LightSail 2 is one of 25 spacecraft aboard a Falcon Heavy rideshare mission called STP-2 — the 'STP' stands for the Air Force’s Space Test Program. The primary payloads are six weather and climate satellites called COSMIC-2 and a space radiation experiment named DSX. The Falcon Heavy's upper stage engine will re-light multiple times to deliver all 25 spacecraft into three different orbits.

Once in space, LightSail 2 will attempt to demonstrate solar sailing as a method of propulsion for small, standardized satellites known as CubeSats. The spacecraft will do this by turning its reflective solar sail against the sun's rays each orbit. Solar photons have no mass, but they have momentum, and will give LightSail 2 a gentle push as they bounce off the sail.

The push is no stronger than the weight of a paperclip, but it is continuous, and will raise the spacecraft’s orbit by up to several hundred meters each day.

LightSail 2 will ride to orbit nested inside the rectangular Prox-1 spacecraft, which measures just 61 centimeters on its longest side. The Falcon Heavy will drop Prox-1 and LightSail into a 720-kilometer-high circular orbit, and after 7 days, Prox-1 will deploy LightSail 2 into space.