With our current technology could we alter the orbit of an asteroid to deliberately impact the Earth or less malevolently put it in orbit around the Earth. I imagine this would depend on the mass and location of said asteroid to a large extent.
Supposedly this has not been actively researched in detail in case some nation decides to use it as a weapon to see the world burn.
Cymek said:
With our current technology could we alter the orbit of an asteroid to deliberately impact the Earth or less malevolently put it in orbit around the Earth. I imagine this would depend on the mass and location of said asteroid to a large extent.
Supposedly this has not been actively researched in detail in case some nation decides to use it as a weapon to see the world burn.
I don’t know in how much detail it has been researched, but it has certainly been discussed.
I’d say the main reason for doing this would be to divert an asteroid that would otherwise hit the earth.
Not doing it in case of malevolent nations just doesn’t make sense when we have a plentiful supply of nuclear devices that could do the job much more easily.
Briefly:
Yes, this would be within humanity’s technological capabilities. Not cheap, though.
Yes, this has been extensively actively researched.
Note that there is an Asteroid Redirect Mission in NASA’s near-term plans. It has not been approved for funding yet, but has been thoroughly planned and if funded would launch four years from now. The mission would redirect a small asteroid (hundred tons or so) into orbit about the moon, after which it would be explored by humans.
https://www.youtube.com/watch?v=lCJjTJZSFMg
With current technology and assuming a very motivated crash program, what would be the minimum warning time? I realise that leaves lots of factors on the table, assume an asteroid of a size able to do significant and major damage and loss of life.
AwesomeO said:
With current technology and assuming a very motivated crash program, what would be the minimum warning time? I realise that leaves lots of factors on the table, assume an asteroid of a size able to do significant and major damage and loss of life.
Not quite sure what you mean … You mean the minimum time to prepare and launch a redirect craft?
As an aside, Brian Cox is on TV tonight. On one of his programs he made a very good case for the imperative of man to populate places other than earth. Not just for our sake as a species, but because as a species we are rare and unique, poised to become an interplanetary species.
dv said:
AwesomeO said:
With current technology and assuming a very motivated crash program, what would be the minimum warning time? I realise that leaves lots of factors on the table, assume an asteroid of a size able to do significant and major damage and loss of life.
Not quite sure what you mean … You mean the minimum time to prepare and launch a redirect craft?
Yes, and with resources enoughto deflect an asteroid of a size that could say, destroy an entire coast of America.
AwesomeO said:
As an aside, Brian Cox is on TV tonight. On one of his programs he made a very good case for the imperative of man to populate places other than earth. Not just for our sake as a species, but because as a species we are rare and unique, poised to become an interplanetary species.
I’d go in a heartbeat even if the odds of survival were poor.
What sort of margin for error would be involved with crashing an asteroid into Earth and getting one to orbit the Earth close enough that we could easily (reasonably speaking) use its resources to build structures in space.
AwesomeO said:
As an aside, Brian Cox is on TV tonight. On one of his programs he made a very good case for the imperative of man to populate places other than earth. Not just for our sake as a species, but because as a species we are rare and unique, poised to become an interplanetary species.
In the short term (say next 1000 years) the prospect of establishing a viable independent human population on another planet is extremely remote, so if we support BC’s long tem goal (which I do) the immediate priority should be maximising the probability of human survival on Earth.
The Rev Dodgson said:
AwesomeO said:
As an aside, Brian Cox is on TV tonight. On one of his programs he made a very good case for the imperative of man to populate places other than earth. Not just for our sake as a species, but because as a species we are rare and unique, poised to become an interplanetary species.
In the short term (say next 1000 years) the prospect of establishing a viable independent human population on another planet is extremely remote, so if we support BC’s long tem goal (which I do) the immediate priority should be maximising the probability of human survival on Earth.
Space
So B.C. was Brian Cox all along?
Bubblecar said:
So B.C. was Brian Cox all along?
Maybe.
But I think it actually stands for Bad Conductor.
For those feeling too hot, here’s a cool temperature map:
https://www.msn.com/en-au/weather/fullscreenmaps/Hornsby,%20NSW/we-city—33.7,151.1?iso=AU&maptype=temperature&mapsubtype=today
Okay, firstly, I don’t know the answer. I’ll take a look. OTTOMH I would put some bounds on it: there’s no way they could get it together within a month, but if it was actually doable and worth it they should be able to get something together within six months. Somewhere in that range. You wouldn’t be worried about optimising anything and you’d have backups etc.
But in abstract the amount of time needed will relate to the mass of the impactor. If you catch it early, you don’t need to impart much delta-v to cause a miss.
A ‘roid 50 metres across would destroy a major city and do damage to a large area around it, and probably mess up agriculture for a while. If it landed in the ocean it could do serious damage to thousands of km of coastal areas. It would have a mass of around 200000 tonnes. A hundred Saturn V’s worth of ion rocketry could impart something like a 0.5 m/s delta-v on such a rock. That could be enough to prevent a collision if applied 4 months before impact (OOM BOTE calcs here). So the amount of warning you’d need would be 4 months plus however long it takes you to make enough rocketry to do this. If it was a more glancing strike, the amount of delta-v required would be less. If you had more warning, you’d need less rocketry, etc.
