New data
The spacecraft does have power and that confirms the solar arrays did deploy and oriented itself towards the sun. So there won't be battery or power problems.
It went into safe mode, NASA believes, when a temperature sensor on the propulsion system overran some limit. There's a limit of 300 degrees on the propellant system. The reading was 326 degrees, triggering safe mode. That is something that should not be a problem long-term, the NASA officials are saying at this hour.
Many past spacecraft, including Hubble Space Telescope, have safed themselves in the past and recovered. So this could be a good thing. We'll have to wait and see.

posted at 5:57 PM

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From http://www.floridatoday.com/blogs/deepimpact/