by neufer » Mon Jan 30, 2017 2:34 pm
Javachip3 wrote:Chris Peterson wrote:
...Almost certainly, there is something on the order of 100 trillion kilograms of U-238 in Saturn, which means that plutonium is continuously being created, in quantities that dwarf the 33 kg that will be introduced by the RTG burning up.
There is a lot of uncertainty in that estimate. But even if it is accurate, then using a uranium:plutonium ratio of a trillion, there could be on the order of 100 kg plutonium on Saturn pre-Cassini, and 33 kg does not seem so trivial.
It is probably
more reasonable to assume that from the ~100 trillion kilograms of U-238 in Saturn's hot dense core perhaps ~100 kilograms of P-238
are produced each year. With a half life of ~100 years that should result in ~20,000 kilograms of P-238. In any event, concern about trashing anyplace that is devoid of any real possibility of life is misplaced.
https://en.wikipedia.org/wiki/Holocene_extinction wrote:
<<The Holocene extinction, otherwise referred to as the Sixth extinction or Anthropocene extinction, is the ongoing extinction event of species during the present Holocene epoch mainly due to human activity. The large number of extinctions span numerous families of plants and animals including mammals, birds, amphibians, reptiles and arthropods. with widespread degradation of highly biodiverse habitats such as coral reefs and rainforest, as well as other areas, the vast majority are thought to be undocumented.
According to the species-area theory and based on upper-bound estimating, the present rate of extinction may be up to 140,000 species per year, making it the greatest loss of biodiversity since the Cretaceous–Paleogene extinction event.
The Holocene extinction includes the disappearance of large land animals known as megafauna, starting at the end of the last Ice Age. Megafauna outside of the African continent, which did not evolve alongside humans, proved highly sensitive to the introduction of new predation, and many died out shortly after early humans began spreading and hunting across the Earth (additionally, many African species have also gone extinct in the Holocene). These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event.
The arrival of humans on different continents coincide with megafaunal extinction. The most popular theory is that human overhunting species added to existing stress conditions. Although there is debate on how much human predation affected their decline, certain population declines have been directly correlated with human activity, such as the extinction events of New Zealand and Hawaii. Aside from humans, climate change may have been a driving factor in the megafaunal extinctions, especially at the end of the Quaternary.
The ecology of humanity has been noted as being that of an unprecedented "global superpredator" that regularly preys on the adults of other apex predators and has worldwide effects on food webs. Extinctions of species have occurred on every land mass and ocean, with many famous examples within Africa, Asia, Europe, Australia, North and South America, and on smaller islands. Overall, the Holocene extinction can be characterized by the human impact on the environment.
The Holocene extinction continues into the 21st century, with meat consumption, overfishing, ocean acidification and the amphibian crisis being a few broader examples of an almost universal, cosmopolitan decline in biodiversity. A ballooning human population along with profligate consumption are considered to be the primary drivers of this rapid decline.>>
[quote="Javachip3"][quote="Chris Peterson"]
...Almost certainly, there is something on the order of 100 trillion kilograms of U-238 in Saturn, which means that plutonium is continuously being created, in quantities that dwarf the 33 kg that will be introduced by the RTG burning up.[/quote]
There is a lot of uncertainty in that estimate. But even if it is accurate, then using a uranium:plutonium ratio of a trillion, there could be on the order of 100 kg plutonium on Saturn pre-Cassini, and 33 kg does not seem so trivial.[/quote]
It is probably [u]more reasonable[/u] to assume that from the ~100 trillion kilograms of U-238 in Saturn's hot dense core perhaps ~100 kilograms of P-238 [u]are produced each year[/u]. With a half life of ~100 years that should result in ~20,000 kilograms of P-238. In any event, concern about trashing anyplace that is devoid of any real possibility of life is misplaced.
[quote=" https://en.wikipedia.org/wiki/Holocene_extinction"]
<<The Holocene extinction, otherwise referred to as the Sixth extinction or Anthropocene extinction, is the ongoing extinction event of species during the present Holocene epoch mainly due to human activity. The large number of extinctions span numerous families of plants and animals including mammals, birds, amphibians, reptiles and arthropods. with widespread degradation of highly biodiverse habitats such as coral reefs and rainforest, as well as other areas, the vast majority are thought to be undocumented. [b][color=#0000FF]According to the species-area theory and based on upper-bound estimating, the present rate of extinction may be up to 140,000 species per year, making it the greatest loss of biodiversity since the Cretaceous–Paleogene extinction event.[/color][/b]
The Holocene extinction includes the disappearance of large land animals known as megafauna, starting at the end of the last Ice Age. Megafauna outside of the African continent, which did not evolve alongside humans, proved highly sensitive to the introduction of new predation, and many died out shortly after early humans began spreading and hunting across the Earth (additionally, many African species have also gone extinct in the Holocene). These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event.
The arrival of humans on different continents coincide with megafaunal extinction. The most popular theory is that human overhunting species added to existing stress conditions. Although there is debate on how much human predation affected their decline, certain population declines have been directly correlated with human activity, such as the extinction events of New Zealand and Hawaii. Aside from humans, climate change may have been a driving factor in the megafaunal extinctions, especially at the end of the Quaternary.
The ecology of humanity has been noted as being that of an unprecedented "global superpredator" that regularly preys on the adults of other apex predators and has worldwide effects on food webs. Extinctions of species have occurred on every land mass and ocean, with many famous examples within Africa, Asia, Europe, Australia, North and South America, and on smaller islands. Overall, the Holocene extinction can be characterized by the human impact on the environment. [b][color=#0000FF]The Holocene extinction continues into the 21st century, with meat consumption, overfishing, ocean acidification and the amphibian crisis being a few broader examples of an almost universal, cosmopolitan decline in biodiversity. A ballooning human population along with profligate consumption are considered to be the primary drivers of this rapid decline.[/color][/b]>>[/quote]