Something more like 1000 metres across could do the damage you are talking about, obliterating an American coast through tsunamis. If you discover it with a year to spare, well, you’re fucked. Perhaps its mass is 1.6 billion tonnes. If this is an inner solar system asteroid, then no matter when you apply the delta-v, you are going to need something in the order of 0.01 to 0.05 m/s to avert the collision. (I’m assuming that no lucky Belbruno-type low-energy options involving a third body present themselves). Let’s say it is 0.03 m/s. The time to apply the delta-v will be a few years before impact, probably when the asteroid is at opposition, maybe three to six years, depending on the orbit. You’d need to get about 2000 tonnes of xenon ion rocketry to the asteroid by then. How long would it take you to build that rocketry and the launchers required to get it there? Given the high stakes, you could direct much of the US economy towards this end and could get it down within a couple of years if required. So bottom line I would think you would need something like five to eight years’ grace.
The good news is that anything of that size in the inner solar system has probably already been discovered and tracked, but there is always a possibility that a very eccentric orbit will bring something like that into the inner solar system by surprise, or that a large planet would deflect it, or even an interstellar object.
At some mass, though, it would get to the point that there is nothing you can do and your efforts would be best placed in other activities. I think that the whole world would struggle to deflect an object, say, 10000 metres across, unless they had a century to work on it, and that’s an extinction level event.
dv said:
Okay, firstly, I don’t know the answer. I’ll take a look. OTTOMH I would put some bounds on it: there’s no way they could get it together within a month, but if it was actually doable and worth it they should be able to get something together within six months. Somewhere in that range. You wouldn’t be worried about optimising anything and you’d have backups etc.But in abstract the amount of time needed will relate to the mass of the impactor. If you catch it early, you don’t need to impart much delta-v to cause a miss.
A ‘roid 50 metres across would destroy a major city and do damage to a large area around it, and probably mess up agriculture for a while. If it landed in the ocean it could do serious damage to thousands of km of coastal areas. It would have a mass of around 200000 tonnes. A hundred Saturn V’s worth of ion rocketry could impart something like a 0.5 m/s delta-v on such a rock. That could be enough to prevent a collision if applied 4 months before impact (OOM BOTE calcs here). So the amount of warning you’d need would be 4 months plus however long it takes you to make enough rocketry to do this. If it was a more glancing strike, the amount of delta-v required would be less. If you had more warning, you’d need less rocketry, etc.
Something more like 1000 metres across could do the damage you are talking about, obliterating an American coast through tsunamis. If you discover it with a year to spare, well, you’re fucked. Perhaps its mass is 1.6 billion tonnes. If this is an inner solar system asteroid, then no matter when you apply the delta-v, you are going to need something in the order of 0.01 to 0.05 m/s to avert the collision. (I’m assuming that no lucky Belbruno-type low-energy options involving a third body present themselves). Let’s say it is 0.03 m/s. The time to apply the delta-v will be a few years before impact, probably when the asteroid is at opposition, maybe three to six years, depending on the orbit. You’d need to get about 2000 tonnes of xenon ion rocketry to the asteroid by then. How long would it take you to build that rocketry and the launchers required to get it there? Given the high stakes, you could direct much of the US economy towards this end and could get it down within a couple of years if required. So bottom line I would think you would need something like five to eight years’ grace.
The good news is that anything of that size in the inner solar system has probably already been discovered and tracked, but there is always a possibility that a very eccentric orbit will bring something like that into the inner solar system by surprise, or that a large planet would deflect it, or even an interstellar object.
At some mass, though, it would get to the point that there is nothing you can do and your efforts would be best placed in other activities. I think that the whole world would struggle to deflect an object, say, 10000 metres across, unless they had a century to work on it, and that’s an extinction level event.
Cheers for the lengthy and considered post.
AwesomeO said:
dv said:
Okay, firstly, I don’t know the answer. I’ll take a look. OTTOMH I would put some bounds on it: there’s no way they could get it together within a month, but if it was actually doable and worth it they should be able to get something together within six months. Somewhere in that range. You wouldn’t be worried about optimising anything and you’d have backups etc.But in abstract the amount of time needed will relate to the mass of the impactor. If you catch it early, you don’t need to impart much delta-v to cause a miss.
A ‘roid 50 metres across would destroy a major city and do damage to a large area around it, and probably mess up agriculture for a while. If it landed in the ocean it could do serious damage to thousands of km of coastal areas. It would have a mass of around 200000 tonnes. A hundred Saturn V’s worth of ion rocketry could impart something like a 0.5 m/s delta-v on such a rock. That could be enough to prevent a collision if applied 4 months before impact (OOM BOTE calcs here). So the amount of warning you’d need would be 4 months plus however long it takes you to make enough rocketry to do this. If it was a more glancing strike, the amount of delta-v required would be less. If you had more warning, you’d need less rocketry, etc.
Something more like 1000 metres across could do the damage you are talking about, obliterating an American coast through tsunamis. If you discover it with a year to spare, well, you’re fucked. Perhaps its mass is 1.6 billion tonnes. If this is an inner solar system asteroid, then no matter when you apply the delta-v, you are going to need something in the order of 0.01 to 0.05 m/s to avert the collision. (I’m assuming that no lucky Belbruno-type low-energy options involving a third body present themselves). Let’s say it is 0.03 m/s. The time to apply the delta-v will be a few years before impact, probably when the asteroid is at opposition, maybe three to six years, depending on the orbit. You’d need to get about 2000 tonnes of xenon ion rocketry to the asteroid by then. How long would it take you to build that rocketry and the launchers required to get it there? Given the high stakes, you could direct much of the US economy towards this end and could get it down within a couple of years if required. So bottom line I would think you would need something like five to eight years’ grace.
