This seems like a pretty big exclusion area for the satellite shot on Thursday. Is it going to disrupt airlanes? I’d be pretty annoyed if my trans-Pacific flight was delayed for it.
Category Archives: Space
What Do They Know?
As Clark says, I don’t know why anyone would think that space scientists or astronauts are experts on business. I don’t really care what Kathy Sullivan thinks the prospects are for suborbital tourism, and if I thought that astronauts’ opinions on the matter were of value, I can find many astronauts (including John Herrington, Rick Searfoss, etc.) who would disagree with her.
And who is this “Alvin” Aldrin of which they speak? Is that Andy’s evil twin? When I do a search for “Alvin Aldrin” I only get one hit–this article.
A couple other questions for Alvin/Andy. What numbers was he using for the Raptor cost? Marginal, or average per-unit? It makes a big difference.
In addition, I always get annoyed when people use a military fighter as a cost analogue for a spaceship. A lot of that dollar-per-pound number for the plane comes from something in it that weighs nothing at all–software. The avionics for the weapons systems, and the defensive systems are non-trivial in cost as well. Designing a combat aircraft, designed to kill other things and avoid being actively killed by other things, is an entirely different problem than designing a vehicle that has to only contend with passive and predictable nature (and pretty benign nature, for the most part, at least for suborbital). I’d bet that Burt’s own cost numbers for the SS2 already put the lie to Andy’s chart.
[Late afternoon update]
Jeff Foust has a much more extensive writeup of the discussion, which he apparently attended. As I suspected, it was Andy, not Alvin, Aldrin.
A Kludge
Is this the future of air travel?
Engineers created the A2 with the failures of its doomed supersonic predecessor, the Concorde, very much in mind. Reaction Engines’s technical director, Richard Varvill, and his colleagues believe that the Concorde was phased out because of a couple major limitations. First, it couldn’t fly far enough. “The range was inadequate to do trans-Pacific routes, which is where a lot of the potential market is thought to be for a supersonic transport,” Varvill explains. Second, the Concorde’s engines were efficient only at its Mach-2 cruising speed, which meant that when it was poking along overland at Mach 0.9 to avoid producing sonic booms, it got horrible gas mileage. “The [A2] engine has two modes because we’re very conscious of the Concorde experience,” he says.
Those two modes–a combination of turbojet and ramjet propulsion systems–would both make the A2 efficient at slower speeds and give it incredible speed capabilities. (Engineers didn’t include windows in the design because only space-shuttle windows, which are too heavy for use in an airliner, can withstand the heat the A2 would encounter.) In the A2’s first mode, its four Scimitar engines send incoming air through bypass ducts to turbines. These turbines produce thrust much like today’s conventional jet engines–by using the turbine to compress incoming air and then mixing it with fuel to achieve combustion–and that’s enough to get the jet in the air and up to Mach 2.5. Once it reaches Mach 2.5, the A2 switches into its second mode and does the job it was built for. Incoming air is rerouted directly to the engine’s core. Now that the plane is traveling at supersonic speed, the air gets rammed through the engine with enough pressure to sustain combustion at speeds of up to Mach 5.
A combination turbofan/ramjet. Hokay.
If I understand this properly, the idea is to fly fast subsonic over land to avoid breaking windows, and then to go like a bat out of hell over the water. When I look at that design, I have to wonder how they can really get the range, with all of the drag that is implied from those huge delta wings, not to mention the wave drag at Mach 5. I also wonder where they put the hydrogen–that stuff is very fluffy, and needs large tanks. It’s probably not wet wing (it would be very structurally inefficient), which is why the fuselage must be so huge, to provide enough volume in there for it.
Sorry, but I don’t think that this will be economically viable. As is discussed in comments and the article, hydrogen is not an energy source–it’s an energy storage method, and it’s unclear how they’ll generate it without a greenhouse footprint. Moreover, it’s not as “green” as claimed, because dihydrogen monoxide itself is a greenhouse gas. I’ll bet that this thing has to fly at sixty thousand feet or more to get itself sufficiently out of the atmosphere to mitigate the drag problem, and that’s not a place where you want to be injecting a lot of water.
