Re: Why did it take so long to reach the moon

On Feb 25, 7:49 am, simberg.interglo...@xxxxxxxxx (Rand Simberg)
wrote:
On Mon, 25 Feb 2008 15:15:18 GMT, in a place far, far away, P...@xxxxxx
made the phosphor on my monitor glow in such a way as to indicate
that:

I was just looking at the Apollo 15 DVD set. It showed them flying
over their landing site at GMT 96 hours and something. that's 4 whole
days after launch. If they were traveling at 25,000 MPH, they should
have made it in about 10 hours. Did they slow down along the way?

Yes. Energy is constant, so as they gain more potential energy by
getting farther from the earth, their kinetic energy (which
corresponds to the square of velocity) is reduced, slowing them down.

Once past the moon's L1 point of no return they proceed to speed up
rather nicely, especially as getting situated into their 100 km orbit
that required a good retrothrust or two. For the likes of robotic
fly-by-rocket expertise, at least that part was simple enough.
.. - Brad Guth

.

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