NASA formula, can someone decipher

[twdeckard]

I'll throw in a few discordant guesses.

The e sin E - peaking thru is Keplers equation.

Wdot (first derivative of W, is the rate of change of vehicle or propellant weight)
Wb is the baseline weight of the vehicle at launch or at insertion.
G is gravity to turn the weights into masses.
The exponential decay is the propellant mass fraction
I say the lower case t is time

For a given change in velocity how much time elapses? a guess.

Todd