Representatives from SpaceX, Blue Origin, and United Launch Alliance participated in a forum last week held by NASA to determine the future of humans on the moon. This isn’t just how they will live, how long they will stay, or what they will do; no, this is far more interesting: this was how humans will travel from lunar orbit from the surface of the moon. The future of the next generation of lunar lander is being determined right now.

The plan right now is entirely unlike Apollo, which sent a pair of spaceships in orbit around the moon, sent one to the surface, then returned to the mother ship for the trip back to Earth. Instead of something somewhat simple, the next era of lunar exploration will happen from a gateway orbiting in cis-lunar space. What makes this so amazing is how weird the orbit is, and the reasons behind it.

It’s The Orbit That’s Special

By now, most of us should know how the Apollo missions went. The Saturn V took off from the cape, went around the Earth for an orbit or so, and then re-lit its engine to send it off to the moon. After a three-day journey, the Apollo command module entered a nearly equatorial orbit, sent the lunar lander on its way, waited a day or two or three, docked, and then sped back to Earth. The equator is the easiest place to land on the moon, and the first three Apollo missions to do so — Apollo 11, 12, and 14 — all landed within a few degrees of the lunar equator. Later missions ventured farther north, but only so far: Apollo 15 landed at 26° North latitude. Sure, we’ve explored the moon, but it’s like saying you’ve explored the Earth if you’ve only been as far North as Florida. There’s interesting stuff in more temperate climes, and on the moon especially so: there is water ice underneath craters on the lunar poles.

Part of this was due to the technology at the time. Apollo could, theoretically, land at the poles. It could also land on the equator. Mid-latitudes were challenging; to get to these latitudes, the command module would have to orbit at an inclination that’s equally far away from 0 as it is from 90. Sure, you could take an Apollo lunar lander down to the moon at 45° North, with the Earth low on the horizon, but to get back, you’d have to rendezvous with the command module. That too could happen, but then you’d be stuck. Apollo simply wasn’t built for landing at mid-latitudes with the Earth low on the horizon.

Sure, it’s rocket science, but so is playing Kerbal Space Program. With Kerbal space center on the equator, and the Mun in a zero degree inclination orbit, you don’t need to think too hard about …read more

Source:: Hackaday