This puzzle requires the “S.A.R.G.E.” spec record and the blueprint of the Cerritos.
The paths that the energy signatures take can pass through walls, floors and ceilings.
The end point of each energy signature will be in a part of the ship that is labeled by a letter on the blueprint.
The path that the “Alpha” energy signature takes ends in the compartment that is two floors below the sickbay that is labeled with a G.
The “AGZEBID” equation that Rutherford mentions will help determine what order to consider the destination letters.
Signature “Epsilon” is extra sneaky: The bottom-ejecting escape pods are labeled in the top view of the Cerritos. Once you narrow down the destination in the top view, you’ll have to find the corresponding part of the ship in the side view to see what letter to note.
ANSWER REVEAL: The destination for each signature, in the order listed, gives the letters G, I, R, Y, V, A, T. The “AGZEBID equation” correlates with the designations Alpha, Bravo, Delta, etc. So the letter from the Alpha signature should be first. The letter from the Gamma signature should be second. Zeta should be third, and so on. Arranging the letters this way spells GRAVITY. Looking at the “duck” envelope, gravity is synonymous with WEIGHT. So WEIGHT is one of the three keywords needed to access the envelope.