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... Any water on Mars is locked up in the ice caps. ... The most recent successful mission to Mars is the Mars Science Laboratory better known as the Curiosity rover. ... CuriosityтАЩs primary role is to search for conditions that may have once been able to harbour any sort of bacterial life concealed beneath the Martian surface. ... Using what we know about life on Earth, where there is water, there is life, signs of water may help us understand what Mars was like billions of years ago. €а . ...

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... Bad Astronomy . ... I think I will break from my usual format of Bad Astronomy/ Good Astronomy by saying that the way we define seasons currently is not strictly bad, but I feel (in my opinion!) that it could be better. The definition of when the seasons begin is at the moment of solstice or equinox; that is, winter (in the north) starts on December 22 nd and summer starts on June 22 nd . ... Now imagine breaking up the Sun's 46 degree up-and-down yearly swing into 1 day intervals. ...

You will need to understand how to set file access permissions numerically before reading this section. Every time you create a file or a directory, its access permissions are set to a predetermined value. ... The values in the mask are subtracted from these values to give a default value for access permissions for the files and directories created by you. For example: 777 (system value for directories) -077 (value of the umask) --- 700 (default access permission of rwx------) . ...