Soapbox:Time we stop acting like an asshat of a species before we go out like dinos

[tokala]

So the technology is there and unlikely to improve much, but there is always the possibility of a blindside hit by an object coming from the wrong direction.

The effective field of view of the 90 cm spacewatch telecope is about 3 square degrees, and they are using 120 seconds integration time per image. With something like 8 hours observation time per night they would scan about 700 square degrees, taking about two month for a all-sky survey.

To assure a meaningful evacuation leadtime for a 10-20m object we would need a hundred of those telecopes. Sun and moon in concert will cause a sizable "blind spot" for a ground based real-time search program, so you would need to put those scopes into orbit.

 

[Valka D'Ur]

It sounds like God is giving us a warning of the future to come.
Revelation 8:10,11 And the third angel sounded, and there fell a great star from heaven, burning as it were a lamp, and it fell upon the third part of the rivers, and upon the fountains of waters;
11 And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter.

In other words, there was a GREAT BIG BOOM!, something bright dropped out of the sky, and the water was made noxious due to such things as sulfur mixing with it.

No supernatural beings required.

Well fine, I don't care about the math that applies to paying taxes, insurance, and bills in pubs, but sadly, it cares about me. You can't really ignore the fact that these events rarely if ever kill anybody. They are therefore acceptable risk which, in terms of severity, is roughly comparable to being killed by one of those storms where it rains frogs. Tough luck.

When did they last kill anyone?

You have an appallingly callous attitude toward frogs and any other animals and plants harmed during the Tunguska Event or any other natural disaster. Sure, no humans were killed. But the ecosystem was absolutely ruined.

Define harm - a few shattered windows? A rock the size of football damaging a roof of a suburban house? I am sorry, but there FAR GREATER threats to people's lives.

You do understand that depending on the force and angle a piece of glass hits you at, it can kill you? If a glass shard gets into your eye, it can blind you? Ever had glass fall on you from a shattered window? I have - luckily I wasn't physically injured, but it was damn scary.

I agree that one of these days an asteroid impact is probably going to kill thousands or millions.

Just look at the moon. Or Jupiter.

http://thewatchers.adorraeli.com/2012/09/12/jupiter-impact-september-10-2012/

http://en.wikipedia.org/wiki/Comet_Shoemaker–Levy_9

Maybe when we finally make it out to Jupiter, we can ask the Jovians what kind of damage Shoemaker-Levy 9 did to their ecosystem and how many lifeforms were affected.

(yes, I am being optimistic that just maybe there might be lifeforms living there)

 

[Traitorfish]

Actually we should be thankful for Saturn, since it has a large gravitational pull that most meteorites that enter the solar system are attracted towards it and thus most don't stand a chance of even getting close enough to earth.

Well, a well-deserved to Saturn, then!

 

[classical_hero]

What about Panspermia. What if meteorite is carrying a quantity of alien bacteria or microrganism. What do we do then?

They wouldn't survive the entry into space and would die from the heat.

 

[TomYo689]

Says the extremophile biology professor

 

[Berzerker]

the impact simulator says the Earth's orbital parameters wouldn't change much if it was struck by something thousands of miles in diameter

there is no Oort Cloud

 

[cardgame]

They wouldn't survive the entry into space and would die from the heat.

It's an alien (read: unknown) organism, you can't say that with any degree of certainty — and neither can anyone else.

 

[timtofly]

It's an alien (read: unknown) organism, you can't say that with any degree of certainty — and neither can anyone else.

Perhaps the next time one of our space fairing vessels comes back with any organisms, they should place some samples on the outside of the re-entry vehicle, just to test that theory?

 

[TomYo689]

It's phrased as if it in effect has not yet occured

 

[Dachs]

They wouldn't survive the entry into space and would die from the heat.

 

[Formaldehyde]

Actually we should be thankful for Saturn, since it has a large gravitational pull that most meteorites that enter the solar system are attracted towards it and thus most don't stand a chance of even getting close enough to earth.

Saturn has just a bit more gravitational force than the Earth has.



