Planet Habitability after Doomsday Scenarios

[mangekyou-sama]

I started this thread with the aim to get feedback from the community regarding the chances of survival and inhabiting and repopulating the Earth after an asteroid impact. Due to a really educational insights people have posted here, I've expanded the thread to include other doomsday scenarios as well.

*All scenarios are simulated in Universe Sandbox 2.*

The asteroid in question was Ceres. I was trying to get a good feel on how it would look like if a Ceres-sized object impacted Earth.

Year 0, here we see Earth and a nice view of the Pacific ocean. Surface temperature sitting at a nice 14.8C

And here's Ceres, with a radius of 476km

No idea why it turned blue, anyway, it's getting really close to Earth, casting its shadow on SE Asia

Impact. At this moment, temperature shot up to 590C and is still increasing

Full impact, surface temp at 801C

Days after the impact, the whole planet is engulfed in seemingly really hot matter (molten rock maybe?)

Year 2 and a half, surface temp 439C. And you can see the remains of America. There is evidence of a shift in Earth's axial tilt.

Year 3 and a half, surface temp 382C. Here are the remnants of the Indian ocean, SEA and Antarctica.

Year 7, first signs of water appear in different parts: Gulf of Mexico, small parts of the Atlantic, impact crater. Again, notice the position of America

Year 8, water has fully covered all the major bodies again. There is evidence of clouds and weather systems again although surface temp is still at 134C

Year 9, surface temp has dropped down to 31C. Massive icing has occurred on some continent though in this screenshot I can't really tell

Year 10, still massive icing which I found to be seasonal (it recedes midyear) which might be due to the change in the Earth's tilt. Surface temp has dropped back to normal.

Year 10, from another angle we see the remains of America which is heavily flooded

Year 10, remains of Africa and Europe (game depicts city lights on the dark side of Europe, so I guess there's people again? lol)

Here are my questions regarding the first scenario...

1. What caused the sudden high temperatures that dried up the bodies of water?

2. What are the chances of a Ceres-like object impacting Earth?

3. Can an asteroid impact that big cause a shift in the Earth's axial tilt?

4. Given that it took 10 years (in the game) for surface temperatures to go back to normal, was the simulation necessarily accurate?

5. Will Earth, or any othet planet, be habitable after an asteroid impact (taking radiation in consideration)?

This scenario aims to simulate what happens if one day, the sun just vanishes (well maybe it's not very realistic, as a star's collapse usually comes with novae, and our Sun is not that old yet to collapse) from the system.

First of all, here's a shot of the solar system we know. The game depicts the orbits of the different bodies around the sun...

...then suddenly, the sun just vanishes (I deleted it lol)

We take a look at earth. Somehow, the simulation has become erroneous since it still simulates daylight (which is not possible since there is no Sun). 5 days after the Sun goes out, surface temperature sits at 14.1C

With no parent star to hold the planets in orbit, each body drifts away from orbit

13 days after sun-out, surface temp drops further to 10C. Ice begins to form in the northern landmasses

105 days after sun-out, surface temp has dropped to -0.0203C and still dropping. Land masses in the northern hemisphere are now covered in ice. Even the once scorching hot Sahara is now beginning to be covered in ice

144 days after sun-out, surface temp @ -3.47C, the whole of Africa is now covered in ice

235 days after sun-out, with the temperature @ -10.6C, bodies of water now begin to freeze from the north, creating an expanding ice cap that will soon cover the northern hemisphere and within months, the world.

More than a year after sun-out, surface temp @ -26C, the northern hemisphere is now completely frozen

A few weeks more, with surface temp @ -29, the rest of the Atlantic and Pacific ocean freezes

In less than 2 years after sun-out, with surface temp @ -36C and still dropping, the world becomes a frozen wasteland as it drifts further into space.

I ran the simulation further and after quite some time (hundreds of years), Earth temp stopped dropping at about -139C.

Here are my questions regarding the experiment:

1. What are the chances that the Sun will suddenly stop giving out energy needed to heat the system?

2. Would it be possible to survive such a scenario by living deep underground and let the Earth's own heat do the work?

3. Can the Earth produce its own heat without gravity from the Sun?

4. Is adaptation totally out of the question? Because well, adaptation against extreme hypothermia and eternal darkness doesn't exactly happen in just a year.

