The extended mission of the Deep Impact spacecraft, which flew past Comet Hartley 2 (103P/Hartley) in 2010 November, photographing its nucleus. There was no spare impactor so this time there was no impact on the nucleus. EPOXI is a combination of two acronyms: EPOCH, Extrasolar Planet Observation and Characterization, which observed eight stars known to have planets for signs of transits; and DIXI, the Deep Impact Extended Investigation, which concentrated on the comet. Contact with the spacecraft was lost in 2013 August.

https://www.nasa.gov/mission_pages/epoxi/index.html NASA page about the mission.