The GLONASS constellation has suffered a major problem for the second time this month.
On Monday, April 14, eight GLONASS satellites were simultaneously set unhealthy for about half an hour, meaning that most GLONASS or multi-constellation receivers would have ignored those satellites in positioning computations. In addition, one other satellite in the fleet was out of commission undergoing maintenance. This might have left too few healthy satellites to compute GLONASS-only receiver positions in some locations.
The unhealthy status of the satellites was noted in the monitoring information provided by the Roscosmos GLONASS Information-Analytical Centre website. The problem was also reported by The Moscow Times, an English-language daily published in Russia.
Richard B. Langley is a professor in the Department of Geodesy and Geomatics Engineering at the University of New Brunswick (UNB) in Fredericton, Canada, where he has been teaching and conducting research since 1981. He has a B.Sc. in applied physics from the University of Waterloo and a Ph.D. in experimental space science from York University, Toronto. He spent two years at MIT as a postdoctoral fellow, researching geodetic applications of lunar laser ranging and VLBI. For work in VLBI, he shared two NASA Group Achievement Awards.
Professor Langley has worked extensively with the Global Positioning System. He has been active in the development of GPS error models since the early 1980s and is a co-author of the venerable “Guide to GPS Positioning” and a columnist and contributing editor of GPS World magazine. His research team is currently working on a number of GPS-related projects, including the study of atmospheric effects on wide-area augmentation systems, the adaptation of techniques for spaceborne GPS, and the development of GPS-based systems for machine control and deformation monitoring. Professor Langley is a collaborator in UNB’s Canadian High Arctic Ionospheric Network project and is the principal investigator for the GPS instrument on the Canadian CASSIOPE research satellite now in orbit.
Professor Langley is a fellow of The Institute of Navigation (ION), the Royal Institute of Navigation, and the International Association of Geodesy. He shared the ION 2003 Burka Award with Don Kim and received the ION’s Johannes Kepler Award in 2007.