I'm looking forward to reading your inputs!

Edited September 12, 2014 by mangekyou-sama

[chaos_forge]

I don't think radiation levels would change appreciably after an asteroid impact: the energy released by an asteroid impact is all kinetic energy, radiation doesn't come into it. So unless the Earth is colliding with a Ceres-sized lump of Uranium (how would that even form in the first place though?), the radiation levels on the Earth's surface would remain more or less the same.

As for what caused the temperature rise, that is the kinetic energy of Ceres. A massive object moving at orbital speeds has a truly ENORMOUS amount of energy. So, when all that kinetic energy is transfered to Earth, it has to go somewhere. The somewhere is goes to is a massive increase in the Earth's temperature.

The chances of a object the size of Ceres impacting the Earth are practically zero. The only situation I can think of in which it *might* happen would be if a rouge gas giant comes in from outside the solar system and messes up the orbits of all the planets/asteroids/etc.

As for whether the specific numbers were accurate, I don't know.

Edited September 11, 2014 by chaos_forge

[lajoswinkler]

Ionizing radiation would increase slightly if a large portion of magma is gouged out because of the radioactive elements in the ground.

Nonionizing radiation would fry everything and everyone.

[Kryten]

1. What caused the sudden high temperatures that dried up the bodies of water?

The energy released from the impact.

2. What are the chances of a Ceres-like object impacting Earth?

Pretty much zero. Anything Ceres-sized or larger (other than Ceres, which isn't going anywhere) is in the kuiper belt; extremely far out. It's very unlikely for one to lose enough energy to enter the inner solar system, and extremely unlikely for one to hit earth if it does.

3. Given that it took 7 years (in the game) for surface temperatures to go back to normal, was the simulation necessarily accurate?

It sounds about right, rock doesn't exactly cool rapidly.

4. Will Earth, or any othet planet, be habitable after an asteroid impact (taking radiation in consideration)?

One the size of Ceres? It might become habitable, after a while, but there'll be nothing left to do the inhabiting.

[mangekyou-sama]

but there'll be nothing left to do the inhabiting.

I guess that opens yet another question in my mind. Let's say people evacuated somewhere before the impact, say the Moon. Would the shock wave (if that can even travel through vacuum) affect the Moon substantially? Or if not, knock all man-made stuff out of orbit at least?

[lajoswinkler]

I guess that opens yet another question in my mind. Let's say people evacuated somewhere before the impact, say the Moon. Would the shock wave (if that can even travel through vacuum) affect the Moon substantially? Or if not, knock all man-made stuff out of orbit at least?

Shock waves are disturbances in matter. Vacuum is absence of matter, therefore no shockwaves. That's why bombs in vacuum are pretty pathetic.

[Tommygun]

I guess that opens yet another question in my mind. Let's say people evacuated somewhere before the impact, say the Moon. Would the shock wave (if that can even travel through vacuum) affect the Moon substantially? Or if not, knock all man-made stuff out of orbit at least?

I'm guessing the Moon would get hit by a lot of debris from Earth and Ceres that gets blasted out at high velocity though.

The Moon has no real atmosphere too, so I can imagine a massive amount of micro meteors as well hitting the Moon's surface.

I would want to be deep under the Lunar surface and preferable on the far side too.

Edited September 12, 2014 by Tommygun

[Armchair Rocket Scientist]

So I was playing around in Universe Sandbox 2 and tried simulating an asteroid impact on Earth.

The asteroid in question was Ceres. I was trying to get a good feel on how it would look like if a Ceres-sized object impacted Earth.

***Will post pictures later***

Minutes after the impact, all bodies of water started to dry up as planet surface temperature shot up to about 200C. I then counted the number of revolutions the Earth made around the sun before things went back to "normal".

In the 5th year after impact, liquid water formed again on the surface. Huge parts of continents were permanently flooded and it took another 2 years for the temperature to go back to "acceptable" levels. Unfortunately, US2 doesnt provide surface radiation data so I cant tell if surface was habitable again.