Jupiter is more massive than Saturn by over a factor of 4 and has more than double the gravitational force, yet even it doesn't attract that many meteorites.

If any celestial body in our solar system would attract meteorites, it would be the Sun that has nearly 28 times the gravitational force of Earth. But even it doesn't have that much effect other than changing their trajectories.

A meteorite has to be on a near collision course before it will be drawn in by gravitational forces.

 

[Vertinari118]

Woh ignore me. Need to refresh threads before posting. This is no longer relevant.

 

[ace99]

Because space rocks are sexy. Everything that you mentioned isn't.

 

[tokala]

Saturn has just a bit more gravitational force than the Earth has.



Jupiter is more massive than Saturn by over a factor of 4 and has more than double the gravitational force, yet even it doesn't attract that many meteorites.

If any celestial body in our solar system would attract meteorites, it would be the Sun that has nearly 28 times the gravitational force of Earth. But even it doesn't have that much effect other than changing their trajectories.

A meteorite has to be on a near collision course before it will be drawn in by gravitational forces.

That chart refers to "surface" gravity. This has no no importance in the context you are trying to set it.
And the mechanism how large planets attract small bodies is a bit more complicated.

 

[Winner]

You have an appallingly callous attitude toward frogs and any other animals and plants harmed during the Tunguska Event or any other natural disaster. Sure, no humans were killed. But the ecosystem was absolutely ruined.

I guess you're joking, but in case you're not (oh the joys of written forum communication):

So it was in Mt. St. Helens eruption or any other natural disaster we cannot prevent.

You do understand that depending on the force and angle a piece of glass hits you at, it can kill you? If a glass shard gets into your eye, it can blind you? Ever had glass fall on you from a shattered window? I have - luckily I wasn't physically injured, but it was damn scary.

I do realize that. It's a risk of having glass windows and living on Earth. What I was saying is that getting seriously injured or even killed by an asteroid impact is VERY VERY VERY remote possibility and therefore hyping up the threat serves nobody and nothing.

---

tokala and uppi have Demonstrated By Maths that detecting rocks measuring in metres is borderline impossible beyond extreme near Earth distances. Rather than waste time, resources, and money chasing the unattainable goal of being able to predict every small impact that rarely kills people, we should perhaps use the money for something more worthwhile.

In space, that means boosting up infrastructure to allow us to detect and *deflect* larger asteroids. Those measuring in hundreds of metres in diameter and more.

You know the semi-joke:

Question: "Does it make sense to have an insurance against asteroids?"
Answer: "Yes, but only against the smaller ones."
Question: "Why, don't the bigger ones cause far more damage?"
Answer: "Yes, but it isn't probable any insurance agent would survive the impact of those."

 

[tokala]

Actually I might have been too conservative in my guesstimate.

If you accept that a "small fry" early warnig system will not get close to 100% effective, you can build a specialized system for the cost of a few million $ that will give you about a 50% chance of catching a Tunguska-like impactor in time to mount an effective evacuation, the larger the object the better the odds.



By focussing specifically on potential impactors instead of a general NEO search you can significantly cut down the effort.
And even such a specialized system would be useful for a lot of other purposes.

 

[LamaGT]

Saturn has just a bit more gravitational force than the Earth has.



Jupiter is more massive than Saturn by over a factor of 4 and has more than double the gravitational force, yet even it doesn't attract that many meteorites.

If any celestial body in our solar system would attract meteorites, it would be the Sun that has nearly 28 times the gravitational force of Earth. But even it doesn't have that much effect other than changing their trajectories.

A meteorite has to be on a near collision course before it will be drawn in by gravitational forces.

As tokala said that's surface gravity and it doesn't matter for orbits. The low surface gravity of Saturn is due to its extremely low density, but its mass is just fine, being one third of Jupiter's and 95 times Earth's.
The planets can't attract meteorites directly, simply because the meteorites already have a speed and orbit of their own. Planets (especially Jupiter) do however deflect the trajectory of asteroids, speeding them up or slowing them down. Indeed, Jupiter is responsible for the formation of the asteroid belt in the first place.

