10 years to evacuate Earth

[DDE]

On 9/22/2020 at 8:58 PM, kerbiloid said:

Novaya Zemlya, Central Asia, US deserts - all of them are by orders of magnitude better than Africa, even with some delta-V decreasing.

http://www.projectrho.com/public_html/rocket/images/enginelist/radiationBelt2.jpg

I think Novaya Zemlya it is.

[Mikenike]

I would take the Sat5 back, load it with nukes from Murica, then launch it at this asteriod. Problem solved.

On 9/22/2020 at 11:22 AM, sevenperforce said:

Yep, exactly.

There is no theoretical upper limit to the size of a multistage thermonuclear device. With just the US, Russia, and China working together we could easily build a dozen gigaton nukes. Throw in nuclear engineers from Israel, France, and the UK and we can probably double our output.

Ten years is a long time, even when you're dealing with interstellar velocities. I would say we could launch the first interceptor in under 24 months and send backup interceptors every six months thereafter.

Ten years is not enough time to develop off-world closed-loop life support for any significant segment of the human race, however.

On the other hand, if you specify that you already HAVE closed-loop life support available (moon or Mars base, for example), the hypo becomes much more interesting.

I agree.

[wumpus]

On 9/22/2020 at 1:07 PM, kerbiloid said:

Nobody would build the launch site in the unpopulated part of Africa, because of logistic arm? leg? tail?

It would be built as close to the industrial base as possible. If necessary - with the population removal to any other place.

At least because they would have just ten years.

Unlikely China has some unique resources which others lack, and US could use the largest nuke as well.
Anyway, the nukes are being built by other people than rockets.

So, I would expect a close cooperation between US/EU/RF/JP and maybe some interaction with China and its own program.

Unless the launch site is in the Sahara (which should be sufficiently close to the equator for similar benefits), there have to be less populated launch sites elsewhere.  I'd claim that the Mohave is probably ideal (huge, unpopulated, East of a huge industrialized population), and China has something similar (or could simply populate the right area by fiat similar to "constructed cities").

I've mentioned in other threads that the Orion needs to be built in Antarctica: even George Dyson pointed out that discovery of how the magnetosphere works showed that the calculation of "minimal fallout" was wrong for Orion.  But you can get back to those levels by launching in a polar orbit in Antarctica.

This assumes you are trying to avoid killing people.  I'd assume that evacuating all living people is impossible and the real way to evacuate Earth involves the four horsemen (War, Famine, Pestilence, and Death.  Although in this case the new guy: Pollution might have a place) and lifting the survivors will be possible.

[kerbiloid]

11 minutes ago, wumpus said:

Unless the launch site is in the Sahara (which should be sufficiently close to the equator for similar benefits), there have to be less populated launch sites elsewhere. 

The closer your launchpad is to your industry, the heavier rockets or the same ones more often you can launch.
So, the greater total mass you can deliver to LEO per year. This makes delta-V ~300 m/s (from ~10 000 m/s for LEO) insignificant for mass launches.

Sahara is one of the worst places for a launchpad, as it's as far from any serious industry as it can ever be.

Also in Sahara they could face diplomatic trading problems which they wouldn't have in the Northern countries.

China would probably run its own program, so not an option.

Mongolia is inside the continent, and the ascent trajectory would pass above the Chinese territory.

18 minutes ago, wumpus said:

I'd assume that evacuating all living people

Has been done in 1986. And it's much easier to evacuate them to an urbanized territory.

[Bill Phil]

On 9/22/2020 at 5:04 AM, coyotesfrontier said:

Let's say an interstellar object is discovered heading straight for Earth's position in exactly 10 years from now. Due to its size and extremely high speed, its impact will melt the Earth's crust and kill all life. You have control of every government on Earth, and your job is to create a plan to save as many people as possible. Additionally, you must ensure that humanity is able to be self-sufficient once in space, and not rely on supplies that will eventually run out. While you have unlimited funding, you are still limited by resource availability. Go!

Hold on, you just said create a plan to save as many as possible - that isn't the same as evacuating the planet. But we could do both if we had the entire planet, or at least try.