Here are my questions regarding my experiment (pardon my ignorance)

1. What caused the sudden high temperatures that dried up the bodies of water?

2. What are the chances of a Ceres-like object impacting Earth?

3. Given that it took 7 years (in the game) for surface temperatures to go back to normal, was the simulation necessarily accurate?

4. Will Earth, or any othet planet, be habitable after an asteroid impact (taking radiation in consideration)?

I'm looking forward to reading your inputs!

Here's what a 500 km asteroid would do:

Ceres is about 8x the mass, so the damage would be even worse.

[SorryDave]

A possible scenario of an object this size hitting earth, would be from a small brown dwarf passing through the Oort cloud about a LY away.

The object would approach at comet or better speeds and we would have little time to react.

The good news is that the end of the world would be spectacular as mile high waves made of molten rock traveling the speed of sound would cover a continent.

[PakledHostage]

A possible scenario of an object this size hitting earth, would be from a small brown dwarf passing through the Oort cloud about a LY away.

Like, for example, the star Gliese 710 probably will in 1.4 million years from now. Heck, Gliese 710 may even have its own Oort cloud. Maybe our entire solar system will pass through Gliese 710's Oort cloud at the same time?

[mangekyou-sama]

Here's what a 500 km asteroid would do: *link*

Ceres is about 8x the mass, so the damage would be even worse.

WOW. Now that's a simulation!

I've updated the OP with screenshots and I think it matches the video you linked, albeit at a much larger scale.

[SorryDave]

Like, for example, the star Gliese 710 probably will in 1.4 million years from now

Exactly, and with any luck it will be televised.

[mangekyou-sama]

Exactly, and with any luck it will be televised.

A shame we won't be alive to see it

[Tommygun]

A shame we won't be alive to see it

You can still program your DVR to record it.

[Nuke]

I'm guessing the Moon would get hit by a lot of debris from Earth and Ceres that gets blasted out at high velocity though.

The Moon has no real atmosphere too, so I can imagine a massive amount of micro meteors as well hitting the Moon's surface.

I would want to be deep under the Lunar surface and preferable on the far side too.

i kinda think the best bet for long term lunar habitation would be several meters underground. send nuclear powered tunnel boring machines to etch out a complex tunnel network. enough to give you appropriate levels of radiation shielding. underground centrifuges may also be neccisary for health reasons and successful reproduction. needs more science.

[Armchair Rocket Scientist]

WOW. Now that's a simulation!

I've updated the OP with screenshots and I think it matches the video you linked, albeit at a much larger scale.

Holy cow! I haven't been following the development of Universe Sandbox the last few months, and look what happens!

What's the Earth's axis tilt after the impact, by the way?

[Tommygun]

i kinda think the best bet for long term lunar habitation would be several meters underground. send nuclear powered tunnel boring machines to etch out a complex tunnel network. enough to give you appropriate levels of radiation shielding. underground centrifuges may also be neccisary for health reasons and successful reproduction. needs more science.

I was thinking four or more kilometers deep for the big impactors, but I don't really know how to calculate it.

I was thinking Earth's escape velocity is 11.2 km/s and some estimates of "Meteor Crater" in New Mexico are that it hit at 12.8 km/s.

That's a big crater from a 50 meter object (about 1200m wide and 170m deep). I'm assuming debris falling back to the far side of the Moon would have to be traveling slower than the Earth's escape velocity.

I wonder if it would be bad enough to almost resurface the Moon to some extent and create a planetary ring for a few hundred years.

Edited September 12, 2014 by Tommygun

[Nuke]

we certainly know how to tunnel that deep into rock. i think the record here on earth is 12km. though that was a vertical bore hole. im not sure how deep a tunnel boring machine could go. one feature is they are capable of adding tunnel reinforcement as they progress. on earth this is usually in the form of prefab concrete sections, that are bolted together and injected with concrete to fill in any gaps between the segments and the wall. i found an old study of tunnel boring machines for use on the moon, where instead of prefab sections, waste heat from the nuclear reactor is used to glassify the material surrounding the tunnel. it has a rather interesting way of disposing of waste heat, which it does by heating up the removed material, and simply trucking the heat away with the rocks. http://www.boomslanger.com/images/lunartbm.pdf

it would be a clever idea for creating an emergency habitation on the moon in the event of such a cataclysm. i suppose to survive any secondary debris, it would be neccisary to have many colony sites. you might improve your chances doing a bore on mars as well, which would likely avoid the debris all together. you might have curricular tunnel loops a few km in radius to build train centrifuges to get a 1g environment. you also need a means for creating airlocks in the tunnels, but that should be a fairly simple thing to do. the nuclear reactors from the tbms can be used for powering the colony when the tunnel boring is complete. then to pressurize the whole thing would require processing the oxygen out of the regolith. subsurface ice provides water. a separate nitrogen source would also be needed to bulk up the atmosphere. then hydroponic farming provides the food supply.