The good news is that anything of that size in the inner solar system has probably already been discovered and tracked, but there is always a possibility that a very eccentric orbit will bring something like that into the inner solar system by surprise, or that a large planet would deflect it, or even an interstellar object.
At some mass, though, it would get to the point that there is nothing you can do and your efforts would be best placed in other activities. I think that the whole world would struggle to deflect an object, say, 10000 metres across, unless they had a century to work on it, and that’s an extinction level event.
Cheers for the lengthy and considered post.
Yes thanks
I think I can be more specific by putting numbers on this. The larger the asteroid, the longer the time required. Also, it’s important to distinguish between near-Earth asteroids (NEA) and main belt asteroids (MBA)
Let’s suppose we were able to deliver a rocket of mass 8.5 tonnes to the asteroid. We can’t yet, but given enough time building a launcher that could do that would be possible.
Look at some possible combinations of thrust (kN) and specific impulse (s).
The Star-37 FM rocket motor weighs 1.15 tonne, has a thrust of 47 kN, specific impulse 290 s and total impulse 3,000 kNs.
Suppose our asteroid has mass M tonnes. Then the velocity attainable with a total impulse 3,000 kNs is, if I calculate correctly, 3000/M m/s. For an asteroid mass of 1 tonne we can get a speed of 3 km/s and for an asteroid mass of 1000 tonnes we can get a speed of 3 m/s.
Asteroid density is roughly 2 tonnes per cubic metre.
Let’s start with near-Earth asteroids (NEA). There are 160 potentially hazardous asteroids larger than 1 km in diameter. Sp let’s stick to 1 km in diameter. That has a mass within a few percent of 1 billion tonnes. 8.5/1.15 = 7 Star-37 rocket equivalents. So maximum speed of asteroid (per launch) cannot exceed 3 m/s * 7 / 1 million = 0.02 mm/s.
To deflect such an asteroid a distance of 1 km would take 1 million / 0.02 = 50 million seconds = nearly 2 years, not counting time to rendezvous. To deflect it a distance of the radius of Earth would take 10,000 years with just the one big push – so lots more pushes would be needed, like 100 pushes over more than 100 years.
mollwollfumble said:
I think I can be more specific by putting numbers on this. The larger the asteroid, the longer the time required. Also, it’s important to distinguish between near-Earth asteroids (NEA) and main belt asteroids (MBA)Let’s suppose we were able to deliver a rocket of mass 8.5 tonnes to the asteroid. We can’t yet, but given enough time building a launcher that could do that would be possible.
Look at some possible combinations of thrust (kN) and specific impulse (s).
The Star-37 FM rocket motor weighs 1.15 tonne, has a thrust of 47 kN, specific impulse 290 s and total impulse 3,000 kNs.Suppose our asteroid has mass M tonnes. Then the velocity attainable with a total impulse 3,000 kNs is, if I calculate correctly, 3000/M m/s. For an asteroid mass of 1 tonne we can get a speed of 3 km/s and for an asteroid mass of 1000 tonnes we can get a speed of 3 m/s.
Asteroid density is roughly 2 tonnes per cubic metre.
Let’s start with near-Earth asteroids (NEA). There are 160 potentially hazardous asteroids larger than 1 km in diameter. Sp let’s stick to 1 km in diameter. That has a mass within a few percent of 1 billion tonnes. 8.5/1.15 = 7 Star-37 rocket equivalents. So maximum speed of asteroid (per launch) cannot exceed 3 m/s * 7 / 1 million = 0.02 mm/s.
To deflect such an asteroid a distance of 1 km would take 1 million / 0.02 = 50 million seconds = nearly 2 years, not counting time to rendezvous. To deflect it a distance of the radius of Earth would take 10,000 years with just the one big push – so lots more pushes would be needed, like 100 pushes over more than 100 years.
So the chances of anyone deliberately pushing one into an Earth intersecting orbit are almost impossible and even if so they’d probably require many of the resources of a nation state and would exactly be subtle.
mollwollfumble said:
I think I can be more specific by putting numbers on this. The larger the asteroid, the longer the time required. Also, it’s important to distinguish between near-Earth asteroids (NEA) and main belt asteroids (MBA)Let’s suppose we were able to deliver a rocket of mass 8.5 tonnes to the asteroid. We can’t yet, but given enough time building a launcher that could do that would be possible.
Look at some possible combinations of thrust (kN) and specific impulse (s).
The Star-37 FM rocket motor weighs 1.15 tonne, has a thrust of 47 kN, specific impulse 290 s and total impulse 3,000 kNs.Suppose our asteroid has mass M tonnes. Then the velocity attainable with a total impulse 3,000 kNs is, if I calculate correctly, 3000/M m/s. For an asteroid mass of 1 tonne we can get a speed of 3 km/s and for an asteroid mass of 1000 tonnes we can get a speed of 3 m/s.
Asteroid density is roughly 2 tonnes per cubic metre.
Let’s start with near-Earth asteroids (NEA). There are 160 potentially hazardous asteroids larger than 1 km in diameter. Sp let’s stick to 1 km in diameter. That has a mass within a few percent of 1 billion tonnes. 8.5/1.15 = 7 Star-37 rocket equivalents. So maximum speed of asteroid (per launch) cannot exceed 3 m/s * 7 / 1 million = 0.02 mm/s.
