Re: Calculating propulsion burns

On Apr 29, 4:19 am, "Mike Dworetsky"
<platinum...@xxxxxxxxxxxxxxxxxxxx> wrote:
"Bruce C. Miller" <bm3...@xxxxxxxxx> wrote in messagenews:1177781057.829169.240630@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

If you were in a space vessel and wanted to calculate the amount of
thrust and length of a burn, what equation(s) would you need to
consider to reach a destination like an asteroid (excluding the
gravity wells of celestial bodies nearby)?

I figure you would at least need the distance to target object, your
velocity, and the velocity and heading of the target. You may also
want to consider the duration of travel and fuel consumption. Am I
missing any other parameters?

If anyone knows a web resource dedicated to this subject, please share
as well.

A lot of the extra complication involves arriving at the target with zero or
nearly zero relative velocity, or (if you intend this) going into an orbit
around the object.

Yes, that's true. If we ignored gravity, and both objects started out
stationary with respect to each other, it would be a simple matter of
applying an equivalent amount of thrust in the opposite direction, I
will probably go with that for now, to keep things simple.

And yes, fuel consumption is a major parameter.

Even back in the 1960s I can remember working with astro-dynamics people who
used numerical methods to calculate a minimum fuel rendezvous manoeuvre by
trial and error methods*. I am not sure if there are any simple analytical
methods other than, for example, the Hohmann ellipse.

*They used what was then a humongous computer to calculate the fuel
consumption for lots of different starting and ending points, then used
mathematical methods to locate the minimum on a contour map of the fuel used
(z-axis) vs starting date (x-axis) and finishing date (y-axis). There was
more to it than that, but you get the idea. They would use a similar method
to find the ideal direction vector for each rocket thrust manoeuvre as well.

.

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