 

[Flying Pig]

You know the semi-joke:

Question: "Does it make sense to have an insurance against asteroids?"
Answer: "Yes, but only against the smaller ones."
Question: "Why, don't the bigger ones cause far more damage?"
Answer: "Yes, but it isn't probable any insurance agent would survive the impact of those."

Or, more to the point, the insurance claimant.

They wouldn't survive the entry into space and would die from the heat.

Actually,see this article - certainly the inside of such an asteroid would still be relatively cool, and quite possibly suitable for the survival of some sort of life within it.

 

[Formaldehyde]

As tokala said that's surface gravity and it doesn't matter for orbits. The low surface gravity of Saturn is due to its extremely low density, but its mass is just fine, being one third of Jupiter's and 95 times Earth's.
The planets can't attract meteorites directly, simply because the meteorites already have a speed and orbit of their own. Planets (especially Jupiter) do however deflect the trajectory of asteroids, speeding them up or slowing them down. Indeed, Jupiter is responsible for the formation of the asteroid belt in the first place.

Good point regarding the surface gravity versus the gravitational force. I stand corrected.

But you are echoing my main point that Jupiter, Saturn, and even the Sun deflect the path of celestial bodies far more than they protect the Earth from impacts from these objects. They might very well cause just the opposite to occur by deflecting something into a collision course.

But that last sentence seems misleading. The gravitational forces of Jupiter apparently caused the asteroids to not accrete into a planet. But they didn't in some way cause the asteroids to form. Jupiter even causes many of the meteorites to impact inner planets when the asteroids collide with each other:

The asteroid belt formed from the primordial solar nebula as a group of planetesimals, the smaller precursors of the planets, which in turn formed protoplanets. Between Mars and Jupiter, however, gravitational perturbations from the giant planet imbued the protoplanets with too much orbital energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals and most of the protoplanets shattered. As a result, most of the asteroid belt's mass has been lost since the formation of the Solar System. Some fragments can eventually find their way into the inner Solar System, leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits.

In general in the Solar System, planetary formation is thought to have occurred via a process comparable to the long-standing nebular hypothesis: a cloud of interstellar dust and gas collapsed under the influence of gravity to form a rotating disk of material that then further condensed to form the Sun and planets.[25] During the first few million years of the Solar System's history, an accretion process of sticky collisions caused the clumping of small particles, which gradually increased in size. Once the clumps reached sufficient mass, they could draw in other bodies through gravitational attraction and become planetesimals. This gravitational accretion led to the formation of the rocky planets and the gas giants.

Planetesimals within the region which would become the asteroid belt were too strongly perturbed by Jupiter's gravity to form a planet. Instead they continued to orbit the Sun as before, while occasionally colliding.[26] In regions where the average velocity of the collisions was too high, the shattering of planetesimals tended to dominate over accretion,[27] preventing the formation of planet-sized bodies. Orbital resonances occurred where the orbital period of an object in the belt formed an integer fraction of the orbital period of Jupiter, perturbing the object into a different orbit; the region lying between the orbits of Mars and Jupiter contains many such orbital resonances. As Jupiter migrated inward following its formation, these resonances would have swept across the asteroid belt, dynamically exciting the region's population and increasing their velocities relative to each other.[28]

Some of the debris from collisions can form meteoroids that enter the Earth's atmosphere.[60] Of the 50,000 meteorites found on Earth to date, 99.8 percent are believed to have originated in the asteroid belt.[61] A September 2007 study has suggested that a large-body collision undergone by the asteroid 298 Baptistina sent a number of fragments into the inner Solar System. The impacts of these fragments are believed to have created both Tycho crater on the Moon and Chicxulub crater in Mexico, the relict of the massive impact which is believed to have triggered the extinction of the dinosaurs 65 million years ago.[62]

 

[LamaGT]

Yes I phrased it poorly, it just prevented the formation of a single planet in the place of the belt.