question about hitching a ride on an NEO

I'm currently reading "Mining the Sky" by John Lewis. He makes much of
the idea of "hitching a ride" on an asteroid whose orbit ranges from
Earth's orbit to the asteroid belt. He even suggests hollowing several
such out, and using them as interplanetary cruise ships (really more
like space colonies, as each trip takes several years) to allow
thousands of people to economically travel from Earth to Mars or the
belt.

But I don't see how this helps. In order to dock with such an asteroid,
you have to match orbits with it. And having matched that orbit, it
really doesn't matter whether the asteroid is there or not -- you're
headed out to the belt (or wherever the asteroid would've been headed)
regardless. Indeed, it seems that rather than trying to find an
asteroid with exactly the orbit you want, it'd be easier to just make
one up, match orbits with this imaginary rock, and head on out.

The only advantage I can think of is that the asteroid provides a large
cache of resources which such a long-trip ship might need anyway. I
suppose there is something to that, but it seems like a fairly small
benefit, given how much equipment you'd need to move into that orbit
anyway to outfit it as a space colony on the fly. It'd probably be
easier to build a space colony in some comfortable, standard location,
and then accelerate it into the desired orbit (even if this takes years
to do).

Am I missing something?

Thanks,
- Joe

Joe Strout wrote:
I'm currently reading "Mining the Sky" by John Lewis. He makes much of
the idea of "hitching a ride" on an asteroid whose orbit ranges from
Earth's orbit to the asteroid belt. He even suggests hollowing several
such out, and using them as interplanetary cruise ships (really more
like space colonies, as each trip takes several years) to allow
thousands of people to economically travel from Earth to Mars or the
belt.

But I don't see how this helps. In order to dock with such an asteroid,
you have to match orbits with it. And having matched that orbit, it
really doesn't matter whether the asteroid is there or not -- you're
headed out to the belt (or wherever the asteroid would've been headed)
regardless. Indeed, it seems that rather than trying to find an
asteroid with exactly the orbit you want, it'd be easier to just make
one up, match orbits with this imaginary rock, and head on out.

The only advantage I can think of is that the asteroid provides a large
cache of resources which such a long-trip ship might need anyway. I
suppose there is something to that, but it seems like a fairly small
benefit, given how much equipment you'd need to move into that orbit
anyway to outfit it as a space colony on the fly. It'd probably be
easier to build a space colony in some comfortable, standard location,
and then accelerate it into the desired orbit (even if this takes years
to do).

Am I missing something?

Thanks,
- Joe

Radiation shielding?

Joe Strout wrote:

But I don't see how this helps. In order to dock with such an asteroid,
you have to match orbits with it. And having matched that orbit, it
really doesn't matter whether the asteroid is there or not -- you're
headed out to the belt (or wherever the asteroid would've been headed)
regardless.

Maybe you could lassoo it as it goes past with a very long elastic cable.

Sylvia.

"Joe Strout" wrote in message
...
I'm currently reading "Mining the Sky" by John Lewis. He makes much of
the idea of "hitching a ride" on an asteroid whose orbit ranges from
Earth's orbit to the asteroid belt. He even suggests hollowing several
such out, and using them as interplanetary cruise ships (really more
like space colonies, as each trip takes several years) to allow
thousands of people to economically travel from Earth to Mars or the
belt.

But I don't see how this helps. In order to dock with such an asteroid,
you have to match orbits with it. And having matched that orbit, it
really doesn't matter whether the asteroid is there or not -- you're
headed out to the belt (or wherever the asteroid would've been headed)
regardless. Indeed, it seems that rather than trying to find an
asteroid with exactly the orbit you want, it'd be easier to just make
one up, match orbits with this imaginary rock, and head on out.

The only advantage I can think of is that the asteroid provides a large
cache of resources which such a long-trip ship might need anyway. I
suppose there is something to that, but it seems like a fairly small
benefit, given how much equipment you'd need to move into that orbit
anyway to outfit it as a space colony on the fly. It'd probably be
easier to build a space colony in some comfortable, standard location,
and then accelerate it into the desired orbit (even if this takes years
to do).