So, we have two solutions. 

Number One - Deflect the Impactor:

This will probably be done with nuclear pulse propulsion. Something like Project Orion. 

Number Two - Evacuate the Population:

This may not be necessary if the impactor is put onto a trajectory that misses, but it could be a reasonable solution.

So how would we go about this?

Well, for the first solution, we have to figure out what we're dealing and come up with a vehicle to do the job. A large enough Orion could do it, at immense cost. Depends on how much impulse this thing will need. If need be, multiple vehicles can be sent. They would probably try to grapple with the impactor and push it. If this fails, then it may be possible to push it using either directed nuclear explosions or by burying nuclear charges in its surface. Or perhaps an impactor could provide enough momentum exchange.

As for evacuating the population... well, we need to lift the human population off the planet. But we should also try to get other parts of nature off as well, or at least try to get genetic material from as many species as possible. Project Orion can be useful here as well. Launching a large enough mass to Earth orbit could enable a significant space based industry. This space based industry could extract oxygen from the lunar surface along with metals and possibly bring hydrogen to make water. Other elements can be sourced from Earth as needed - it's going to die off anyway if the impactor hits. 

So the first step is to establish a massive space based industry. The goal for this industry will be to build enough orbital habitats to house the human population. Large solar power and agriculture satellites could be built as well. 

Of course, building enough space habitats is an immense challenge. We can minimize the number by packing people in high density dwellings. 500 thousand per square kilometer is possible, though it will not be comfortable or enjoyable. But standard of living isn't the concern - survival is. If the world has 8.5 billion people by 2030 (ten years from now), then we'll need 17 thousand square kilometers worth of space habitats - if ever space habitat is 10 square kilometers, then we'll need 1700 of them. 

Can that be done? Probably not. But we know that a space habitat might require 15 tonnes per square meter of shielding, with non-shielding mass being much smaller. That's 255 billion tonnes of shielding - which can be just about anything. Structurally we might need around a twentieth of that, about 13 billion tonnes. If we take this production as occurring in around 5 years, with the first 5 years spent establishing this industry, then we need to produce around 2.6 billion tonnes of metal per year, definitely more to build agricultural satellites. So let's call it a good 3 billion tonnes per year. That is a damn lot. And of course we'll also need to handle much, much more.

Of course we could pack people more densely, which would reduce the requirements. 2 million per square kilometer was nearly reached in the Kowloon Walled City... definitely won't be comfortable. This would reduce the needed area, and thus mass, by 4. This reduces the needed metal production per year to 750 million tonnes - which is quite achievable. Indeed, current industries could be leveraged along with space based industries to reach a larger number if needed... crude steel production is already over twice that. We could reasonably expect an excavator of sufficient size to excavate around 180 tonnes of soil/regolith per hour. Assuming each excavator only operated for half of a day, we can find how many excavator would be needed to excavate sufficient material for shielding. Using the higher population density you need around 64 billion tonnes of shielding. This requires around 355 million excavator-hours. Over 5 years and half of the time is operating time, we'll need around 16 thousand excavators. A bit more, actually. This isn't actually a huge amount. Excavators like this could be around 50 tonnes, for a total of around 810 thousand tonnes. This could be delivered to the Moon, along with a lot of other equipment, with Project Orion vehicles. The hard part in this instance will likely be developed a lunar excavator and mass producing them fast enough. Of course, the other aspects of the logistics would need to be addressed as well.

But... it could be possible. If everything went perfectly. Obviously it won't, but getting a good tenth of the global population into space could be doable. Maybe even more. 

[Lewie]

I think that to avoid petty political squabbles, martial law would be declension. All funding would be diverted from anything deemed ‘unnecessary’. (Ea. Schools) Elon Musk would see his starship development be backed by the full might of the world, and as soon as possible, starship is used to create an orbiting colony, filled with humanities’ brightest. It would contain classic literature, The Bible, and seeds of various plants. The mass majority would be moved to mars by starship, where everyone pitches in to create permanent settlements. All efforts go into re building humanity, and bit by bit, we begin reaching to the stars. After all, mars really is tiny. 

