Space

Journey 1.5 billion kilometres to Saturn's most bewildering moon: Iapetus. This world of stark contrasts features a divided landscape where light battles darkness, while a colossal mountain range encircles its equator, towering higher than Mount Everest. This celestial trickster defies explanation, vanishing before astronomers' eyes, only to reappear like cosmic sleight of hand. As we explore this enigmatic moon, what shocking truths about our solar system's violent birth might finally be revealed?

A major part of NASA's nearly complete Nancy Grace Roman Space Telescope just passed a lengthy thermal test to ensure it will function properly in the space environment.

"This milestone tees us up to attach the flight solar array sun shield to the outer barrel assembly and deployable aperture cover, which we'll begin this month," said Jack Marshall, who leads integration and testing for these elements at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Then we'll complete the remaining environmental tests for the flight assembly before moving on to connect Roman's two major assemblies and run the full observatory through testing, and then we'll be ready to launch."

Prior to this thermal testing, technicians integrated Roman's deployable aperture cover, a visor-like sunshade, into the outer barrel assembly, which will house the telescope and instruments, in January, then added test solar panels in March. They moved this whole structure into the Space Environment Simulator test chamber at NASA Goddard in April.

cross-posted from: https://lemmy.bestiver.se/post/363441

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cross-posted from: https://lemmy.world/post/29045618

The European Space Agency’s Gaia mission has spotted an unusual family of stars all strangely eager to leave home – a family we couldn’t have discovered without the star-surveying spacecraft, and one unlike all others we have spotted to date.

In the scenario Mumpower proposes, a massive star begins to die as its nuclear fuel runs out. No longer able to push up against its own gravity, a black hole forms at the star's center. If the black hole is spinning fast enough, frame-dragging effects from the extremely strong gravity near the black hole wind up the magnetic field and launch a powerful jet. Through subsequent reactions, a broad spectrum of photons is created, some of which are at high energy.

The jet blasts through the star ahead of it, creating a hot cocoon of material around the jet, "like a freight train plowing through snow," Mumpower said. At the interface of the jet with the stellar material, high-energy photons (that is, light) can interact with atomic nuclei, transmuting protons to neutrons.

Existing atomic nuclei may also be dissolved into individual nucleons, creating more free neutrons to power the r process. The team's calculations suggest the interaction with light and matter can create neutrons incredibly fast, on the order of a nanosecond.

Because of their charge, protons get trapped in the jet by the strong magnetic fields. Neutrons, which are chargeless, are plowed out of the jet into the cocoon. Having experienced a relativistic shock, the neutrons are extremely dense compared with the surrounding stellar material, and thus the r process may ensue, with heavy elements and isotopes forged and then expelled out into space as the star is ripped apart.