Category Archives: Space

Space

Hubble Fix

16 Comments

Fifteen minutes until launch. We’re heading over to the beach to watch. It will be the last Shuttle mission ever to launch due east.

[Update a while later]

Well, that was the first time we ever tried to watch from Spanish River Park. The problem is that down here, the beach runs north and south, but the Cape is north-northeast of us, so the launch actually starts inland from our vantage point, and there was an apartment building blocking the lower portions of the ascent. From here (about a hundred fifty miles away) we saw the first-stage burn once it cleared the building, but once the SRBs went out, there was nothing left to see. Too far away and the sun was too bright (another cursed day of no clouds and no rain here, with us almost a foot below normal rainfal for the year). If it had been dark, we would have no doubt seen it much longer.

[Tuesday morning update]

In comments, I speculate on how they’ll inspect the Shuttle tiles (the first priority, so they know ASAP whether or not they’ll have to launch a rescue mission). Here’s a description of the process.

[Afternoon update]

So they found a few dings, but it doesn’t look like anything serious.

[Bumped again]

Media Criticism, Space, Technology and Society

The Myth That Won’t Die

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.

Business, Economics, Space

Virgin Vision

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.