Curium

Curium was first made in 1944 at Berkeley by Glenn Seaborg, Ralph James and Albert Ghiorso, by bombarding plutonium with alpha particles, though wartime secrecy delayed its announcement. It was named in honour of Marie and Pierre Curie, the pioneers of radioactivity. Curium is a hard, silvery, intensely radioactive metal that glows in the dark from its own radiation, and it has served as a compact power source and as the alpha source in the instruments that analysed Martian rocks. Warm and self-luminous from its intense decay, curium has powered instruments and provided the alpha source in the spectrometers that analysed the composition of rocks on the Moon and Mars, and it is a stepping-stone for synthesising still heavier elements.

Curium-244 sources have flown to Mars aboard NASA's Curiosity and Perseverance rovers, powering the alpha-particle X-ray spectrometer instruments that identify the chemical composition of Martian rocks and soil by bombarding them with the isotope's steady alpha radiation and reading the resulting X-ray signature, a fittingly appropriate use for an element named after the pioneers of radioactivity itself. Wartime secrecy also delayed curium's announcement, so despite being made before americium it was revealed to the public only after its sibling element.

Curium's naming honours Marie and Pierre Curie, whose discovery of polonium and radium had opened the science that made the synthetic elements possible, and the choice was made by deliberate analogy with the element directly above it, gadolinium, which had been named for the chemist Johan Gadolin. The pairing set curium as the actinide counterpart of a lanthanide named for a scientist, one of the neat symmetries Seaborg built into the lower rows of the table. Curium has no ancient or alchemical association, being a creation of the 1940s, but it carries forward the memory of the two scientists most identified with radioactivity itself, an apt tribute in an element born of the very radiation the Curies first learned to measure. It later powered instruments on Mars.

Curium's radioactivity is intense enough that a sizeable sample generates visible heat and can glow faintly from its own decay, a property that makes handling and storing more than trace quantities a genuine engineering challenge requiring active cooling, quite unlike the merely trace amounts of most other transuranium elements that never accumulate enough mass to warm noticeably at all. This self-heating is precisely what made curium's cousin plutonium-238 useful as a spacecraft power source, though curium itself has mostly remained a laboratory curiosity rather than a practical generator fuel.