Question

An astronaut is drifting away from the spaceship how can he returned back to his spaceship using only n aerosol spray

Answer 1

here newtons 3rd law is used
every action has an equal and opposite reaction and gravity and friction are too absent to oppose it

Answer 2

According to law of conservation of momentum, the total momentum of a system is always constant in the absence of an external force.

The astronaut can return back to the spaceship by using the principle of conservation of momentum.

To return to spaceship, the aerosol should be sprayed in the direction away from the spaceship so that the astronaut moves towards the spaceship by conserving the momentum.