cwnl:

Inside Earth’s Moon

The all natural satellite that orbits us daily. Now in infographic for your visual digest.

matthen:

If you are on orbit not far from the Earth, but want to transfer to a higher orbit- how should you do it? You can’t just blast upwards- that will put you in a strange elliptical orbit, not the desired circular orbit. The best idea is to use an elliptical transfer orbit which touches the smaller and larger circular orbits each at one point. You can use just two boosts to go in and out of the transfer orbit. This is a pretty good example of how moving about in space isn’t as simple as just pointing the rocket nose in the right direction (unless you want to waste fuel). [more] [code]