Watching the Earth get hit by a giant asteroid from space

In My Humble Opinion
1

Hey! Let’s say that you were an astronaut that was flying in geosynchronous orbit, 36,000 miles above the surface of the Earth, and were flying over a region during the time that it was day for the people on the surface, and an asteroid 80 miles wide hit the Earth as you were watching it.

Explain, in a paragraph or two, or to whatever length you wish, the thoughts running through your head. Assuming you knew that everybody on Earth would be dead, and that your spacecraft wasn’t destroyed or damaged by the impact (geosynchronous orbit is 36,000 miles away from Earth), or from its ejecta and debris, and that the time it would take for Earth to become habitable at any point on its surface would be 100 years, and you were the only person alive in the world (nobody else in the spacecraft but you). You have provisions and food, water, entertainment, to last you 40 years.

  1. Call it quits, and press the self-destruct button on the spacecraft?
  2. Live the rest of your life the only human being in the entire universe?

*I have never really thought about what it would be like to be actually the only person alive - not only that, the only life form that I know that exists within a light year. But if I could put some reasonable words to describe that, I think it would make me feel like Earth was an alien planet. It would mean an utter depersonalization, knowing that with your passing, the universe might have no sentient being, yet it would still exist. I would probably last for a year…

*1) is predicated on right-to-die legislation being passed. =)

2

Reported.

3

I’d take the spaceship back to Earth. There’s got to be one woman alive somewhere. And if not, I’d go to New Zealand and find a sheep.

4

Moved from General Questions to IMHO.

samclem, Moderator

5

I’d see if the Fithp are taking in hitchhikers.

6

Or head back down and make peace with the cockroaches.

7

Is it just me or have we had a raft of homework questions just recently?

8

Finals week.

9

Kilometers. 22,000 miles.

10

First thought? Great Gig In The Sky, especially appropriate given your vantage point.

Good luck finding women or sheep after the fact; an 80-mile wide meteor is a planet-killer.

11

Is it?

If it hits the ocean somewhere, we might get a year of rainfall and enough moisture in the atmosphere to start another ice age… and I agree we’d lose most of humanity as our systems to grow and distribute food broke down.

But there would be people left, and frankly, the people left could probably survive for a year on the food that’s left.

Or am I underestimating the effect of such a collision?

12

Available evidence seems to indicate that the Chicxulub impactor, which coincides with the K-T extinction, practically incinerated the Earth’s surface–and it’s estimated to have been about six miles wide. I think 80 is a definite planet killer. Something would survive, but not us.

13

The ocean, at its absolute deepest, is ~7 miles deep; between that and the fact that water is roughly 1/3 the density of rock, the ocean ain’t gonna do much to stop a rock 80 miles across coming in at 25,000 MPH.

At least one mass extinction of dinosaurs is believed to have been caused by a meteor just 6 miles across impacting the ocean; an 80-mile-wide meteor would deliver nearly 2400 times as much energy.

14

I’m staying. I’d feel like a total idiot if the aliens / Battlestar Galactica Fleet / Vulcan Federation / Barbarella were to show up in 2 years, and I’d offed myself.

How good is the entertainment.

15

From this calculator, the impact wouldn’t kill everything, but you’d want to be a very, very long way away from it. Like on the other side of the globe away from it. And I’m sure it’s understating the considerable effects that dumping several hundred thousand cubic miles of water vapor into the atmosphere would have. As many other posters have already said, the Dinosaur Killer was a great deal smaller than this hypothetical rock.

On the plus side, per the authors of the calculator, there aren’t any 80 mile wide asteroids on Earth-crossing paths within the solar system. As far as we know. Make it extra-solar in origin though…but then the chances of an extrasolar rock coming through the system on a path to strike Earth are so blindingly small, that I’d attribute it to intentional action rather than chance.

Anne Neville’s comments in another related thread made me wonder: how much would you have to “nudge” this rock in order to get it to miss? I guess this would depend on how far away the nudge occurred, and on how big the nudge was. Probably also depends on whether the rock is in an orbit around the Sun, or just passing through.

