Re: Asteroids or bust!

From: Hop David (hopspageHATESSPAaMmM_at_tabletoptelephone.com)
Date: 06/02/04 

Date: Wed, 02 Jun 2004 12:37:22 -0700

Alex Terrell wrote:
> Sander Vesik <sander@haldjas.folklore.ee> wrote in message news:<1085752782.723641@haldjas.folklore.ee>...
>
>>>It isn't uncommon for NEOs to pass within 10 lunar distances of earth.
>>>Sometimes the relative velocity is less than Lunar escape velocity.
>>
>>But AFAIK
>
>
> which isn't very far, like the rest of us

This is why I'd like a series of Discovery class missions to the lunar
poles and NEOs before we ramp up manned space flight missions. I believe
manned space exploration/colonization will be far more doable when we
have a better inventory of resources within easy reach.

>
>
>>NEO-s don't really contain that much nitrogen.
>
>
> Some though were recently comets, and should still have Ammonia.
>
>
>>Plants (and animals,
>>inc humans) need nitrogen-based compounds to live.
>>
>>
>>>If the goal is bring organic compounds and volatiles to colonies in
>>>orbit or on the moon, I remain unconvinced Earth is the cheapest source.
>>>
>>
> NEOs certainly have carbon, perhaps with nitrogen added.

Presence of carbon maybe important both as a life sustaining resource
and for making rocket fuel.

Henry Spencer has noted that watery NEOs may not be much good for
supplying LEO fuel depots. It takes a lot of energy to split water into
H2 and O2. Plus H2 is hard to store.

Presence of carbon in watery asteroids may make it possible to store the
hydrogen as methane.

If the NEO is a former comet, there may already be CH4 and other useful
hydrocarbons in its core.

>
>
>>The alternative known to be abundant resource of nitrogen compunds is Titan.
>

You'd need to escape Titan's gravity well plus Hohmann entry from a
1,221,830 km Saturn parking orbit and a Hohmann exit to (say) a 300 km
earth parking orbit.

My BOTE: 11.6 km/sec delta vee.

I believe Titan has a _thicker_ atmosphere than earth's which would be a
pain to launch through.

Earth would be a better nitrogen source than Titan -- at least for near
Earth space. 

-- 
Hop David
http://clowder.net/hop/index.html