On: NASA Declares End to Deep Impact Comet Mission

[aptwebapps]

It seems to be approximately 2^32 tenths of second into the new millennium. Which is an odd way to do things, but I guess there were reasons.

[michaelhoffman → aptwebapps]

The standard for astronomical measurements today is the J2000.0 epoch.

http://en.wikipedia.org/wiki/Epoch_%28astronomy%29#Julian_ye...

[lelf → aptwebapps]

Seems so

  h> logBase 2 . realToFrac $ (secs "2013-08-11" - secs "2000-01-01")*10
  31.999992174768167

[tinco → lelf]

Totally off-topic, but that looks a lot like Haskell, what did you do to make ghci have such handy calculator functionality? (I can't find secs in Hoogle)

[lelf → tinco]

It's just

  secs = utcTimeToPOSIXSeconds . readTime defaultTimeLocale "%F"

[tinco → aptwebapps]

I bet there's a:

    \\TODO: reset the clock before launch day

Somewhere that would have allowed it a ~13 years lifetime from launch day on instead of from 2000 on..

[munkeegutz → aptwebapps]

I bet that during the initial design phase, they wanted to keep the design simple, have enough timekeeping range to cover the mission and then maximize temporal resolution.

Someone realized that a counter operating on tenths of a second from 2000 was both easy to use and sufficient for the primary mission... they then thought nothing of it until the loss of contact