Am I missing something?

Thanks,
- Joe

Suppose that they squeeze ten people into a small ship. Once it reaches the
asteroid, they move into bigger quarters. Once they approach their
destination, they move back into the small ship. The rocket fuel
consumption would be similar to flying direct without the asteroid. Six
months without exercise could cause the body to deteriorate, so the asteroid
would make the journey healthier and happier.

Frogwatch wrote:
Joe Strout wrote:
I'm currently reading "Mining the Sky" by John Lewis. He makes much of
the idea of "hitching a ride" on an asteroid whose orbit ranges from
Earth's orbit to the asteroid belt. He even suggests hollowing several
such out, and using them as interplanetary cruise ships (really more
like space colonies, as each trip takes several years) to allow
thousands of people to economically travel from Earth to Mars or the
belt.

But I don't see how this helps. In order to dock with such an asteroid,
you have to match orbits with it. And having matched that orbit, it
really doesn't matter whether the asteroid is there or not -- you're
headed out to the belt (or wherever the asteroid would've been headed)
regardless. Indeed, it seems that rather than trying to find an
asteroid with exactly the orbit you want, it'd be easier to just make
one up, match orbits with this imaginary rock, and head on out.

The only advantage I can think of is that the asteroid provides a large
cache of resources which such a long-trip ship might need anyway. I
suppose there is something to that, but it seems like a fairly small
benefit, given how much equipment you'd need to move into that orbit
anyway to outfit it as a space colony on the fly. It'd probably be
easier to build a space colony in some comfortable, standard location,
and then accelerate it into the desired orbit (even if this takes years
to do).

Am I missing something?

Thanks,
- Joe

Radiation shielding?

That's about it, right off the top. For small asteroids, it makes more
sense to build a large rotating space structure out of discarded tankage
and engines, and then migrate that into orbit around the desired object.
Then you could have automated regolith recovery craft deliver shielding
to the structure. It's a short hop from the surface in the microgravity.

If further fuel could be extracted from the regolith, the entire
structure could be migrated fairly easily to yet another asteroid.

I think Ceres is going to be a major source of water, but that is a much
deeper gravity well (if you can call 1/30 Earth gravity very deep).

Carbon and stainless steel asteroids appear to be rather common, though.

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Joe Strout wrote:
I'm currently reading "Mining the Sky" by John Lewis. He makes much of
the idea of "hitching a ride" on an asteroid whose orbit ranges from
Earth's orbit to the asteroid belt. He even suggests hollowing several
such out, and using them as interplanetary cruise ships (really more
like space colonies, as each trip takes several years) to allow
thousands of people to economically travel from Earth to Mars or the
belt.

But I don't see how this helps. In order to dock with such an asteroid,
you have to match orbits with it. And having matched that orbit, it
really doesn't matter whether the asteroid is there or not -- you're
headed out to the belt (or wherever the asteroid would've been headed)
regardless. Indeed, it seems that rather than trying to find an
asteroid with exactly the orbit you want, it'd be easier to just make
one up, match orbits with this imaginary rock, and head on out.

Head on out with minimal radiation shielding, water, air & space.

I've talked about Aldrin & Niehoff cyclers many times. The craft
undergoing large delta vees would be "taxis" (a term coined by Oberg and
Aldrin) whose mass is quite small compared to the main cycler craft.

The expense of accelerating small taxis is much less than accelerating
the main cycler craft (which Oberg and Aldrin call "castles")


The only advantage I can think of is that the asteroid provides a large
cache of resources which such a long-trip ship might need anyway. I
suppose there is something to that, but it seems like a fairly small
benefit, given how much equipment you'd need to move into that orbit
anyway to outfit it as a space colony on the fly.

Initially the equipment you'd move into orbit would be the start up
equipment to establish a mining camp.

It'd probably be
easier to build a space colony in some comfortable, standard location,
and then accelerate it into the desired orbit (even if this takes years
to do).

And how many tons would you lift from earth's gravity well and then send
into a cycler orbit?

