[1] Deep Impact (spacecraft) - Wikipedia, , https://en.wikipedia.org/wiki/Deep_Impact_(spacecraft)#Contact_lost_and_end_of_mission
According to chief scientist A'Hearn,[79] the reason for the software malfunction was a Y2K-like problem. August 11, 2013, 00:38:49.6, was 232 tenth-seconds (deciseconds) from January 1, 2000, leading to speculation that a system on the craft tracked time in one-tenth second increments since January 1, 2000, and stored it in an unsigned 32-bit integer, which then overflowed at this time, similar to the Year 2038 problem.[80]
[5] NASA's Deep Space Comet Hunter Mission Comes to an End, https://www.jpl.nasa.gov/, https://www.jpl.nasa.gov/news/nasas-deep-space-comet-hunter-mission-comes-to-an-end
After losing contact with the spacecraft last month, mission controllers spent several weeks trying to uplink commands to reactivate its onboard systems. Although the exact cause of the loss is not known, analysis has uncovered a potential problem with computer time tagging that could have led to loss of control for Deep Impact's orientation. That would then affect the positioning of its radio antennas, making communication difficult, as well as its solar arrays, which would in turn prevent the spacecraft from getting power and allow cold temperatures to ruin onboard equipment, essentially freezing its battery and propulsion systems.