Man, reading all of your ideas on what would happen, makes what I came up with stupid. I dunno, but that’s my 2 cents.

[kerbiloid]

The evacuation plan should begin from the estimated period of evacuation and the self-sustaining food supply calculation.

The Earth gets totally uninhabitable for how long? A week? Several millenia? Forever?

In the two latter cases they need a food production loop unbound from the Earth, i.e. pre-built space or extraterrestrial colonies with agricultural infrastructure.

***

Mars is ~1/6 of the Earth total area and has a limited amount of water. Its insolation is 2 times weaker than on the Earth, and it's cold there.
So, farming on Mars is literally farming in arctic greenhouses. Possible, but low-productive.

So, even if turn the whole Mars into a green farm, it can't feed more than 5..10% of humanity, i.e. ~500 mln.

And the low gravity should cause great (almost unsolvable) problems in child growing.
So, even if turn the whole Mars into a green farm, the habitats still should be orbital, and anyway just for tens-hundreds of millions in the best case.

***

A fusion-powered farm has its own problems.
To grow as much plants as you can do on the Earth, you need produce nearly same power as the Earth plants get from the Sun.

But then you produce the waste heat several times greater than your lamps inject into plants.
I.e. you have to produce nearly as much heat as the Earth gets from the Sun.
This means raising the equilibrium Earth temperature by ((2^1/4 - 1) * 273) ~50 K.

So, even by using the inexhaustible deuterium fusion to produce more food on the Earth, you should limit the artificially powered greenhouses with same 5..10% of the solar food production.

***

On the Earth you can dissipate the waste heat in air, water, and rocks.
In space you can just dissipate it with radiators.

So, the larger and more bulky gets an orbital colony, the greater radiator area should it have per the habitat size.
Even ISS for the crew of 6 is almost flat.

Growing food out of solar light requires ~1 hectare of not shaded area per human.
So forget any O'Neil cylinder (did he even calculate the basic numbers?).

The ways are::

1. Limit your orbital colony population with a village size.
Implausible, as everyone should be an experienced specialst in fusion or in greenhousing. Most of people just couldn't.

2. Put the farms on ground.
If the Earth is unavailable, this means either Moon, or Mars, or Venus. Other places are too dark.
The Moon is much smaller than the Mars, it can provide not more than several tens millions even if deliver an ocean of water there.

The Venus is well-insolated, but has its own known minor problems with farming.
Even if condense its atmosphere and make it inhabitable, or spread aerial algae, it anyway lacks water a little.
So, its capacity is not greater than the Mars have, but requires by orders of magnitude more efforts.

3. Launch billions of crystal spheres in HEO, with algae inside, so that their total cross-section area exceeds the cross-section of the Earth.
Launch millions or long-lasting orbital tugs to deliver raw materials and gather their product.
Possible, but a little expensive. Plausible for a very hi-tech civ which unlikely is 8 bln large in one place.

***

So, the extraterrestrial colonies population unlikely can exceed ~500 mln in the best case, in total. Actually, even fewer.
(Mars covered with greenhouses, some algae balloons above Venus, farms on the Jupiter moons powered with its magnetic field and deuterium fusion).

This means that the only way to save billions outside of the Earth is to discover a stasis field to "freeze" them in time and "unfreeze" later.
In any other case only first several hundred millions can be saved in extraterrestrial colonies, while others should hide in the on-ground vaults on the Earth and face the obvious problems.

(This btw makes to treat as unlikely probable a wide international collaboration in the evacuation from Earth.
In the vault building - why not.
Also this makes to think that Sahara is a laughingly improbable place for a launch site even witthout logistic problems.)

***

As unlikely the Mars, Callisto, Venus, and Moon get green soon, probably just tens of millions are the exttraterrestrial limit.

***

Also we should remember that in case of a earthocalypse the LEO will be full of ground scraps, so the orbital vaults should be placed in high orbit, with total delta-V comparable to the Mars flight.

So, probably the best way is to turn Phobos and/or Deimos into a set of rotating habitats and start covering Mars with greenhouses.

