31.5 Exercise 30

Data from the appendices and the periodic table may be needed for these problems.

The Galileo space probe was launched on its long journey past several planets in 1989, with an ultimate goal of Jupiter. Its power source is 11.0 kg of $^{238} \text{Pu}$, a by-product of nuclear weapons plutonium production. Electrical energy is generated thermoelectrically from the heat produced when the 5.59-MeV $\alpha$ particles emitted in each decay crash to a halt inside the plutonium and its shielding. The half-life of $^{238} \text{Pu}$ is 87.7 years. (a) What was the original activity of the $^{238} \text{Pu}$ in becquerel? (b) What power was emitted in kilowatts? (c) What power was emitted 12.0 y after launch? You may neglect any extra energy from daughter nuclides and any losses from escaping $\gamma$ rays.