16

I’d be humming Yakety Sax to myself.

17

It really depends on how long before the rock’s impact with Earth you manage to catch it, how massive the rock is, and how fast it’s going. If you find a long-period comet (things coming from farther out in the solar system are generally going to be going faster when they get to Earth) that’s on a course to collide with Earth in two years, there’s nothing we could do about it. If you find a near-Earth asteroid that has a chance of hitting us in 100 years, that’s quite another story. Things like the composition of the rock might complicate things as well (nuking an asteroid that is a rubble pile probably wouldn’t do much good, for example).

Bricker, you are seriously underestimating the damage an impact with a rock this size would do. 80 miles is about 129 km. That’s much, much bigger than the asteroid that killed off the dinosaurs. I suspect there would be planet-wide fire storms, years of pitch darkness (from debris and ash in the atmosphere), that sort of thing. Most animals that survived the dinosaur killer were small burrowing animals or animals that could live under water for a while. This is a lot bigger than that. AFAIK, we have no plans for long-term human survival under circumstances like this, and we might not get much time to make such plans, depending on how long before impact we discovered this thing. If there are astronauts in space when it hits, I would guess we didn’t discover it until less than a year and a half before it hit (the longest stay in space until now has been 437 days, by Valeri Polyakov). I don’t think we’d be sending anyone into space if we knew something like this was coming, unless we had a moon base or somewhere else safe that they could go.

I also don’t think it’s at all likely we would have an astronaut in orbit with several years’ supply of food, water, and air, unless they were going on a manned Mars mission or something like that. Food, water, and even air has weight, and sending weight into orbit is not cheap. They don’t send a lot of extra consumables on a space mission, because that would hugely increase the cost. Things like space stations get periodically resupplied from Earth, instead.

Stars are so far apart, we don’t think asteroids regularly come into the solar system from outside. An asteroid that wasn’t in orbit around the Sun hitting the Earth is so incredibly unlikely, we can pretty much discount the possibility.

If there somehow were an asteroid from another solar system on a collision course with Earth, we probably wouldn’t know about it very far in advance. Most asteroids in our solar system are dark-colored, and it’s probably pretty safe to assume that asteroids from other solar systems would be, too. That means they don’t reflect a lot of sunlight, and would be hard to spot. They don’t have tails like comets do. It would be going screaming fast, with whatever velocity it had left after escaping its parent star, plus the velocity it would gain from falling all the way from the outskirts of the solar system to where Earth is. It would be going faster than Comet Hale-Bopp was when it passed by Earth (since Comet Hale-Bopp is gravitationally bound to the Sun), which was moving at about 52.5 km/sec when it passed by Earth.

18

That still won’t save you; you may not immediately die (you still get a 176 mph shock wave, according to the link, using similar parameters to the OP) but you’d be screwed just the same; not sure how long it would remain in the air (water would quickly leave in a week or so, but most of what would be thrown up would be melted/vaporized rock), but huge amounts of dust would be thrown into the atmosphere, probably making it seem like night all the time for many(?) years (large volcanic eruptions like Pinatubo leave dust in the stratosphere for several years, but this is vastly larger and thrown up much higher, possibly even low-Earth orbit). I’m guessing that any life left would be almost solely bacteria and other simple organisms, and those that live in caves, deep sea vents, etc.

19

We are talking about an asteroid bigger than the state of Rhode Island hitting the Earth at hypersonic speeds. Such an impact would throw up debris the size of Dinosaur Killer asteroids.

In fact, it would probably look something like this.

20

If it hasn’t, who’s going to prosecute whom?

Spacecraft don’t have self-destruct buttons, but they do generally have things like hatches. I’m sure an astronaut in space determined to off themselves could manage it, if no one else were around to prevent it.

We don’t send astronauts up solo any more. We generally haven’t since the 1960s. Astronauts are usually sent up for a reason, and most modern space missions are too complex for one person to do everything.