From Destinypedia, the Destiny wiki
Esta Tel was a Guardian who fought during the Red War. During the campaign, Esta watched over a bridge she'd rigged to explode via detonator for an ambush on a group of Cabal in transit. As she heard the sound of an approaching vehicle, Esta instinctively primed the detonator before registering the affiliation. To her horror, it was an allied medical vehicle. Acting on impulse with five seconds to spare, Esta drew her sniper rifle and severed the connection between the explosives and her detonator with a well-placed shot.
The medical vehicle crossed without issue, however the Cabal weren't far behind. With no ammo to spare, Esta would need another plan to halt the Cabal convoy.
List of appearances