But anyway for just several tens millions (let it be 100 mln for certainty.)

***

As a long space journey requires at least 28 m³ per human, the Martian orbital habitat should be at least ~3 km³, i.e. at least 2 km in size.

As this habitat should lasr for at least several millenia, it should be larger and have thick walls.

So, Phobocities and Deimocities looking like a set of rotating bunches of cylinders should be made out of the Phobos and Deimos metal totally reworked,

All agriculture and industry is obviously on the surface of Mars, with no permanent population there.

It's tens of millions. If the Earth stays uninhabitable, they anyway should start mining her when it gets possible.

The orbital habitats and the ground infrastructure construction should start on advance.

***

Others should hide in on-ground vaults.
As the Moon agricultural abilities are very poor, the gravity is low, so a lunar vault is a vault, not a colony; they should return asap and repopulate the Earth.
The low gravity is bad for child forming, so its reasonable lifespan is limited with "while the existing fertile stay fertile", i.e. 44-14 = 30 years max.
Actually, 20 years, due to anyway low-g health problems.

So, the lunar vault should have a ready-to-use food reserve for 20 years, i.e. ~10 t/human.
Or at least for 2 years, to survive a volcanuclear winter. Then ~1 t/human.

So, depending on the estimated time of the Earth uninhabitability, they should temporarily evacuate to the Moon amount of humans varying by 10 times.
But anyway not longer than for 20 years, after which the moon "colony" will die.

***

The lunar vault size is limited only with amount of supplies delivered from the Earth in advance and stored there.
2 t * 8.5 bln ~= 20 bln t of food to be delivered from the Earth.

On one hand, it looks enormous. On the other hand, it's a 2-year global food reserve which looks wise.
In any case, this is far beyond the capabilities of anything flying even from near-future.

But a 2-year global food reserve looks good, so, let it be planned.

So, they should evacuate to the Moon either everyone for 2 years, or 1 of 10 for 20 years.

As a person requires ~ 1 t of a spaceship capsule today, and probably will take 2..3 times less in the evacuation ship,
and there is 2 t of supplies to be delivered and then rotated once per at least 50 years,
so the transfer capacity of the lunar fleet is ~2000 / 50 = 40 kg/(y*human), and this is ~1/10 of the 300..500 kg/human required.

So, actually the lunar vault capacity is limited with 1/10 of the humanity. I.e. ~1 bln.
And they can survive on the Moon for 20 years before getting out of food and get extinct.

Other 90% of humanity should hide in the Earth vaults.

***

The Earth vaults should be big, strong, and thick, to quickly hide a whole city of them and provide them with supplies at least for several years until the volcanuclear winter ends.
If the cataclysm lasts longer than that, they unlikely can survive longer than a century due to the food reserve decay.

So, it should be the storages of "the main global food reserve", providing the whole humanity with food for "as long as possible, but <= 100 years".

As the vaults should be large but compact, and have vertical size of hundreds meters, there is no need to make them underground and face unstable rock layers of overheat problems.
They should be hand-made armored-concrete hills of kilometers horizontal size, and hundreds of meters vertical, built on rocky ground in many places, next to the largest cities.
Actually, they should be a city stronghold from the "geofront" to the average downtown height.
This also allows faster hiding.

If one hemisphere can be considered devastated, some of them on the opposite side may survive.
So, it can save for several decades about 10..20% of humanity more if the crust is not melted.

***

So,
~<100 mln in orbital Phobocities and Deimocities to survive for millenia and maybe longer, with industry and greenhouses on uninhabited Mars.

up to ~10% on the Moon, surviving for 20 years

~20% on the Earth, surviving for 0..100 years

P.S.
As we can see, the total amount of Martian and Lunar evacuees are ~1 bln of humans.
So, I bet they are from highly-developed industrial countries, with spaceports in their local areas.

***

This demonstrates how important is to start building a swarm of semi-intellectual orbital telescopes and spread them around the Solar System, to list every meter-sized rock, and to detect various `Oamuamuas before they approach and can be hit.

Edited September 25, 2020 by kerbiloid