Talk:Orbital maneuver

Assessment

I added the WP Space exploration template, hoping to encourage members of that WikiProject to help with (or assess) this article. Sdsds 20:05, 16 March 2007 (UTC)

'Maneuver'?

Isn't it 'manoeuver'? LarRan 21:41, 6 August 2007 (UTC)

English: manoeuvre (from French!) American: maneuver

English Wikipedia expects American spelling!

Stamcose (talk) 21:21, 6 August 2011 (UTC)

No it doesn't. It expects no particular type of spelling. All common variants are acceptable. The rules are don't change from one to another, and use the preference of the first major editor. 82.27.8.177 (talk) 15:57, 4 January 2015 (UTC)

WikiProject class rating

This article was automatically assessed because at least one WikiProject had rated the article as start, and the rating on other projects was brought up to start class. BetacommandBot 10:00, 10 November 2007 (UTC)

For WPSpace, I explicitly made this a "Stub" class article because it contains no reference citations. (sdsds - talk) 04:25, 14 February 2008 (UTC)

Deorbit burn

I know there exists a substantial literature on deorbit burns; I'm just unfamiliar with it. The article is currently silent on the topic. Anyone know of a few good sources? N2e (talk) 15:13, 10 January 2011 (UTC)

Non-impulsive maneuvers

I don't understand the first line in this paragraph, can someone explain it to me? Or.... is this a huge typo? Rocketmaniac ^RT 13:53, 10 February 2011 (UTC)

Impulsive maneuver, strange statement

It presently says:

However, even for long burns, impulsive maneuver approximations remain fairly accurate outside the Earth's atmosphere, and when the gravitational potential energy doesn't change significantly over the length of the burn.

This has really nothing to do with "Earth's atmosphere" and also nothing to do with "gravitational potential energy not changing significantly"

It has something to do with the gravitational gradient, though! Should be re-formulated/expanded somewhat!

And this picture should be included

Approximation of a finite thrust maneuver with an impulsive change in velocity

Stamcose (talk) 21:07, 6 August 2011 (UTC)

The following text could be used. It is important to stress that what matters is not the abolute time of a maneuver (seconds, hours, days, weeks) but this time in relation to the "gravity gradient". For an interplanetary space probe in heliocentric orbit a maneuver using electrical propulsion extending over several weeks can be "quasi impulsive" while a burn with a duration of only an hour close to pericentre where the gravity gradient is large can be "low thrust".

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Figure 1: Approximation of a finite thrust maneuver with an impulsive change in velocity

An "impulsive maneuver" is the mathematical model of a maneuver as an instantaneous change in the spacecraft's velocity as illustrated in figure 1. In the physical world no truly instantaneous change in velocity is possible as this would require an "infinite force" applied during an "infinitely short time" but as a mathematical model it in most cases describes the effect of a maneuver on the orbit very well. The off-set between the velocity vector after the end of real burn from the velocity vector at the same time resulting from the theoretical impulsive maneuver is only caused by the diffence in gravitational force along the two pathes (red and black in figure 1) which in general is small.

In the planning phase of space missions designers will first approximate their intended orbital changes using impulsive maneuvers what greatly reduces the complexity of finding the correct orbital transitions.

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Stamcose (talk) 19:48, 8 August 2011 (UTC)

Other sub-optimal text

I think the sections "Non-impulsive maneuvers" and "Finite burn trajectories" should be one section. Text in many places somewhat strange, for example:

"where 'non-impulsive' refers to the maneuver not being of a short time period rather than not involving impulse- change in momentum, which clearly must take place"

??????

Stamcose (talk) 19:58, 9 August 2011 (UTC)

A potentially confusing term is clarified, what is the problem?--Patrick (talk) 22:28, 9 August 2011 (UTC)

I merged the two sections as proposed.--Patrick (talk) 10:05, 24 June 2012 (UTC)

Inclination change without propellant

If I'm not mistaken, a change in orbital inclination in addition to a propellant burn at the two gee nodes also includes the possibility of effecting an inclination change by shedding or acquiring mass. The http://en.wikipedia.org/wiki/Orbital_maneuver#Orbital_inclination_change discusses the burning of a propellant however the ejection or acquisition of mass at the nodes given the required vector and momentum transfer would also work exactly as a propellant burn.

I mention this because some missions have utilized spring-loaded mounts for massive cowling and shielding to be shed in specific vectors after explosive bolts allow for spring un-loading to discard the mass, allowing for orbital inclination to be changed without utilizing propellant.

If I could find some suitable references for this I would make an addition to the entry. Damned if I can find anything even remotely definitive for the process. Damotclese (talk) 22:26, 3 December 2012 (UTC)

if the mass is ejected with a non-zero velocity, it will produce momentum change. Ejecting mass at a velocity is what a rocket does, so this is just a different way of making a rocket. Unless the mass is pretty large, and the springs ejecting it produce a very large amount of energy, it's unlikely that ejecting a mass with a spring will give you enough inclination change to notice. Geoffrey.landis (talk) 21:48, 6 January 2015 (UTC)