Space/Science — HabitableZone

Space/Science » in reply to Why "shuttle" solves this

Unfortunately, that doesn't work
Larry J — (archived)

The Apollo spacecraft were doing about 25,000 MPH when they hit the Earth's atmosphere. Had they skipped off the atmosphere because they came in too shallow, they wouldn't have entered a 24 hour orbit. In fact, they were going so much faster than orbital velocity that they might've ended up in orbit around the sun instead of the Earth.

Remember, LEO orbital velocity is roughly 17,500 MPH. 25,000 MPH is pretty much escape velocity where the Earth's gravity can no longer hold the object. If it did go into an Earth orbit, the apogee would've been out around 200,000 miles so the orbital period would've been several days, far longer than their oxygen supply. The same constraints would apply to any inbound vehicle coming in from Mars or the moon.

There is no practical way to launch a stock Shuttle orbiter to the moon. I ran the numbers last year. Using hypergolic propellants, it'd take close to 500,000 pounds of propellants to fly from LEO to lunar orbit and back. Cyrogenic LH2/LOX would still need over 300,000 pounds of propellants, many times the Shuttle's cargo capacity. That vehicle simply has too many tons of dead weight for the mission, making it completely unsuitable.

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