Added 1 new A* page:According to this NASA article, the GRAIL spacecraft are scheduled for launch next Thursday, September 8th. Here they are--the two copper-foil-covered-looking boxy things--sitting on their booster as the payload fairing is put in place:|
image by NASA (source)
"GRAIL" stands for "Gravity Recovery And Interior Laboratory," and it's a pretty interesting mission: two probes will drop into a very low 50 km orbit over the Moon, about 200 km apart. Getting into such a low orbit is a tight piece of flight engineering: their launch window lasts just one second, and only comes along twice a day. Once in lunar orbit, they'll send each other radio signals to measure their exact distance from each other, which is expected to vary ever so slightly due to "regional gravitational differences" as they fly around the Moon. Measuring those differences, then, should yield a detailed map of the Moon's gravitational field and that, in turn, will reveal the underlying density of the lunar landscape, which should tell scientists a lot about its composition.
This isn't the first time NASA has tried to pry deep into the Moon's interior: to quote myself from this old A* news article: "Back in '71, they smashed Apollo 14's rocket booster into the surface, leaving an impressive 115'-wide crater and generating 'moon quake' readings read by seismographs that had been placed on the Moon by the Apollo 12 crew two years earlier." But as the mission's lead investigator, Maria Zuber of MIT, noted in this 2008 podcast interview, "We’re actually going to produce a gravity map of the moon that’s going to have a spatial resolution better than the global gravity model for Earth," and that's because, due to the Moon's lower gravity, the mapping satellites can orbit a lot closer to the surface there than they can around the Earth. She also mentions that we don't even have a good idea how thick the Moon's crust is--GRAIL should give us that answer.
Noticed a couple other sorta interesting random articles today:
- This one is about a certain western Australian dolphin population, which has already been observed developing several foraging techniques (one involving breaking off a conical piece of sea sponge and wearing it on their head like a hat to shield themselves as they forage on the sea floor) and spreading them "vertically" through the female population, from mother to daughter. Now they've got a new trick--picking up conch shells in their mouths and shaking them to dislodge and swallow the fish sheltering inside--that seems to be spreading "horizontally"--from friend to friend, as it were. Just a reminder that humans didn't invent social networking. :P
- This one is actually not so much an article as it is a little slideshow of a Chinese farmer's self-made miniature submarine.