is a Spanish radar technology satellite designed to address not only security and defence requirements, but also others of civilian nature. It is capable of daily taking more than 100 images of up to 25 cm resolution, both day and night, and independently of weather conditions.
It cover an area of over 300,000 square kilometers a day, and orbit the Earth fifteen times a day at an altitude of 514 kilometers and a speed of seven kilometers per second. Thanks to its slightly inclined quasi-polar orbit, PAZ cover the entire Earth with an average revisit time of 24 hours.
The satellite’s total weight is about 1400kg. It is 5 metres high and 2.4 metres in diameter. Its radar has been designed to be extremely flexible and has the ability to operate in a large number of configurations, thus supporting a variety of image types and qualities. It has 256 GB of image memory and can transmit images to Earth at 300Mbits/second in X-band.
PAZ provides Earth Observation capabilities for multiple purposes: border control, intelligence, environmental monitoring, protection of natural resources, military operations, enforcement of international treaties, surface monitoring, city and infrastructure planning, monitoring of natural catastrophes and high-resolution mapping, among many others.
The satellite features a ground-configurable electronic radar able to work in different modes combining resolution and image size. PAZ was designed to work in five different modes: spotlight (with up to 1 metre resolution and covering areas of 5 x 5km), stripmap (up to 3 metres and areas of 30 x 50km), scansar (for areas of 100 x 150km and resolutions of 18.5 metres), as well as two additional modes now being developed: the ultra high resolution (up to 25cm) staring spotlight, and wide swathe scanradar covering areas of 270 x 200km.
The design and manufacture of PAZ was contracted out to Airbus Defence & Space Spain (formerly EADS Astrium Casa), which has created an unprecedented opportunity for the Spanish Space Industry, as it was the first time that the challenge of building a satellite of this size and complexity has been taken on in our country.
The project has been a highly successful collaboration between a consortium of 15 Spanish companies and 3 universities, all involved in the manufacture of different parts and components.
TerraSAR-X/PAZ Radar Satellite Constellation
In 2012, Hisdesat signed an agreement with Airbus Defence and Space (formerly Astrium GEO Services) for the creation of a constellation of radar satellites that would use in a coordinated manner the resources that PAZ, TerraSAR-X and TanDEM-X make available to customers.
Among the advantages that this constellation offers are:
• The revisit time is significantly reduced to between 4 and 7 days, which is important for interferometric processes and applications with strict temporal requirements.
• Improved acquisition capacity for surveillance and map generation applications.
• Streamlining of the customer request process via a single request portal and using a single catalogue of services.
Numerous activities that require large quantities of timeous data, like crisis management or the monitoring of surface movements, will benefit from this new constellation.
Hisdesat has adapted the PAZ mission to incorporate the use of direct access stations (DAS) defined by the constellation. These kinds of stations, owned by clients, allow us to offer a very flexible service with Near Real Time characteristics.
PAZ is launched on the 22nd of February 2018 from the Vandenberg Air Base in California, using the SpaceX Falcon 9 rocket.
The geographical location of the Vandenberg launch site provides access to polar and high inclination orbits, and is frequently used by constellations of communications, Earth Observation and defence/intelligence satellites, as well as some lunar missions. Launching here means being able to benefit from infrastructure including highly advanced security and control capabilities, weather conditions monitoring, ground support, and effective tracking cameras for the observation of launches from take-off to the separation and ignition phases over the Pacific.
Transport to California
Relocation of the satellite was carried out on a specially adapted Antonov AN-124-100 owned by Volga Dnepr Airlines, which departed from the Torrejón Air Base near Madrid on 28 December 2017, arriving in California on 29 December.
A team of Hisdesat engineers was stationed at the Space X facilities to perform the last pre-launch tests.
The satellite-based maritime traffic information system is managed through the Canadian company exactEarth, which is the result of a joint venture between COMDEV and Hisdesat. The satellites in this new constellation receive AIS signals from the over 165,000 vessels that are equipped with this system. The data are then relayed to ground stations, where the information is collated and prepared in accordance with the requirements of the system’s various users, providing an accurate picture of the world’s maritime traffic in real time.
Working from space, AIS compiles static, dynamic and route-related data, identifying ships that are close to the coast and those that are on the high seas. All of this information is available via internet to any computer on Earth, where it can be processed and put to use. Accuracy is an essential element of the AIS. The system can offer details on the vessel’s identity, its location, course, speed, navigational status, destination and cargo, any maneuvers made, draft, length, registry, surf conditions, rocky areas, fuel consumption, etc. This information can be of great use to government, maritime, port and fishing authorities.
The relevant processors have been developed in collaboration with the Department of Signal Theory and Communications at the Higher Polytechnic School of the University of Alcalá de Henares.
Also in the field of maritime surveillance, Hisdesat has developed, in collaboration with INDRA, an anomaly detection processor based on AIS technology that allows surveillance of any incident in an area of defined interest during a set time, such as surveillance of an area to provide information about the presence of ships, interception of a vessel in a defined nearby area, ships adrift at sea or showing anomalous speeds, groupings of vessels, ships entering and exiting ports, etc.
Radio Occultation Experiment
PAZ collaborates on an innovative scientific experiment in the field of atmospheric radio occultation. The occultation of radio signals in the two polarisations will be measured for the first time.
The radio occultation experiment will show how GPS signals are blanketed when passing through the atmosphere and analyse the changes introduced in the received signals by different atmospheric elements and, in particular, by extreme precipitation. This will lead to an improvement in the prediction of atmospheric behaviours like rainfall and floods and assist in the taking of the necessary measures to avoid potential disasters.
The project is currently in the validation phase, and will later be integrated into the PAZ satellite systems, in order to make use of the new findings stemming from the study of radio signals in the two polarisations. The development of a network, which will directly receive data recorded by PAZ and distribute it to the different meteorological bodies in near real time, is planned in collaboration with NOAA, and will serve as a valuable aid in predicting various phenomena and preventing some of their consequences.
The Radio Occultation and Extreme Precipitation project (ROHP) is led by the Institute of Space Sciences (ICE) of the CSIC, in collaboration with the NASA Jet Propulsion Laboratory (JPL), the National Oceanic and Atmospheric Administration (NOAA) and Hisdesat.
This new satellite also make it possible to substantially improve the positioning of Spain within Copernicus, the European programme for global environmental and security surveillance, the main initiative in the field of Earth observation led by the European Union and the European Space Agency (ESA).