PTDS (Persistent Threat Detection System) es un sistema diseñado por Lockheed Martin, que básicamente consiste en un enorme Aerostato de Helio, anclado a tierra, con el soporte de poderosos sistemas de radar y sensores de todo tipo, que permiten proveer a las tropas terrestres de inteligencia, vigilancia y reconocimiento de largo alcance, así como asistencia a las comunicaciones. El US Army ha venido usando Aerostatos fijos (Anclados) con sensores diversos, en misiones ISR (Intelligence ,Surveillance , Reconnaissance) con excelentes resultados, en apoyo a las fuerzas de la coalición en Iraq y Afganistan. Este tipo de sistemas es además una de las herramientas ISR más empleadas actualmente para la detección temprana de amenazas del tipo IED (Improvised Explosive Device) ocultas a lo largo de carreteras.
The US Army is using tethered aerostats with multi-mission sensors to provide long endurance intelligence, surveillance, reconnaissance (ISR) and communications in support of coalition forces in Iraq and Afghanistan.
The aerostat-based Persistent Threat Detection System (PTDS) is one of the ISR tools the Army uses to detect improvised explosive devices (IEDs) buried along roadsides…
An aerostat is a lighter-than-air craft that relies on a ground tether for movement and often for power as well, as opposed to blimps which are self-powered, free-flying craft. DID has more coverage of military applications of aerostats.
The aerostat for the PTDS 
[PDF] is smaller than the aerostat used in the Tethered Aerostat Radar System (TARS), which provides surveillance along the US-Mexican border. The PTDS aerostat is 115 feet long with 74,000 cubic feet of helium and a 1,102 pound payload; the TARS aerostat made by Lockheed Martin is 1,640 feet long with 420,000 cubic feet of helium and a 2,205 pound payload.
In addition, the mooring for the PTDS aerostat is mobile and relocatable, making it suitable for use in combat situations and difficult terrain.
In addition to the aerostat, the PTDS includes:
- tether (powered with fiber optics)
- mobile mooring platform
- mission payloads
- ground control shelter
- maintenance and officer shelter
- power generators and site handling equipment
The PTDS uses a wide-area, secure communications backbone to communicate threat information from multiple sensors to the commanders in the field.
