N is for Navigation.
O is for Optical Communications.
P is for Passive Sensor.
Q is for Quantum Entanglement.
R is for Return Link.
S is for Solar System.
T is for Tracking and Data Relay Satellite (TDRS).
U is for Universe.
V is for Velocity.
On Oct. 19, 2017, the Moon photobombed NASA’s Solar Dynamics Observatory, or SDO, when it crossed the spacecraft’s view of…