Thoughts on the anniversaries from Austin Bay. In one of these eras, it would be nice to move from space exploration to space development and settlement. I think we have a lot better shot at that now, though.
[Mid-morning update]
The meaning of human spaceflight — twenty essays over at The Atlantic. I haven’t had time to read them yet — I suspect I’ll agree with some and disagree with others. I hadn’t previously heard of many of the authors.
Overall, it’s a good article but he uses the word “missile” to describe the Falcon 1 booster. Words mean things. The Falcon 1 was never a missile (unlike the ancestors of the Atlas and Delta boosters), at least not in the military sense of the word.
@Larry, on the one hand I agree with the sentiment, but on the other hand I think the terminology raises an interesting point about the dual use of orbital launchers. If you can develop an ICBM you can push the design just a bit farther to develop an orbital launcher. That describes the development path of many of the earliest launch vehicles (Soyuz, Atlas, etc.) However, the equivalence works the other way as well, a launch vehicle can be pressed into ICBM service just as easily.
This helps explain why commercial launch vehicle development was so stunted throughout the Cold War. Because developing a launch vehicle was tantamount to developing an ICBM, and the geopolitical situation was far too sensitive for people to be developing ICBMs privately. It’s no surprise then that the end of the Cold War brought about a rapid change in the launch vehicle development business, with rocketry finally entering a proper “barn-stormer” period (with Space Ship 1, XCor, Armadillo, Masten, et al) and finally seeing real commercial innovation take hold and become competitive (SpaceX).
We have yet to see the DC-3 and 707 moments in spaceflight but I wager they are closer than most people appreciate. Commercial spaceflight has still be a constant uphill battle against entrenched interests in government and industry, but we’re coming to a point where the money and momentum will be on the other side, and then the pace of innovation will be staggering.
The requirements that make for a good ICBM don’t necessarily make for a good space booster. For example, an ICBM needs to be able to launch very quickly so it won’t be caught on the ground in an attack. That’s why the first generation of ICBMs (Soviet R-7, Atlas I, and Titan I) had such short operational lifespans as missiles. They were fueled by O2 and kerosene so they weren’t exactly rapid response weapons. They were quickly replaced by missiles using hypergolic propellants (e.g. Titan II) or solid propellants like the Minuteman.
The Titan II was used successfully as a booster, both for Gemini and for later satellite launches after the vehicle was retired from missile duty. That was after the Air Force spent several million dollars per rocket to refurbish it for space launch duty.
Kerosene and O2 make for dandy space booster propellants but aren’t so good for missiles unless you’re either prepared to use them for a first strike or hope they can survive being hit before liftoff. LH and O2 is even worse from a missile perspective.
Missiles need very precise guidance systems if they’re going to be very accurate. While I don’t have any numbers to back up my speculation, I believe you need greater precision to achieve a small CEP than to achieve a desired orbit. Also, missile warheads need heat shielding to survive reentry, something most space boosters don’t require. Finally, a great deal of effort has resulted in some remarkable small and lightweight warheads, meaning missiles don’t need a lot of throw weight. The old R-7 was huge because the Soviet nuclear warheads of the era were huge. That gave them a big advantage during the early days of the space race. Our missiles were designed for smaller warheads so they didn’t have the lifting capacity of those huge Soviet missiles.
Larry: ICBMs also need entirely self-contained guidance systems. A civilian launcher could use GPS as part of its guidance, in combination with inertial systems.
BTW, do civilian launchers actually do this? It would seem to me to make sense, since inertial and GPS complement each other nicely (inertial providing better short term positioning; GPS allowing drift in the inertial system to be estimated and canceled out.)
According to SpaceX’s Falcon 9 User’s Guide, they have GPS receivers as part of their avionics package. It stands to reason they use GPS signals as part of their guidance system. Odds are other booster companies do the same thing but I don’t have time right now to check.
I’ve read articles in recent years about using GPS position reports broadcast from boosters to track their trajectories as part of range control. The current range control system is very old and can take a couple days between flights to reconfigure.
This is another argument for colonization now before governments figure out that once out in space bad guys have a lot of options.