To deflect such an asteroid a distance of 1 km would take 1 million / 0.02 = 50 million seconds = nearly 2 years, not counting time to rendezvous. To deflect it a distance of the radius of Earth would take 10,000 years with just the one big push – so lots more pushes would be needed, like 100 pushes over more than 100 years.
Note that these calcs are reasonable for periods much shorter than orbital periods, but not over times comparable or greater than orbital periods. It doesn’t matter whether you’ve got a 100 years or a 1000 years to deflect a NEA to avoid the earth: the delta-v is going to basically be the same.
Cymek said:
So the chances of anyone deliberately pushing one into an Earth intersecting orbit are almost impossible
I wouldn’t say that.
Cymek said:
and even if so they’d probably require many of the resources of a nation state
Yes.
dv said:
Cymek said:So the chances of anyone deliberately pushing one into an Earth intersecting orbit are almost impossible
I wouldn’t say that.
Cymek said:
and even if so they’d probably require many of the resources of a nation state
Yes.
goes back to World Domination blackboard.
Boris said:
goes back to World Domination blackboard.
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
the rockets would be tracked by various nations so hard to get away with without anyone noticing.
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
NASA could send a mission to an asteroid that plans to bring it to orbit the moon so other nations will watch but by the time they realise it is headed for Moscow it will be too late…
dv said:
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
dv said:
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
Yes but would they assume it was for nefarious reasons if you said it was to mine the asteroid but in actually fact you wanted to alter it’s orbit. They’d have a massive head start before it was noticed something wasn’t quite right.
furious said:
- Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
NASA could send a mission to an asteroid that plans to bring it to orbit the moon so other nations will watch but by the time they realise it is headed for Moscow it will be too late…
pfft..
‘sif
Cymek said:
dv said:
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
Yes but would they assume it was for nefarious reasons if you said it was to mine the asteroid but in actually fact you wanted to alter it’s orbit. They’d have a massive head start before it was noticed something wasn’t quite right.
Okay, okay. So suppose you could claim it was some experimental space mining operation, but instead of mining equipment you took a huge stack of xenon ion rockets.
Still, I think other nations would keep an eye on you and would notice once you’ve redirected the asteroid.
And then what? How would this be different from just nuking someone? They’ll respond, and they’ll have heaps of time to respond.
Still, I’d fall off my chair if the major powers were not working on this.
Dr Evil “While no one was looking I altered the orbital path of the asteroid so that it will hit the Earth and take out my nemesis Austin Powers, when they see it it will be too late”
Dr Evil laughter
https://www.youtube.com/watch?v=7edeOEuXdMU
I’d fall off my chair if the major powers were not working on getting something into space without anyone else knowing…
furious said:
- Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
NASA could send a mission to an asteroid that plans to bring it to orbit the moon so other nations will watch but by the time they realise it is headed for Moscow it will be too late…
Exactly and you could say “Sorry my bad”, it isn’t is rocket science you know
stumpy_seahorse said:
furious said:
- Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
NASA could send a mission to an asteroid that plans to bring it to orbit the moon so other nations will watch but by the time they realise it is headed for Moscow it will be too late…
pfft..
‘sif
they going to use the big guy in the second row as a gravity tractor.
Boris said:
stumpy_seahorse said:
furious said:
- Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
NASA could send a mission to an asteroid that plans to bring it to orbit the moon so other nations will watch but by the time they realise it is headed for Moscow it will be too late…
pfft..
‘sif
they going to use the big guy in the second row as a gravity tractor.
Is he the even bigger guy from Lost
furious said:
- Still, I’d fall off my chair if the major powers were not working on this.
I’d fall off my chair if the major powers were not working on getting something into space without anyone else knowing…
That would be really fkn hard/impossible.
OTOH you could disguise your launches. e.g. have a lunar mission, which pops out some other craft and goes off somewhere else. Paint it black, make it well shielded. They’d detect rocketry but if you did your burn while on the far side of the moon, it would be hidden.
Hmmm, you’ve won me round, when do we start?
dv said:
furious said:
- Still, I’d fall off my chair if the major powers were not working on this.
I’d fall off my chair if the major powers were not working on getting something into space without anyone else knowing…
That would be really fkn hard/impossible.
OTOH you could disguise your launches. e.g. have a lunar mission, which pops out some other craft and goes off somewhere else. Paint it black, make it well shielded. They’d detect rocketry but if you did your burn while on the far side of the moon, it would be hidden.
Hmmm, you’ve won me round, when do we start?
kii knows a rocket scientist….and her hubby can weld.
What if Dr Evil has made a death star using Vantablack? and put it in an orbit with voids in the background to make it difficult to see.
Dr Evil Laughter
https://www.youtube.com/watch?v=7edeOEuXdMU
Might be better off you don’t know anyhoo.
In July 2013 the southern hemisphere part of the Catalina Sky Survey at Siding Springs ran out of funding and was shutndown.
“without a southern lookout, any object approaching Earth from below 30 degrees latitude would be invisible, says Tim Spahr of the International Astronomical Union’s Minor Planet Center in Cambridge, Massachusetts.
