Messenger finds web of debris on Mercury

日期:2017-04-13 02:00:23 作者:福荤 阅读:

By Rachel Courtland (Image: NASA/JHU APL/CIW) NASA’s Messenger probe returned images of new regions of Mercury on Tuesday, after a flyby that took the spacecraft within 200 kilometers of the planet’s surface. See a slideshow of the new images of Mercury Team members are now converting raw data from the 6 October flyby into images. The pictures will cover 30% of the planet that has not yet been seen by spacecraft. Until now, astronomers had only blurry images of these regions obtained with telescopes on Earth. “It’s a little bit like Christmas-time, and we’re still in the process of opening a lot of the presents,” says Messenger project scientist Ralph McNutt of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The first images released reveal scarps, lava flows, and a vast web of lines emanating from a crater near the planet’s north pole. NASA’s Mariner 10 probe, which flew close past the planet in 1974 and 1975, spotted some of these debris rays. “But it wasn’t clear where they were radiating from,” McNutt told New Scientist. The crater had been imaged from the Earth with radar, but the new images are the first to show the extent of the collision. Some of the rays seem to extend 2000 km, says Messenger science team member Mark Robinson of Arizona State University in Tempe, Arizona. Mercury is 4880 km in diameter. Given the fairly small size of the impact crater, the rays are probably very tenuous, wispy deposits of material, Robinson says. And as they have not been erased by other impacts, the crater may be fairly young, perhaps only a few million years old. The pass was the probe’s second close look at the scarred, rocky planet. On 14 January, Messenger’s first close pass of the planet captured detailed images including about 20% of the planet’s surface that had not been seen by a spacecraft before. Team members plan to create nine image mosaics from more than 1200 pictures taken during this second flyby. Combined with photographs taken in 1974 and 1975 with NASA’s Mariner 10 probe, the resulting images should cover 95% of the planet. A global view of features like the long rays could eventually shed more light on the frequency of collisions in the inner solar system and the strength of Mercury’s crust,