Sail on, pushed by the wind of sunlight. Over the past week, engineers have demonstrated how they can steer LightSail-2, a small privately financed spacecraft with a billowing silver sail. The technology could be used to propel future space probes. Most space missions are propelled by engines that provide bursts of acceleration with limited amounts of fuel. The rest of the time, the spacecraft are coasting. By contrast, with LightSail-2, particles of light from the sun bounce against the spacecraft's 344 square feet of sails, generating a modicum of force, the equivalent of the weight of a paper clip pushing on your hand. But because the sun always shines, the sail offers a continuous nudge that adds up to faster speeds — all without fuel.
Male black widows thrive on competition
It's a myth that black widow female spiders always kill and consume their mates. But courtship remains perilous for males, cannibalism or no. The terrain, navigated in the dark, is challenging. The female's web releases pheromones, but only about 12% of prospective males manage to reach it. And once there, they can expect to face male rivals. But male black widows seem to thrive on the competition, said a study in the Proceedings of the Royal Society B: Biological Sciences. Researchers found that males find potential mates faster by following the silk trails left behind by other males. "Males have to race to find females," said arachnologist Catherine Scott. "It makes sense for them to try to use all the tricks they can."
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