How Fast Can Dangerous Near Earth Objects Be Detected?

[jimmydasaint]

This is a question that puzzles me. I take it that Near Earth Objects such as Comets or Asteroids that are on a trajectory that will hit the Earth can be detected well in advance of hitting us. However, does the technology yet exist to deflect a dangerous asteroid? For example, if an asteroid was over 1km in diameter, do we have any chance for survival? Views and opinions welcome.

[foodchain]

This is a question that puzzles me. I take it that Near Earth Objects such as Comets or Asteroids that are on a trajectory that will hit the Earth can be detected well in advance of hitting us. However, does the technology yet exist to deflect a dangerous asteroid? For example, if an asteroid was over 1km in diameter, do we have any chance for survival? Views and opinions welcome.

 

 

It depends on the object I think. Such as its composition or speed for instance will select what weapons can be used to combat such I think, and I also think we cant defeat ever possible scenario currently involving such. I also think detection is proportional to the amount of people, equipment and funding in use and currently I do not think these values are staggering really.

[Arch2008]

Does the theoretical response exist to deflect NEO’s? Yes.

Does the hardware exist? No.

Also, although a lot of NEO’s have been logged, a comet coming at us from the direction of the Sun would not provide much warning or response time. The more time we have, the greater our chances for survival.

Be aware that a Gamma Ray Burst would come at us from the depths of space (up to 1000 light years away) at the speed of light, so there would be no response time. A supernova within 40 light years would also destroy life on Earth without much warning. Or a mini Black Hole singularity might rip through the Earth.

Of course, none of these events are very likely.

[swansont]

An object heading straight for us is harder to detect than one that will miss, because it won't move much with respect to the background stars. — It will look like one. Parallax is the tool you'd need to detect it (or perhaps a change in brightness), so it will take time for the earth's position to change and the luck that the right region of the sky is being watched and somebody's analyzing the data.

[jimmydasaint]

Does the theoretical response exist to deflect NEO’s? Yes.

Does the hardware exist? No.

Also, although a lot of NEO’s have been logged, a comet coming at us from the direction of the Sun would not provide much warning or response time. The more time we have, the greater our chances for survival.

Be aware that a Gamma Ray Burst would come at us from the depths of space (up to 1000 light years away) at the speed of light, so there would be no response time. A supernova within 40 light years would also destroy life on Earth without much warning. Or a mini Black Hole singularity might rip through the Earth.

Of course, none of these events are very likely.

 

In reality, there is not a lot of hope is there? I take it that you cannot nuke an asteroid which is above 1km diameter to avoid contamination of the Eart's atmosphere. I just wonder if it is possible to nudge it away somehow. However, how much time would be required to organise such a life-saving mission - 24hrs, 48 hrs, a week. For example if you could take a spaceship up to land or to fire a solar sail on the asteroid, it could be nudged away right?

[Cap'n Refsmmat]

Depends on how big it is. A solar sail would have to be enormous, and it would only have a very slight effect -- you'd have to plant it on the asteroid with years of warning.

 

If you want to organize an asteroid-blasting mission in just a week you'll need the technology ready to go. If we were to detect an asteroid now, there'd be nothing we could do unless it was years away. We just don't have the systems built.

[Kil]

Here is Neil DeGrasse Tyson explaining how a dangerous asteroid could be deflected:

 

 

If you don’t mind, I’d like to share a little anicdote about my few minutes with Niel deGrasse Tyson that I wrote for The Skeptic Friends Network on the night of the reception. (I was posting up in my room every night while at TAM.)

 

Note: I am paraphrasing the actual conversation. I wrote this from memory, but since it had only just happened, it’s pretty accurate. I have refined it a bit from the original, mostly for grammar.

 

Me:

On my way out an amazing thing happened. Neil deGrasse Tyson was near the door posing for pictures with people. Not to let a chance like that go by, I asked if he would pose with me. “No problem.” Then he asked where I was from.

 

“Santa Monica.”

 

“Oh, too bad. That is where Apophis

might hit the earth just outside of Santa Monica in 2036 creating a series of Tsunamis. “ There is a “keyhole” that the asteroid must pass through in order to put it in harms way. The chance of that happening is small but significant.

 

One of the folks listening asked with such a small chance why worry?

 

“Well, the odds of it happening are significantly greater than winning the lottery” was Tyson's reply.

 

Then he grabbed my arm. My arm represented Apophis . He plucked a straw from a surprised woman’s drink who was listening, (he promised to return it) bent it in half and demonstrated how the asteroid could be deflected using the gravitation of an object that we could send up to meet it. Only problem, he said, is that so far, no one wants to spend the money on the technology to do that.

 

My arm was used some more as an example of the nearness of the possible hit. This went on for a bit while we asked him questions about it.

