The End of Time
You may have noticed that one of the details we give for each image is the Mission Elapsed Time, or MET, of when it was acquired. MET is the time, in seconds, since the MESSENGER mission began in 2004. As a testament to how long MESSENGER has been in space (over eight years!), the number of seconds has added up to over 250 million, and has come close to reaching the limit of how high the spacecraft clock can count. Thus in January, the MESSENGER team reset the clock, starting over at a time of 1,000 seconds. Why 1,000 seconds rather than zero? The MET clock was originally set to start counting 1,000 seconds before launch, so that launch was actually at an MET of 1,000 rather than zero; the clock reset follows that precedent.
Date acquired: January 10, 2013
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington