Centauri Dreams 2 Nov 2018, 16:25 UTC It seems to be a week for endings. Following the retirement of the wildly successful Kepler spacecraft, we now say goodbye to Dawn following an extraordinary eleven years that took us not only to orbital operations around Vesta but then on to detailed exploration of Ceres. The spacecraft ran out of hydrazine, with the signal being lost by the Deep Space Network during a tracking pass on Wednesday. No hydrazine means no spacecraft pointing, vital in keeping Dawn’s antenna properly trained on a distant Earth.
Starts With a Bang! 2 Nov 2018, 14:01 UTC One of the most astonishing facts about science is how universally applicable the laws of nature are. Every particle obeys the same rules, experiences the same forces, and sees the same fundamental constants, no matter where or when they exist. Gravitationally, every single entity in the Universe experiences, depending on how you look at it, either the same gravitational acceleration or the same curvature of spacetime, no matter what properties it possesses. At least, that’s what things are like in theory. In practice, some things are notoriously difficult to measure. Photons and normal, stable particles both fall as expected in a gravitational field, with Earth causing any massive particle to accelerate towards its center at 9.8 m/s². Despite our best efforts, though, we have never measured the gravitational acceleration of antimatter. It ought to accelerate the exact same way, but until we measure it, we can’t know. One experiment is attempting to decide the matter, once-and-for-all. Depending on what it finds, it just might be the key to a scientific and technological revolution.
EarthSky Blog 2 Nov 2018, 10:20 UTC Not all that long ago, it was thought that Earth was the only place in the solar system with liquid water. Other planets and moons were either too hot or too cold. But now, thanks to various spacecraft sent out to explore these worlds, we know that is not the case. Water is actually abundant throughout the solar system, and some moons even have more water than Earth does. We just can’t see it on their surfaces – the water is, instead, below ground.
Astro Bob 2 Nov 2018, 02:52 UTC As we wait for the Event Horizon Telescope team to assemble the first image of the supermassive black hole at the center of the Milky Way Galaxy, astronomers are pushing ever closer to the object’s fringes. A team of scientists with the European Southern Observatory has recently observed flares of infrared light coming from the spinning disk of gas around Sagittarius A*, the official name for the massive object at the heart of the galaxy. The flares provide crucial confirmation of the existence of the Milky Way’s monster black hole, an object with a mass of more than 4 million suns.
Centauri Dreams 1 Nov 2018, 17:50 UTC Usually when we talk about outer planet moons with oceans, we’re looking at Jupiter’s Europa, and Saturn’s Enceladus. But evidence continues to mount for oceans elsewhere. In the Jupiter system alone, Callisto and Ganymede are likewise strong candidates, while Saturn’s Titan probably has a layer of liquid water. Pluto’s moon Charon may possess an ocean of water and ammonia, to judge from what appears to be cryovolcanic activity there. At Neptune, Triton’s high-inclination orbit should produce plenty of tidal heating that may support a subsurface ocean. Let’s pause, though, on another of Saturn’s moons, Dione. Here we have evidence from Cassini that this world, some 1120 kilometers in diameter and composed largely of water ice, has a dense core with an internal liquid water ocean, joining Enceladus in that interesting system. But what engages us this morning is not liquid water but a set of straight, bright stripes discovered on the surface and discussed in a new paper from Alex Patthoff (Planetary Science Institute) and Emily Martin (Center for Earth and Planetary Studies, Smithsonian Institution).
Many Worlds 1 Nov 2018, 15:22 UTC The Kepler Space Telescope is dead. Long live the Kepler. NASA officials announced on Tuesday that the pioneering exoplanet survey telescope — which had led to the identification of almost 2,700 exoplanets — had finally reached its end, having essentially run out of fuel. This is after nine years of observing, after a malfunctioning steering system required a complex fix and change of plants, and after the hydrazine fuel levels reached empty.
Starts With a Bang! 1 Nov 2018, 14:01 UTC If you want to take the most pristine, unpolluted images of the Universe, your best bet is to leave the Earth behind. Here on our planet, there are all sorts of effects which interfere with our imaging capabilities. Light pollution limits how deep we can see; the atmosphere harms our resolving power and our ability to observe clearly; clouds and weather interfere with our light-collecting goals; the Sun and the Earth itself block our view of large portions of the sky from all terrestrial locations. Yet observatories like Hubble, Chandra, Fermi, Spitzer and more have showcased how remarkably effective a space telescope can be. The views and data they’ve returned to Earth have taught us more than any similar observatory could have revealed from the ground. So why not put a telescope on the Moon, then? Believe it or not, it’s a terrible idea in all ways except one. Here’s why.