This concept doesn’t learn the true lessons of Concorde: like Shuttle, a lot of people have learned lessons from Concorde, but the wrong ones. The correct lesson is that we need to get rid of shock waves and drag. Once we do that, we’ll be able to cruise at reasonable speeds (say, Mach 2.5) everywhere, over both land and water, so we won’t have to build the vehicle out of exotic materials and eliminate windows. We’ll also be able to have fast transcontinental trips (two hours coast to coast) which is another huge market that this concept doesn’t address at all. Finally, it has to do it with a reasonable lift/drag ratio, so that ticket prices will be affordable. And I think that the fuel issue is superfluous–Jet A will be just fine for the planet, as long as fuel consumption is reasonable, which makes the vehicle design much easier, with much more dense fuel.
Fortunately, I’ve been working for over a decade with a company that thinks it knows how to do this, and I’m hoping that we’ll be able to start to move forward on it very soon.
[Via Clark Lindsey]
[Update in the late afternoon]
In response to the question in comments, there’s not much publicly available on the web about shock-free supersonics, but here’s a piece I wrote a few years ago on the subject.
Never Mind
There was a little bit of a buzz in the blogosphere a few days ago about Gizmodo’s report that the Japanese plan to bombard the planet with frickin’ laser beams from outer space. No word on whether or not they would be attached to the heads of sharks.
I thought it was a little strange, myself. While lasers have been proposed for space solar power, most of the concepts over the past four decades (ed– wow, it’s really been four decades since Peter Glaser came up with the idea? Yup) have been to transmit the power with microwave beams. Lasers (probably free-electron lasers with tuned frequencies) have the advantage of higher power density (and thus less need for large ground receivers). But they don’t penetrate the atmosphere and clouds as well, and they are less efficient for power conversion. Also, they raise exactly the fear described in the Gizmodo piece–that higher power density is a double-edged sword. Microwaves are preferred because the energy conversion efficiency is very high, and the beam density is less than that of sunlight (it’s better than sunlight despite this, because the beam is available 24/7 and the conversion efficiency is much better, at least with current solar cell technology). It’s much more difficult to weaponize, by the nature of the technology.
Anyhoo, I’m assuming that what was actually being referred to was this:
On February 20, JAXA will take a step closer to the goal when they begin testing a microwave power transmission system designed to beam the power from the satellites to Earth. In a series of experiments to be conducted at the Taiki Multi-Purpose Aerospace Park in Hokkaido, the researchers will use a 2.4-meter-diameter transmission antenna to send a microwave beam over 50 meters to a rectenna (rectifying antenna) that converts the microwave energy into electricity and powers a household heater. The researchers expect these initial tests to provide valuable engineering data that will pave the way for JAXA to build larger, more powerful systems.
Microwaves, not lasers, as Gizmodo mistakenly claimed. The article does mention lasers as a potential means of getting the power down, but that’s not what next Wednesday’s test is about.
This Makes No Sense
AP is reporting that the Pentagon is planning to “shoot down” the errant NRO bird.
You can’t “shoot down” a satellite. In order to do so, you have to remove its momentum, so it falls out of orbit. All you can really do (at least with something as crude as a missile) is break it up into smaller pieces. If that’s what they plan to do, they certainly can.
Won’t it make a mess? Yes, for a while. Some of the pieces will enter immediately, others will be given a higher apogee (but lower perigee, so they’ll enter half an orbit later). The orbits of those that aren’t given much of an energy change will continue to decay as the satellite’s original orbit was, except at a higher rate, because they’ll have a lower mass/drag ratio. So in theory, if they do this, all of the pieces will have entered within a month or so (i.e., none of them will survive longer than the satellite itself is expected to).
This just points up the fact, once again, how nice it would be to actually have a robust in-space infrastructure of tugs and servicing facilities that would allow us to take care of things like this in a more elegant fashion. In fact, it would allow us to even go get the thing and put it in the right orbit, so we wouldn’t have to dispose of it, and replace it. Unfortunately, it’s not a capability that either NASA or the Air Force evidence any interest in developing.
[Late afternoon update]
Daniel Fischer is live blogging the Pentagon briefing on NASA TV, here and here.
Overblown Headline
Sorry, but there’s nothing classified about the Space Shuttle, as this silly headline implies:
Former Boeing Engineer Charged with Economic Espionage in Theft of Space Shuttle Secrets for China
If one reads the article, what is really at issue is Rockwell (now Boeing) trade secrets–that is, proprietary information, presumably on things like materials and manufacturing techniques. Language like this simply reinforces the mistaken notion of many that NASA, and the Shuttle program, are military in nature. Not that that excuses the spy, of course–he should still be prosecuted, because in theory, it could help the Chinese advance their technology. Though in the case of the Shuttle, as Charles Lurio notes in an email, it will probably set them back ten years.
