Hi!

I've a question relating to asteroid mining.

Reading some of the earlier discussion of asteroid mining, in the
works of Pournelle and other writers, I've read quite a lot of
speculation suggesting that it would be relatively easy, energy-wise,
to move an asteroid into Earth orbit.

None of these authors can be faulted for not knowing, as we do now,
that many of those small asteroids are rubble piles or otherwise
fragile. One thing does leave me puzzled: How did they plan to get the
mineral resources in these asteroids down to Earth? Or did they not
plan on that at all?

All the best,
Randy

In article <9f100219-cc1c-4307-a0ae-1113498aef4b@m34g2000hsf.googlegroups.com>,
<randy.mcdonald@gmail.com> wrote:
>Hi!
>
>I've a question relating to asteroid mining.
>
>Reading some of the earlier discussion of asteroid mining, in the
>works of Pournelle and other writers, I've read quite a lot of
>speculation suggesting that it would be relatively easy, energy-wise,
>to move an asteroid into Earth orbit.

Which isn't true for a lot of asteroid. Yes, I know about
NEOs but my memory of the 1970s discussions is that they focused
on main belt rocks.

>None of these authors can be faulted for not knowing, as we do now,
>that many of those small asteroids are rubble piles or otherwise
>fragile. One thing does leave me puzzled: How did they plan to get the
>mineral resources in these asteroids down to Earth? Or did they not
>plan on that at all?

There's always aerobraking.
--
http://www.livejournal.com/users/james_nicoll
http://www.cafepress.com/jdnicoll (For all your "The problem with
defending the English language [...]" T-shirt, cup and tote-bag needs)

randy.mcdonald@gmail.com wrote:
> Hi!
>
> I've a question relating to asteroid mining.
>
> Reading some of the earlier discussion of asteroid mining, in the
> works of Pournelle and other writers, I've read quite a lot of
> speculation suggesting that it would be relatively easy, energy-wise,
> to move an asteroid into Earth orbit.

I was never sure where that came from. Relatively easy on a per-pound-of
-asteroid basis, and relatively easy period are not the same thing. We
can currently handle things around the earth on the order
(optimistically) of a hundred tons. (Skylab was 77 tons. Yes, I know ...
ISS is bigger ... no more Saturn V's ... shuttle is almost shot ... make
it in pieces ... shuttle derived big boosters ... yadayadayda ... Bugger
that. A hundred tons.)

Small NEO's that we can reliably detect are the size of a couple of
football fields. We've found a few smaller than that which came close to
the earth, partially by chance. They'd be worth something and probably
movable. (See below.)

- March 18, 2004 saw a very close recorded approach of a near-Earth
object (NEO). Asteroid 2004 FH, about 30 meters (100 feet) in diameter

- Only two weeks later on March 31, 2004, meteoroid 2004 FU162 set a new
record for closest recorded approach, passing Earth only 6,500 km (4,000
miles) away (nearly one-sixtieth of the distance to the Moon). Because
it was very small (6 meters/20 feet), FU162 was detected only hours
before its closest approach.

> ...One thing does leave me puzzled: How did they plan to get the
> mineral resources in these asteroids down to Earth? Or did they not
> plan on that at all?

Handwaving of sufficient strength to produce orbital decay and
aerobraking? The be fair, they viewed the materials as most valuable
when used in cislunar space.

Regards,
Jack Tingle

Wasn't it Jack Tingle who wrote:

>I was never sure where that came from. Relatively easy on a
>per-pound-of -asteroid basis, and relatively easy period are not the
>same thing. We can currently handle things around the earth on the
>order (optimistically) of a hundred tons. (Skylab was 77 tons. Yes, I
>know ... ISS is bigger ... no more Saturn V's ... shuttle is almost
>shot ... make it in pieces ... shuttle derived big boosters ...
>yadayadayda ... Bugger that. A hundred tons.)

But getting a hundred tons into low Earth orbit is a completely
different prospect to getting a hundred tons from the asteroid belt into
Earth orbit.

Probes that we've sent to the asteroid belt and beyond have had to use
at least one gravity assist swingby to achieve the required velocity.
Since there's no friction in space, reducing the velocity would need to
use the same trick. Note that each swingby adds something like a year to
the duration of the trip.

--
Mike Williams
Gentleman of Leisure

On Sat, 2 Feb 2008, randy.mcdonald@gmail.com asked:
>I've a question relating to asteroid mining.
>[...] One thing does leave me puzzled: How did they plan to get the
>mineral resources in these asteroids down to Earth? Or did they not
>plan on that at all?

Well, if they were working from the 1970's Gerard K. O'Neill plan,
then off-Earth resources were meant for building (a) space colonies,
and colonies were for (b) solar power satellites. It was *energy*
shipped to Earth's surface, not matter.

In Jack Williamson's _Lifeburst_ (1984), metal is dropped to Earth's
surface in buckets on a large number of beanstalks. This is also used
to generate most of the world's electricity.

In one story in mid-90s _Analog_, the iron asteroid was carved into a
hollow, vacuum-filled sphere -- one that was *buoyant* in atmosphere
once it was deorbited. (The miners hung the balloon over the White
House, ready to rupture and drop it, if their demands weren't met.)

