But Publius is typical of many commentators who took issue with my advocacy of semi-ballistic reentry vehicles. There appear to be many in the space advocacy community who are still loyal to inefficient and dangerous winged designs at the very moment NASA seems to be having second thoughts about them. Clearly, we are still suffering from the lingering after-effects of years of pro-Shuttle propaganda. We need to get our minds straight on some space history before we can discuss the future intelligently:

• Winged RVs are NOT "more advanced" or even "later" designs than ballistic ones. Winged rockets have a long history in both science-fictional and serious proposals for spaceflight. The first flight test dates back to 1944 (prophetically, the prototype A9 lost a wing during reentry).

  Von Braun's 1952 Ferry Rocket established the winged and piloted vehicle as everyone's mental model of what manned space vehicles should look like. However, at that time there was no body of flight or wind-tunnel data that would allow the aerodynamic design of such vehicles, and no way to predict the heat loads.

  When the military ballistic-missile program had to actually confront the problem of re-entry, a high-priority program of tests began (with essentially unlimited funding) which quickly revealed that hypersonic heat loads on the traditional pointed shapes were excessive.

  A blunt shape creates a detached shock wave that reduces heat transfer to the vehicle. The designers of Vostok and Mercury were taking advantage of a huge body of free research that allowed them to produce safe and efficient manned spacecraft without ten years of development.

  Even today, winged and lifting-body designs have a much smaller design database. Indeed, 40 years after Dyna-Soar there is not a single high L/D shape that has been comprehensively flight-tested at all Mach numbers from 25.0 to 0.3 (except of course Shuttle/Buran).

  The X-38 design team implicitly admitted this when they surprised NASA with an elaborate test program of near-full-scale vehicles, even though the "tested and proven" nature of the X-23/X-24A shape had been a major selling point of their original proposal.

• There are some good reasons for combining the ISS crew-exchange and supply functions in one vehicle, but safety isn't one. In the microchip age, automated navigation and piloting systems are far superior to manual control. They don't get tired, "deconditioned", distracted, or require hundreds of hours of training on expensive simulators. Everybody but NASA will be sending unmanned supply vehicles to ISS. Is it really possible that everyone in the platoon is out of step except us?

• The idea that "sick or deconditioned" astronauts need to ride down at low-g in winged vehicles is just another of the phony requirements which NASA thinks up to steer their "competitions" in the direction of the design they have already picked (for political reasons that wouldn't stand the light of day).

  Badly deconditioned astronauts have returned from Mir and ISS in Soyuz vehicles without encountering any medical complications. This is because the crew seats in ballistic RVs have the correct orientation for taking g-forces (eyeballs in).

  The forward-facing seats in winged RVs are correct for launch, but incorrect for reentry, and potentially fatal in some launch abort scenarios where a steep reentry will tear the crew out of their seats. (Informed sources tell me that at least one design team in the OSP competition has abandoned their winged design for just this reason.) Of course one could rotate the seats around in flight, but then the "pilots" couldn't look out a windshield and pretend that they are flying the vehicle.

• My idea of using refurbished Apollo CMs drawn from museums for the CRV function has drawn a lot of criticism. These critics must not be aware that the Shuttle program is currently flying hardware that NASA repossessed from an OUTDOOR DISPLAY at the Huntsville space museum.

  At least the Apollos have been in carefully protected indoor storage! Here, as in so many areas, NASA and its cheerleaders are using double standards. Just compare NASA's new safety standards for manned vehicles with the actual "abort modes" available to Shuttle.

• The term "cannonball" is actually a pretty good summary of the advantages of ballistic vehicles. Like cannonballs, they are simple, robust, inherently stable spacecraft that can survive launch aborts, botched retroburns, and emergency landings in unexpected locations on land or sea.

  Winged shuttles, on the other hand, require elaborate stability augmentation systems, constant high-speed adjustments of control surfaces, and careful management of kinetic energy to reach the few 15000' runways or dry lakes where they can land.

So Publius and his comrades in the Imperial Roman Air Force can stick with wings if they want to. Those of us who want space travel to be as cheap as possible and as safe as possible will stick with cannonballs.

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