I'm looking for primary references on the early space settlement designs such as Island One. The High Frontier has some information on these, but it's rather spread out, and many of the details seem to be omitted. For example, I can't even find the radius of Island One -- Mike Combs' FAQ [1] says it should be 159 m (for a circumference of 1 km), but at that size, the rotation period of 31 sec as described in The High Frontier (p. 59) would produce only 0.67 G. To get the 1 G claimed for Island One, the radius must be about 238 m, but I'd much prefer to see this in an original document rather than inferring it in this way.

Even if that question is answered, I have more questions about things like the exact latitude and extent of the windows, and so on. I'd also like to fill out some of the details on our new space settlements Wiki (e.g. [2]). Can anyone provide references to any original papers describing these early designs?

Many thanks,
- Joe

[1] http://members.aol.com/oscarcombs/spacsetl.htm
[2] http://www.cygo.com/wiki/index.php/Island_One

Joe Strout -- joe@...

For example, I can't even find the radius of Island One -- Mike Combs' FAQ [1] says it should be 159 m (for a circumference of 1 km), but at that size, the rotation period of 31 sec as described in The High Frontier (p. 59) would produce only 0.67 G. To get the 1 G claimed for Island One, the radius must be about 238 m, but I'd much prefer to see this in an original document rather than inferring it in this way.
__._,___ The funny thing is that I would have sworn it was 1 mile in circumference, not 1 kilometer. But I used The High Frontier as my source when writing my FAQ, so I'm sure that's what it says, at least in one spot. But now I'm thinking thatif we instead assume 1 mile circumference (1.6 km), doesn't that give us the right radius for a period of 32 seconds?

Regards,
Mike Combs

>> For example, I can't even find the radius of Island One -- Mike Combs'
>> FAQ [1] says it should be 159 m (for a circumference of 1 km), but at that
>> size, the rotation period of 31 sec as described in The High Frontier (p. 59)
>> would produce only 0.67 G. To get the 1 G claimed for Island One, the radius
>> must be about 238 m, but I'd much prefer to see this in an original document
>> rather than inferring it in this way.
>
> The funny thing is that I would have sworn it was 1
> mile in circumference, not 1 kilometer. But I used The High Frontier as my
> source when writing my FAQ, so I'm sure that's what it says, at least in one
> spot.

Could be -- The High Frontier is a popular text, and a bit frustrating to use as a technical reference; information on each of the models is rather scattered throughout the book. I couldn't even find any statement on the size of Island One, though it wouldn't surprise me to learn that it's in there somewhere.

> But now I'm thinking that if we instead assume 1
> mile circumference (1.6 km), doesn't that give us the right radius for a period
> of 32 seconds?

Pretty darn close. A 1 mile circumference is a 256 m radius, which with a rotation period of 31 sec (1.94 RPM -- see p. 59 of the latest edition), produces 1.08 G. But it could be that O'Neill actually had in mind a radius of 238 m, which gives a circumference of 0.93 mile -- in a popular text, I could easily imagine this being described as "about one mile in circumference."

Best,
- Joe

Joe Strout -- joe@...

But it could be that O'Neill actually had in mind a radius of 238 m, which gives a circumference of 0.93 mile -- in a popular text, I could easily imagine this being described as "about one mile in circumference. "
I'm so convinced that's what's happened that I'll amend my FAQ to say "1.5 km (>0.9 mi) in circumference".

Regards,
Mike Combs

>> But it could be that O'Neill actually had in
>> mind a radius of 238 m, which gives a circumference of 0.93 mile -- in a
>> popular text, I could easily imagine this being described as "about one mile
>> in circumference."
>
> I'm
> so convinced that's what's happened that I'll amend my FAQ to say "1.5 km (>0.9 mi) in
> circumference".

That's reasonable. It's also possible that, since this design is a sphere, O'Neill assumed a flat floor whose radius was a bit less than the actual sphere radius (as it must be, or it wouldn't be flat). 238 m could be the radius of the "bottom" flat part of the valley, even while the sphere itself had a radius of 250 m. There would simply be 12 m of dirt, or some combination of dirt and empty space, under your feet at the equator. This flat, 1G area would be 153 m wide.

(Reverse-engineering 30-year-old designs -- wahoo!)

Best,
- Joe

Joe Strout -- joe@...

> Could be -- The High Frontier is a popular text, and
> a bit frustrating to use as a technical reference;
> information on each of the models is rather
> scattered throughout the book. I couldn't even find
> any statement on the size of Island One, though it
> wouldn't surprise me to learn that it's in there
> somewhere.
>
> > But now I'm thinking that if we instead assume 1
> > mile circumference (1.6 km), doesn't that give us
> the right radius for a period
> > of 32 seconds?
>
> Pretty darn close. A 1 mile circumference is a 256
> m radius, which with a rotation period of 31 sec
> (1.94 RPM -- see p. 59 of the latest edition),
> produces 1.08 G. But it could be that O'Neill
> actually had in mind a radius of 238 m, which gives
> a circumference of 0.93 mile -- in a popular text, I
> could easily imagine this being described as "about
> one mile in circumference."
>

We could appeal to the authority of The High Frontier,
but why bother when we have mathematics?

The formula for centripetal acceleration is a = v^2/r,
and our v is the circumference divided by time so
v=(2)(pi)(r)/t. Rearranging we get a
=(4)(pi^2)(r)/(t^2). If we set a to equal the
acceleration due to gravity at earth's surface (9.81
m/s^2) and rearrange the formula to isolate the
radius, we get:

r = (9.81)(t^2)/((4)(pi^2))

Assuming a rotational period of 32 seconds, we get a
radius of 254.45 meters, or a circumference of 1598m.
A mile is 1609 meters, so this circumference is about
99.4% of a mile.

Or, we could abandon imperial units altogether (and
good riddance).

Ed

> We could appeal to the authority of The High Frontier,
> but why bother when we have mathematics?

Well, that's what we've already done. You and I came up with the same results, except that you're assuming a rotation period of 32 sec, and I'm using 31 sec (as stated in the aforementioned authority).

However, it is interesting to note that Mike got the figure of 32 seconds from somewhere, and also seems to remember a mile circumference, and that these two match pretty well (in producing 1 G). It just doesn't match page 59. Perhaps there was a mistake in the book, or maybe there was more than one variation of Island One.

This is why primary peer-reviewed references would be nice, but I'm coming to the conclusion that there aren't any (for Island One at least).

Best,
- Joe

Joe Strout -- joe@...