In Peter F. Hamilton's _The Naked God_ (2000, third book in his
"Night's Dawn Trilogy,") we finally get to Earth, and learn that
asteroid metal is shaped into hollow lifting bodies and dropped into
the ocean, then towed to refineries on the shoreline.

Mike Williams wrote:

> Wasn't it Jack Tingle who wrote:
>
>> I was never sure where that came from. Relatively easy on a
>> per-pound-of -asteroid basis, and relatively easy period are not the
>> same thing. We can currently handle things around the earth on the
>> order (optimistically) of a hundred tons. (Skylab was 77 tons. Yes, I
>> know ... ISS is bigger ... no more Saturn V's ... shuttle is almost
>> shot ... make it in pieces ... shuttle derived big boosters ...
>> yadayadayda ... Bugger that. A hundred tons.)
>
> But getting a hundred tons into low Earth orbit is a completely
> different prospect to getting a hundred tons from the asteroid belt into
> Earth orbit.
>
> Probes that we've sent to the asteroid belt and beyond have had to use
> at least one gravity assist swingby to achieve the required velocity.
> Since there's no friction in space, reducing the velocity would need to
> use the same trick. Note that each swingby adds something like a year to
> the duration of the trip.

They're different prospects, but they're not _completely_ different.
Going from the surface of the Earth to low Earth orbit is far harder (in
deltavee and stress) than going from low Earth orbit to the asteroid belt.

--
Erik Max Francis && max@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis
It's gonna be cold / There may even be snow
-- Sade

On Sat, 02 Feb 2008 23:56:02 -0500, Phillip Thorne
<pethorne@comcast.net> wrote:

>On Sat, 2 Feb 2008, randy.mcdonald@gmail.com asked:
>>I've a question relating to asteroid mining.
>>[...] One thing does leave me puzzled: How did they plan to get the
>>mineral resources in these asteroids down to Earth? Or did they not
>>plan on that at all?
>
>Well, if they were working from the 1970's Gerard K. O'Neill plan,
>then off-Earth resources were meant for building (a) space colonies,
>and colonies were for (b) solar power satellites. It was *energy*
>shipped to Earth's surface, not matter.
>
>In Jack Williamson's _Lifeburst_ (1984), metal is dropped to Earth's
>surface in buckets on a large number of beanstalks. This is also used
>to generate most of the world's electricity.
>
>In one story in mid-90s _Analog_, the iron asteroid was carved into a
>hollow, vacuum-filled sphere -- one that was *buoyant* in atmosphere
>once it was deorbited. (The miners hung the balloon over the White
>House, ready to rupture and drop it, if their demands weren't met.)
>
Anyone remember the title to that one?

>In Peter F. Hamilton's _The Naked God_ (2000, third book in his
>"Night's Dawn Trilogy,") we finally get to Earth, and learn that
>asteroid metal is shaped into hollow lifting bodies and dropped into
>the ocean, then towed to refineries on the shoreline.

I also recall someone suggested using the iron (70's data) to make
large foamed iron ballistic cones with the more valuable/finished
products in the center then put them on a ballistic drop into an
ocean and tow them to shore for unloading and cut the cone up for its
metal. Supposedly a cheap method, no guidance or controls on the cone
its self.

J Larson

Mike Williams wrote:
> Wasn't it Jack Tingle who wrote:
>
>> I was never sure where that came from. Relatively easy on a
>> per-pound-of -asteroid basis, and relatively easy period are not the
>> same thing. We can currently handle things around the earth on the
>> order (optimistically) of a hundred tons. (Skylab was 77 tons. Yes, I
>> know ... ISS is bigger ... no more Saturn V's ... shuttle is almost
>> shot ... make it in pieces ... shuttle derived big boosters ...
>> yadayadayda ... Bugger that. A hundred tons.)
>
> But getting a hundred tons into low Earth orbit is a completely
> different prospect to getting a hundred tons from the asteroid belt into
> Earth orbit.
>

OK, what's your estimated tonnage limit.

Regards,
Jack Tingle

On Sat, 2 Feb 2008 11:55:54 -0800 (PST), randy.mcdonald@gmail.com wrote:

>Hi!
>
>I've a question relating to asteroid mining.
>
>Reading some of the earlier discussion of asteroid mining, in the
>works of Pournelle and other writers, I've read quite a lot of
>speculation suggesting that it would be relatively easy, energy-wise,
>to move an asteroid into Earth orbit.

Well, of course. It takes exactly as much energy for a science fiction
writer to type, "...and then attach a nuclear rocket with a million tons
of fuel to an asteroid", as it does "...and then attach a chemical rocket
with a thousand tons of fuel to a shuttle", so we can see that it is
relatively easy to move an asteroid into Earth orbit. No harder than
launching a space shuttle into Earth orbit, and we clearly know how to
do that :-)


>None of these authors can be faulted for not knowing, as we do now,
>that many of those small asteroids are rubble piles or otherwise
>fragile. One thing does leave me puzzled: How did they plan to get the
>mineral resources in these asteroids down to Earth? Or did they not
>plan on that at all?

They mostly planned to use the resources to build cities and whatnot
in Earth orbit, in the grandest SFnal tradition. For bringing refined
metals and whatnot down to Earth, the usual handwave is to form the
stuff into hollow aerodynamic shells and lob them towards some desert
or ocean where they can be safely recovered.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*John.Schillin@alumni.usc.edu * for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *