Indigo Aerospace turned my 2D plot into 3D. This is ejecta blown completely off the Moon by the rocket exhaust of a 40 ton lunar lander. Gravity wraps it around the Moon, it cross-crosses on the back side of the Moon, then it flies off into orbit around the Sun.
https://twitter.com/indigoaero/status/1461024523072024577
2/ The dashed ellipse is the Near Rectilinear Halo Orbit of the planned Lunar Orbital Gateway. The damage the ejecta will cause to GW is only slight since the particles are very tiny and traveling “relatively” slow at that height above the Moon. Impact velocity will be ~400 m/s.
3/ However, the damage to spacecraft in Low Lunar Orbit can be unacceptably large. The impact velocity at that height may exceed 4000 m/s (relative speed of the ejecta and the orbiting spacecraft), so these will be hypervelocity impacts.
4/ Estimates say that 1% of the surface of the spacecraft could be impacted, which doesn’t sound like much but it is actually huge. It can degrade sensors or other optics.
5/ This is why we made a rule about coordinating your lunar landings with NASA mission control to ensure you don’t land at just the wrong time to sandblast another spacecraft in lunar orbit. We put the rule into this document: nasa.gov/directorates/h…
6/ Although we wrote that document as “Voluntary Guidelines,” I have been told that the FAA is enforcing it, requiring companies to abide by the guidelines as a condition for getting a launch license. Also, Congress has subsequently written it into law, iirc.
7/ From page 15 of that document, here is where we wrote about coordinating your landing time to avoid damaging any orbiting spacecraft. 
• • •
Missing some Tweet in this thread? You can try to
force a refresh
