Momentum

The momentum will be conserved. In this case there is no external force so the motion of the centre of mass of the burning meteroid does not change.

This is like a cracker that bursts in mid-air. Its fragments fly off in different directions. The  momenta of all fragment in one direction is equal and opposite to the momentum of the fragments flying off in the opposite direction.

So you will find that all fragments will not fly in one direction, if some fragments fly in one direction there will be others flying off in the opposite direction. In this manner momentum of the system remains conserved.