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Broken Logic

There's an interesting discussion in comments over at Selenian Boondocks on the value of microgravity processing (that veers into other subjects, such as utility and value of propellant depots). I think that Jon gets the better part of the argument, and that "Googaw" is overreacting to overhype. Not to mention ignorant of orbital mechanics. As Jon says, I don't think that he's thought through the concept of a propellant depot in GTO.


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googaw wrote:

Do you care to try to justify these slanders?

Rand Simberg wrote:

Can you be more specific, or are you attempting to extend your illogic?

googaw wrote:

You have made four false claims, without even an attempt to justify them:

(1) that I am overreacting to overhype.

(2) that I don't understand orbital mechanics.

(3) that I haven't thought through the relative benefits of GTO vs. other orbits for orbital depots (specifically the debate was GTO vs. 28 degree low earth orbit).

(4) That I have committed some logical fallacy.

Forget about (1), as it's mere opinion. But (2)-(3) are statements of fact about me for which you have no clue, and there is no writing by me demonstrating any sort of logical fallacy. Prove your statements or retract them.

Rand Simberg wrote:

I base numbers two and three on your supposition that a GTO propellant depot makes sense. You'll have to provide some quantitative analysis to put these to bed.

I base number four on number one...

googaw wrote:

In other words, you make up lies about my knowledge and expertise based merely on the fact that your opinion disagrees with my opinion. Then, instead of making any serious effort to back up what you say, you want a free tutorial in orbital mechanics! If you do not apologize and retract your slanders, it is you who will have proven that you are a truly sleezy character.

Rand Simberg wrote:

If you do not apologize and retract your slanders, it is you who will have proven that you are a truly sleezy character.

Well, boo, and hoo. Sorry, no, I have no need of tutorials on orbital mechanics. I used to do it for a living. Still do, occasionally, actually.

Guess I'll just have to live with your whining, until you can actually justify your comments that I criticized.

I'm wondering why an anonymous coward would be so upset about having their orbital mechanical knowledge criticized. But then, I always wonder about anonymous cowards.

Just who is it that I'm supposed to "apologize" to, and who is it that I've slandered...?

Do I have to instruct you in the law, as well as orbital mechanics?

googaw wrote:

Guess I'll just have to live with your whining,

No, you and your readers will have to live with the knowledge that you are a sleazebag who makes up lies about people rather than engaging in serious discussion. You need go no further than examining your own blogging tactics to discern why serious professionals like myself use nom-de-plumes when engaging in Internet discussions.

Rand Simberg wrote:

No, you and your readers will have to live with the knowledge that you are a sleazebag who makes up lies about people rather than engaging in serious discussion.

In your dreams. Apparently, you're as unfamiliar with the concept of "lies" as you are with orbital mechanics and "slander."

Do you have any concept what a laughing stock you make of yourself here?

Probably not. Clueless squared is always a tragedy.

Ryan Olcott wrote:

I found the comment thread over at the boondocks to be interesting, and when taken together, Jon's and Googaw's comments I thought complemented each other well by inspiring a greater insight of the topic...

but... uh... this behavior isn't making either of you look good, and it pains me to say it.

Rand Simberg wrote:

I'm very sorry you feel that way, Ryan. How would you suggest that I had responded to "googaw's" anonymous complaints about being slandered?

Ed Minchau wrote:

There is no slander going on here. Slander is spoken, not printed. Googaw, the word you are looking for is "libel". Gee, looks like I learned something from that first Spiderman movie.

Habitat Hermit wrote:

Heh libel against someone anonymous? I'm sure everybody anonymous are deeply offended... maybe you should make it a class action suit googaw? ^_^

Next to zero real content (or at least nothing new) just boilerplate criticism and denial mixed with a bad attitude: smells like a troll.

Rand Simberg wrote:

Actually, libel is published words. I think that it's still legally unsettled whether or not a blog (or a comment on the web) is considered a publication, at least for the purposes of determining whether it is libelous or slanderous. But I'm pretty sure that it's not possible to either slander or libel an anonymous entity.

Larry J wrote:

The point remains that Rand is right and googaw is wrong. The maximum benefit from a orbital propellant depot is in LEO where a tug can be refueled to take a payload to GEO. You've already had to add several thousand feet per second of delta-v (meaning a lot of energy) to get the spacecraft into GTO. It makes little sense to put your depot there.

Consider the extreme case of a Proton launch from Balkinour. Due to the high latitude, they have to spend an enormous amount of energy to get a payload to GEO. From old numbers that may no longer be current, the basic Proton booster is capable of putting 20 metric tons into a 51 degree inclination LEO orbit. It did this several times when launching Salyut, Mir and a ISS module. However, the Proton is only able to put about 2 metric tons into GEO. The other 18 tons are for the upper stage necessary to raise the orbit and to lower the inclination.

Launches from the Cape intended for GEO are typically into an inclination of 28 degrees. Depending on the launch profile, they may go straight to GTO or they may go into a brief (even fractional) parking orbit before burning for GTO. When the time is right, they'll then do the circularization/plane change burn (apogee kick). All of that requires a substancial amount of energy.

Now, consider the case of a reusable space tug. If you wanted to send a payload of say 3 metric tons to GEO, you'd put it into a stable parking orbit perhaps 200 miles high. The tug would rendezvous and attach itself to the payload and then perform the GTO burn. If the payload has an integral apogee kick motor (many of them do), then the tug's job is done. If not, it'll need to do the apogee burn. Once the payload is delivered, the tug will need to lower it's orbit so it can be refueled for the next mission.

The beauty of this is that the booster required to launch 3 metric tons to LEO is much smaller and less expensive than one needed to put the same payload to GEO. You could probably do it with a Delta II or even smaller.

If the apogee kick wasn't required, all the tug would need to do is lower the perigee a bit so that aerobraking could lower the apogee over a period of time. If the apogee burn was required, then the tug will need enough propellant to lower the perigee from GEO altitudes down to aerobraking altitude. They'll also have to increase the inclination back to the desired parking orbit value but they may be able to do that with aerobraking.

Once the tug is back in the parking orbit, it'll need to be refueled. This will require another launch but the booster wouldn't have to be as reliable (or expensive) as for an expensive payload. The rocket engines, attitude control system, and related expensive components of the tug could be potentially be reused many times, lowering the cost of sending payloads to the most profitable orbit. Who knows, if we ever do return to the moon and find harvestable quantities of ice there, we might even be able to refuel the tug using lunar-derived propellants. That, IMO, would be a big step in establishing a true space infrastructure.

Rand Simberg wrote:

Googaw also assumes, without basis, that the only market for a propellant depot is GEO, when in fact the primary market is for earth escape missions.

Jonathan Goff wrote:

To be fair to googaw, he has mentioned other uses for propellant depots that I largely agree with. He hasn't been entirely wrong, and in fact I think he's made several good points. I just haven't had the bandwidth lately to really spend the time on this discussion that I would like. I still think that Googaw is fundamentally wrong on a few points, and that he's arguing against an argument other than what I'm trying to put across (though that may be more my fault than an attempt on his part to construct a strawman). But as annoying as his tone may be, I still think it deserves respectful discussion.


Rand Simberg wrote:

But as annoying as his tone may be, I still think it deserves respectful discussion.

I disagree. He's certainly not respecting your opinion, and (as is often the case) there are a lot of underlying (and unstated) assumptions in his comments that are not shared by us.

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This page contains a single entry by Rand Simberg published on May 7, 2008 10:01 AM.

Plan B From Outer Space was the previous entry in this blog.

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