January 14, 2004

Space is hard

In his posting A Quality All Its Own, Rand Simberg highlights the simple truth that small numbers of space launches does not provide enough experience to improve quality and reliability of launchers.

Mark Oakley also talks about the vicious chicken-and-egg cycle of low demand vs. high costs of space access in his Breaking the Cycle posting.

Posted by Tom Nugent at 09:21 AM | Comments (0)

No longer daily

OK, I'm giving up on posting daily. It could be done, but the size and quality of postings was not great. The whole point of this blog is to get me to improve my writing, and throwing out small, stream-of-consciousness ramblings wasn't serving the purpose. So I'm going to write when I can put up something at least a bit useful or interesting.

Posted by Tom Nugent at 09:18 AM | Comments (0)

January 07, 2004

Too much coding

I'm not a programmer, either by training or by trade. But I do an occasional bit of web programming for various projects. I spent a good hunk of the day today working on some PHP code, and I'm glad I'm not a programmer by trade. :-) It's interesting at a high level, but when it comes to debugging, I get sick of it. The debugging wasn't actually bad at all today; perhaps that's why I was able to make so much progress. But I know that debugging drives me crazy, and the errors I make are often very simple, dumb ones, which is what makes them so frustrating to find.

Posted by Tom Nugent at 10:41 PM | Comments (0)

January 06, 2004

Rocketry is hard, part 1

(I'll give you fair warning: This blog entry is going to be only half-baked, a semi-stream-of-consciousness wandering about problems with chemical rockets, based on arguments I've gone through over the last couple of years. At some point in the future I'll likely clean it up, but for now, rambling is what you'll get.)

Rocketry is hard. Really hard. That is, to make a chemical rocket which successfully ignites and launches onto its intended path is a complicated piece of systems engineering. There are different kinds of "difficult" when you say that something is hard. In one (over-simplified) sense, making a space elevator is difficult mainly because of the extreme material requirements (i.e., something with a strength-to-weight ratio at least an order of magnitude better than Kevlar). Chemical rockets, on the other hand, are difficult because they require so many interdependent systems to be designed all at the same time. You have to iterate back and forth on your choice of and pressurization of fuel and oxidizer, nozzle cooling method, plumbing, heat transfer, thrust to weight ratio of the engine, et cetera, and et cetera, ad nauseum.

The big problem with chemical rockets is, well, that they rely on chemical combustion for propulsion. The basic idea of a rocket is to throw mass (your propellant) in one direction so that your rocket will move in the opposite direction. You want to throw the propellant with as high a velocity as possible, in order to be more efficient. You "throw" propellant generally by making it hot and then expanding it out a nozzle. Currently the most efficient way to generate heat in propellant is to combust it in a rapidly oxidizing environment — explode it, in other words.

There's just one minor problem with this design. Exploding chemicals are difficult to control. A rocket is generally 85-90% fuel and oxidizer, by mass, and so your rocket is pretty much a big pile of explosives, waiting for you to toss on a match. If everything goes right, you can control the flow of fuel and oxidizer, keep just barely on the safe side of your material limits, and direct your thrust in such a way as to put you into orbit. Any small leak of fuel, or just a tiny bit too much unexpected heat, or a control problem in your thrust, and you're suddenly S.O.L. (Shit Out of Luck, if you haven't seen the acronym before).

There's another problem with rockets: they don't get used very often. This lack of flight experience means that the design process has lots of guesswork in it, which must be compensated for by tons of testing. In the last few years, there have been about 60 rocket flights per year throughout the entire world. Compare that to the number of automobiles that have been sold, or even the number of airplanes that have been flown, and you'll begin to get some idea of the scale difference in testing and feedback that car manufacturers get, and what rocket builders get.

It's getting late, so I think I'll continue this thread some other time.

Posted by Tom Nugent at 10:38 PM | Comments (0)

January 05, 2004

2003 space launch pace

Jeff Foust wrote an excellent article dated December 29th and titled "A year-end reality check". In it he argues that the launch industry is in a funk, and not launching at a "blistering pace" as one newsletter claimed. Read his article for details.

In another article on the same date, also on the Space Review website, Taylor Dinerman discusses the rockets that should be the future of the launch industry, as opposed to its current, lethargic present. With luck, the X Prize will be won by one of these companies in 2004.

Posted by Tom Nugent at 12:09 AM | Comments (0)

January 04, 2004

Housing this year

I'm one of those people who believes that the housing market is in some sort of bubble - maybe big, maybe small. I don't know how big it is, but there are a number of reasons to believe that the bubble exists.

First, there's a study I saw referenced perhaps six months ago (by John Mauldin in his excellent weekly newsletter) which claimed that historically house prices rise with inflation. But in the last 5-10 years, housing prices have risen about 30% higher than inflation, suggesting that they will fall or be flat for some time in order to match inflation.

Another factor arguing for a fall in housing prices is the fact that mortgage interest rates can't go much lower, and are generally expected to rise somewhat in the next year or so. If interest rates go up, then the amount of house any given buyer can afford goes down, and since it's the current buyers who determine the expected value of everone's houses, then it would seem that increased interest rates would drive down house prices.

Finally, the Baby Boomers are going to retire over the next decade, and many of them will probably move into other housing, which should create excess supply.

All of these factors and more indicate that housing prices should go down. But at the moment, on average, they're still going up. Here in the Boston region, rents have been going down a bit, while house prices are still skyrocketing, and this discrepancy is another factor indicating that something is out of whack in the housing system. I, however, don't have any good feel for how much prices might go down, and I don't think anyone else does either. Nor do we know when they might go down. So, if you wanted to buy a different house, what should you do? That question is one I'm asking myself right now, because we'd like to get a different house in which to raise our baby, but I'd rather not buy a bigger house right at the peak in housing prices. If you have a suggestion, please let me know what it is...

Posted by Tom Nugent at 10:58 PM | Comments (0)

January 03, 2004

Preparing for Baby, part 1 of many

What a day! As part of my in-laws' visit this week, today they helped us to re-arrange some of the furniture in our house in preparation for our baby. We decided to move our paperback book shelves into a coat closet, in order to free up space in the living room (and keep the books from prying little hands). We expected the bookshelves to fit in the closet a bit tightly, but without a problem.

There was a sea of books on our living room floor once the paperbacks were unloaded from the shelves. Jon (my father-in-law) and I worked on making supports for the bookshelves since we needed to lift them over some heating pipes in the closet. We got two out of three done today, and tested them out. It's really tight in that closet with those bookshelves in there!

The time went by quickly, but at the end of the day it certainly felt like a lot of effort was involved in something that sounds as simple as "moving the bookshelves." I'm wondering whether or not I'll have time to even breathe once the baby is actually here...

Posted by Tom Nugent at 11:58 PM | Comments (0)

January 02, 2004

New Year

D'oh. I missed another day. I blame it on my in-laws. :-) They flew into town late New Year's Eve, and yesterday we went out and registered at Babies R Us (a story in and of itself).

Regardless of my own lame excuses for not posting yesterday, this is a New Year. 2004. Seems like just yesterday we were getting over the Y2K scare. Where does the time go?

I had to pass along a funny quote from the Sluggy Freelance page today:

My 2004 Resolution is 1024x768!

It just made me giggle. If you haven't seen Sluggy Freelance, you should go read it - it's a hilarious online comic. Start from the beginning, because some of the funniest stuff happened early on, plus you'll be lost in the storyline if you start at this point.

Posted by Tom Nugent at 07:39 AM | Comments (0)