A Telemetry Probe is a UNSC device, most likely produced by ONI. The device functioned by attaching onto a Covenant warship's hull, and tracking its position as it moves through Slipspace, although it may also serve other auxiliary purposes.
In 2537, a prowler, the UNSC Razor's Edge, managed to attach one to a Covenant ship at the Battle of New Harmony. The warship was tracked to K7-49, a Covenant shipyard facility seventeen light years from the furthest reaches of human space.
This sparked Operation: PROMETHEUS, in which the all 300 of the SPARTAN-IIIs in Alpha Company were deployed to destroy the shipyard. Although the mission was a strategic victory, with the Covenant abandoning what was left of the facility, Alpha Company was wiped out in its entirety.
- There is a Covenant counterpart to this, called the spy probe. It functions practically identically, latching onto a ship and relaying its position to the Covenant. It was used to track the UNSC Iroquois from the Battle of Sigma Octanus IV back to Reach, causing the Fall of Reach shortly after.
- It could be conjectured that the Covenant spy probe may be based upon captured telemetry probes, as is the case with many other Covenant technologies like Associated Intelligences. However, the reverse could also be true.