In article ,
Hop David wrote:

Indeed, it seems that rather than trying to find an
asteroid with exactly the orbit you want, it'd be easier to just make
one up, match orbits with this imaginary rock, and head on out.

Head on out with minimal radiation shielding, water, air & space.

Maybe -- but OTOH, you'd be heading out in an ideal orbit, rather than
the orbit of whatever rock was most suitable (no doubt a compromise of
many factors, of which orbit is just one). So your trip time might be
noticeably less.

I've talked about Aldrin & Niehoff cyclers many times. The craft
undergoing large delta vees would be "taxis" (a term coined by Oberg and
Aldrin) whose mass is quite small compared to the main cycler craft.

The expense of accelerating small taxis is much less than accelerating
the main cycler craft (which Oberg and Aldrin call "castles")

This makes good sense once the cycler is built. The part I'm dubious
about is making an asteroid into a cycler, rather than building a cycler
in one place and then putting it into exactly the orbit you want.

Initially the equipment you'd move into orbit would be the start up
equipment to establish a mining camp.

Sure. But consider building a skyscraper. You could, in principle,
start by finding a site with lots of iron, silicon, and other primary
raw materials, and moving in mining equipment to mine these ores. You'd
then move whatever's needed to build refineries, smelters, factories,
etc. in order to make steel beams, cranes, concrete, glass, and so on.
Then (a decade or two later?) you'd finally start building the
skyscraper, and when you're all done, cannabilize the mining equipment,
refineries, smelters, and factories for other purposes.

Or, you could just make use of mines, factories, smelters, etc. that are
already around (because you live in an industrial society), even though
they're not exactly at the site of your building. You have them do
their thing, and transport finished steel beams, glass panes, cabling,
etc. to the work site, where you build your building using equipment
that's also built other skyscrapers, and which, when this one is done,
will be moved elsewhere to build something else.

The latter obviously makes a lot more sense on Earth. I don't see why
it wouldn't make more sense in space too. By the time we could talk
seriously about converting an asteroid, we're going to have a LOT of
industrial infrastructure in a few places: cislunar space, maybe Martian
orbit, maybe around Ceres. There will be flows of refined material and
finished products going through these locations already. It doesn't
make sense to try and start with raw rock and build a complete space
colony as it flies away from this infrastructure. Instead, you put
minimal equipment on the NEOs as they fly around, and ship their ore (or
perhaps, at most, refined metals and volatiles) back to the major
industrial centers. There, those materials are built into finished
products, like space habitats.

And how many tons would you lift from earth's gravity well and then send
into a cycler orbit?

Who said anything about lifting anything from Earth's gravity well?
We're obviously talking about an advanced space infrastructure here, or
else the whole idea of converting an asteroid into anything is a
nonstarter.

Best,
- Joe

"Joe Strout" wrote in message


Similar to walking on our physically dark, salty and extremely IR/FIR
hot moon:

you'll need an actual fly-by-rocket lander that's proven to work.

you'll need whatever's the next best thing to having rad-hard DNA.

you'll likely need a healthy cache of banked bone marow as your plan-B.

Bring along lots of ductape for patching them pesky micrometeorite
holes.

Take along a good optical UV filter if not a near-UV (425 nm) spectrum
cut-off for taking pictures.

You'll need a cache of Po/210 for neutralizing the highly electrostatic
dust.

At best you've got hours upon whatever NEO (worse case you're down to
minutes), to accomplish whatever's the task before reaching your career
dosage limit of gamma and hard-X-rays, and you still have to get
yourself back home w/o further TBI trauma to your frail DNA that's by
now most likely already past the red-line of what's survivable without
utilizing your banked bone marrow.
-
Brad Guth


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

"Joe Strout" wrote in message


Question about hitching a ride on an NEO: what's to question

It's similar to walking on our physically dark, salty and extremely
IR/FIR hot and naked moon.

You'll need an actual fly-by-rocket lander with lots of spare fuel for
accommodating those fully modulated and fly-by-computer driven reaction
thrusters, plus those fairly substantial momentum reaction wheels that's
proven to work on your behalf of dealing with maneuvering about such a
local mascon that's continually imposing different gravity in most all
locations, and don't so much as move an inch or fart, because that'll
screw up whatever maneuvers.

