A telemetry probe uses a local stellar configuration to determine its location, then transmits this location back to its point of origin in a small memory canister fired through a miniature slipspace field. They can also be attached to a Covenant ship and track it through slipspace. In 2537, at the Battle of New Harmony, the prowler UNSC Razor's Edge managed to attach one to a Covenant warship at the battle, and track it to K7-49, a Covenant shipyard facility seventeen light years from the UNSC outer colonies.
By September 2558, the newest model of UNSC telemetry probe could fit into a small handheld case. A vast improvement over previous models, this new model's micro slipspace drive no longer requires days to charge, and is completely reliable. It is also noted as being extremely expensive. This type of telemetry probe was to be used on Operation: ATHENA to relay the Absolute Record's location back to the UNSC, but the probe was destroyed when the ship it was on suffered heavy damage.
Their purpose is similar to that of the Covenant spy probe.