Article (space.com) on fly-by of Asteroid 2004 MN4 in 2029.

[tony873004]

Using Horizons data in Gravity Simulator, I can paint a before and after picture on what Earth's gravity will do to this asteroid's orbit.

before
after

[andersa]

Wouldn't it be soooo cool if we could figure out a way to capture it into a permenant earth orbit so we can study it?

To get something into Earth orbit without substantial propulsion probably requires a Moon gravity assist operation, and we would then have to adjust its new orbit somehow in order to avoid having the Moon interfer with it again in the future. Provided that can be done, it will probably be easier to aim a more distant asteroid our way than capturing 2004 MN4 in 2029. Proximity merely helps getting to the object; when applying propulsion you want it to be sufficiently far away (in time, but also in space) for maximum effect and precision.

When driving at 100 mph, you don't engage the brakes and begin looking for parking space only four seconds before you arrive home.

[andersa]

I expect meteorologists will not be happy with a streak of an asteroid in one of their pictures.

I doubt that would be much of an issue. It's a 300 meter mountain a few thousand km further down, moving at perhaps 7 km/s. It may momentarily obscure a small town but hardly a hurricane. "Will that asteroid in front of the camera please sit down? Now for tomorrow's weather forecast..."

Better is to shoot the asteroid with a long long harpoon with a radar reflector on the end. The reflector (as on ships and boats) is merely a passive device of three planes of metal forming an octahedral shape, causing three reflections that send the echo straight back to where it came from. No need for power, and the large radar cross-section will give an excellent point spread function allowing auto-focus of ISAR (inverse synthetic radar aperture) imagery.

You are right, of course. I can see it now, thousands of Near Earth Objects with centuries of accumulated reflectors hanging around them in wires, as if they have Just Married... Or, we'll hear stories about Captain Ahab spending a lifetime's supply of harpoons on his White Rock!

Now, what if a reflector is accidentally detached from its asteroid; how long will it take before the discrepancy between the radar image and the position of the real object is detected? Can you even tell two different reflectors apart remotely, in case two asteroids come close to each other?

No need for that oversight with a passive target, though are you talking Huygens here?

It wasn't me! Honest!