Category Archives: Economics

Business, Economics, Political Commentary

Milquetoast Mitt

21 Comments

Mark Steyn says that Romney has to get a little more apocalyptic:

As noted here previously, the International Monetary Fund predicts that China will become the world’s dominant economic power by 2016. So the guy elected in November will be the first president since Grover Cleveland to know what it feels like to be the global also-ran. Even this, however, understates the size of catastrophe the United States faces. There are no precedents in history for a great power spending itself to death on the scale America is doing. Obama has added $5 trillion to the national debt, and has nothing to show for it. Do you know how difficult that is to do? Personal debt per citizen is currently about 50 grand, but at least you got a La-Z-Boy recliner and a gas-fired barbecue out of it. Obama has spent America’s future, and left no more trace than if he and his high-school “choom gang” had wheeled a barrow of 5 trillion in large notes behind the gym and used them for rolling paper. Right now, combined total debt in the United States is just shy of $700,000 per family. Add in the so-called “unfunded liabilities” that a normal American business would have to include in its SEC filings but that U.S.-government accounting conveniently absolves itself from, and you’re talking about a debt burden per family of about a million bucks. In other words, look around you: the paved roads, the landscaped shopping mall, the Starbucks and the juice bar and the mountain-bike store . . . There’s nothing holding the joint up.

Hmm. “There’s nothing holding the joint up. Steyn 2012”: How’s that poll with the focus groups? Not exactly “Morning in America,” is it? But what happens when you blithely ignore debt for a few decades? Here’s a headline from the Wall Street Journal’s “Smart Money” this very week: “More retirees are falling behind on student debt, and Uncle Sam is coming after their benefits.” Maybe that’s the slogan. “It’s twilight in America: More retirees are falling behind on student debt.”

The good news is that this was probably written before the news of the Ryan pick. It will be interesting to see Mark’s response to that.

Business, Economics, Mathematics, Space, Technology and Society

My Mars Spreadsheet

32 Comments

As a response to popular request (actually, no one asked except Jon Goff), I’ve cleaned up and uploaded my spreadsheet.

Other than the astonishing results themselves, the only thing that makes me suspicious is that the total delta V required for the mission with the stop for gas is less than that required for the direct trip (about seven km/s for the latter and about six for the former). But I’ve looked at it multiple times, and don’t see anything wrong with what I did. I’m guessing that, if this is right, it has something to do with the oddities of patched conics. But it would be nice to get some more eyes looking at the problem.

[Update a few minutes later]

Don’t waste too much time looking at that. I just noticed some problems. I’ll update when I’ve fixed.

[Update a few minutes later]

OK, I’ve uploaded a new version. The good news is that I found the problem, and the total delta V is now more for the trip with the gas stop than without (which it seemed it should have been). It’s now about four and a half kilometers per second for the direct case, and about six for the gas stop. The bad news is that the advantage has dropped significantly. The propellant ratio, rather than ten and more than twenty for the EML1 and LEO cases without refueling, is now more like three and five. Still, it’s a significant improvement.

I should note that this is an excellent example of a need to have a feel for the numbers, and not just trust what comes out of a computer (as I fear too many young people do these days). If you don’t know intuitively proper orders of magnitude, or recognize suspicious results, you’re likely to make a lot of errors when doing complex calculations, particularly if you are operating in an environment of confirmation bias (I really, really liked the first, incorrect results). I’m looking at you, climate modelers…

[Update a few minutes later]

One more update to the spreadsheet. I noticed that in fixing the calculations, my delta Vs had become unbalanced, so I adjusted the gas station orbit slightly to rebalance them. The new orbit is 1.256 AU.

Business, Economics, Space, Technology and Society

Refueling On The Way To Mars

26 Comments

In my talk on the commercial space panel at the Mars Society Convention on Saturday afternoon, one of the things I said that we needed was “gas stations on the road to Mars.”

