U.S. President Barack Obama signed a spending bill into law Oct. 28 that denies the Department of Energy’s request to spend $30 million in 2010 to restart production of plutonium-238 (pu-238), which is needed to power NASA planetary probes bound for sunlight-deprived destinations.

The House of Representatives initially approved $10 million for restarting pu-238 production. The Senate provided no funding in its version of the 2010 Energy-Water Appropriations bill (H.R. 3183), and the House agreed to the Senate position in conference.