Yes, it's not even an asteroid, just a boulder they plan to lift off an asteroid. If it ever goes ahead. Started off as moving an asteroid, now it's just a boulder.

There are experiments proposed to try to redirect asteroids. One of them is by the ESA, to crash a spacecraft into an asteroid moon and see what happens to its orbit.

AIDA (mission)

The asteroids are much heavier than the spacecraft that would crash into them in the redirect test missions if they go ahead. So will make only the slightest of changes to the orbit.

If we ever do an asteroid redirect for real - and I expect we will, though maybe not this century - well then it would mean very careful calculations. You want to be sure your redirect pushes it away from Earth rather than towards it - you want to change a hit into a near miss - but not change a near miss into a hit!

Asteroid impacts are very rare. As you can see from history. There's no equivalent of Pompei for asteroid impacts in recorded history. So though a small 100 meter asteroid could be easily as devastating as a volcano - this has just never happened - never landed in a populated area as far as we know. They are quite rare, every few thousand years for the 100 meter ones, so it is quite possible that none has ever landed on a city or village or even a hamlet. Because much of the Earth's surface is still desert, mountains, sea, ice fields etc. And even more so in the past.

And the dinosaur extinction level ones are even rarer, only a one in ten million chance of one this century now that we have found all the NEOs of ten kilometers diameter or larger already.

So, it's entirely possible that we don't need to deflect any asteroids this century. Indeed that's by far the most likely outcome. Because for smaller ones like the Chelyabinsk meteorite - it would be enough to warn people to stay away from windows, and if necessary evacuate the impact zone if it was headed somewhere populated. Very unlikely they come close enough to an inhabited area to be of concern.

But perhaps we might deflect one of those tiny ones as an experiment rather than evacuate the impact zone. Or if it was due to impact on somewhere particularly sensitive. If so maybe we will try this out for real.

The priority right now though is to find them. If we can map them all out, even the small ones, we'd have a couple of decades warning and then deflection would be easy. If you have a decade of warning you only need to give it a delta v of 2 cm / second to move it by more than the radius of the Earth ten years later. If it does a close flyby of Earth first before the predicted impact, then an even tinier delta v is needed, it might have a keyhole of only a few hundred meters it has to go through before it can hit the next time. If so, a delta v right now of only microns per second would be enough to make sure it misses the time after that.

And the technology needed would depend on what we find. In some cases it might be enough to just "paint" the asteroid white - dust it with something light coloured, which could change its orbit by the Yarkovsky effect.

So the main priority has to be to find the things. It doesn't even cost that much. The Sentinel telescope which would find most of the smaller NEOs in less than a decade would cost less than half a billion dollars. We are already finding the larger ones using Pan Starrs and Linear at a rate of 1 a month, have already found all the ones of 10 km and 90% of those of 1 km and will get to 99% by the 2020s. But the smaller ones are tricky, we find about 500 or so of those a year which may sound a lot but there are so many that some step up of effort is needed to reach the target of 90% by the 2020s. There's another proposal NeoCam - which is similar to Sentinel but not so capable.

See also my Giant Asteroid Headed Your Way? - How We Can Detect And Deflect Them