Talk:Interplanetary travel

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"Mars travel is basically a matter of deciding to put up the cash."

-- And being willing to live with it if crash the thing. (Or any of 1001 other potential fatal problems.) (I vote we go.)

Should we put some of the advanced techniques in the main article or link to them? Such as: tethers, Aldrin cyclers, etc. Also should we give a link for the British Interplanetary Society for further reading? mirwin 06:05, 12 Sep 2003 (UTC)

Yes. :-)WolfKeeper 23:18, 8 October 2006 (UTC)

Contents

[edit] Restructure "Orbital Mechanics" section?

The "Orbital Mechanics" section's content is good but the title no longer matches the contents (aerobraking is not really orbital mechanics)

I think aerobraking is orbital mechanics because it's used to turn hyperbolic orbits into elliptical orbits or circular orbits, for example on Mars missions, which very much are orbital mechanical processes. Also, you can't totally neglect aerodynamics in LEO. I agree that reentry isn't much to do with orbital mechanics though.WolfKeeper 22:49, 16 February 2007 (UTC)
I see your point. But: (a) newbies to the subject wouldn't see it that way; (b) I'd still prefer aerobraking to follow the other techniques, which are based solely on gravity.Philcha 16:59, 17 February 2007 (UTC)

and the sub-sections are not in the most logical order.

I suggest that the section should be re-titled "Economical techniques for interplanetary travel" and should have the following sections:

I don't like the name. Simply 'Techniques for interplanetary travel' would be better.

—The preceding unsigned comment was added by Wolfkeeper (talk • contribs) 22:51, 16 February 2007 (UTC).

I admit it's a mouthful, but I think "Economical" is important - continuous acceleration / deceleration would be much faster and would avoid the need to wait for launch windows, but the fuel cost is too high. Would you like "Economical travel techniques" any better? Or would you like to suggest a title which reflects the need for economy?Philcha 16:59, 17 February 2007 (UTC)
  • Explanation of the need for economical techniques. This would include: the problem of velocity matching (as in the current version); deceleration and velocity-matching require fuel, this fuel has to be launched along with the payload, and therefore even more fuel is needed in the acceleration phase.
  • Hohmann transfer
  • Gravitational slingshot
  • Fuzzy orbits, but with a more generalised explanation - it's about taking advantage of any nearby gravity sources to gain useful delta-V without using fuel. For example in some circumstances the moon's gravity can give a small boost to a vehicle in Earth orbit. And point out that in most cases "fuzzy orbits" save fuel but take a lot longer than Hohmann transfers.
  • Aerobraking last, since it's less clearly about orbital mechanics than the rest.

Any comments?Philcha 21:14, 16 February 2007 (UTC)

[edit] Larger-scale re-structuring?

I also think the article would be improved by larger scale re-structuring:

  • Introduction as in the current article.
  • Why should we want to travel within the solar system?
  • "Current achievements" as in the current article.
  • "Economical techniques for interplanetary travel" (re-titled and restructured version of the "Orbital mechanics" section, see above).
  • "Possible improvements in propulsion technologies" - ion thrusters, mass drivers, tethers, etc. Should be brief and refer to the main article on Spacecraft propulsion.
  • "Reducing the cost of launching from planetary surfaces". Point out that so far for each mission we've launched everything (hull, fuel, etc.) from the bottom of Earth's gravity well. Cover cyclers (good article at http://www.esa.int/gsp/ACT/mission_analysis/design_past.htm), space bolas, Arthur C Clark's space lifts ("Fountains of Paradise"), mining celestial bodies for fuel and reaction mass, etc.
  • "Difficulties of manned interplanetary travel" - probably expanded.
  • "Feasibility of manned interplanetary travel"

Any comments?Philcha 21:52, 16 February 2007 (UTC)

[edit] Deleted para from "economical travel techniques"

I've deleted the paragraph which begins, "All objects in a star system are in orbit around the star ..." as it is simply another way of describing the velocity matching problem, but without showing how difficult it is. Philcha 13:03, 17 April 2007 (UTC)

[edit] Slingshot advantage only relative to centre.

I have added a note to the section on the Slingshot manoeuvre pointing out that any velocity gained not relative to the two objects involved, there is only a gain in velocity relative to the centre of mass (the sun?). The two objects still have the same velocity relative to each other (Conservation of energy). --Metaheurist 01:40, 21 April 2008 (UTC)

Probably relative to an inertial observer. Philcha (talk) 11:50, 21 April 2008 (UTC)