That won’t be much of a problem for massive objects like the asteroid that wiped out the dinosaurs. These are rare and astronomers estimate they have already found and are tracking 94 per cent of them via software models. The worry is asteroids about 30 metres wide, which could flatten a city. Such a hit is blamed for the Tunguska event in 1908, which levelled a 2000-square-kilometre swathe of forest in Siberia.”
https://www.newscientist.com/article/mg21528724-800-vital-eye-for-killer-asteroids-could-shut-imminently/
Ian said:
Might be better off you don’t know anyhoo.In July 2013 the southern hemisphere part of the Catalina Sky Survey at Siding Springs ran out of funding and was shutndown.
“without a southern lookout, any object approaching Earth from below 30 degrees latitude would be invisible, says Tim Spahr of the International Astronomical Union’s Minor Planet Center in Cambridge, Massachusetts.
That won’t be much of a problem for massive objects like the asteroid that wiped out the dinosaurs. These are rare and astronomers estimate they have already found and are tracking 94 per cent of them via software models. The worry is asteroids about 30 metres wide, which could flatten a city. Such a hit is blamed for the Tunguska event in 1908, which levelled a 2000-square-kilometre swathe of forest in Siberia.”
https://www.newscientist.com/article/mg21528724-800-vital-eye-for-killer-asteroids-could-shut-imminently/
“What you don’t know can’t hurt you!” – some dumb fuck
So that means Grafton NSW and Dongara WA are OK given that a rocket can be made and launched blah blah…
But anyone to south… HEADS UP!
:-)
dv said:
Note that these calcs are reasonable for periods much shorter than orbital periods, but not over times comparable or greater than orbital periods. It doesn’t matter whether you’ve got a 100 years or a 1000 years to deflect a NEA to avoid the earth: the delta-v is going to basically be the same.
Yes. But there are a couple of subtleties. One is that moving an orbit changes the period. The relative period of Earth and asteroid is what matters, not the period of the asteroid itself. A second is that multiple pushes always work best at asteroid perihelion and aphelion, not at locations in between.
mollwollfumble said:
dv said:Note that these calcs are reasonable for periods much shorter than orbital periods, but not over times comparable or greater than orbital periods. It doesn’t matter whether you’ve got a 100 years or a 1000 years to deflect a NEA to avoid the earth: the delta-v is going to basically be the same.
Yes. But there are a couple of subtleties. One is that moving an orbit changes the period. The relative period of Earth and asteroid is what matters, not the period of the asteroid itself. A second is that multiple pushes always work best at asteroid perihelion and aphelion, not at locations in between.
Sure, sure.
Deflection technology concerns
Carl Sagan, in his book Pale Blue Dot, expressed concern about deflection technology that any method capable of deflecting impactors away from Earth could also be abused to divert non-threatening bodies toward the planet. Considering the history of genocidal political leaders and the possibility of the bureaucratic obscuring of any such project’s true goals to most of its scientific participants, he judged the Earth at greater risk from a man-made impact than a natural one. Sagan instead suggested that deflection technology only be developed in an actual emergency situation.
All low-energy delivery deflection technologies have inherent fine control and steering capability, making it possible to add just the right amount of energy to steer an asteroid originally destined for a mere close approach toward a specific Earth target.
According to Rusty Schweickart, the gravitational tractor method is controversial because, during the process of changing an asteroid’s trajectory, the point on the Earth where it could most likely hit would be slowly shifted across different countries. Thus, the threat for the entire planet would be minimized at the cost of some specific states’ security. In Schweickart’s opinion, choosing the way the asteroid should be “dragged” would be a tough diplomatic decision.
Analysis of the uncertainty involved in nuclear deflection shows that the ability to protect the planet does not imply the ability to target the planet. A nuclear explosion that changes an asteroid’s velocity by 10 meters/second (plus or minus 20%) would be adequate to push it out of an Earth-impacting orbit. However, if the uncertainty of the velocity change was more than a few percent, there would be no chance of directing the asteroid to a particular target.
Cymek said:
Deflection technology concernsCarl Sagan, in his book Pale Blue Dot, expressed concern about deflection technology that any method capable of deflecting impactors away from Earth could also be abused to divert non-threatening bodies toward the planet. Considering the history of genocidal political leaders and the possibility of the bureaucratic obscuring of any such project’s true goals to most of its scientific participants, he judged the Earth at greater risk from a man-made impact than a natural one. Sagan instead suggested that deflection technology only be developed in an actual emergency situation.
All low-energy delivery deflection technologies have inherent fine control and steering capability, making it possible to add just the right amount of energy to steer an asteroid originally destined for a mere close approach toward a specific Earth target.
According to Rusty Schweickart, the gravitational tractor method is controversial because, during the process of changing an asteroid’s trajectory, the point on the Earth where it could most likely hit would be slowly shifted across different countries. Thus, the threat for the entire planet would be minimized at the cost of some specific states’ security. In Schweickart’s opinion, choosing the way the asteroid should be “dragged” would be a tough diplomatic decision.
Analysis of the uncertainty involved in nuclear deflection shows that the ability to protect the planet does not imply the ability to target the planet. A nuclear explosion that changes an asteroid’s velocity by 10 meters/second (plus or minus 20%) would be adequate to push it out of an Earth-impacting orbit. However, if the uncertainty of the velocity change was more than a few percent, there would be no chance of directing the asteroid to a particular target.
Hardly be a worry. Pretty soon we’ll all be living in a 3 million sq km area, eating tilapia and sweet potato. Not much chance of being hit.