Of course, if we really wanted to set them back and keep them planet bound, we’d send them the current plans for Ares and Orion…
[Update a few minutes later]
Just in case anyone is wondering, while this guy presumably worked in Downey during the eighties, I never knew him, or even heard of him, until now.
A Billion Here, A Billion There
There’s an interesting post on military aircraft procurement over at Winds of Change today (interesting if you’re interested in such things, that is).
Norm Augustine, former head of Martin Marietta (now part of Lockheed Martin) wrote an amusing (and insightful) book back in the eighties called “Augustine’s Laws” (it’s now on its sixth edition
One point made in comments over there is that the reason these things cost so much per unit (I was shocked to read that the Raptor is a third of a billion dollars per unit) is because it includes amortization of the development and fixed production costs–if they had decided to purchase the originally planned seven hundred, the price per aircraft would be much lower. The problem is that, though we get more bang for the buck, we never want to spend that many bucks.
We did the same thing with the Shuttle. It was about a five-billion-dollar development program, in seventies dollars, but when the fleet size was cut from seven to five during Carter-Mondale (Mondale actually wanted to completely kill the program) as a cost saving, the price per orbiter went up a good bit. It would have probably only cost an additional billion or so to get the two extra vehicles, and we’d be in a lot better shape now (all other events since being equal) with a remaining fleet of five, instead of three. Having had two more might have made us more willing to continue to press forward even in the face of the losses, because even if the president hadn’t decided to end the program next year, we’d probably have to do it anyway, particularly if we lost one more, and had only two left. In fact, one of the few smart moves made on the program in the eighties was to order “structural spares” (things like the titanium keel and spar) before the production was shut down and tooling dismantled. That allowed us to build Endeavor after Challenger, something that would not have been possible otherwise, and in the absence of that new vehicle, we’d have been down to two after the Columbia loss.
We’re not just penny-wise pound-foolish in production. The Shuttle has a similar problem in ops. If we’d had more vehicles, and made the investment in facilities for them, we could have doubled the flight rate, without that much of an increase in annual fixed costs (perhaps a billion more a year). Which would have been a better deal: four flights a year for three billion a year (a typical number), resulting in a cost of three quarters of a billion per flight, or eight flights a year for four billion, with a cost of half a billion per flight?
Neither number is attractive, but the taxpayer would have gotten a lot more for the money if the purse strings had been loosened on the program. It might have made it a lot more sustainable.
Uh Oh
A post that I just put up today is now in the top ten (number eight, right now) of a Google search for “Mike Griffin NASA.” And I didn’t even get an Instalink on it.
Then And Now
Who’s got it right, the Mike Griffin of today, or the Mike Griffin of five years ago?
In the 1950s and 1960s, the term “man rating” was coined to describe the process of converting the military Redstone, Atlas, and Titan II vehicles to the requirements of manned spaceflight. This involved a number of factors such as pogo suppression, structural stiffening, and other details not particularly germane to today’s expendable vehicles. The concept of “man rating” in this sense is, I believe, no longer very relevant.
Does he still agree with this congressional testimony?
Now to be fair, he may not be saying that Atlas isn’t safe enough–he expresses interest in using it for COTS. The problem, as Jon Goff points out at the Space Politics thread, is that he’s chosen an architecture that replicates Apollo, which requires a large CM and SM on a single launch. If one is willing to break these up into separate launches, an EELV can handle it easily. But instead of spending his budget getting flight rate up and launch costs down, and doing the R&D necessary to learn how to truly become spacefaring (e.g., space assembly, docking/mating, propellant storage and transfer), he wants to relive the days of von Braun.
Clean Ascent
Looks like there were no tile problems yesterday, and the ECO sensors performed as advertised.
It’s kind of ironic that they seem to have finally wrung some of the last bugs out of the system just before they’re going to retire it.
You know, given what a technical and economic disaster ESAS is turning out to be, I could be persuaded to extend Shuttle past 2010 at this point, and just wait for the private sector to take over its duties, particularly if the money would go toward a propellant depot and the development of lunar injection and landing hardware. I don’t know what it would take to resurrect the contracts and production lines that have been shut down, though.