1.   He asserts that the risks are higher than stated and that an accident involving its plutonium batteries could doom thousands or perhaps millions of people to death by cancer.

2.   Officials of NASA and of the Energy Department, which makes the plutonium batteries, also said no possible Cassini accident could pose significant risks to the public.

3.   The gulf between the two sides is significant because plutonium batteries are not likely to go away soon.

4.   Howard said Russian authorities had informed the US the plutonium batteries were designed to withstand re-entry into the atmosphere and impact on Earth.

5.   Defence and emergency officials were put on full alert Monday when it was feared a disabled Russian space probe with plutonium powered batteries could crash in Australia.

6.   The debris contains plutonium batteries, and Hodges said nuclear emergency teams were standing by as nuclear fallout was considered the greatest danger.