Out of existing technology, the only system we have that has enough performance to do the job effectively is the old Project Orion.
We should never have stopped the project, we need it.
dv said:
Hardly be a worry. Pretty soon we’ll all be living in a 3 million sq km area, eating tilapia and sweet potato. Not much chance of being hit.
O, wonder!
How many goodly creatures are there here!
How beauteous mankind is! O brave new world,
That has such people in’t!
dv said:
Note that these calcs are reasonable for periods much shorter than orbital periods, but not over times comparable or greater than orbital periods. It doesn’t matter whether you’ve got a 100 years or a 1000 years to deflect a NEA to avoid the earth: the delta-v is going to basically be the same.
There are a couple of subtleties. One is that moving an orbit changes the period. The relative period of Earth and asteroid is what matters, not the period of the asteroid itself.
So, let’s say an asteroid was scheduled to hit the Earth in 1000 years. That means that the orbits cross in 1000 years, changing the orbital period of the asteroid by a small amount, a delta-v so that it misses 1000 years from now can be done with a small delta-v. But you’d need ten times that delta-v if the scheduled hit was only 100 years in the future. Or to put it another way, a delta-v changes the asteroid period, and the change in period causes a linear change in miss distance over periods of time up to millions of times longer than the asteroid’s orbit.
If a big one is on the way and unable to be deflected, would blowing it up be the better option, under the theory that some of the bits will miss, and other bits will burn up in the atmosphere.
Spiny Norman said:
Out of existing technology, the only system we have that has enough performance to do the job effectively is the old Project Orion.
We should never have stopped the project, we need it.
Would be handy for short-notice deflections, sure.
AwesomeO said:
If a big one is on the way and unable to be deflected, would blowing it up be the better option, under the theory that some of the bits will miss, and other bits will burn up in the atmosphere.
This is a very famous question. No. The danger from the impact of lots of smaller bits is almost always much worse than the impact from a single big bit.
Nothing will be done because no one will care. It is, someone else’s problem (SEP) …
dv said:
Spiny Norman said:
Out of existing technology, the only system we have that has enough performance to do the job effectively is the old Project Orion.
We should never have stopped the project, we need it.
Would be handy for short-notice deflections, sure.
It’s also got a lot of performance to get to the outer planets quickly, if anything needed deflecting out that far.
Cymek said:
dv said:
Cymek said:
So if someone did try and alter the orbital path of an asteroid so it hit Earth how long might it take observers to notice the change, years I’d assume which would probably mean it would be too late to stop it.
Look, this would be a major operation. It would be hard to do surreptitiously. If a country sends a huge craft to an asteroid, other countries will notice and track it.
Yes but would they assume it was for nefarious reasons if you said it was to mine the asteroid but in actually fact you wanted to alter it’s orbit. They’d have a massive head start before it was noticed something wasn’t quite right.
Not a chance. Any attempt to change the orbit would be noticed immediately, if not sooner. There wouldn’t be a significant head start.
Spiny Norman said:
dv said:
Spiny Norman said:
Out of existing technology, the only system we have that has enough performance to do the job effectively is the old Project Orion.
We should never have stopped the project, we need it.
Would be handy for short-notice deflections, sure.
It’s also got a lot of performance to get to the outer planets quickly, if anything needed deflecting out that far.
A long term strategy for destroying the Earth (turning the whole crust of Earth molten and digging a temporary big hole out of it) would be to slingshot a Kuyper belt object off first Pluto and then a giant planet. I say long term, because a nudged orbit out there would take a long time to come close enough to Pluto for a gravitational interaction.
AwesomeO said:
If a big one is on the way and unable to be deflected, would blowing it up be the better option, under the theory that some of the bits will miss, and other bits will burn up in the atmosphere.
Why not create a massive explosion parallel with its movement on its port or starboard side to nudge it
or can it be taken a bit further?
have a number of nuclear weapons land on the surface of the asteroid each placed and shaped in such a way to maximize a preferred direction. The nuclear weapons on the surface are triggered by a shock wave from nuclear explosions a bit further out
calculate a distance to maximize 4 nuclear explosions that hit the asteroid from behind on a slight angle, the explosions are shaped to create a shock wave which spreads itself over a wider areas while triggering focused explosions on the surface
furious said:
- So, let’s say an asteroid was scheduled to hit the Earth in 1000 years.
Nothing will be done because no one will care. It is, someone else’s problem (SEP) …
Only if you agree that no one cares about climate change.
There’s nothing like a true apocalypse to focus people’s attention on the long term.
Tau.Neutrino said:
AwesomeO said:
If a big one is on the way and unable to be deflected, would blowing it up be the better option, under the theory that some of the bits will miss, and other bits will burn up in the atmosphere.
Why not create a massive explosion parallel with its movement on its port or starboard side to nudge it
or can it be taken a bit further?
have a number of nuclear weapons land on the surface of the asteroid each placed and shaped in such a way to maximize a preferred direction. The nuclear weapons on the surface are triggered by a shock wave from nuclear explosions a bit further out
calculate a distance to maximize 4 nuclear explosions that hit the asteroid from behind on a slight angle, the explosions are shaped to create a shock wave which spreads itself over a wider areas while triggering focused explosions on the surface
or create multiple shock waves to steer it
Tau.Neutrino said:
Tau.Neutrino said:
AwesomeO said:
If a big one is on the way and unable to be deflected, would blowing it up be the better option, under the theory that some of the bits will miss, and other bits will burn up in the atmosphere.
