[HN Gopher] Astronomical Engineering: A Strategy for Modifying P...
___________________________________________________________________
Astronomical Engineering: A Strategy for Modifying Planetary Orbits
(2001)
Author : _Microft
Score : 48 points
Date : 2021-08-10 17:27 UTC (5 hours ago)
(HTM) web link (ui.adsabs.harvard.edu)
(TXT) w3m dump (ui.adsabs.harvard.edu)
| causi wrote:
| Combining the odds of us developing much better mitigation
| techniques if we survive the next million years with the odds of
| fucking this up and either ruining the moon's orbit or smashing
| the rock into the earth, this is an unbelievably bad idea.
| engineer_22 wrote:
| There is no mitigation technique for being swallowed by the
| sun.
|
| It's a thought exercise, not a proposal, you need not be
| worried about a catastrophic collision.
|
| Bravo to the scientist for doing the calculations.
| LorenPechtel wrote:
| This *is* a mitigation technique for being swallowed by the
| sun--if we stay far enough away not to get too warm we also
| stay far enough away not to burn.
| perihelions wrote:
| This is so backwards-looking. Why on Earth would you go to all
| this trouble to preserve a planet intact, when with comparable*
| effort you could _dismantle it entirely_ and create _orders of
| magnitude_ more habitable ecology in the form of free-floating O
| 'Neill cylinders?
|
| *(The solar gravity well is ~12 km/s deep and the Earth's gravity
| well is ~11 km/s, so dismantling the Earth and ejecting it are
| ~similar)
| abecedarius wrote:
| Yes, and after that we ought to get started on dismantling the
| sun. The sun is offensively wasteful, not to mention short-
| lived.
| [deleted]
| azernik wrote:
| Ejecting and minor adjustments are very different things.
|
| Plus, the idea is to extract the energy from Jupiter's orbit.
| perihelions wrote:
| > _" Ejecting and minor adjustments are very different
| things."_
|
| Sure, but going out to 1.5 au is already 1/3rd of the way to
| ejection.
| arthurcolle wrote:
| Dare I say "Galaxy brain engineering"
| sxp wrote:
| This seems very inefficient due to the high energy cost and the
| long timescales in the proposal. The long timescales means it
| would be hard to adapt this method to counteract rapid weather &
| climate fluctuations.
|
| A better option to control climate due to the sun would be to
| build a https://en.wikipedia.org/wiki/Space_sunshade between
| Earth and the Sun. While the common design is a monolithic piece
| of metal to block the sun, a more practical design would involve
| a swarm of reflective robots flying in the appropriate set of
| orbits. They would be powered by solar panels and maneuver using
| solar sails to constantly adjust their orbits. That would allow
| your to block as much sunlight as you want and adjust the levels
| on a daily basis.
|
| You could also divert sunlight rather than blocking it which
| means you could increase the amount of sun the Earth gets if you
| want more light. Or you could use the swarm to focus sunlight on
| a certain part of the Earth while blocking light to other parts.
| This would allow for localized climate modification or even
| weather modification if you had a powerful enough supercomputer
| to predict the chaotic effects.
|
| Since you could adjust the light distribution on the order of
| days rather than centuries, there would be a lot more room for
| fine-grained control compared to orbital modification.
| pankajdoharey wrote:
| I believe, much before those timescales humans would have
| become a Type 2 or Type 3 civilisation.
| sxp wrote:
| In Accelerando [1], humanity becomes a Type II civilization
| and builds a Matrioshka swarm. But it shines sunlight on
| Earth by opening up a hole in the swarm so that the sun is
| visible to Earth. That would allow harnessing almost all of
| the Sun's energy but would let Earth remain as a stable
| nature preserve for nostalgia purposes.
|
| [1] http://www.antipope.org/charlie/blog-
| static/fiction/accelera...
| Retric wrote:
| A sunshade is almost feasible using current technology,
| though it would have some negative impacts.
|
| Solar Cruiser is a 1,672 m2 solar sail being sent to L1 for
| 65 million. Which is of course nowhere close to cost
| effective for lowering global temperatures, but the basic
| components are there.
| nonameiguess wrote:
| The Montgomery Burns plan. The Simpsons will have again
| predicted the future better than any science fiction writer
| could dream.
| alanbernstein wrote:
| ...except that 1) it hasn't happened in the real world, 2) it
| was proposed in December 1989, about the same time as the
| first episode of The Simpsons aired. https://ui.adsabs.harvar
| d.edu/abs/1989JBIS...42..567E/abstra...
| Voloskaya wrote:
| > This seems very inefficient due to the high energy cost and
| the long timescales in the proposal.
|
| This is efficient for what the paper is about: A solution to
| the sun's gradual evolution towards a red giant. So long
| timescale is not a problem, since we have 1B year before the
| sun becomes too hot for where we are today, and 5B years before
| being engulfed by it.
