Kalpana One design (was Rotating space colonies)

--- In spacesettlers@yahoogroups.com, Matt Gallimore wrote:
>
> From: brooksn bhn1700@...
>
> "But we aren't taking large asteroids from the asteroid belt, we are taking 5 to
> 10 meter asteroids that are passing by Earth, in fact they pass within the
> moon's orbit all the time. The amount of fuel needed to divert that small an
> asteroid just enough to enter the upper atmosphere for aerobraking, strap on a
> heat shield and you preserve more of the asteroid, is not very costly
> energetically. And then adjust the new elliptical orbit until you meet up with
> the ISS. "
>
> Agree that this can be done, but I have liability concernsbringing objects
> larger than 1 to 2 meters into the LEO.

http://en.wikipedia.org/wiki/Meteoroid
"Beech & Steel writing in Quarterly Journal of the Royal Astronomical Society proposed a new definition where a meteoroid is between 100 m and 10 m across."

"The biggest asteroid to hit Earth on any given day is likely to be about 40 centimeters, in a given year about 4 meters, and in a given century about 20 meters."

If the above is accurate, then 10 m is considered the upper limit for a meteor. So it is expected to burn up without incident, especially considering its estimated that 4 m bodies hit Earth every year. I definitely agree we should start small 1 to 2 but going up to around 5 shouldn't be a problem after proof of concept on the smaller bodies.

http://en.wikipedia.org/wiki/Near-Earth_asteroid#Near-Earth_asteroids

"Objects smaller than about 150 m (500 ft) in diameter (i. e. H = 22.0 with assumed albedo of 13%), are not considered PHOs (Potentially Hazardous Objects)."

Not that I'd want to get remotely close to that limit.

> "You have to travel to the location, mine it, then strap it to a rocket (or
> expensive mass driver) and then launch it. An asteroid can weight 100's of tons
> and can be captured easily by adjusting an already Earth crossing orbit. I doubt
> 100's of tons can be sent up from the moon for the same cost."
> .....
> "But the purpose of your base was to launch material into orbit, you need fuel
> for that and volatiles in particular. Regolith or asteroid scrap, radiation
> shielding will be the easy part. What should be the number one concern is cost,
> energetically and monetarily and I don't see how a new lunar base beats an ISS
> small NEA capture. "

> Depends on the goal. For basic research / processing, getting a couple tons to
> the ISS should be easier than moving equipment to the moon. If we are planning
> to build something big, the moon looks more interesting, at least for the next
> few decades. Though the mass driver is starting to look not as easy as Oneal
> proposed,nonetheless, the moon offers some advantages:
>
> 1. Production scheduling
> If we are doing orbital processing, then asteroid capture is done on a schedule
> of years to minimized fuel use adjusting dv.
> With lunar facilities(admittedly more expensive) a more predictable production
> schedule is possible.

Why? We can agree that start up costs favor ISS, but if 4 m bodies are raining down on Earth once a year, how many are coming between Earth and the moon? The Earth is ~6,300 km in radius, from Earth to the moon is ~375,000 km, if we get one 4 m a year hitting Earth I can only imagine we are getting over a dozen a year (being very conservative) between us and the moon. 12 a year to pick from sounds like a pretty generous production schedule. Sure you'll have to plan ahead for these encounters and the first one will be a couple of years out (depending on how much adjustment it needs) but once you get the 'train' of bodies coming they'll come like clockwork from that point on.

> 2. Short communication lags
> Being closer, teleoperation is easier.

Agreed, since we've pretty successfully ran rovers on Mars though, I think it may be manageable.

> 3. Hardware reuse
> Orbital capture approaches would have small craft hunting individual asteroids.
> If problems develop (communication, mechanical), the craft is lost. On the
> moon, there is a chance for repair or using salvaged components to repair other
> units.

Also agree, but how much of an increased risk is this? Sure it goes in lunar's favor but compared to all the other costs?

> 4. Processing
> After some thought, I am not sure that material processing is more difficult in
> zero g. There are ways to address it with a large enough facility. That said,
> actual mining and material handling are aided by gravity. Initial ore
> collection should be easier to engineer on the moon. No de-spinning of ore
> needed.

Agreed.

> 5. Scalability
> In many ways it is easier to leverage fixed facilities. Managing a flotilla of
> small asteroid capture craft and orbital insertion involves long investment
> cycles and more complexity as production increases. Expanding the processing
> facilities in LEO would be less expensive than the moon, but high production
> rates will be elusive until asteroid processing moves out of LEO. Once
> asteroids weighing many thousands of tons can be handled, things look very
> different. Until then, the moon offers potentially easier production
> scalability. Most hab mass is not heavily processed. Very little mass of a
> shielded hab is related to volatiles, carbonor metals uncommon to the moon.
> Thereore, facilities could be progressively expanded with, hopefully, better
> predictability of production. This becomes important when trying to build
> structures weighing hundreds of thousands of tons.

As production increases in LEO I would expect complexity to drop, the first few will be the trickiest, as hardware is used in all areas the bugs work out and the personel becomes more experienced. How much scalability are you anticipating? If we process six 5 m asteroids a year in LEO at 400 tons a pop, that's 1200 tons a year. After a few years of production and expansion we should have quite a station built up I would think. On the mass for shielding, both locations provide it, though moving around 100's of tons of mass on the moon will be more difficult then in zero g. But volatiles provide a monetary/energy problem for the moon, there is a greater need on the moon and a greater shortage as well.

Brooks