Dyson sphere alternatives, L1 control

[PB666]

Given: no evidence of dyson spheres in other galaxies

Given: great technical difficulty if supporting mass outside of orbital inertial points along the sphere

Given: the general unavailability to build such objects.

What kind of space engineering might be done.

Lagrangian points exist inside, L1, outside, L2, leading, lagging and opposing planetary orbits

Objects at L1 can assume partially stable orbits, and disks at L1 can be used as stationary platforms.

Solar blocking or harvesting arrays block sunlight, so for instance you could block some of the sunlight reaching earth and thus cooling it. The problem is that climate change is not a single process, its two competing processes. The one process, insulation, is created by gases that reflect radiant energy back toward the surface. The second process is the absorbtion of atmospheric light by absorbant particles like soot and jettrails that lower pan evaporation rates and diminish rainfall rates. Many areas of the world, such as africa and arabia are more affected by the second process than the first. In fact the highest rate of rainfall seen in N. Africa was at the holocene climate maximum starting around 9000 years ago and lasting for only about 3000 years and form a geological perspective we would be heading for an ice age. Such a disk makes the problem worse, except for global warming.

So for such a scheme to work we would need to stop the burning of coal, wood, clearing land by fire, and jet engines as we know them, otherwise we could be making the drought problem worse.

Next target. Venus, this has already been discussed before, but provided we could mine carbon you could block 3/5 ths of the light hitting venus and it would become a paradise.

Not exactly, what has happened to venus is that its oceans are in its atmosphere because of the heat, in fact its proably lost a considerable amount of water which the earth has prolly picked up some, the rest heading out to jupiter.

The planet is what i would call salt split. Most salts are composed of non-volatile metal portion that are basically grounded, a volatile anion portion that a moderate to high temperatures can split from the cation and become a gas. It takes a considerable amount of energy. On earth this occurs at the degrading edge of subductuion zones resulting in the ring of fire. The anions of salts basically evolving and percolating to the surface.

On venus this mostly has occurred on or close to the surface. The most reactive of the anions is sulfate, sulferic acid has a low pka, so low in fact it cannot be measured, pure sulferic acid and water is an explosive combination. Sulferic acid has a relatively high boiling point. So that the first antropogenic rain storm on venus would be one kraken of a storm. The surface of venus would literally begin to explode.

Over 1000s of years venus surface would tame down but it would be quite some time before the effects of the acid had washed away. Maybe after a few thosand years you would have highland lakes with acid wtaer capable of sustaining life and land capable of growing grases, but no tropical paradise.

There is no harm in doing this to venus, but the risk, in materials, is high. It would take trillion of kg of carbon to produce the material to build such a platform and yearly cost to maintain orbit would be immense.

Another choice is to sheild comets, sheilding comets protects the from proxi-sloar encounter, during the periods they can be steared for useful orbits and harvested. much more practical.

So now if we were looking for sentients should we be looking for the impractical or the practical evidence of beings?

[YNM]

I should say we better off just "invading" other stellar system than making crazy feats here and there. Even going to an icy moon with liquid mantle is quite an improvement, as they'd likely orbit gas / ice giants than the same icy planet, making them viable interstellar bases. Guess other sentients would also do the same.

Although, having such disks would results in we detecting it's radius in transits than the planet radius.

[PB666]

I should say we better off just "invading" other stellar system than making crazy feats here and there. Even going to an icy moon with liquid mantle is quite an improvement, as they'd likely orbit gas / ice giants than the same icy planet, making them viable interstellar bases. Guess other sentients would also do the same.

Although, having such disks would results in we detecting it's radius in transits than the planet radius.

A disk would absorb and reflect differently than a planet. A disk absorbs in the daytime and reflects at night. A disk absorbs and emits all the time, it would give the same signature as a dyson disk and second you would not see the disk an miss the planet, you would see a planet shadowing a disk, because some of the starlight still reaches the disk.

I must say neither are a good idea, but the disk is a better idea than a dyson sphere or even dyson ring, particularly in the case of venus where you have alot more hv (it would be about 1.5 million km closer to the sun than venus), so at least you have alot of solar power and potential hv for orbit keeping (direct emission).

Dyson shere is advantageous because what is inside becomes invisible, and because hv can be used as a tool for spacecraft acceleration on the ring. It is impractical for just about every other reason one can imagine.

Circumstellar ring can be used to produce hv for spacecraft acceleration. If we can imagine this, suppose we had a ring 10000m thick and we can reduce the output down to a band of about 100m, then we could concentrate solar power 100 fold, instead of accelerating at 0.01g we can accelerate at 1g for say the distance between venus-earth and the asteroid belt. Lets say the path length is 500,000,000,000.

In this scenario we are given a infinite ability to dissipate heat, we can generate 1g (10 m/s) for 314000 seconds (3.64 days) giving us a final velocity except that lost to the suns gravity, a miniscule amount, of ~3,170,000 meters per second. Light travels at 3,000,000,000 meters per second, so we obtain 0.01C, Alpha centauri takes only 100 years, and we go wizzing through the system with no way of stopping, and everyone on board is a mummified corpse because we have no provisions for food or water (best to use a probe). The electronics on the probe is fried by the cosmic radiation the high velocity produces as well as numerous electro-static storms created by the ship as it passes through differential plasma of interstellar space (those little processors are made with 5v in mind, not millions of volts). OK so we are not ready to use a ring even if we have one. To make such a ring useful we need a really big ship, with lots and lots of panels (Km^2) and lots of protection on the front end, some sort of unrealistically gigantic space parachute that begins slowing us down years before we reach the target, and a specially designed, probably nuclear driven insertion ship.

Planetary-Stellar L1 disk can be used to control planetary climate, but also offers a potential highpower launch point for VASIMR like spacecraft launches to other parts of the system (imagine that we use reflected starlight to concentrate solar power on panels of the VASIMR ship, most panels can handle 5-20 times the sunlight so no need for nuclear and can use normal solar to insert. Still no way to dissipate the heat, but we could use such a ship to get a LfOx ship into planetary orbit with a really large payload, all we have to do is get the ship to a rather low dV position near L1. The problem with this plan is although we leave with lots of dV once we get to Mars or Ceres, we are heading at high velocity to cut the trip short, the radial velocity is high and lots of dV are needed not where the disk is, but at the destination. So this plan needs another disk at Mars or Ceres to provide the power to stop the ship. Since venus would already have a disk earth venus travel would be complimentary, but again, venus as a destination is prolly going to be difficult.

The alternative is redirecting asteroids and comets, much better plan. Place them together and shield them from degassing and mine and build station in the mine and create a space based colony at whatever orbit you like.