HF Glossary wrote:
Adjacent – A spacecraft is adjacent to a position if it is in the next
space, where each intersection, BURN, and site counts as a space.
However, for this purpose, CRASH HAZARDS (including burns
containing crash hazards) and LANDER BURNS (G4) do not count
towards adjacency. Also, sites connected by BUGGY ROADS (B4)
are not adjacent (because line of sight is blocked by the horizon).
• Any space adjacent to one end of a SPACE ELEVATOR (I2) is also
adjacent to the space on the other end.