1. Assume that you need to increase the space shuttle's payload by 2,000 kg, and you have decided to increase the fuel volume of the ET (external tank) based on its higher trade-off ratio in the "Space Shuttle Trade-Off Ratios" table in the text, where mPL/mp = 0.161 and mPL/ms = -0.964. Note that these values already incorporate the effect of small changes on the lower stages. a. Use the appropriate ratio to determine the necessary total mass (both propellants, kg) needed to provide this payload increase only, ignoring the possible structural weight increase