 

So there I was, my arm standing in as a visual aid in a learning experience. During this little impromptu lesson on Apophis, Tyson was so animated and excited about the subject, you could see the joy in him just sharing that information to the small group (at that moment) who had noticed he was there (at the reception) and wanted to meet him. He is a born teacher using whatever is available to him to make his point. In this case, my arm and a bent straw…

 

That was the single most exhilarating several minutes I have experienced at any TAM I have been to. It was almost too cool for words.

 

I hope I didn’t overstep here…

[Arch2008]

Sweet!

I hope that this event is still a fond memory for you in 2037.

[D H]

However, how much time would be required to organise such a life-saving mission - 24hrs, 48 hrs, a week. For example if you could take a spaceship up to land or to fire a solar sail on the asteroid, it could be nudged away right?

Think years. If we see something massive coming straight at us a few months before impact there is nothing much useful we can do. There are some very harmful things we could do. Nuking it is one of those harmful things.

 

Nuking a potential impactor a very short time before impact would be far worse than doing nothing. We'd still be hit, but we'd be hit with a bunch of rocks and nuclear byproducts instead of a small number of big, non-glow-in-the-dark rocks. Most of the Earth is ocean, and most of the land is lightly inhabited. A biggish rock most likely won't do all that much damage. A bunch of irradiated rocks might well tear a hole through the ozone layer and spread the nuclear contaminants world-wide.

 

We need to do something years in advance. Fortunately, that is not so far-fetched. Congress has mandated NASA to have identified 90% of the larger (more than 1 kilometer in diameter) near-Earth objects by the end of this year. The greatest known threat is one with a 1 in 300 chance in hitting the Earth 800 years from now. The threat of this one asteroid outweighs the threat of all other known asteroids combined.

[Kil]

Sweet!

I hope that this event is still a fond memory for you in 2037.

 

I know what you mean. I hope we will do something and start project bent straw before it's too late.

 

Plus, the idea of changing the trajectory of an astroid with a man made and powered gravitational pulling device would be a worthy scientific project on its own, and might well be a handy device to have around even if we determine that Apophis will ultimately miss us...

[Deja Vu]

We need to do something years in advance. Fortunately, that is not so far-fetched. Congress has mandated NASA to have identified 90% of the larger (more than 1 kilometer in diameter) near-Earth objects by the end of this year. The greatest known threat is one with a 1 in 300 chance in hitting the Earth 800 years from now. The threat of this one asteroid outweighs the threat of all other known asteroids combined.

 

Yes, that asteroid is called 1950 DA. It is about a kilometer wide. I would hate to be around when that thing hits us, as that would cause destruction on a scale not seen since the time of the dinosaurs. Luckily, we have 800 years to deal with it, if we decide to continue with space exploration that is.

[jimmydasaint]

Yes, that asteroid is called 1950 DA. It is about a kilometer wide. I would hate to be around when that thing hits us, as that would cause destruction on a scale not seen since the time of the dinosaurs. Luckily, we have 800 years to deal with it, if we decide to continue with space exploration that is.

 

Very interesting. However, would it be possible for an asteroid to slip by unexpectedly which is unaccountable in terms of predictable elliptical orbits? For example are we as a Solar System not moving round as well? I just wonder what would happen if our Solar System rotated into an area of the Milky Way that is heavily populated by asteroids? Or are these factors taken into account by NASA?

[Deja Vu]

Very interesting. However, would it be possible for an asteroid to slip by unexpectedly which is unaccountable in terms of predictable elliptical orbits? For example are we as a Solar System not moving round as well? I just wonder what would happen if our Solar System rotated into an area of the Milky Way that is heavily populated by asteroids? Or are these factors taken into account by NASA?

 

For an asteroid to slip unexpectedly like that, there would have to be an object, with a large mass of it's own, to perturb it's orbit.

 

Related to this topic, there is a hypothesis out there that speculates that we have an unknown stellar companion called Nemesis that comes by once every 26 million years or so, and perturbs the Oort Cloud, thereby sending some of the massive objects our way. As a direct consequence, some of those objects come close enough to NEO's to perturb their orbits and send one crashing down to Earth. Or, they themselves end up colliding with the Earth.

 

Presumably, between now and 800 years into the future, there is no object that will come close enough to 1950 DA to perturb it and end up sending it on a premature collision course.

[John Cuthber]

I think this "An object heading straight for us is harder to detect than one that will miss, because it won't move much with respect to the background stars. — It will look like one." is true in principle, but how can an object head directly towards us when we are moving?

[swansont]

I think this "An object heading straight for us is harder to detect than one that will miss, because it won't move much with respect to the background stars. — It will look like one." is true in principle, but how can an object head directly towards us when we are moving?

 

That's where parallax comes in. But it makes it hard to detect, since you need to observe over time, and look for small differences in position.