Luminoth Datapacs are portable devices used by the Luminoth Keybearers to record their Lore Testaments. Unlike Luminoth Lore Projectors, Samus is always capable of translating data from Luminoth Datapacs, whereas Lore Projectors would frequently require her to upgrade her Translator Module.
"A new [Lore] entry has been downloaded to your Logbook.
Luminoth Datapac translated.
([Keybearer name]'s Testament)
Data transferred to your Logbook for further review."