Recent comments in /f/space

rocketsocks t1_je42f1p wrote

A solar system is formed out of a mix of gas and tiny nanoscopic dust (and ice) grains. Those dust grains contain the whole variety of elements that exist in nature, from hydrogen to uranium, including things like gold. As those grains stick together and form into balls of rock and ice there is a certain size range where the energy released by impacts starts becoming enough to start melting the material of the grains. As you progress through the ladder of accretion of larger and larger objects (from gravel to rocks to boulders to mountain sized asteroids to moon and planet sized objects) eventually the heat released from these impacts becomes enough that it can keep a whole object molten for an extended period of time, not just an isolated melting but a full molten asteroid or "planetesimal".

When this happens the grab bag of materials in the dust grains that made up all of the component parts of the object become liquid and start to separate based on mutual solubility. Just like oil and water don't mix, different kinds of molten elements and minerals either mix or don't mix. In broad strokes you can categorized elements and minerals into the group that is more soluble along with molten iron and nickel (the siderophilic elements and minerals) and the group that is more soluble along with molten silicate rocks (the lithophile elements and minerals). When a large planetary body exists in this molten state for an extended period (perhaps as short as hours or days even) it separates into layers of materials based on mutual solubility and density, with the denser iron and siderophilic materials sinking down into the core and the lighter silicate rock materials floating to form a mantle and crust.

Many precious metals including gold, platinum, palladium, iridium, etc. are siderophiles, and preferentially separate out into the core of a planetary body. Earth contains an enormous amount of gold and other precious metals effectively locked away within the core, on the crust gold is much rarer due to this differentiation process which has occurred. During the formation of the solar system some planetesimal bodies became large enough to become differentiated but then cooled to become solid, and some of them were disrupted by impacts and their pieces ended up not becoming parts of planets or moons. Today there are multiple types of asteroids. Many are made of very primordial material (chondrites) and were likely never part of a larger body and never underwent differentiation. Some are the debris of larger bodies which became differentiated and then were smashed into pieces by impact events, leaving behind floating chunks of stony crust or metal rich cores.

The metallic asteroids are fragments of the cores of larger differentiated bodies, and they represent a peak into the sorts of collections of materials that on Earth are mostly abundant within the core. Psyche does not have the density to be purely a chunk of iron-nickel core material, it likely is some mixture of metallic and stony materials. However, the metallic materials will include mostly iron, nickel, and cobalt.

(Here's the tl,dr part):

The precious metals within 16 Psyche exist at trace levels, with higher concentrations within the metallic portions of the asteroid. For gold, platinum, iridium, palladium, etc. these levels would typically be somewhere in the 10s of parts per million range. They do not exist as native metals or in the form of flakes, grains, veins, or nuggets. Those require hydrothermal processes which do not occur on asteroids or asteroid parent bodies. This means that in terms of precious metal content even a high metal content asteroid represents merely an ore body that would need to be processed in order to produce bulk quantities of those precious metals. It would take processing tens to hundreds of tonnes of asteroid material just to produce a singular kilogram of gold or other precious metals, for example.

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Andromeda321 t1_je3y1r9 wrote

Magnetars. We have traced some FRB-like signals to a magnetar within our own galaxy so it’s pretty convincing a lot of them are created by even higher energy magnetars, IMO.

I feel that then begs the next question which is if ALL FRBs are created via the same mechanism, but I’m not sure we have a convincing answer there yet.

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rocketsocks t1_je3uy7c wrote

That's just how many GRBs happen. There are certain kinds of stellar deaths which result in the collapse of an extremely massive star into a black hole. As a considerable chunk of the rest of the star gets swallowed by the black hole it forms into an accretion disk and the rotation creates high energy axial jets. The axial jets contain super energetic material being propelled at close to the speed of light, this creates a relativistic effect which substantially increases the brightness of the emitted energy near the axis of the beam. Many of these events occur throughout the universe routinely, projecting intense gamma ray beams across billions of lightyears. When Earth happens to be in one of these beams we detect a gamma ray burst.

This particular event wasn't inherently exceptionally bright, nor exceptionally close (it was about 1.9 billion lightyears away), but we were basically directly in the brightest part of the beam, which is very narrow.

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[deleted] t1_je3q196 wrote

All science creates these days are skeptics. Dreamers need to look elsewhere. God forbid we break some physical "laws" and get some actual new, tangible physics in our lifetimes. I'm glad they are taking it up and trying it. Even if it doesn't work, it's one thing we've ruled out. We need to accept the fact that without a substantial propulsion breakthrough we will be stuck here, so we need to start looking enthusiastically, even if it means looking under rocks or throwing things at the wall to see if they stick.

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CMDR_Shazbot t1_je3k59i wrote

Government I can see, but as a tech worker I wouldn't move to a state where my partner couldn't get adequate medical treatment if pregnant, where there's poor labor laws, and the general Alabama stigma. I'm sure there's nice areas, and it's beautiful, but..yeah hard pass. I'll stack checks elsewhere.

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