The System: Two More Threes for Space

January 1, 2014  - By 0 Comments
Artist's concept of a GPS III satellite in orbit, courtesy of Lockheed Martin.

Artist’s concept of a GPS III satellite in orbit, courtesy of Lockheed Martin.

Air Force Orders GPS III Satellites 05 and 06 from Lockheed Martin

A December 12 contract modification provided Air Force funding to Lockheed Martin to complete the fifth and sixth GPS III space vehicles (SV 05-06).  Lockheeed originally received funding to procure long-lead parts for satellites five through eight (SV 05-08) in February 2013.

The $200,700,415 cost-plus-incentive-fee modification (P00276) on an existing contract (FA8807-08-C-0010) for GPS III space vehicles 05 and 06 means that work will be performed at Littleton. Colorado and Clifton, New Jersey, and is expected to be completed by Dec. 14, 2017 for space vehicle 05 and June 14, 2018 for space vehicle 06.  The Air Force Space and Missile Systems Center Contracting Directorate, Los Angeles Air Force Base, California, is the contracting activity.

Galileo Achieves First Airborne Tracking

The European Space Agency’s Galileo satellites have achieved their first aerial fix of longitude, latitude, and altitude, enabling the inflight tracking of a test aircraft.

ESA’s four Galileo satellites in orbit have supported months of positioning tests on the ground across Europe since the first fix in March. Now the first aerial tracking using Galileo has taken place, determining the position of an aircraft using only its own independent navigation system.

The milestone took place on a Fairchild Metro-II above Gilze-Rijen Air Force Base in the Netherlands on November 12. It was part of an aerial campaign overseen jointly by ESA and the National Aerospace Laboratory of the Netherlands, NLR, with the support of Eurocontrol, the European Organisation for the Safety of Air Navigation, and LVNL, the Dutch Air Navigation Service Provider.

A pair of Galileo test receivers was used aboard the aircraft, the same kind employed for Galileo testing in the field and in labs across Europe. They were connected to an aeronautical-certified triple-frequency Galileo-ready antenna mounted on top of the aircraft.

Tests were scheduled during periods when all four Galileo satellites were visible in the sky. The receivers fixed the plane’s position, as well as determining key variables such as the position, velocity, and timing accuracy; time to first fix; signal-to-noise ratio; range error; and range–rate error.

Testing covered both Galileo’s publicly available Open Service and the more precise, encrypted Public Regulated Service, whose availability is limited to governmental entities.

Flights covered all major phases: take off, straight and level flight with constant speed, orbit, straight and level flight with alternating speeds, turns with a maximum bank angle of 60 degrees, pull-ups and push-overs, approaches and landings.

The flights also allowed positioning to be carried out during a wide variety of conditions, such as vibrations, speeds up to 456 km/h, accelerations up to 2 ghorizontal and 0.5–1.5 gvertical, and rapid jerks. The maximum altitude reached during the flights was 3,000 meters.

GPS III Prototype Proves Constellation Compatibility

The Lockheed Martin prototype of the next-generation GPS satellite, the GPS III, has proven that it is backwardly compatible with the existing GPS satellite constellation in orbit.

During tests concluded on October 17, Lockheed Martin’s GPS III testbed successfully communicated via cross-links to Air Force simulators of the current GPS constellation in orbit. The current GPS constellation includes GPS IIR, GPS IIR-M, and GPS IIF satellites.

Testing also demonstrated the ability of an Air Force receiver to track navigation signals transmitted by the GPS III Nonflight Satellite Testbed (GNST). The GNST is a full-sized, functional satellite prototype at Cape Canaveral Air Force Station.

“These tests represent the first time when the GNST’s flight-like hardware has communicated with flight-like hardware from the rest of the GPS constellation and with a navigation receiver,” explained Paul Miller, Lockheed Martin’s director for GPS III Development. “This provides early confidence in the GPS III’s design to bring advanced capabilities to our nation, while also being backward-compatible.”

The first flight-ready GPS III satellite is expected to arrive at Cape Canaveral in 2014, for launch by the Air Force in 2015.
GPS III satellites will be the first GPS space vehicles with a new L1C civil signal designed to make it interoperable with other international global navigation satellite systems.

The GNST has helped to identify and resolve development issues prior to integration and test of the first GPS III flight space vehicle (SV 01). It has gone through the development, test, and production process for the GPS III program first, significantly reducing risk for the flight vehicles, improving production predictability, increasing mission assurance, and lowering overall program costs.

The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center.

Lockheed Martin is the GPS III prime contractor, with teammates including ITT Exelis, General Dynamics, Infinity Systems Engineering, Honeywell, ATK, and other subcontractors.

Good News for Users and Manufacturers

The U.S. Air Force is directing transmission of continuous CNAV message-populated L2C and L5 signals starting in April 2014. The move is designed to help development of user equipment compatible with the civil signals. Full text of the CNAV memo appears below.

CNAV-header

Galileo FOC Satellites Endure Simulated Space Tests

The European Space Agency’s newest Galileo satellite has emerged from five weeks of simulated space conditions. On November 29, a hatch slid open to end its thermal-vacuum test, a milestone on the way to orbit.

The satellite was placed in the 4.5-meter-diameter Phenix chamber in ESA’s ESTEC Test Centre in Noordwijk, the Netherlands, in late October. Once inside, the air was pumped out to create a space-quality vacuum. Temperature extremes were also reproduced, with the six copper walls of the thermal tent cooled by liquid nitrogen down to –180°C.

A second Galileo vehicle has  been undergoing the same rigors at the site, along with a vibration and shock test to reproduce separation from the launcher. Thermal-vacuum testing on the second model will begin in early 2014. The two satellites will be launched on a Soyuz rocket from Europe’s Spaceport in French Guiana in mid-2014.

The next satellite is expected to arrive at ESTEC in March, with further satellites following every seven weeks or so. A total of 22 FOC satellites are being built by OHB in Germany, with navigation payloads being delivered from Surrey Satellite Technology Ltd. in the UK.

The first Galileo Full Operational Capability satellite emerges from the Phenix test chamber after five weeks of thermal–vacuum testing.

The first Galileo Full Operational Capability satellite emerges from the Phenix test chamber after five weeks of thermal–vacuum testing.

Alan Cameron

About the Author:

Alan Cameron is editor-in-chief and publisher of GPS World magazine, where he has worked since 2000. He also writes the monthly GNSS System Design e-mail newsletter and the Wide Awake blog.

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