As of Friday afternoon, a notice on NASA's kepler.arc.nasa.gov website was reading "Down for Maintenance: The requested webpage is down for maintenance. Please try again later."
The site is only one of what appear to be 14 hacked subdomains, hosted in the heart of Silicon Valley, that were defaced on Tuesday and stayed offline for some time.
via "Stop spy on us!" 14 NASA sites hacked | Naked Security.