The United States Global Positioning System (GPS) employs a constellation of 24 to 32 satellites in near-circular earth orbits at an altitude of 11 000 nautical miles. These satellites broadcast radio signals from which a GPS receiver can compute its location and the current time. A Block IIF GPS satellite is powered by solar panels generating as much as 2900 W. It is designed to operate for 15 years. Suppose the solar panels for a GPS satellite were to be replaced by a Stirling-cycle converter (31% efficiency) powered by Pu-238. Compute the mass of Pu238 O2 required to provide at least 2900 W for 15 years