posted on Aug, 1 2015 @ 05:13 PM
originally posted by: CB328
CRAWL compared to orbital velocities closer to Earth
It's still very fast. Another issue that's not addressed is since they left the earth at 25,000 mph, wouldn't they have to leave the moon at the same
speed or reach it soon after for the return trip to not take much longer? Yet as I mentioned, the moon escape velocity is only 5000 and the speed of
the orbiting stage was 2100 mph, so after docking they would have to accelerate another 23,000 mph. Where was the fuel for that?
Hint: It's called Gravity.
Specifically the Earth's gravity. Which can have a major effect on things up to 1.5 million miles from the planet.
When the rockets finished their lunar injection burn to leave Earth orbit, the moment that burn stopped, Earth's gravity was the only force continuing
to act on them after that, which would slow them down, so that by the time they reached the moon, they would only have to burn for a short time to
slip into orbit around the moon.
Leaving the moon: burn to leave the moon's orbit, enough to break orbit but not enough to leave the Earth. The Earth pulls on your ship and pulls you
back toward it.
They didn't need to burn to accelerate to 23,000 Mph. They only needed to burn so that once they left Lunar orbit (which puts you in Earth orbit),
that orbit now intersects the Earth. Earth's gravity then pulls on you, and as you get closer to the Earth, your craft will accelerate, more and
ETA: While it is only game, it does simulate orbital mechanics and gravity quite well. I suggest that any who are interested, go to YouTube and search
for Kerbal Space Program videos, specifically tutorials on how to put something in orbit, leave orbit, travel to the Mun, enter Mun orbit, how to land
on the Mun, how to leave the Mun, how to leave Mun orbit and return to Kerbal. I think people might find it a bit educational (and if you have the
edit on 8/1/2015 by eriktheawful because: (no reason given)