Category Archives: Space

Media Criticism, Space, Technology and Society

The Myth That Won’t Die

May 12, 2009 Rand Simberg 6 Comments

Once again, scramjet proponents are touting them for space access:

Officials hope the engine eventually will provide a speedier transition between conventional aircraft in the atmosphere and rockets in outer space for deployment of satellites, and reconnaissance or strike missions.

“The long-range goal of this for the Air Force is access to space,” said Charlie Brink, an Air Force Research Laboratory propulsion directorate official who manages the X-51 program from Wright-Patterson Air Force Base.

I wonder if he’s actually done any systems studies to see whether that’s going to pan out? I have.

I’m all in favor of scramjets — they have lots of interesting and useful military applications, but it is very unlikely that they will be helpful for space access. I won’t repeat what I wrote the last time this issue came up (geez was it really five years ago?), but you can go read it here:

Proponents claim that by allowing airbreathing up to high Mach numbers, there is no need to take along as much oxygen for the rocket engines, because they can gather it for “free.” This argument assumes that space transportation is expensive because propellants are, but those aren’t the cost driver. If they were, space would already be affordable, because liquid oxygen is actually about as cheap as milk. Propellant costs are such a tiny fraction of launch costs that they’re down in the noise. If we ever get to the point where they become a real issue (as they are for airlines), we’ll have solved the problem.

Their argument also fails on the grounds that collecting oxygen isn’t really “free.” As the old joke goes, there’s no free launch.

If your space transport were to be single stage, you’d now need three propulsion systems — conventional jet, scramjet, and rocket for when you left the atmosphere (which you must do by definition to go into space). It may be possible to have a scramjet lower stage and a rocket upper stage, but the bottom line is that time spent in the atmosphere (necessary to utilize the scramjet) is time spent fighting drag, defeating the purpose. Rockets want to spend as little time as possible in the atmosphere, and carrying two other kinds of engines along and spending enough time in the air to utilize them, just to save on a propellant as cheap as oxygen, just doesn’t make design sense.

In addition, a scramjet engine is designed to operate at a specific vehicle speed, and has poor performance in “off design” conditions, rendering it a poor propulsion choice for an accelerating vehicle.

Henry Spencer debunked airbreathers to orbit earlier this year as well.

Star Trek

May 12, 2009 Rand Simberg

…as reviewed by one of its greatest fans (in multiple meanings of the word): Lileks. Possibly spoilers, but not a lot of plot reveals, so perhaps safe for those who haven’t seen (I haven’t).

Space

Misguided

May 11, 2009 Rand Simberg 19 Comments

It’s always interesting when an outsider comes into the space community to try to educate us on why we don’t have low-cost space access, particularly when he’s clearly unfamiliar with the history and literature on the subject. It happened again this morning at The Space Review. I was going to write something more extensive about it, but Clark beat me to it.

Political Commentary, Space

Bad News About Augustine

May 11, 2009 Rand Simberg 5 Comments

Bob Park is a big fan.

Economics, Science And Society, Space, Technology and Society

Why Space?

May 11, 2009 Rand Simberg 13 Comments

With yet another national commission on the subject being formed, Dennis Wingo has some thoughts.

Business, Space

Commercial Friendly?

May 9, 2009 Rand Simberg 1 Comment

Taylor Dinerman says that NASA is finally moving in the right direction. We’ll see. Particularly after the Augustine review.

Humor, Satire, Space

The Mission Continues To Shrink

May 8, 2009 Rand Simberg

Doug Messier has a scoop on the latest cost cutting efforts at NASA. One small step for a dummy, one giant leap for dummykind.

Political Commentary, Space

Reading The Tea Leaves

May 8, 2009 Rand Simberg

There’s a lot of interesting and disputatious discussion of the NASA budget and its implications for Ares I over at Space Politics this morning.

Business, Economics, Space

Virgin Vision

May 7, 2009 Rand Simberg 28 Comments

Will Whitehorn talks a good game:

He foresees uses of the spaceship for science experiments, for example as an alternative to visiting the International Space Station or using unmanned flights for pharmaceuticals companies seeking to use microgravity to change particles.

Later, the aircraft could be used to launch small satellites or take other payloads into space, Whitehorn says. “We could put all of our server farms in space quite easily…”

…Eventually, he sees the possibility of transporting passengers to terrestrial destinations in spacecraft outside the atmosphere instead of by plane. He says a journey from Britain to Australia could be done in about 2-1/2 hours.

“That’s a 20-year horizon,” he said.

I’d take that a lot more seriously if he had liquid engines…

And of course, he never misses an opportunity to bad-mouth the competition:

Virgin is not the only non-governmental party trying to develop space travel in the private sphere, but Whitehorn is confident it will be the first to take passengers into space.

SpaceX, led by veteran Silicon Valley entrepreneur Elon Musk, is developing space-launch vehicles but they are not designed to carry passengers.

Well, yes, if you ignore the Dragon…

And of course, XCOR might beat them, though if they don’t get to a hundred klicks, the claim will be that they’re not in space, despite the stars, curvature of the earth, and minutes of weightlessness.