Answer:
force exerted by Jet pack is 63 N on the astronaut
Step-by-step explanation:
As per Newton's II law we know that
Rate of change in momentum of the system is net force on it
so we have

so we have

so we have
Since he used jet pack to return back towards the spaceship
so here we will have




force exerted by Jet pack is 63 N on the astronaut