Rdivine

Safe asteroid collision course with Earth

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Hello!

So NASA has plans to return a small asteroid/boulder from an asteroid to lunar orbit, and send crew to retrieve samples from it. However, why go through all that trouble?

I propose a mission that sends a small probe to a large asteroid( roughly between 300m - 1km in diameter) which would already be on a trajectory that will intersect Earth's, and place it in orbit. The satellite could use gravitational tugging to set the asteroid on a near-collision course with Earth. The asteroid would then undergo aerocapture into an eccentric orbit around Earth, and it's perigee would be raised slightly so that it's orbit would decay slowly. After a planned amount of time, the asteroid would undergo reentry and land somewhere on Earth. Hopefully, due to it's large size, it wouldn't burn up completely, but large boulders of it would make it safely to Earth for recovery and analysis. To prevent any endangering of population, it could be done over Antarctica. 

It might be a less-costly and less-complicated idea, and it would allow for more samples of the asteroid to be taken. Do you think it is possible?

Edited by Rdivine

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56 minutes ago, Rdivine said:

Hello!

So NASA has plans to return a small asteroid/boulder from an asteroid to lunar orbit, and send crew to retrieve samples from it. However, why go through all that trouble?

I propose a mission that sends a small probe to a large asteroid( roughly between 300m - 1km in diameter) which would already be on a trajectory that will intersect Earth's, and place it in orbit. The satellite could use gravitational tugging to set the asteroid on a near-collision course with Earth. The asteroid would then undergo aerocapture into an eccentric orbit around Earth, and it's perigee would be raised slightly so that it's orbit would decay slowly. After a planned amount of time, the asteroid would undergo reentry and land somewhere on Earth. Hopefully, due to it's large size, it wouldn't burn up completely, but large boulders of it would make it safely to Earth for recovery and analysis. To prevent any endangering of population, it could be done over Antarctica. 

It might be a less-costly and less-complicated idea, and it would allow for more samples of the asteroid to be taken. Do you think it is possible?

NO. Numerous reasons.

1. The current ARM proposal is mainly to test human-rated SEP, return Asteroid samples, and test asteroid defense tech (and to make a mission for Orion). Orion would not get a mission in what you propose- I also highly doubt you can make something large enough and with enough Delta V and Thrust to deorbit a asteroid large enough for large chunks to survive reentry

2. You have no choice, and often very little idea what the rock is like, which can impact the mission. Unless you can predict which asteroid will enter Earth SOI and when, you would also not be able to study it beforehand, and have to keep the ARM unmanned spacecraft in storage for extended periods of time while you wait, and then the robotic spacecraft would need to be quickly readied for launch.

3. It would also reduce the scientific purpose. The entire point of sample return is to get untainted samples. The samples from this would be tainted.

4. Noone wants to have a rock reentring the atmosphere on purpose. NASA puts this thing in Lunar Orbit so it has no way of entering Earth's atmosphere. Good luck getting this funded and through congress.

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Chelyabinsk meteor was basically a big rock - mere meters in diameter. You are proposing dropping an equivalent of small mountain into the atmosphere. There is no way it would end well.

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5 hours ago, Rdivine said:

Do you think it is possible?

Yes, but I also think it's insane.  Like, the kind of idea that would have the international community seriously considering if Dr. Evil was behind it, and taking pre-emptive action to ensure it didn't happen would seem like the logical thing to do.

Good question, bad idea.

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Alone aerocapture of such a big object will take ages (mass is cubed with radius, area, hence braking is only squared with radius). Hence, you will have only very little control over where it will finally go down. Also will a 1 km chunk have apocalyptic impact even if it goes down in Antarctica.

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5 hours ago, pxi said:

Yes, but I also think it's insane.  Like, the kind of idea that would have the international community seriously considering if Dr. Evil was behind it, and taking pre-emptive action to ensure it didn't happen would seem like the logical thing to do.

Good question, bad idea.

I'm not Dr. Evil, i swear.

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7 hours ago, pxi said:

Yes, but I also think it's insane.  Like, the kind of idea that would have the international community seriously considering if Dr. Evil was behind it, and taking pre-emptive action to ensure it didn't happen would seem like the logical thing to do.