I’d never really thought about it much, because I don’t think about Mars much, but I wondered just how advantageous it was, so I decided to take a break from the space safety stuff and play with the idea in a spreadsheet. I haven’t triple checked the numbers yet, but what I found blew me away. For a hundred metric tons of payload delivered to Mars orbit in the vicinity of Phobos, I looked at three mission scenarios: departure from LEO direct to Mars, departure from EML1 direct to Mars, and departure from EML1 with a fuel stop half way. For the latter scenario, you can deliver a ton of payload to Phobos’s orbit for less than a ton of propellant. For the EML1 scenario without refueling, it takes over ten times as much. For the LEO scenario, it takes over twenty times as much. That is, for the refueling scenario, you start with an IMEML1 (Initial Mass in EML1) of about a hundred and fifty tons, two thirds of which is payload bound to Mars (the total mission propellant needed is twice as much as you start with, because you pick up the other half, about 43 tons, on the way). For the non-refueling case in EML1, the IMEML1 is over a million tonskilograms, and for the LEO case, IMLEO is almost two-and-a-half million tonskilograms.

Such is the power of the rocket equation, and refueling.

What’s the catch? There are two. First, of course, it assumes the delivery of the propellants to EML1 and the gas-station orbit. If it were done chemically, the savings would go away, but it could be done electrically. The other catch is that it obviously both complicates and increases the time of the mission. I’d recommend it for cargo only. The gas station orbit I chose was at a distance of 1.25 AU, which turns out to exactly split the delta V between earth departure and Mars arrival, which means that you just refill the tanks at the gas station. That orbit turns out to have a synodic period with earth of about three and a half years, and with Mars of about five and a half years. But with the savings, you could afford to put a dozen stations in that orbit, which would give you an opportunity every month, and then you could take more of the savings and do faster trajectories, so you don’t have to wait for Hohmann line ups.

If anyone wants to check my numbers, I ignored the moon’s gravity, just doing a departure from EML1 starting at EML1 velocity with patched conics (same thing going into Mars orbit to co-orbit with Phobos). I used a stage fraction (ratio of propellant to total stage weight) of 0.85 and an ISP of 460 seconds (lower ISPs would just make the numbers even worse for the non-refueling scenario). I also didn’t do any aerobraking at Mars, so the numbers would work the same in either direction. So if PR wants to sell water, that’s the location for the gas station — 1.25 AU.

[Update a few minutes later]

Just looking at the difference between LEO and EML1, it seems insane to not use propellant depots with electric propulsion.

[Update a while later]

Let me put this another way. This implies that you could deliver a hundred metric tons (that is, 80% of a Saturn V payload) to Mars orbit in four Falcon Heavy launches. Two launches for electric depots (one of which has cryo propulsion, probably RS-68 class if you can start it in space, or a bunch of RL-10s if you don’t mind the gravity loss) and two for the payload. Less than half a billion in transportation costs to LEO. Leaves a lot of money left over for the other stuff.

[Late afternoon update]

OK, I found an error in the spreadsheet. As I note at the new post, the propellant advantage is not as dramatic as I indicate above, but it is still significant.

Business, Economics, Media Criticism, Political Commentary

The Depravity Of Nancy Pelosi

48 Comments

Jonah Goldberg is fed up:

The dishonesty and/or stupidity of all this is really quite breathtaking — and obvious. First of all, you could cut government funding down to 1950 levels and still have money for food safety. But this is what liberals do. They metaphorically lash children to the fenders of government so that the budget cutting blade must slice through them first. Then, after insanely putting them in harm’s way, they proclaim it is the sane budget cutters who seek to harm children. In fairness, sometimes liberals hold the young human shields in reserve and put firehouses, historic monuments, and old-age homes outside the budgetary walls of the fiscal keep. And, again, they declare that the fiscally sane want to get rid of fire fighters and the Washington memorial — and not, say, the Export-Import Bank or agricultural subsidies.

And too many people buy their BS, judging by polls. What’s most infuriating, of course, is that their partners in crime in the media don’t call them on it.