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space (spās) n. 1. space beyond the atmosphere of the earth.

prag·ma·tism (prgm-tzm) n. A way of approaching situations or solving problems that emphasizes practical applications and consequences.

Tuesday, April 19, 2005

Heavy Lift vs Multiple Lift : Why I write this blog

Okay, I have been behind lately and there a lot of ideas I have on the back burner but this the Heavy Lift vs Multiple Lift debate is poking its head a lot lately. This is exactly the kind of thing I started this blog for.

Rather than filling this post with a lot of quotes (which are really not the point) from the debate, I am going to speak my mind and provide links at the bottom.

For those in my target audience who have, thankfully, been spared the details of this almost religious debate, here is the gist of it. A heavy lift rocket (or vehicle) is a big rocket, such as the Saturn V, which can carry around 118 metric tons to LEO (about 260,000 lbs). A medium lift rocket is along the lines of the Boeing Delta IV medium lift rockets, which can carry about 12 metric tons or 26,000 lbs to LEO.

I am sure your first reaction is well the big one got us to the Moon last time. That is true. In order to for medium lift rockets to carry us to the moon, there will have to be multiple launches of pieces which link up in orbit and then go on to the Moon or Mars or wherever.

Those of you with well thought out and long held opinions, please forgive me for this oversimplification. I don't have the time or the stomach for all the statistics and IMHO minor points.

The argument can be broken down to this. Heavy lift gets you few launches, and therefore fewer chances for failure. Also, as I am sure propionate would be sure to point out, no (or at least fewer) difficult "hook ups" in orbit. Launch and go straight to the Moon.

Multiple launchers will give the same fact, but the interpretation is different. More launches gives you more redundancy, so while there is more chance for a single failure, there is less chance of a mission failure. The launches are cheaper and frankly when we get to "beyond" no heavy lift vehicle is going to big enough for a direct trip. "Hook ups" are going to have to happen eventually. Plus we already have medium lift vehicles. No development cost for the rockets.

I have read both arguments and you know what. Your both right. It's called a trade-off. Pick one. You know what the fastest way to the Moon is? By building and launches some rockets. There is a term in Software Engineering (stolen from the Navy I think) "paralysis by Analysis." If you continually analyze the options, hopping one will prove a the perfect choice, you will be studying it for years. Follow the Agile Methods for software Engineering. Just build something. If it works, great, if not, build something else.

Work is always more productive than debate, in the long run.

If we build a heavy lift vehicle, I believe we will get to the Moon. If we don't , I believe we will get to the Moon. If we don't choose and get behind our choice, we will go nowhere.

Links for information: (These are all people I respect)

Rand Simberg's Views
Clark Lindsey's Views
Bob Zubrin's Views
Mike Griffins Views
Jon Berndt's Views (of the AIAA)


DDAY said...

"Just build something. If it works, great, if not, build something else."

This is not a viable option when the things that are under discussion cost tens of billions of dollars. You have to have a sense that it will work before you decide to spend all that money.

In addition, your premise is flawed--you assume that because a few people with websites have discussed the issue it has therefore been analyzed to death. It hasn't. Blogs are not a viable alternative to parametric cost analysis. Detailed cost analysis of these options has not been done and needs to be done. There have been far too many vast, sweeping generalizations and not enough careful analysis.

Dan Schrimpsher said...

Okay, it was a simple statement. I don't mean build a rocket, then scrap it and build another. But you gotta start somewhere.

And you are wrong. This same argument was debated during the Apollo missions. Books have been written about it. I am forewarning what I see as a storm of point and counter-point.

And just to point out, either will work....

Rob said...

"If we don't choose and get behind our choice, we will go nowhere."

You seem to be assuming that there will never be a free market in space transportation. Why choose? In a free market, there's no reason not to do both. Technology is only part of the story in creating an economical and profitable space transportation system. Remember the VCR format wars! The market itself will sort things out. May the best entrepeneur win!

Dan Schrimpsher said...

I am. And If we do not get off this rock, I do not believe a viable, long-term free market space launch market will exist. The transcontnential railroad wouldn't have worked if people weren't moving out west in the first place.

I would like to think that with cheaper lauches, groups of exploreres would pool there resources and start a private space colony on the Moon, or Mars, or wherever. But I don't beleive it. I think (sadly) the government is going to get us out there and the private enterprise will follow.

Rob said...

Dan - With all due respect, this kind of "only a push from the government will make people do anything" line just doesn't make sense to me. I've seen way too much evidence for a long time that there are any number of people who would jump at the chance to do something if they had the opportunity. There is no doubt in my mind that there are plenty of human beings who want to be explorers and pioneers. Take Paul Allen, for starters. He put his own money into SpaceShipOne, and he's not the only person doing that. The best thing the government can do to encourage more people to get involved in building a private spance transportation industry is to get out of the way. Read Burt Rutan's latest interview on

Dan Schrimpsher said...

Okay, fine. I love that idea. Truth be told, I would prefer private companies to build the first moon colony. Then I could guarntee my spot with cash. I don't see history bearing it out, but you never know. Louis & Clark could have opened the west for Fred's Cart and Buggy company rather than Jeffereson. Columbus could have come for the Swiss Chocolate Cooporation instead of Spain.

History shows governments spending money to open up frontiers and people coming behind them to make money (fur traders, trading posts, and evetually homesteaders).

I would argue Sub-orbit and orbit are no longer frontiers, so bring it on. If we can talk NASA into buying launch services I would be thrilled. But, I belive that the Moon is still a frontier.

Doesn't affect the argument, though. Private companies have to make this same decision and I am sure, internally, they will be faced with the same argument. Granted it will likely be less "paralysis by analysis" as there is a "dictator" in a company who can force a decision to be made.

Of course this is not a one or nothing, each launch company can pick there own method to get to the Moon.

Michael Mealling said...

Well, since there wasn't chocolate before Columbus that would have been hard. Lewis and Clark ran into fur traders and Indians who had been trading with Europeans at several points along their route. They weren't the first ones into that region. They were just the first ones to map a direct route.

I think the discussion also needs to differentiate between private effort, private money, public effort and public money. Using public money to pay for a private mission is much more enabling of an industry than public money going to fund a government agency doing all of the work. SpaceX's recent $100 million Responsive Small Launch contract is a good example of public money that enables private/cheap access to space.. NASA folding CEV integration and management back into NASA isn't.

Plus, everyone getting behind "one big program" simply results in something that isn't robust enough to statistically significant numbers of us off planet. Private enterprise might be a bit slower at the beginning but it is capable of a hockey stick effect whereas government funded programs aren't.

BTW, I've blog rolled you on Rocketforge...