Why not create a massive explosion parallel with its movement on its port or starboard side to nudge it
or can it be taken a bit further?
have a number of nuclear weapons land on the surface of the asteroid each placed and shaped in such a way to maximize a preferred direction. The nuclear weapons on the surface are triggered by a shock wave from nuclear explosions a bit further out
calculate a distance to maximize 4 nuclear explosions that hit the asteroid from behind on a slight angle, the explosions are shaped to create a shock wave which spreads itself over a wider areas while triggering focused explosions on the surface
or create multiple shock waves to steer it, a series of nuclear weapons placed long a projected turning line
so say 4 explosions go off , wait a bit then another 4 nukes go off, wait a bit then another 4 go off etc
the idea that multiple shock waves steer the asteroid to another direction
It would be interesting to send up a nuclear bomb or send it up in stages to be assembled later
then send the bomb to a test asteroid
send a probe with it to record the test and send back the details
how much of this mission could be simulated ?
would 4 or more nuclear shock waves work hitting the asteroid
orwould the shock waves need to be reinforced by focused surface explosion / s on the asteroid
or
would there need only to be surface explosion/s on the asteroid?
which sort of bomb could create the highest shock wave ?
mollwollfumble said:
furious said:
- So, let’s say an asteroid was scheduled to hit the Earth in 1000 years.
Nothing will be done because no one will care. It is, someone else’s problem (SEP) …
Only if you agree that no one cares about climate change.
There’s nothing like a true apocalypse to focus people’s attention on the long term.
Ah well probably DJT will just say the “Imminent Impactor Theory” is just a conspiracy by the Chinese to waste American resources.
How about 8 rocket powered space tugs that are attached to metal ropes which are tied to anchors that are fired into the surface of the asteroid, while on the other side 8 space tugs push the asteroid
placement of the space tugs would have to be carefully worked out
Tau.Neutrino said:
How about 8 rocket powered space tugs that are attached to metal ropes which are tied to anchors that are fired into the surface of the asteroid, while on the other side 8 space tugs push the asteroidplacement of the space tugs would have to be carefully worked out
Why not just put 16 pushing?
Anchoring is hard.
Could a powerful magnetic field alter the course of an object, if say it was there all the time just in front of the object?
Tau.Neutrino said:
Could a powerful magnetic field alter the course of an object, if say it was there all the time just in front of the object?
what are you going to attach the magnetic field generator to?
Tau.Neutrino said:
Could a powerful magnetic field alter the course of an object, if say it was there all the time just in front of the object?
Well, yeah, if the object was made of ferromagnetic materials …
dv said:
Tau.Neutrino said:
How about 8 rocket powered space tugs that are attached to metal ropes which are tied to anchors that are fired into the surface of the asteroid, while on the other side 8 space tugs push the asteroidplacement of the space tugs would have to be carefully worked out
Why not just put 16 pushing?
Anchoring is hard.
Density of the asteroid would have to be calculated
a probe would first have to get a deep sample for density analysis and send back the details
then number of pull and push points would have to be worked out and calculated
a probe would also have to first obtain density readings if the nuclear shockwave or surface explosions options were used
A test asteroid should be first chosen
Seems that in wookies absence Tau has been seconded to that position.
Boris said:
Tau.Neutrino said:
Could a powerful magnetic field alter the course of an object, if say it was there all the time just in front of the object?what are you going to attach the magnetic field generator to?
haven’t figured that out yet, say hypothetically a magnetic field is present in front of the asteroid all the time, could the magnetic field push the asteroid
Tau.Neutrino said:
Boris said:
Tau.Neutrino said:
Could a powerful magnetic field alter the course of an object, if say it was there all the time just in front of the object?what are you going to attach the magnetic field generator to?
haven’t figured that out yet, say hypothetically a magnetic field is present in front of the asteroid all the time, could the magnetic field push the asteroid
Could it do a better just than, you know … just pushing the asteroid? What’s the benefit of the magnetic field?
AwesomeO said:
Seems that in wookies absence Tau has been seconded to that position.
a fleet of rocket powered b52s could move it
dv said:
Tau.Neutrino said:
Boris said:what are you going to attach the magnetic field generator to?
haven’t figured that out yet, say hypothetically a magnetic field is present in front of the asteroid all the time, could the magnetic field push the asteroid
Could it do a better just than, you know … just pushing the asteroid? What’s the benefit of the magnetic field?
if a magnetic field could move an object then it would be better than sending a bunch of nukes to nudge it off course
Well at least no one is suggesting sending the ISS to fetch an asteroid.
why make a mag field when you can just use gravity?
https://en.wikipedia.org/wiki/Gravity_tractor
A gravity tractor (GT) is a theoretical spacecraft that would deflect another object in space, typically a potentially hazardous asteroid that might impact Earth, without physically contacting it, using only its gravitational field to transmit the required impulse.
The gravitational force of a nearby space vehicle, though minuscule, is able to alter the trajectory of a much larger asteroid if the vehicle spends enough time close to it; all that is required is that the vehicle thrust in a consistent direction relative to the asteroid’s trajectory, and that neither the vehicle nor its expelled reaction mass come in direct contact with the asteroid.
