[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

# Re: new web site/status report

```
Rex:
>Kevin:
> >(At 1G continuous thrust)...Even the antimatter rockets can't
> >get up to .99 lightspeed with a mass ratio of 52.
>
> Two points--
>
> 1. With the saturation of apparent velocity, the implications
> of .99 lightspeed are obscured.  A peak apparent velocity of

I'm not sure I understand what you mean by this first sentence.

> 0.99 ltyr/yr represents a peak proper velocity of 7.0179
> ltyr/yr and an acceleration distance (at 1g) of 5.90 ltyr.
> (I.e., a destination distance of 11.8 ltyr with 1g deceleration,
> also.  BTW, my astronomy book gives the distance to tau Ceti as
> 10.3+/-0.3 ltyr.)  What mass ratio does MARS require to decel-
> erate at 1g from this peak velocity?  (I think that's the 52,
> from Timothy's 3/30 table, that you're quoting, which is for
> 100 percent conversion of captured microwave energy to exhaust
> kinetic energy.)
>
> 2. An optimum antimatter rocket with a peak proper velocity Uend
> of 7.0179 ltyr/yr has an optimum constant exhaust velocity Vexh
> of 0.8851.  The required mass ratio (r = exp[asinh(Uend)/Vexh])
> is 19.89.  (These calculations assume no energy losses, but also
> assume no gain from optimizing the exhaust-velocity profile.)
>

Okay, I stand corrected on the mass ratio point.  but at least we can
make microwaves  :)  (and don't tell me about the nine or so anti
hydrogens that CERN got to live about 40 nanoseconds)

I do think we should explore anti-matter rockets and see if they solve
any of the really hard problems (like energy cost)

Kevin

```