System of Systems: GPS III update, Galileo launch

November 29, 2017  - By
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GPS III 11+

The fully digital Mission Data Unit (MDU) will create precise civil and military timing navigation signals for GPS III satellites 11 and beyond. Pictured here is the advanced MDU on navigation payloads being delivered for GPS III Space Vehicles 1-10. (Photo: Harris)

Harris Corporation has completed development of its fully digital Mission Data Unit (MDU), which is at the heart of its navigation payload for Lockheed Martin’s GPS III satellites 11 and beyond.

Harris has already provided MDUs and payloads for the first 10 GPS III satellites, one of which has been declared “available for launch” and the second of which is completing its testing. The other eight are in various stages of production assembly.

Payloads for the satellites 11 and beyond bring further signal transmit capabilities, providing more powerful signals and built-in flexibility to adapt to advances in GPS technology, as well as future changes in mission needs.

The new MDU that will eventually go aboard satellites 11+ “can be upgraded incrementally over its mission life due to built-in adaptability,” according to a Harris spokesperson.

GPS OCX

The U.S. Air Force Space and Missile Systems Center has accepted delivery of the GPS Next Generation Operational Control System (GPS OCX) Launch and Checkout System (LCS) baseline from Raytheon Intelligence and Information Systems. Also known as Block 0, LCS demonstrated conformance through test and analysis with all contractual requirements. OCX Block 0 is the foundation for Raytheon’s future Block 1 and 2 delivery, slated for 2022.

A Galileo satellite undergoes its fit-check validation at the Spaceport. Flight VA240. (Photo: Arianespace)

LCS is a fully modernized cyber-secure ground system complete with the computing hardware, operations center workstations, and mission application software necessary to launch the first GPS III satellite into orbit and perform initial on-orbit testing.

Mission operators are now using LCS in the GPS III Mission Readiness Campaign. The ground system is performing as expected during the rehearsals and space vehicle checkout.

Galileo Launch

As this magazine goes to press, final preparations are underway for Galileo’s quadruple launch on Dec. 12. The Ariane 5 rocket has completed its build-up at the spaceport in French Guiana and is moving toward payload integration and rollout to the launch zone.

The four 700-kilo (1,543-pound) Full Operational Capability (FOC) Galileo satellites have completed checkout and one-by-one verification of their interfaces with the payload dispenser that will release them once aloft in mid-Earth orbit.

They will soon take on fuel for their long space life.

The satellites will bring the Galileo operating constellation to 22, and, according to the European Space Agency, this will provide availability to users anywhere in the world for a high-quality position solution — defined as position dilution of precision (PDOP) less than 5 — 99.8% of the time.

About the Author:


Tracy Cozzens has served as managing editor of GPS World magazine since 2006, and also is editor of GPS World’s sister website, Geospatial Solutions. She has worked in government, for non-profits, and in corporate communications, editing a variety of publications for audiences ranging from federal government contractors to teachers.

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