Glow rod
From Halopedia, the Halo wiki
Glow Rods are used by UNSC personnel to help guide incoming aircraft in low light situations. These rods are also used by Marines and ODSTs to mark out a location for ammo and equipment drops. One of them appears in the first cutscene in Halo: Combat Evolved, at the start of the first level, The Pillar of Autumn, and bunches of glow rods can be seen at Pelican crash sites on flood levels in Halo: Combat Evolved.[1]
