Inhabitable Planets Too Close Together?

SWM wrote:That's just for the oxygen--you'll need even more to get enough nitrogen.

Is there any theoretical way to add a proton (and associated neutrons and electrons) to Carbon to manufacture Nitrogen? Or other way to manufacture Nitrogen from fusing some other waste product?

We're presuming that we can produce enough H2 for fusion reactor fuel that we'll have to pipe it away to dispose of it -- that might give us enough raw material to build up whatever element we need.

Here is a good reference on Jean's escape mechanism.

Forgot the link, damn it.

http://sci.esa.int/science-e/www/object ... ctid=50647

The bottom line is that at 1,000 K which is the temp at the top of the thermosphere, rms for Oxygen molecules is 1 km/s while rms for hydrogen molecules is 4 km/s. While the rms of Hydrogen is far short of escape velocity, a significant fraction of molecules (1 in 10,000) exceed escape velocity. CO2 has a higher molocular mass than Oxygen but rms velocity is only marginally lower.

This suggests that heating theatmosphere (or a significant portion of it) to about 16,000 K would result in Oxygen having the same velocity profile as hydrogen at 1,000 K. However; at this temperature you will have mostly atomic oxygen so 10,000 K would be quite adequate.

An orbiting solar mirror of perhaps 1,000 km diameter that focuses sunlight onto a region of atmosphere a few kilometers in diameter would create a region of rapid cook off.

Here is a good reference to atmospheric temperature profile.

http://apollo.lsc.vsc.edu/classes/met13 ... p_all.html

Weird Harold wrote:

SWM wrote:That's just for the oxygen--you'll need even more to get enough nitrogen.

Is there any theoretical way to add a proton (and associated neutrons and electrons) to Carbon to manufacture Nitrogen? Or other way to manufacture Nitrogen from fusing some other waste product?

We're presuming that we can produce enough H2 for fusion reactor fuel that we'll have to pipe it away to dispose of it -- that might give us enough raw material to build up whatever element we need.

You might want to look up the CNO cycle of burning hydrogen.
http://en.wikipedia.org/wiki/CNO_cycle

I'm inclined to suspect that terraforming (which we haven't actually seen done) is carried out on a planet by using large quantities of handwavium in a process powered by unobtainium. Or in other words, it's RFC's universe so if we can swallow his wormhole junctions and FTL communications system why can't we just accept his terraformed Grayson?

John Prigent wrote:I'm inclined to suspect that terraforming (which we haven't actually seen done) is carried out on a planet by using large quantities of handwavium in a process powered by unobtainium. Or in other words, it's RFC's universe so if we can swallow his wormhole junctions and FTL communications system why can't we just accept his terraformed Grayson?

Grayson wasn't terraformed significantly. We don't know of any planet with any terraforming more elaborate than introducing Earth-type plants and animals, and processing of local zones for agriculture or habitation.

Most of these ideas aren't mutually exclusive. The colonists could use industrial production methods AND drop comets AND use genie coral etc (although while they're at it they might as well toss in some other genie organisms, archaebacteria can survive in some extremely harsh environments and could be engineered to do a variety of useful things). Although as an order of addition problem, if I was going to combine techniques I'd drop comets first as dinosaur killers may disrupt the new ecosystem and may damage any industrial structures.

biochem wrote:Most of these ideas aren't mutually exclusive. The colonists could use industrial production methods AND drop comets AND use genie coral etc (although while they're at it they might as well toss in some other genie organisms, archaebacteria can survive in some extremely harsh environments and could be engineered to do a variety of useful things). Although as an order of addition problem, if I was going to combine techniques I'd drop comets first as dinosaur killers may disrupt the new ecosystem and may damage any industrial structures.

The problem that namelessfly is trying to deal with is that the only example we have of a purely biological process going from a pre-oxygen atmosphere to one with a modern proportion of oxygen took about 2.5 billion years to get there. This is probably somewhat outside of the payback horizon for even the most far-sighted transstellar to consider.

That doesn't mean it couldn't be done faster, but a single example doesn't provide any support for the notion.

The biggest issue that none of these proposals deal with is that, in a pre-oxygen environment, there are a huge number of oxygen sinks, such as reduced iron, which will promptly absorb all the oxygen you can produce. That's what took close to a billion years of that 2.5 billion before there was any more than trace amounts of oxygen in the atmosphere.

namelessfly wrote:Here is a good reference on Jean's escape mechanism.

Forgot the link, damn it.

http://sci.esa.int/science-e/www/object ... ctid=50647

The bottom line is that at 1,000 K which is the temp at the top of the thermosphere, rms for Oxygen molecules is 1 km/s while rms for hydrogen molecules is 4 km/s. While the rms of Hydrogen is far short of escape velocity, a significant fraction of molecules (1 in 10,000) exceed escape velocity. CO2 has a higher molocular mass than Oxygen but rms velocity is only marginally lower.

This suggests that heating theatmosphere (or a significant portion of it) to about 16,000 K would result in Oxygen having the same velocity profile as hydrogen at 1,000 K. However; at this temperature you will have mostly atomic oxygen so 10,000 K would be quite adequate.

An orbiting solar mirror of perhaps 1,000 km diameter that focuses sunlight onto a region of atmosphere a few kilometers in diameter would create a region of rapid cook off.

What proportion of the energy gets absorbed by the atmosphere in that focus sphere, and what proportion goes through? To reiterate an earlier point, I have a suspicion that what you'd be doing is melting the surface.

This was in the back of my mind.

The total capacity of the Oxygen sinks is important but the rate at which the Oxygen sinks can absorb Oxygen is critical. If your process for creating Oxygen can exceed Oxygen sequestration by a wide enough margin, you can create and maintain breathable atmosphere.

JohnRoth wrote:

biochem wrote:Most of these ideas aren't mutually exclusive. The colonists could use industrial production methods AND drop comets AND use genie coral etc (although while they're at it they might as well toss in some other genie organisms, archaebacteria can survive in some extremely harsh environments and could be engineered to do a variety of useful things). Although as an order of addition problem, if I was going to combine techniques I'd drop comets first as dinosaur killers may disrupt the new ecosystem and may damage any industrial structures.

The problem that namelessfly is trying to deal with is that the only example we have of a purely biological process going from a pre-oxygen atmosphere to one with a modern proportion of oxygen took about 2.5 billion years to get there. This is probably somewhat outside of the payback horizon for even the most far-sighted transstellar to consider.

That doesn't mean it couldn't be done faster, but a single example doesn't provide any support for the notion.

The biggest issue that none of these proposals deal with is that, in a pre-oxygen environment, there are a huge number of oxygen sinks, such as reduced iron, which will promptly absorb all the oxygen you can produce. That's what took close to a billion years of that 2.5 billion before there was any more than trace amounts of oxygen in the atmosphere.