starship-design: Re: Into detail

[TLG.van.der.Linden@tip.nl (Timothy van der Linden)]

Kelly,

>>Well a factor 2 bigger 300,000 miles instead of 3,000 miles will resolve
>>objects of:
>>
>>d=1.22 * 9.45E16 * 5.3E-7 / 5.556E8 = 110 metres
>
>Not bad over interstellar distences.  If you see anything really interesting
>you could probably get funding to scale up the scope array.  A 4 order of
>magnitude improvement should get you 1 meter res.  8 order centimeter rest.
> Enough to study life forms (if any).
>
>Expensive, but not compared to the starship project.

Resolution power doesn't seem to be the biggest problem, it "merely" needs a
few small telescopes that are far apart.
More essential is the brightness problem for which we would need really huge
telescopes that can be more expensive that a starship project.

>>We make a 1 second photograph. (Can't do longer, otherwise the planet has
>>turned much more than 110 meters)
>
>The scope aray or post processors could compensate for the rotation.

Yes, that might work. so you may indeed decrease the telescope size a bit if
you can make longer exposures.

>>Therfore we need an aperture surface of 1E6*6.6E8=6.6E14 square meters.
>>
>>Hmmm, that means a aperture radius of 14.5 kilometers. Most of my estimates
>>have been quite optimistic, so it could well be that one needs a few orders
>>bigger. 
>
>Ah, I make that 2.5e7 meters per side.  How'd you get 14,500?

I used a circular aperture, but also accidentally devided by 1E6 instead of
1E3 to get kilometers. The mistake was mine, so the aperture radius has to
be 1000 times bigger. Not a trivial upscale!

Regarding resolving 1 meter details, I'd rather not think about that
anymore. Multiple exploring missions would be cheaper and easier to do.

Timothy