The tractor spacecraft could either hover near the object being deflected, or orbit it, directing its exhaust perpendicular to the plane of the orbit. The concept has two key advantages: namely that essentially nothing needs to be known about the mechanical composition and structure of the asteroid in advance; and that the relatively small amounts of force used enable extremely precise manipulation and determination of the asteroid’s orbit around the sun. Whereas other methods of deflection would require the determination of the asteroid’s exact center of mass, and considerable effort might be necessary to halt its spin or rotation, by using the tractor method these considerations are irrelevant.
dv said:
Well at least no one is suggesting sending the ISS to fetch an asteroid.
why don’t we send ISIS to fetch an asteroid?
How powerful are shock waves from nuclear explosions?
I mean is a surface explosion at one kiloton better than say a shockwave hitting the asteroid from a one kiloton bomb?
dv said:
Well at least no one is suggesting sending the ISS to fetch an asteroid.
But it would put them to better use.
Boris said:
dv said:
Well at least no one is suggesting sending the ISS to fetch an asteroid.
why don’t we send ISIS to fetch an asteroid?
That’s silly.
ISIS are not even rated above 20,000 ftTau.Neutrino said:
dv said:
Well at least no one is suggesting sending the ISS to fetch an asteroid.
But it would put them to better use.
Scratch that, I thought of sending Islamic State terrorists to fetch the asteroid
that would would them to better use
not the Space Station astronauts
Could an object in space be moved by using sound waves and other waves of the frequency spectrum
how many different parts of the frequency spectrum could be used at all the same time
could solid light move an object
Tau.Neutrino said:
Could an object in space be moved by using sound waves and other waves of the frequency spectrumhow many different parts of the frequency spectrum could be used at all the same time
could solid light move an object
Okay, sound waves don’t work in space.
Yes, light can be used to move objects. I don’t know what “solid light” is.
But again … in what way is this better than just pushing?
Tau.Neutrino said:
Could an object in space be moved by using sound waves and other waves of the frequency spectrumhow many different parts of the frequency spectrum could be used at all the same time
could solid light move an object
Scientists Create Solid Light
http://www.iflscience.com/physics/crystallized-light-reveals-potential/
How powerful could they make solid light?
dv said:
Tau.Neutrino said:
Could an object in space be moved by using sound waves and other waves of the frequency spectrumhow many different parts of the frequency spectrum could be used at all the same time
could solid light move an object
Okay, sound waves don’t work in space.
Yes, light can be used to move objects. I don’t know what “solid light” is.
But again … in what way is this better than just pushing?
Okay, sound waves don’t work in space.
but don’t they still propagate as energy or do they disintegrate?
Tau.Neutrino said:
dv said:
Tau.Neutrino said:
Could an object in space be moved by using sound waves and other waves of the frequency spectrumhow many different parts of the frequency spectrum could be used at all the same time
could solid light move an object
Okay, sound waves don’t work in space.
Yes, light can be used to move objects. I don’t know what “solid light” is.
But again … in what way is this better than just pushing?
Okay, sound waves don’t work in space.
but don’t they still propagate as energy or do they disintegrate?
They don’t even exist there. Sound is a compressive wave in matter.
dv said:
Tau.Neutrino said:
dv said:Okay, sound waves don’t work in space.
Yes, light can be used to move objects. I don’t know what “solid light” is.
But again … in what way is this better than just pushing?
Okay, sound waves don’t work in space.
but don’t they still propagate as energy or do they disintegrate?
They don’t even exist there. Sound is a compressive wave in matter.
ok, no sound waves then
Boris said:
why make a mag field when you can just use gravity?https://en.wikipedia.org/wiki/Gravity_tractor
A gravity tractor (GT) is a theoretical spacecraft that would deflect another object in space, typically a potentially hazardous asteroid that might impact Earth, without physically contacting it, using only its gravitational field to transmit the required impulse.
The gravitational force of a nearby space vehicle, though minuscule, is able to alter the trajectory of a much larger asteroid if the vehicle spends enough time close to it; all that is required is that the vehicle thrust in a consistent direction relative to the asteroid’s trajectory, and that neither the vehicle nor its expelled reaction mass come in direct contact with the asteroid.
The tractor spacecraft could either hover near the object being deflected, or orbit it, directing its exhaust perpendicular to the plane of the orbit. The concept has two key advantages: namely that essentially nothing needs to be known about the mechanical composition and structure of the asteroid in advance; and that the relatively small amounts of force used enable extremely precise manipulation and determination of the asteroid’s orbit around the sun. Whereas other methods of deflection would require the determination of the asteroid’s exact center of mass, and considerable effort might be necessary to halt its spin or rotation, by using the tractor method these considerations are irrelevant.
Much quoted, but not much use. Consider.
1) In order to keep your spacecraft adjacent to but not orbiting the asteroid you have to use constant power on it. This involves exactly as much energy as pushing the asteroid directly.
2) Because the gravity tractor is so weak it has to be applied also at times when the effect on the asteroid’s orbit is sub-optimal. By contrast, a direct push need only be applied at perihelion and aphelion when they will do the most good.
In favour of the gravity tractor, however is:
3) Easier to control when the asteroid is rapidly rotating.
I still prefer my much-stated harpoon and bungee cord method for hauling asteroids and comets around. Harpoon the asteroid close enough to the pole and then there is no need to worry about rotation. The bungee cord smoothes out tugs to make them more uniform.