Nasa's asteroid mission

I have a suggestion for the manned asteroid visit mission that NASA has planned to be done by 2025 {another
description here}. The mission is a great idea to get ready for any dinosaur
exterminating sized earth targeted asteroids. Earlier rendezvous with
asteroids by satellites have noticed that the space rock's paths can be changed
by the gravitational attraction of the man made visiting object itself.
One idea is to use the manned mission to attempt to do this. I thought
adding a magnetic field to a satellite or capsule would increase this effect
greatly for most any metallic rock.

Another perhaps better plan would be to use whatever ion
drive engine that is functional at the time and attach several of them to a
large asteroid. With an on board computer for each engine that could
communicate with each other maybe they could autonomously drive the asteroid to
a destination. If one fails the others could recalculate and proceed in
the most efficient manner. This could be used later if we ever start "mining"
asteroids for their high metals & water {fuel} content.

I think postponing the moon mission and converting to a project that will aid
in protecting earth, a much more immediate concern, was a wise decision by the
current administration. Anyone care to comment? a glass or wine or two
first might help ;-)

An interesting article about a game plan for rogue asteroids.

"World Action Plan Emerging to Combat Asteroid Threat "
http://www.space.com/news/asteroid-threat-global-action-plan-101109.html

Solar Sail Flotilla Could Divert Possibly Dangerous Asteroid

Is the title of a Space.com article describing a way to divert the
"planet killer" asteroid that is headed our way on April
13, 2036 for a  near {hopefully} miss.  The plan is to shade the
asteroid from the Sun's rays.  I am uncertain if this would slow the rock
by removing an accelerating source or speed it up. 

 I know the science channel had a bit with a scientist suggesting another tack - to have solar reflectors concentrate
sun rays on the rock whereby you could either accelerate or slow down its
speed.  I assume by the hot spot's position relative to the rock's orbital
path.  Feel free to educate me on the procedure if anyone is familiar with
it or knows of a more explanatory source.

:::Edit::: I found a good source for manipulation of the space rocks:
TOP 10 WAYS TO STOP AN ASTEROID