Radioactive decay is the source, yes, which means we won’t be out of it until the earth is out of all of the radioactive isotopes that are undergoing alpha decay.
By the time that happens, Bussard collectors will probably escape from the realm of fiction.
Radioactive decay is the source, yes, which means we won’t be out of it until the earth is out of all of the radioactive isotopes that are undergoing alpha decay.
By the time that happens, Bussard collectors will probably escape from the realm of fiction.
Yes, but right now it’s “cheap” because it’s a byproduct of natural gas mining. As we transition off fossil fuels it won’t be so easy to acquire.
One of the reasons the shortage was alleviated was the expansion of gas mining and the subsequent discovery of a bunch in Tanzenia.