.

big-g-landing

Coming in for a dry-land landing under its triangular parachute, the Rogallo wing. Public domain image from McDonnell Douglas briefing to NASA, December 1967.

As previously mentioned, the end of the mission would see the re-entry capsule of the Big G bring its  astronauts home to somewhere in the United States by landing with a Rogallo wing. The capsule itself would have three landing skids that would cushion the impact of swooping into the ground, and then bring the vehicle to a stop.

Using the Big G as its transportation backbone, NASA’s hope was to have a 12-man space station in orbit by the time the Space Shuttle was ready to fly in 1975 (to use what turned out to be the optimistic estimate of 1969).

What happened to make it fail: The late 60s were an era of falling budgets for NASA, and there was a great deal of concern that the cost of launches was going to sink the manned space program—the Saturn V was notoriously expensive on a per kilogram-to-LEO basis (one figure, adjusted for inflation to modern dollars is $US22,000 per kilogram). Prices were anticipated to come down, but in general even the cheapest expendable launch vehicles have only beaten this figure by about a factor of three.

A re-usable launch vehicle had the promising appeal of bringing these costs down a great deal (projections, unfortunately based on unrealistic launch schedules, ranged as low as $US1,400 per kilogram). For crew return this made a glider of some sort necessary—either a lifting body or a winged craft—and when a high cross-range capability in NASA’s next spacecraft was cemented as desirable about 1970, wings became an absolute necessity. All possibility of a capsule, Big G included, fell by the wayside.

What was necessary for it to succeed: In retrospect the Space Shuttle looks like a mistake—its most basic reason for existence was to be a cheaper way to orbit than missions launched on expendable launchers and it never did so—most calculations pin it as more expensive per kilogram to orbit than the already expensive Saturn rockets it replaced. It’s important not to apply too much hindsight to this decision, but even in 1969 there were signs that sticking with capsules for manned spaceflight was the way to go. NASA had a strong constituency for this approach including, at first, the chief designer for the manned spaceflight program Max Faget. If he had stayed on-board with capsules, there’s a good chance that things would have turned out that way.

If they’d decided to go with a capsule, the two main options were continuing using Apollo spacecraft or building the Big G. Apollo had the advantage of still being in production, and it could have been launched on very similar rockets to the ones suggested for Big G. Big G, as mentioned, had the advantage of considerably more cargo space. Which of the two would have been picked comes down to an impossible-to-settle question of which advantage would be seen as tipping the scale.

The other possibility is that the Shuttle could have gone ahead, but that NASA could have realized just how long it was going to take before it flew: instead of going to space in 1975 its first mission was pushed back to April 12, 1981. If in 1967-69 they had had a better handle on the challenge they faced, the idea of using Big G as an interim logistics craft until the Space Shuttle was ready to fly would have been more attractive. The only problem with this scenario is that the Shuttle’s development costs put a big dent in NASA’s budget through the 1970s, so the space station that the Big G would have supported would have been hard to build while also going ahead with the orbiters.