You'll need whatever's the next best thing to having rad-hard DNA.

Besides taking steroids, you'll likely need a healthy cache of banked
bone marrow as your plan-B.

If you're planning upon any long NEO stay, as such it might also be a
good idea for having a private cache of stem cells incase you start
going a little blind or something worse.

Bring along lots of ductape for patching them pesky micrometeorite or
larger holes.

Take along a good optical UV filter, if not a near-UV (425 nm) spectrum
cut-off, for taking those pictures that'll otherwise turn out as though
somewhat vibrant bluish looking, along with planets (especially Venus)
and even a few stars such as Sirius showing up, as otherwise due to all
the raw near-UV, UV-a and the unavoidable secondary/recoil of photons
that are derived off anything natural or artificial that's
UV/black-light reactive should by rights push whatever's local into
getting recorded as being somewhat extra blue.

You also need to utilize a robust CCD digital camera with a little extra
internal bias current instead of whatever well shielded film that's
essentially too easily affected by such raw/unfiltered energy, some of
which being of gamma and hard-X-ray spectrum, and then as always fending
off those pesky thermal extremes that'll have to include the local
secondary IR/FIR by day.

You'll likely need a cache of Po/210 for neutralizing the highly
electrostatic dust.

At best you've got hours upon whatever NEO (on a bad solar day worse
case you're down to minutes), to accomplish whatever's the task before
reaching your career dosage limit of gamma and hard-X-rays, and don't
forget that you still have to get yourself back home w/o further TBI
trauma to your frail DNA that's by now most likely past the red-line of
what's survivable without utilizing your banked bone marrow.
-
Brad Guth


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

Joe Strout wrote:

Sure. But consider building a skyscraper. You could, in principle,
start by finding a site with lots of iron, silicon, and other primary
raw materials, and moving in mining equipment to mine these ores. You'd
then move whatever's needed to build refineries, smelters, factories,
etc. in order to make steel beams, cranes, concrete, glass, and so on.
Then (a decade or two later?) you'd finally start building the
skyscraper, and when you're all done, cannabilize the mining equipment,
refineries, smelters, and factories for other purposes.

Or, you could just make use of mines, factories, smelters, etc. that are
already around (because you live in an industrial society), even though
they're not exactly at the site of your building. You have them do
their thing, and transport finished steel beams, glass panes, cabling,
etc. to the work site, where you build your building using equipment
that's also built other skyscrapers, and which, when this one is done,
will be moved elsewhere to build something else.

The latter obviously makes a lot more sense on Earth. I don't see why
it wouldn't make more sense in space too.


The chief difference is much higher transportation costs. That said I
expect computers & electronics to come from earth's surface for some
time to come. Even I-beams and plates will probably be made in cislunar
space.

However much of the mass of a cycler need not come from sophisticated
industrial infra structure. The asteroidal material might be used for
radiation shielding as is (especially if it has lots of hydrated clays).
It's possible water and oxygen might be extracted with relatively simple
asteroidal infrastructure.

Often Mike Combs will talk about value of asteroidal resources with no
deep gravity well. I believe an asteroid's momentum might also be
valuable. IF the asteroid is already close to a useful orbit. I
acknowledge that's a big IF. However, given the large number of NEOs,
I'm betting there are at least a few that are endowed with valuable
velocity vectors.

I will confess Dr. Lewis' vision of transport asteroids perplexed me (on
page 115 of my copy of Mining the Sky). I agree that a cycler should
have an earth resonant orbit. However Aldrin and Niehoff cyclers pay
attention to the approximately 2 1/7 year Mars-Earth synodic period. A 2
year cycler could be useful for hauling people to the main belt, but I
see little utility for transportation to Mars.

A cycler capable of carrying 220,000 passengers seems ambitious. Much
more plausible in my view is a mining camp accomodating 50. The miners
would also be geologists and planetary scientists studying the asteroid.
Some could disembark during Mars fly-by. I don't think such a cycler
could afford non-working passengers.