Re: Mars in two weeks?

From: Michael S. Lorrey (
Date: Fri Jan 05 2001 - 10:50:09 MST

Brent Allsop wrote:
> On Fri, 5 Jan 2001, John Clark wrote:
> > They figure a Americium-242 rocket could get to Mars in two weeks
> > not two years as with a chemical rocket.
> I've always figured the optimal interplanetary travel speed
> was accelerating at 1 g until you get half way there, and then
> decelerating at the same rate the rest of the trip. Then you wouldn't
> require centrifical force to simulate gravity right? How fast would
> this be? How fast would you be going at the midpoint? And could you
> get to Mars in two weeks with this? If not, how much acceleration
> would be required to get there in 2 weeks? How many gs can a human
> stand for extended periods of time? That's the ultimate speed limit
> for humans right?

Since you are undergoing constant acceleration at 1 g, your velocity is
constantly changing, so 'how fast' is a meaningless concept. How fast at
the midpoint depends on when you launch from earth and Mars' relative
position to earth at that point. With such transit times, trajectory
would be essentially a straight line, giving a little windage to Mars'
projected position in two weeks time. Lets assume a 90 million mile
trajectory which would occur at some point near Earth-Mars conjunction
periods. Thats 45 million miles to the halfway point. Accelleration at 1
G is 32 feet per second squared. Velocity equals accelleration times
time. Distance equals accelleration times time squared divided by 2 plus
initial velocity times time. Do the math.

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