Category Archives: Technology and Society

#GnuCash

Is there a doctor in the house?

I have one set of books for my personal expenses, and another for the business. It seems obvious that it would be useful to have them both open simultaneously to coordinate entries, but despite the theoretical capability to have multiple windows, it doesn’t seem to actually allow that. When you open one book it closes the other. Any suggestions?

[Friday update]

OK, problem solved. All I had to do was control-N to create a new instance.

[Bumped]

Von Braun And Elon Musk

Is Elon Wernher’s heir?

Regardless of what NASA envisioned for COTS—indeed, regardless of what it had ever envisioned or accomplished under any program—the sum total of Congressional interest in NASA was always just ensuring a maximum of federal money goes into their district or state (and thereby, into their own campaign funds). So to their ears, COTS was simply another revenue stream that could go to Lockheed Martin, Boeing, or other established players under a slightly different operating scheme.

But a program that meant barely anything to Congress was taken up with enthusiasm by NASA as a way to modestly reduce the costs of one aspect of its program, and then “hijacked” by Elon Musk to radically and fundamentally alter the economics and pace of spaceflight. Every synergy he could find between NASA’s modest objectives and his own radical ones was exploited, driving the evolution of SpaceX technology and the rapid buildup of its infrastructure. No one saw him coming.

SpaceX’s conspicuous achievements only fed energy back into the system, driving NASA to become more ambitious, and the Congressional advocates of COTS to push forward with the commercial crew program. Only now were establishment forces in Congress beginning to raise eyebrows at SpaceX, but still did not yet see it as a threat. After all, transporting cargo was one thing, but surely crew flight was still over their weight class. This program, they assured themselves, would be a gimme for Boeing and/or Lockheed, and SpaceX would perhaps rise to a junior partner role in the system.

That confidence, however, quickly bled away as SpaceX continued to march forward with ever more drastic advances, offering prices far below a merely competitive advantage, and steadily developed hardware not even on the drawing board among the big prime contractors. Before these politicians knew it, and with the large-scale financial and technical assistance of NASA, a company they had barely heard of a few years ago was beginning to threaten the viability of long-established, multi-billion-dollar corporations with rock-solid Congressional relationships.

In a panic, the more powerful among them have repeatedly tried to scale back funding for commercial programs that would feed SpaceX, and sought to convince government agencies to throw roadblocks in its way in seeking additional contracts. But SpaceX’s popularity and political weight have grown even more quickly than its technical capabilities, and appears to be within a few years (at most) of transitioning from being an upstart to becoming simply the Program of Record.

Just as von Braun had originally hijacked a cruel, cynical weapon to pursue a dream of wonder and peace; as Korolev redirected the same dumb, unimaginative weapons program for his own people into achievements that will live in memory long after the name of the Soviet Union is long forgotten; and just as von Braun awakened a timid and pragmatic power to shoot for the Moon “because it is hard”; so it seems that soon — knock on wood — Elon Musk may have grown an afterthought commercial cargo-delivery program, one that sought merely to deliver junk to a space station at a slightly lower cost than before, into a revolution with no end, opening up the cosmos to humankind.

A very interesting, and I think insightful historical and political analysis.

Orbits And Suborbits

I’ve updated yesterday’s piece at Ricochet to clarify, for those in comments. I’ve probably discussed this here before, but…

Per discussion in comments, there seems to be some confusion about the difference between high-altitude flight, suborbital flight, and orbital flight. As John Walker points out, orbital flight requires a minimum speed to sustain the orbit, but while that is necessary, it is not a sufficient condition. In fact, a flight can be suborbital with the same speed (energy) as an orbital flight. The best, or at least, most rigorous way to define a “suborbit” is an orbit that intersects the atmosphere and/or surface of the planet. So if you launched straight up at orbital velocity, it would still be a suborbit, because it would (after an hour or two, I haven’t done the math) fall back to the ground. So John’s numbers in terms of comparative energy are roughly correct for the particular vehicles being discussed here (XCOR Lynx and VG SpaceShipTwo), they can’t be generalized for any suborbital vehicle (e.g., a sounding rocket isn’t orbital, but it goes much higher than those passenger vehicles, often hundreds of kilometers in altitude).

The speed necessary to achieve orbit is partly a function of the mass of the body being orbited, but it is also a function of its diameter, and whether or not it has an atmosphere. If the earth were a point mass, an object tossed out at an altitude equivalent to the earth radius (that is ground level) would have very little velocity, but it would have a lot of potential energy. It would fall, gain speed, whip around the center and come back up to the person who had tossed it. That is, it would orbit. So even for the relatively low-energy suborbital vehicles discussed in this post, the reason that they’re not orbital is simply that the planet gets in the way.

One other interesting point is that, under the definition above, subsonic “parabolic” aircraft flights in the atmosphere, to offer half a minute or so of weightlessness (offered by the Zero G company), are suborbital flights, in terms of their trajectory. I put “parabolic” in quotes because in actuality, if properly flown, they are really elliptical sections, as all orbits and suborbits are. The parabola is just a close approximation if you assume a flat earth, which is a valid assumption for the short distances involved. Galileo did his original artillery tables based on flat earth, which is why beginning physics students model cannonball problems as parabolas, but modern long-range artillery has to account for the earth curvature, and it does calculate as elliptical trajectories.

Finally, one more extension. Ignoring the atmosphere, every artillery shell fired, every ball thrown or hit, every long jumper, every person who simply hops up into the air, is in a suborbit. The primary distinction for the vehicles discussed is that they are in a suborbit that reaches a specific altitude (at least a hundred kilometers to officially be in “space”), and leaves the atmosphere.

Clear as mud?