Talk:1244: Six Words

Explain xkcd: It's 'cause you're dumb.
Jump to: navigation, search

I believe the "Oberth Kuiper Manuver" refers not to the exploitation of the Kuiper belt, but to its the maneuver's usefulness for crossing the belt efficiently. There are multiple various points supporting this conclusion:

1. The size and positioning of the circles strongly indicates that they represent Venus, Earth, and Jupiter (or Eve, Kerbin, and Jool). 2. Reaching the Kuiper belt (which begins at Neptune) requires a great deal of delta-v. Even if you were to slingshot around gas giants (which, in the current explanation, is not shown in the diagram), the trip would consume the majority of a spacecraft's propellant, making the extreme exploitation of the Oberth effect largely ineffective. 3. Kuiper belt objects are very small and therefore would not effectively serve to redirect or slingshot the spacecraft. 10:11, 29 July 2013 (UTC)

"This makes no sense, as it it is vastly more expensive in terms of fuel to get to a Kuiper belt object (which is at least 10 billion km from earth) than it is to get to the sun."
This is incorrect. To go directly to the Sun takes a delta-v about equal to Earth's orbital speed (30 km/s). Escape speed is √2 * v_c = 42 km/s; since you start with v_c, you need a delta-v of 12 km/s to get out to the Kuiper Belt. Once you're far from the Sun, a very small delta-v will put you on an orbit passing near (or into) the Sun.Wwoods (talk) 16:47, 29 July 2013 (UTC)
Okay, that's true. But I have another objection to the interpretation: how long would it take to get a probe to the Kuiper belt? And of course there's the problem of actually finding a Kuiper belt object to slingshot around, especially when you've got much better candidates, e.g. Jupiter, Saturn, etc. available for the maneuver. Emurphy (talk) (please sign your comments with ~~~~)
The term "Oberth Kuiper Maneuver" does not exist, but Randall did add the word "Kuiper" to the well known "Oberth Maneuver". So he means a Kuiper Belt object. Wwoods' statement is absolutely correct. The trip will just take a long time.--Dgbrt (talk) 18:25, 29 July 2013 (UTC)
I have to agree with the IP address. You're not correct about the Delta_v benefit of going to the Kuiper belt, because Jupiter provides a gravity assist. The probe fires the thrusters at the closest approach to Jupiter in the direction opposite of motion, and this causes it to take a sharper turn, requiring lower Delta_v. This is not possible with the Kuiper belt objects because they are significantly less massive than Jupiter. Yes your speed will be less, but not by enough. The closest approach potential is greater for Jupiter by a factor much greater than the velocity difference. You could do the equations, and I'm sure Jupiter will be more propellant-efficient, in addition to taking less time. AlanSE (talk) 21:40, 29 July 2013 (UTC)
Why the hell you all do TWO spaces after a sentence? Like "IP address.__You're not". But back to the discussion, as more far you are of the massive sun, the the energy for changing the speed direction is reduced, you go back to the sun at HIGH speed.--Dgbrt (talk) 22:57, 29 July 2013 (UTC)
Because that's how you do in on a typewriter. Do you remember typewriters? --Thnidu (talk) 23:07, 29 July 2013 (UTC)
You do not leave Jupiter with zero speed. That's the only way that your argument makes sense. It's not true, so your argument is not true. I am saying that if you sent two of these probes, one doing the incorrect Kuiper object assist, and one just doing a Jupiter assist, the Jupiter-assisted probe would be faster even as the Pluto-assisted was passing Jupiter. That is because the Jupiter-assisted probe does not grid to a screeching halt as it passes the planet like you seem to argue that it does. AlanSE (talk) 15:55, 30 July 2013 (UTC)
Sure, Jupiter would maybe a good option, but Randall mentions the Kuiper Belt. He definitively talks not about Jupiter. The voyage would take more than a decade but the delta-v you need is much smaller than at Jupiter. Randall is just joking about this long lasting mission.--Dgbrt (talk) 19:47, 30 July 2013 (UTC)
