SoylentNews is people
SoylentNews
Giant mud balls roamed the early solar system
The earliest asteroids were probably made of mud, not rock. Radioactive heat in the early solar system could have melted globs of dust and ice before they had a chance to turn to rock [open, DOI: 10.1126/sciadv.1602514] [DX], a new simulation published July 14 in Science Advances shows. The results could solve several puzzles about the composition of meteorites found on Earth and may explain why asteroids are different from comets.
[...] Bland reasoned that heat from radioactive decay would melt the ice, and the resulting body would be an enormous dollop of mud. The mud would suspend sediment particles, so they wouldn't be stripped of their sunlike elements. And it would allow the early asteroids to be any size and remain cool.
Bland and Bryan Travis of the Planetary Science Institute, who is based in Los Alamos, N.M., ran computer models of how the mud balls would evolve. Convection currents, like those that move molten rock within the Earth's mantle, would develop, helping to transfer heat into space, the models showed. After several million years, the ball would harden completely, yielding the asteroids seen today.
NASA will make a decision within the next two months on whether to extend the Dawn mission to another asteroid, leaving Ceres.
(Score: 2) by kaszz on Saturday July 15 2017, @08:16AM (1 child)
I don't interpret the articles finding that way. Small masses in free space means microgravity at most. And the convection currents should mix all of it continuously while at the same time making any fluid evaporate. When there's no fluid left it will be as it was, ie mixed. The non-spherical shape may come from being smashed by other objects and ripped apart by gravity wells.
(Score: 3, Interesting) by deimtee on Saturday July 15 2017, @12:33PM
If you haven't got enough gravity for density separation then you aren't going to get convection either. They are basically the same mechanism, with density changes due to different materials being a much stronger effect than temperature-related density changes.
I would surmise that you would only get convection within layers of otherwise uniform density. i.e. after a while you would have a core of heavy metals, a thick layer of rock shading into silt, then the layer of water. The water would presumably boil off into space.
Would possibly explain really high % nickel-iron meteorites, they are parts of cores of smashed asteroids with all the rock knocked off.
If you cough while drinking cheap red wine it really cleans out your sinuses.