Good question, bad idea.

Lot of the (crazy) people I know already think that about ARM.

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On a different, but vaguely related topic...

Would it be possible to place a largeish asteroid in any sort of stable Earth orbit where it could be used as a gravitational tractor for LEO insertion assist, without destabilizing GTO or LEO?

I'm thinking about an orbit with a perigee a little above LEO and an apogee a little below GTO. Instead of needing to carry almost 9 km/s of dv to reach LEO, launch vehicles could merely execute a nearly-vertical ascent timed to slingshot around the asteroid at its perigee into a medium-low Earth orbit. After all, it's a lot easier to get to space than it is to stay in space.

This is probably hella dangerous, but I'm just wondering if it's even vaguely possible.

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1 minute ago, sevenperforce said:

On a different, but vaguely related topic...

Would it be possible to place a largeish asteroid in any sort of stable Earth orbit where it could be used as a gravitational tractor for LEO insertion assist, without destabilizing GTO or LEO?

I'm thinking about an orbit with a perigee a little above LEO and an apogee a little below GTO. Instead of needing to carry almost 9 km/s of dv to reach LEO, launch vehicles could merely execute a nearly-vertical ascent timed to slingshot around the asteroid at its perigee into a medium-low Earth orbit. After all, it's a lot easier to get to space than it is to stay in space.

This is probably hella dangerous, but I'm just wondering if it's even vaguely possible.

The asteroid's orbit would degrade due to drag and also due to energy transfer to these ships. You don't get anything for free. I'm thinking the cost to put an asteroid into this kind of orbit would be way more than the cost of just launching the ships normally.

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14 minutes ago, mikegarrison said:

The asteroid's orbit would degrade due to drag and also due to energy transfer to these ships. You don't get anything for free. I'm thinking the cost to put an asteroid into this kind of orbit would be way more than the cost of just launching the ships normally.

You'd likely need to use a solar sail approach to get the asteroid into place, which would then double as your station-keeping mechanism.

I'm curious whether it would be possible to have a large enough body to allow for successful assists, but still be small enough and in the right spot to avoid destabilizing existing orbits.

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On 1/30/2016 at 7:35 AM, Rdivine said:

I'm not Dr. Evil, i swear.

 

Adam Savage said:

I'm not sure he's evil and I'm not sure he's a genius.

P.S. Take that, IPB editor.

Edited by K^2

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1 hour ago, sevenperforce said:

On a different, but vaguely related topic...

Would it be possible to place a largeish asteroid in any sort of stable Earth orbit where it could be used as a gravitational tractor for LEO insertion assist, without destabilizing GTO or LEO?

I'm thinking about an orbit with a perigee a little above LEO and an apogee a little below GTO. Instead of needing to carry almost 9 km/s of dv to reach LEO, launch vehicles could merely execute a nearly-vertical ascent timed to slingshot around the asteroid at its perigee into a medium-low Earth orbit. After all, it's a lot easier to get to space than it is to stay in space.

This is probably hella dangerous, but I'm just wondering if it's even vaguely possible.

I'm 90% sure this wouldn't be practical... and the TWR would likely be too low.

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13 hours ago, sevenperforce said:

On a different, but vaguely related topic...

Would it be possible to place a largeish asteroid in any sort of stable Earth orbit where it could be used as a gravitational tractor for LEO insertion assist, without destabilizing GTO or LEO?

I'm thinking about an orbit with a perigee a little above LEO and an apogee a little below GTO. Instead of needing to carry almost 9 km/s of dv to reach LEO, launch vehicles could merely execute a nearly-vertical ascent timed to slingshot around the asteroid at its perigee into a medium-low Earth orbit. After all, it's a lot easier to get to space than it is to stay in space.

This is probably hella dangerous, but I'm just wondering if it's even vaguely possible.

aren't we need somthing like mun size thing to do that?

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On 30/01/2016 at 10:35 AM, Rdivine said:

I'm not Dr. Evil, i swear.

Tell us the truth!

*prod, prod*

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