The idea is difficult in practice because of the proximity to the sun combined with the volatility of propellants, and is entertained seriously by NASA: [1]. We have an sufficient explanation for the use of the word Kuiper. A more troubling detail of your theory is how it would work in Kerbal Space Program. Jool is the Jupiter analog. There is no Pluto analog. The "icy" planet in KSP is Eeloo, and it is in a resonance with Jool. In other words, it is no further than Jool. The comic makes no sense with your theory, because it would have been impossible to do that maneuver in KSP, and one of the few things we know about the maneuver is that it was done in KSP. AlanSE (talk) 20:59, 30 July 2013 (UTC)
Your second links tells me this: "The physical characteristics of Eeloo are most likely an analogue of the ice moon Enceladus, and its orbit is similar to that of Pluto...". So we have the Kuiper Belt at this program. The first link refers to the NASA Institute for Advanced Concepts, but they are not talking about a Kuiper Belt object as an bad option. And because of their time line they should consider this. And, why Randall should rename the "Oberth Maneuver" to an non existing "Oberth Kuiper Maneuver"?--Dgbrt (talk) 21:59, 30 July 2013 (UTC)
I see where you get the Pluto thing, and I can see where the developers were going with that. The idea is that Pluto hasn't cleared its own orbit. But Pluto crosses Neptune, whereas Eeloo crosses Jool. That's a big difference in terms of distance from the sun. The NASA study's diagrams did use Jupiter in the diagrams, but you're right in that they didn't dismiss the use of other objects. AlanSE (talk) 23:18, 30 July 2013 (UTC)
I find the Jupiter explanation more plausible. Not only it is more consistent with the diagram (as far as body sizes and configuration, but also orbit shape, which would be a much narrower ellipse with periapsis near Venus and apoapsis in the Kuiper Belt), but also flyby around a Kuiper Belt body would be quite pointless: its low mass would make it a particularly lousy target for both gravity assist and Oberth maneuver - and yes, you only need a small velocity change at such distances to head for the Sun, but you could just as well do a deep space maneuver in empty space without any Kuiper Belt object nearby; its presence or non-presence would make little difference. - More importantly though, the whole travel so far outwards would be completely unnecessary, because Jupiter's gravity is already sufficient to send a spacecraft on a close Sun flyby trajectory (or even straight into the Sun, if desired) with a single unpowered flyby, no engine burn needed at all. Saving lots of time and/or fuel (as the unnecessary detour via Kuiper Belt would take more fuel/flybys than a simple trip to Jupiter, not even mentioning the roundtrip duration). The reference to Kuiper Belt is explained just as easily with that being the intended mission target (also following from the word order, Oberth-Kuiper, more logical for Kuiper Belt visit after the Oberth maneuver, rather than before). -- 12:12, 31 July 2013 (UTC)
I think the idea is actually to use gravity assist from a Kuiper Belt object, Pluto or Eris. Of course this will be ridiculously ineffective, but that's part of the joke! Using gravity assist from Pluto for a destination that could be reached using gravity assist from Jupiter is an insane idea that could work in theory, but there are too many risks in real life. Only in Kerbal would you use this trajectory. 10:30, 16 April 2014 (UTC)
strictly an orbiter shop

According to this [2] that is not true. 11:59, 29 July 2013 (UTC)

Indeed - thanks! I added that in. Now, is there any evidence that they play Orbiter?? Nealmcb (talk) 16:55, 29 July 2013 (UTC)

I just made a few for sense (undergoimplement), punctuation (possessive it'sits), grammar (and → comma before "eventually leaving"), and logic (inserting if it succeeded,).

--Thnidu (talk) 23:16, 29 July 2013 (UTC)

a.k.a. Dr. Whom: Consulting Linguist, Grammarian, Orthoëpist, and Philological Busybody


Randall adds the transcripts sometimes later. We now know the planets are Earth and Jupiter and at the center is, of course, the sun.--Dgbrt (talk) 16:21, 12 August 2013 (UTC)

Personal tools


It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal or Bitcoin?