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Joseph William Kennedy (May 30, 1916 – May 5, 1957) was an American chemist who co-discovered plutonium, along with Glenn T. Seaborg, Edwin McMillan, and Arthur Wahl. During World War II , he led the CM (Chemistry and Metallurgy) Division at the Manhattan Project 's Los Alamos Laboratory , where he oversaw research onto the chemistry and ...
Plutonium remained present in his body for the remainder of his life, the amount decaying slowly through radioactive decay and biological elimination. Stevens died of heart disease some 20 years later, having accumulated an effective radiation dose of 64 Sv (6400 rem) over that period, i.e. an average of 3 Sv per year or 350 μSv/h .
Trace amounts of plutonium-238, plutonium-239, plutonium-240, and plutonium-244 can be found in nature. Small traces of plutonium-239, a few parts per trillion , and its decay products are naturally found in some concentrated ores of uranium, [ 54 ] such as the natural nuclear fission reactor in Oklo , Gabon . [ 55 ]
The earliest evidence for life on Earth includes: 3.8 billion-year-old biogenic hematite in a banded iron formation of the Nuvvuagittuq Greenstone Belt in Canada; [30] graphite in 3.7 billion-year-old metasedimentary rocks in western Greenland; [31] and microbial mat fossils in 3.48 billion-year-old sandstone in Western Australia.
Plutonium-244 (244 Pu) is an isotope of plutonium that has a half-life of 81.3 million years. This is longer than any other isotope of plutonium and longer than any other known isotope of an element beyond bismuth, except for the three naturally abundant ones: uranium-235 (704 million years), uranium-238 (4.468 billion years), and thorium-232 (14.05 billion years).
“We have discovered that next step on a pathway to life.” This mosaic image of asteroid Bennu, was taken on December 2, 2018 by the OSIRIS-REx spacecraft from a range of 15 miles.
For decades, scientists have theorized that volcanic lightning on an early Earth played a crucial role in kickstarting life on the planet by breaking molecules into useful, biological components.
[10] [11] Carl Zimmer has speculated that the chemical conditions, including boron, molybdenum and oxygen needed to create RNA, may have been better on early Mars than on early Earth. [12] [13] [14] If so, life-suitable molecules originating on Mars would have later migrated to Earth via meteor ejections.