/summon dragon_fireball ^ ^ ^2 {Motion:[0,0,0],direction:[0.0,0.0,0.0],ExplosionPower:0}

The fireball vanishes quickly This also works with a tiny direction value (such as x=0.00001).

It acts as if the fireball is not redrawn if it has not moved.

Also, at a visible but small motion (such as x=0.1) the fireball moves for a few ticks and then dies. I think it has a limited lifespan which (afaict) cannot be changed