The Apollo astronauts landed on the Moon and explored it. When they lifted off to return home, they first needed to make lunar orbit, which required a speed of about 5, 500 ft/s The lunar module ascent engine developed a vacuum specific impulse of 310 s. What is the vehicle mass ratio that will allow the engine to achieve the required speed?

The Apollo astronauts landed on the Moon and explored it. When they lifted off to return home, they first needed to make lunar orbit, which required a speed of about 5, 500 ft/s The lunar module ascent engine developed a vacuum specific impulse of 310 s. What is the vehicle mass ratio that will allow the engine to achieve the required speed?