They are micro laser spectrometers designed to 'sniff out' chemicals used in explosives in the air and to alert UNSC personnel of these dangerous explosives if found. It was mainly used against Insurrectionist bombers, who used simple countermeasures to easily fool the devices. They mixed the explosive compounds into non-reactive substances, such as a bar of soap or the rubber of a tire. Although the UNSC was able to add these mixtures into its database after they were used, it was rare to ever catch something dangerous like this beforehand. The larger ARGUS detectors were deployed at major transportation hubs to limit the movement of bombs, and smaller tactical versions were employed by Marines during raids.
The ARGUS device is not infallible; Avery Johnson was a witness to at least one incident where an innocent civilian was killed due to suspected explosives detected in his vehicle. These suspicions proved to be false.
In 2524, the ARGUS device was utilized successfully in Operation: TREBUCHET after a raid on an Insurrectionist cell operating in Tribute to locate a tanker rigged to explode. However, the UNSC forces were unable to successfully stop its owners before they managed to detonate it near a Jim Dandy, a restaurant local to the Casbah area. Death reports stated that three Marines and 38 civilians were killed by the tanker's detonation.
The device may be named after Argus Panoptes of Greek Mythology, a giant with a hundred eyes and servant of Hera. It killed the bull that ravaged Arcadia, which is also the name of a UNSC colony world, Arcadia.
List of appearances
- Halo: Contact Harvest, page 12