In 2041 - 25 years from now - a cosmic event will sterilise the Earth down to a depth of at least 2 km and at most 10 km beneath the surface of the crust. Life at the bottom of the oceans may survive, but probably will not. The event will last over 24 hours so the entire Earth will be sterilised. Fortunately, it is discovered that both Mars and one of the more massive asteroids will be shielded by the Sun from the event. It is expected that Earth’s atmosphere will survive, though the ozone layer may not be intact. As you are the one with the plan, Earth’s entire resources are put at your disposal to effect that plan.
On a more serious note, given a mere 25 year timespan 1. It would be difficult to build anything to go to Mars and
Be able to stay there for any length of time. (I wouldn’t try for the asteroid as there would be no atmosphere),
Mars does at least have a thin atmosphere which will help somewhat
Then at best, I would expect that there would be a limited number of people who could go. (20 - 30, maybe 100 or so) and I would try to make multiple ships as well
Then there would the problem of who to go ?
Watch the 1951 movie “When Worlds collide” to get an example of the panic involved.
Next problem would be trying to return to Earth after 10 years (Assuming that would be possible)
You have all the resources of the Earth at your command. There’s no need to stay on Mars for 10 years after the event. You could launch the day after the event and be safe - from the event, that is.
Physical items on Earth will survive the event, so you could have great fuel tanks and launch facilities prepared for your return or for survivors when they emerge from deep mines.
Sorry, I assumed that there was a 10 year window before returning.
Living underground at 10 km is not going to happen (Just for the temperature alone).
Even building a livable location 2 km beneath the surface will be difficult.
The only alternative would be to go to Mars and there are a number of threads here on how that could be done.
As for the ozone layer being gone, I have no idea on that except to say that I would expect it to be reestablished eventually as things tend to go to equilibrium rather quickly
Sorry, mate, but with today’s technology – or anything available within 25 years – the job can’t be done. Buh-bye.
With a strong and established multi-planetary economy, with advanced rocketry able to jet from the Saturn to Venus in a week, with an asteroid-belt civilization, with real cities in space, with gobs of energy and megatons of resources…
And with frozen biostorage of plant and animal species samples in large enough diversity to establish survivable populations (i.e., two elands won’t do; you’d need around a hundred, otherwise genetic drift will destroy them)…
Well, the best that could be done is to drop gobs of bacteria onto earth’s surface and then wait thousands of years. After that, some preliminary planting of grasses could take place.
Given 25 years (and the entire resources of the Earth), it MIGHT be possible to get a small number of people to Mars but one other thing that I didn’t think of is whether there could be any other animals to take as well.
From what I can tell, the OP is trying to get some speculation on what humanity could do if there was a known threat coming up that would wipe out all life on earth.
What sort of cosmic event could cause that is not specified. It is more of a brainstorming activity but I think you knew that
Just make a record of the life of one ordinary human, pick a musical instrument, and send them out into space on a rocket. Let’s hope that some future space explorer will find them and remember us.
In 22ish years I think we could manage to launch a manned spacecraft or to circle mars and come back. NASA’s goal is a manned mission to Mars 2030 Seats are going to be rather limited. Timing is an issue to be worked out, to have a ship at mars during a specific event period might be difficult if the planets orbits aren’t cooperative. NASA is estimating manned Mars missions taking 6 months travel each way and 20 months at Mars waiting for the planets to line up.
So a small number of people returning to a sterilized but otherwise intact earth at their disposal might be able to work their way up to livable conditions again. Biologists are going to have to figure out what the new food supply will be. I think the menu is going to suck.
All those other billions of people, well it was nice knowing them.
With all the Earth’s resources available I don’t see why we couldn’t build a big, rotating space colony. It doesn’t need to be built to last forever, just long enough for a quick trip to the other side of the sun and back. Don’t even need to go to Mars. Pack the colony with as many seeds and other biological samples as we can, as many people as will fit and come back home.
I’d suggest packing as wide a variety of decomposers as possible. The Earth is going to be covered in dead stuff that isn’t decomposing. I wonder how long it would take to repopulate the oceans with oxygenating algae?
Repopulating the Earth with humans should be pretty easy, since all our cities and infrastructure is intact. We’d have all the energy we need. Just start planting crops and forests, reintroduce whatever animal & aquatic life we saved and watch everything start spreading, adapting and evolving.
This might be fighting the hypothetical, but what about some kind of habitats at the bottom of the ocean? That would certainly involve some fairly insane engineering challenges, but it seems more plausible than Mars.
If it’s get-off-the-planet-or-else, I think it at least partially depends on how committed every human on earth is. If I’m god-king and everyone is unswervingly loyal to me, then I can upend all the economies of the world to focus solely on this effort, not being concerned about anything more than 25 years in the future. If suddenly all the people of the world stop expending human energy and ingenuity to anything other than solving a problem, well, it’s hard to imagine what could be accomplished. But it will not remotely resemble NASA as we know it.
Neal Stephenson’s Seveneves covers an at least somewhat similar hypothetical, and makes the space mission seem brutally difficult but not flat out impossible.
Do you mean we could safely return the day after the event? If that’s the case, it doesn’t seem like it would be necessary to go as far as Mars. Would the International Space Station be safe? How about our moon?
Given the choice, the asteroid would be easier to get to, and return from. No need for atmospheric entry and landing. If money is no object, I think 25 years is enough to develop the necessary technology to send a crew, large sample of genetic material (I guess frozen sperm and eggs?), plant seeds, etc to the asteroid and back.
The hard part is re-terraforming the earth afterwards. How many seeds, eggs, etc do we need to take to the asteroid and back to start a functional ecosystem? How long would it take? I have no idea.
Will structures and equipment on earth survive? If so, we’d want to build a huge sealed habitat (something like Biosphere II) for the returning survivors to live in. That way they can live in the habitat for decades or even centuries while they re-terraform the planet.
Build several arks under the crust to varying depths, even down to 11km. No, do not set up each ark with its own quirky rules as social experiments.
Heat would be a problem but with enough energy, you can keep things cool enough.
I don’t know enough about the biochemistry of plant nutrition to say what it would take to grow vegetation after the sterilization. Anyone have an idea?
Earth is fucked. I’ll be 75 when the cosmic whammy hits, if I’m still alive, and I really can’t be arsed to save humanity. As the fictional but philosophical Remo Williams observed, that’s the biz, baby.
Theoretically, but anything in the vicinity of Earth is going to get sterilised without at least 10 km of rock overhead. So a big cavern deep in the moon would work nicely.