Space batteries from Cumbria

 

This article in the local paper alerted me to something I didn't know. I knew that radioactivity was used to power space craft but I didn't know how. Turns out it is called an RTG and works by bolting one end of a thermocouple to the container for a radioisotope. The other end of the thermocouple is bolted to a heat sink. A lot of outer space is very, very cold away from direct sunlight so there will be a big temperature difference from the warmth coming from the radioactive decay products. The thermocouple generates electricity from the temperature difference. Maybe "generates" isn't the right term to use here. I'll think about that. The Wikipedia page has a wonderful assessment of the pros and cons of Americium-241 vs Plutonium-238.