Is it feasible to soft land an asteroid on Earth?

[Nereus]

I wonder if an asteroid could possibly be soft landed on Earth. I mean, if it could be brought down to the surface without causing havoc with its impact and dust clouds. I've seen news about parts of satellites and rockets falling down rather intact without burning up in the atmosphere. What does it take to put something into a gentle fall like that from space? Is there a size limit? It's the speed which makes asteroid impacts dangerous, so my thought is to drop them down at minimum speed.

 

I imagine that some asteroids might not be so very difficult to move into near Earth orbit using gravity slings, collisions, reflected solar light, rockets et cetera. And if they could be brought down to the surface, mining them could be quite lucrative. If I understand it correctly, many valuable elements exist on the surface of the Earth only as a result of asteroid impacts, otherwise they've gravitated to the core of the Earth.

 

I assume that asteroids are very loose aggregates of materials, since they have formed under low gravity, so at least they should be fairly easy to take apart and drop down to Earth in smaller pieces once they are in low orbit. Or is the whole idea impossible or too dangerous?

[insane_alien]

well, it depends on your definition of 'soft' all you really need to do is have the asteroid come in at as shallow an angle as possible.

 

but even then you're not going to be able to do it with asteroids more than a few tens of meters across. there just won't be enough atmosphere to slow them down to terminal velocity (which would still be supersonic).

 

but then, why spend all that dV on moving the whole asteroid back to earth. you could do some simple refining on site and send back some partially refined product for less energy expenditure. LEO is halfway to anywhere in the solar system.

 

EDIT:

 

Okay, I got bored and made you a python script to simulate the re-entry into the Earths atmosphere.

 

BE WARNED: It makes a few small assumptions for the sake of simplicity(and its an earlier program i used for predicting how far an air rifle would shoot)

1/ flat earth (shouldn't be too bad)

2/ euler integration is used

3/ the atmospheric density follows an exponential curve

4/ normal aerodynamic assumptions apply to a body as massive as an asteroid

 

Have fun.

 

Note: It's written in python, if you use linux you should be able to just run it in windows you'll probably need the interpreter from python.org it's written in V3

 

For a non simulation approach (it uses estimates based on empirical data) you can try this website http://impact.ese.ic.ac.uk/ImpactEffects/

 

It also tells you how big an explosion it will be in terms of nukes. but really if you land this thing in the middle of the sahara where nobody is, who will mind if it has a few kilotons behind it, you don't get the radiation so it's just blast and heat you need to worry about which will only go out for say, 100km.

ProjectileSim.py.txt

Edited April 22, 2012 by insane_alien

[Airbrush]

Soft landing asteroids is possible but takes a lot more energy, technology, and money, than simply diverting one on a collision course. Safer to keep them away from Earth, or at most in orbit so we can work on disassembling or processing them while in orbit.

Edited April 23, 2012 by Airbrush

[Enthalpy]

...python script to simulate the re-entry into the Earths atmosphere. BE WARNED: flat earth (shouldn't be too bad)

Pity! The flat Earth IS very bad for your model. This is in fact what prevent a very flat re-entry angle, thus needing a brutal deceleration at reentry capsules. At a bigger object with worse mass-over-area ratio, the deceleration is limited, and it will impact Earth brutally.

 

...some asteroids might not be so very difficult to move into near Earth orbit using gravity slings, collisions, reflected solar light, rockets et cetera...mining them could be quite lucrative...I assume that asteroids are very loose aggregates of materials...

Gravity sling needs gravity at the right position, the rest needs serious engineering! Put some figures on it, it's challenging.

I expect lucrative asteroids to be very compact, as ore needs gravity to separate the elements. These differentiated bodies result from the destruction of a big, compact and dense object.

[Phi for All]

Wouldn't it be just as effective to keep Earth resources for Earth and use asteroids for anything we need to build off-planet, at least in terms of net energy gain (if this can be applied to mining mineral resources)? This assumes that by the time we have the ability to mine asteroids, we'd probably have facilities in space for refining and manufacturing. I always thought it would be extremely efficient to build and launch satellites for Earth from a facility on the moon.

[Externet]

Nasa did bring back to earth asteroid particles on the Stardust spacecraft on January 2006.

Check the cost of the mission, multiply it by a number, to capture larger ones.

 

----> http://en.wikipedia.org/wiki/File:Stardust_Capsule_on_Ground.jpg

 

----> http://en.wikipedia.org/wiki/File:Aerogel_labtest.jpg

 

The problem is to stop the asteroid speed to zero relative to earth in order to 'drop it' with a parachute for soft landing.

[insane_alien]

Pity! The flat Earth IS very bad for your model. This is in fact what prevent a very flat re-entry angle, thus needing a brutal deceleration at reentry capsules. At a bigger object with worse mass-over-area ratio, the deceleration is limited, and it will impact Earth brutally.

 

it was a two minute bodge of something that was never meant to be used for distances more than 100m. basically all i added was a simplistic atmospheric model where the density drops of exponentially.

 

will it give accurate results? no. will it give you some idea of what's required to do a soft landing, yes, a bit.

 

feel free to modify the script by the way, if you want to add a spherical earth then go for it. I might do it later if the mood takes me but at the moment i can't be bothered.