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An overview of the latest PNT satellite launches

February 19, 2019  - By
History of the program: NTS-1, 2 and 3. (Illustration: Lt. Jacob Lutz, AFRL Space Vehicles Directorate)

Satellites NTS-1, 2 and 3. (Illustration: Lt. Jacob Lutz, AFRL Space Vehicles Directorate)

Just last month we celebrated the kickoff of the GPS III campaign, reporting on the launch of the first space vehicle of that generation in the closing days of 2018. A new era had begun, heralded by a rocket’s blazing path, bearing aloft a new “lighthouse in the sky serving all humankind.”

Turn around and­ — whoa! Where did all these other new PNT satellites come from?

We attempt to chronicle them all in this issue, though I’m not sure we haven’t still missed some.

For years we’ve been talking about the Iridium constellation, a low-Earth orbit telecommunication network that can also deliver timing services to improve accuracy, and signal acquisition in urban environments. Were it not for the fact that 10 more of its satellites just launched in January, bringing the total of its second-generation NEXT constellation to 75, this would practically qualify as old news.

But let’s move on to the real new news. NTS-3 is the new kid on the block most closely related to the GPS family. In fact, integrally a part of it. This third Navigation Technology Satellite will go even beyond GPS III —­ whose capabilities, mark you, are not yet online — to investigate new experimental antennas, flexible and secure signals, increased automation and use of commercial ground assets.

Learn about 72 nanosatellites of the Spire constellation piggybacking on Galileo signals to offer GNSS radio occultation products for the weather community. This may not be exactly direct-to-user PNT, but it’s a derivative.

Finally, absorb the latest on Hawkeye 360 formation-flying Pathfinders, designed to detect and geolocate radio frequency (RF) signals, and use the data in search-and-rescue as well as commercial maritime operations.

Don’t stop there! Read about Planet, the breadloaf satellites, current population 300 with more coming, beaming down 1.2 million high-resolution Earthly images per day, useful for agriculture, defense, mapping and GIS, and a few other industries.

If a group of satellites is a constellation, what do you call a group of constellations? If we are to follow astronomy’s lead, I’ve just learned that the proper technical term is an asterism. However, I think galaxy will be easier to handle.

About the Author: Alan Cameron

Alan Cameron is the former editor-at-large of GPS World magazine.