|
| Space sunshades works well to reduce incoming radiations by a
| few % (e.g. for current climate change problem), it won't work
| so well when the earth will be within the sun's corona.
| LorenPechtel wrote:
| No--we have nowhere near a billion years. It's roughly a
| billion until all life is wiped from the planet, but it will
| be uninhabitable for humans *long* before that point.
|
| We have only 50 million years before Earth's ability to adapt
| to solar warming pegs and the temperature starts crawling up
| --and note that even that will not be good for an awful lot
| of plant life because of low CO2 levels. Earth needs to start
| it's retreat before then.
| montalbano wrote:
| > supercomputer to predict the chaotic effects.
|
| This might be the hardest part of your proposal to achieve.
| Chaotic systems are fundamentally difficult to simulate, not
| just because of their differential equations but our lack of
| perfect knowledge of their initial conditions. Blanket solar
| reduction seems more feasible?
| simonh wrote:
| Putting them in Earth orbit would allow for local variation,
| but would be much less efficient overall. Firstly because they
| would only be between the Earth and the sun for a very small
| fraction of their orbital period, and also because they would
| be so close to the earth they would only shade a relatively
| small multiple of the area of the satellites.
|
| This is why most proposals put the sun shade(s) in sun
| synchronous orbit between the earth and the sun. They would be
| a lot closer to the sun, and so intercept a lot more sunlight
| per area of satellite, and they would be blocking it all the
| time, or for as long as you wanted.
| kurthr wrote:
| I think that's what the parent is referring to (from the
| wikipedia page they are in L1). Of course that does require
| the active orbital stabilization also described (though not
| as around L1). Being closer to the sun is a big advantage,
| but also impulse heavy to get there.
|
| Perhaps an initial lift up to an unshadowed low earth orbit
| could boot strap a solar ion/sail to get them to L1?
| parksy wrote:
| 12000 years from now, Cockbert Roachstein, upon examining the
| peculiar dynamics of a passing moonlet, sets the scientific and
| philosophical community clicking and chirping with controversy on
| the suggestion that a mysterious ancient intelligence designed
| the scheme keep the planet's temperature in equilibrium as the
| sun heats up...
|
| "You mean to suggest a bunch of *click* _monkeys_ could steer the
| planet? Those creatures-in-the-dust who couldn't even survive
| _radiation_? You are hereby sentenced for *chirp* roach-heresy."
| hirundo wrote:
| They propose steering a very large rock around the solar system
| to transfer momentum from Jupiter to Earth. The point is to
| increase the orbit of Earth to accommodate the brightening of the
| Sun over the next 10^9 years. So it's a long term global warming
| mitigation project.
|
| If the rock is big enough to do the job, the tides, earthquakes
| and volcanism around perigee could be inconvenient. Also, the
| power to set the gimbals on the rock is the power to extinguish
| the planet, and what organization could stay incorruptible for
| 10^9 years?
| lmilcin wrote:
| It is not global warming mitigation. This method has no hope of
| counteracting any kind of change in climate even on geological
| timescales. The only thing it can do is to slowly move Earth
| away from Sun over billions of years in imperceptible
| increments roughly every 6 thousand years.
|
| I hope humanity can even survive 6 thousand years.
| lisper wrote:
| That was my first reaction as well: let's start mucking with
| earth's orbit, what could possibly go wrong? But the problem
| statement is trying to avoid being incinerated when the sun
| goes red-giant in a few billion years, so doing nothing is
| clearly not a viable alternative here.
|
| On the other hand, given our current blase response to climate
| change, I'll give you long odds against human civilization
| being around in a billion years, or even a million -- or, for
| that matter, a thousand. And unless something changes radically
| in the next few years, I'll give you even odds against it
| lasting to the end of this century.
| blacksmith_tb wrote:
| I can't see how we'd call any descendants of ours 'human' in
| a billion (or even a million) years, but I would be surprised
| if modern humans were wiped out in the next thousand years -
| we've lasted tens of thousands up to now. We certainly need
| to make some changes, but I'm at least semi-optimistic we can
| do that.
| lisper wrote:
| Oh sure, _humans_ will be around. But whether human
| _civilization_ will be around is far less clear.
| reidjs wrote:
| What makes you so sure about that? Humans require VERY
| specific environmental conditions to survive.
| LorenPechtel wrote:
| Actually, I would be amazed if "humans" exist at that
| point. I wouldn't be surprised if they don't exist in
| even a thousand years.
|
| Assuming we don't do ourselves in there will be
| sentients, but species are defined by the ability to
| interbreed and I expect genetic modification will reach
| the point that interbreeding with a stock human is no
| longer possible. At that point we will be a new species,
| not "human".
| kavalec wrote:
| The future GOP will poo-poo the solar growth myth and complain
| about the effect on the economy.
___________________________________________________________________
(page generated 2021-08-10 23:01 UTC)