GRAIL 探月衛星成功完成任務

mca

新聞報導
http://science.nasa.gov/science- ... 12/17dec_sallyride/

NASA 發表的 GRAIL 墜落地點


從十吋望遠鏡拍攝的 GRAIL 墜落地點



GRAIL 的探測成果

From March to May, Ebb and Flow (the twin spacecraft) flew an average of just 30 miles above the lunar surface.

With its primary mission complete, the team upped the ante, lowering the spacecraft so that they surveyed the moon's bumpy gravitational field from an average of about 15 miles above the surface, Zuber said. Late in the mission, Ebb and Flow came within a mile and a half of prominent features.

The result was the most detailed map ever made of the moon's gravitational field.

The unprecedented up-close survey revealed a host of findings. The researchers found that the moon's crust is even thinner than originally thought, and that there are deep fractures in the crust, showing that it may have taken a greater beating from asteroids and comets than planetary scientists had believed. Those results were reported this month in the journal Science.

With the wealth of complex data from the primary mission already available and more from the extended mission to follow in about six months, scientists will be able to dig deeper into the data to see what it reveals about the moon's core, Zuber said.

The extended mission came with one drawback: Flying so low required more hands-on navigation to maneuver the spacecraft over ridges and keep them from crashing into basins. All that steering required mission scientists to burn fuel some three times per week, causing Ebb and Flow to run out of gas much sooner.

Image Gallery
http://www.nasa.gov/mission_page ... /gallery-index.html

The Moon in simple language
https://moonkam.ucsd.edu/about/moon