Dust to pebbles to planets

How nature gets microscopic dust and tiny, pebble-sized pieces of proto-planetary material to clump and stick together to make bigger and bigger objects is still puzzling. In a gas-rich disk of material around a forming star these small components are buffeted, dragged, and broken. What may help are ‘dust traps’, regions in the disk where gas pressures are high and solids can slow down for long enough to get bulked up. New work by Gonzalez et al. suggests an ‘aerodynamic drag back-reaction’ (where dust helps squeeze gas into dense traps) that could help.

Juno orbit stuck

Problems with the main propulsion on NASA’s Juno mission have led to the decision to keep the spacecraft’s orbit in its present configuration – a longer-than-expected 53 day loop around Jupiter. All the primary science should still get done, and Juno may even last longer because it will avoid more of the intense Jovian radiation environment, but a longer mission also costs more.

Lava flavors on Mars

Researchers studying data on the Elysium lava flows on Mars have concluded that these great, ancient, outflows show signs of geochemical diversity. This chemical variation indicates a complex geophysical history for Mars (and its mantle), making the planet more similar to the Earth than perhaps we thought. The most recent lava deposits in Elysium seem like they could be a mere 3-4 million years old.

Planet makes star pulse?

Big planets that orbit close to their host stars might cause some stellar ‘irritation’. De Wit et al. report evidence that the 8 Jupiter mass planet around the star HAT-P-2 is somehow perturbing the stellar atmosphere into a pulsating or flaring behavior.