its not the kind of thing that would happen in the absence of impending doom (politicians wouldn't let you launch massive nuclear tunnel boring machines aboard gargantuan rockets otherwise), but it can be done in a pinch.

[Technical Ben]

A possible scenario of an object this size hitting earth, would be from a small brown dwarf passing through the Oort cloud about a LY away.

The object would approach at comet or better speeds and we would have little time to react.

The good news is that the end of the world would be spectacular as mile high waves made of molten rock traveling the speed of sound would cover a continent.

What are the chances of hitting something with a moon, and thus an off set centre of gravity? That and the fact "space is big". You can shine a laser out of earth, and possibly never actually hit ANYTHING on it's way out of the Universe (that's no type, not Galaxy, but actually universe).

[Laie]

we certainly know how to tunnel that deep into rock. i think the record here on earth is 12km. though that was a vertical bore hole. im not sure how deep a tunnel boring machine could go.

No need to go very deep. It's a bit as with nuclear bombs: if it goes off close to you, no shelter will be good enough. But from as little as a couple hundred yards away, a slit trench will offer enough protection from the explosion (not from fallout, though, but that's not the question here). So subway-deep ought to do, but you want more than one site.

it would be a clever idea for creating an emergency habitation on the moon in the event of such a cataclysm.

Clever? For this to make sense, you need to be able to ship lots of humans plus supplies to the moon on short notice. You also need to build & maintain the site in a time when there's no clear and present danger. AFAIK, the levies of New Orleans were supposed to be high and strong enough; they were approved and in the works for like thirty years. Somehow I suspect that a lunar refuge would fail for similar reasons.

If you have both material means and political resolve / public support to *really* do it, you could do a lot of other things as well. Not sure if a lunar bunker would be the most clever solution under these circumstances.

[78stonewobble]

Hmm I still believe it will be quite possible for life to survive even rather large impacts. As long as they don't impart enough energy to... well ... melt or shatter the entire earths surface.

As long as they don't do that, life would still be able to survive in deep holes and what not. The seismic shocks might collapse such a thing as the cheyenne mountain complex and kill every human in there, but it seems quite possible that some life could survive in places like that.

"If you have both material means and political resolve / public support to *really* do it, you could do a lot of other things as well. Not sure if a lunar bunker would be the most clever solution under these circumstances. "

A suitably large and relatively selfsufficient spacestation could do it... Heck, we could make an "ark" type thing, with... if not large animals and humans, then seeds and bacteria.

[mangekyou-sama]

Hey guys! I've updated the OP again and added a new scenario. From a really hot one, to something really cold. Once again I'm very eager to read your thoughts on Scenario 2

Edited September 12, 2014 by mangekyou-sama

[magnemoe]

Hey guys! I've updated the OP again and added a new scenario. From a really hot one, to something really cold. Once again I'm very eager to read your thoughts on Scenario 2

Well the sun is out scenario is simple, all life dies with an exception, the hydrothermal vents in deep sea is not affected, not sure how deep the sea freezes but at least in areas where they are common life will continue as long as earth have them.

An more realistic scenario here is that earth is pulled from its orbit and into interstellar space, as I understand the hydrothermal vents would cause earth to support life far longer than 5 billion years.

[mangekyou-sama]

An more realistic scenario here is that earth is pulled from its orbit and into interstellar space

Maybe I could do a simulation of that. What could pull it off its orbit though?

[Helix935]

Maybe I could do a simulation of that. What could pull it off its orbit though?

tugging caused by a passing orbit from an object of sufficient mass and size that pulls us out of orbit toward the edge of the solar system...

what else?