Challenges/Halo: Reach
From Halopedia, the Halo wiki
Challenges are daily objectives for Halo: Reach posted on Bungie.net. All challenges are reset at 11am GMT (3am PDT) with Daily Challenges resetting each day and Weekly Challenges resetting each Monday. A player is awarded a certain number of Credits[1] after completing an objective.
Players who complete a Weekly challenge are awarded the achievement One Down, 51 to Go. Players who complete all of the Daily Challenges on a single day are awarded the achievement A New Challenger.