If you put the laser in orbit instead of on the ground, you (a) get more solar power to collect there, and (b) don't need to correct for atmospheric distortion

If you put the laser in orbit instead of on the ground, you (a) get more solar power to collect there, and (b) don't need to correct for atmospheric distortion and losses on the outgoing beam. And bonus (c) you can point a microwave beam at the ground for more Earth power when you're not using it to sling spacecraft.