drain

宇宙での快挙です。ここのdrainはどのような意味でしょうか。名前につながりのあるAstroriverくん、どうぞ。（Ume）

Spacecraft Lands on Comet’s Surface

The European Space Agency’s ambitious attempt to place a spacecraft on the surface of a comet succeeded when a signal arrived at the mission control center at Darmstadt, Germany, at 5:04 p.m. local time (11:04 a.m. Eastern time).

The lander, Philae, and its 10 instruments have now begun 64 hours of scientific operations before its batteries drain. Solar panels will then recharge the batteries, allowing intermittent operations over the coming months, about one hour every two days.

http://www.nytimes.com/2014/11/12/science/space/the-descent-of-philae-toward-the-comet-in-tweets.html?emc=edit_na_20141112

http://jp.wsj.com/articles/SB10113763752903943770504580273120598572084?mod=trending_now_1