What's in your wallet?
It's not clear from the summary (or the linked article), but this isn't a mission at this point. This is a concept selected for Phase I study.
From the NASA Innovative Advanced Concepts (NIAC) news release:
"NIAC Phase I awards are approximately $100,000, providing awardees the funding needed to conduct a nine-month initial definition and analysis study of their concepts. If the basic feasibility studies are successful, proposers can apply for Phase II awards, which provide up to $500,000 for two more years of concept development."
This effort is independent of the ongoing Europa mission studies (e.g. the Clipper concept.) The Draper concept may end up getting a mission if the results prove promising. Personally, I have doubts that this will prove credible, but that's the whole point of the NIAC studies.
And for goodness sake, don't let them drive the bus.
Not the whole ring system. Only the A-D rings are within the Roche limit. But the phenomenon discussed here is happening in the A-ring, so this limitation does indeed apply. I don't understand how a moon could accrete here.
Actually, I always had wanted Stewart cast as Denethor. Not only could he have played the character much closer to how he's portrayed in the book, he'd have been a great foil to McKellen's Gandalf.
We certainly will be observing this comet with our Mars spacecraft. http://www.nasa.gov/jpl/mars/c...
In fact, there was a practice run with ISON last year. I think the goal is to point every telescope in the solar system at this thing during the pass.
Well, at least the Canadian pennies should stop being such a problem. They stopped making them a couple years ago. http://www.cbc.ca/news/canada/...
A prolate spheroid doesn't taper to points on the end. You'd need an infinite series of spherical harmonics to describe an American football, not just the degree-2 term. Though it's sufficiently elongated that spherical harmonics might not be the best basis set. Bessel functions?
Well, you have to admire the restraint, but I think this calls for a more forceful protest.
Like how Jor-El sent his only son to Earth to save mankind?
I'd also be confused if this site were in my current directory.
It's always bothered me when a radio program is called a "show". What exactly are you showing me?
They should have used Planet Express!
A few points of clarification.
1. The major heat-producing elements are all lithophiles, preferentially bounding to silicates. So there's virtually no radioactive decay in the core. It's all in the crust and mantle.
2. Thorium is an important heat source now due to its long half-life (14 Gy IIRC). But back in the day, Uranium and Potassium-40 were much more abundant, and produced the majority of the radioactive heating.
3. Assuming the Earth and Mars initially had similar bulk compositions, they would have similar rates of radioactive heating. But Mars surely cooled more quickly. The heat production scales as the mass, and therefore the volume. Heat loss scales as the surface area. So smaller planets have the lower surface to mass ratio and cool more quickly.
Earth already had its iron core at the time of the Moon forming impact. Most of the impactor accreted onto the Earth and the cores of the two bodies merged (Canup and Asphaug, 2001, Nature). A fraction of the silicate crust and mantle of the impactor and target was ejected into orbit. That debris accreted into the Moon. Since it is largely made of the silicate portion of the original bodies, it is depleted in metal, and has a relatively small core.