Russia’s GLONASS constellation moved a step closer to full global coverage with the launch of three new satellites on September 2, 2010. At present, twenty-one GLONASS satellites are operational, and two others are considered spares. Three additional satellites are scheduled for launch in November, and the first in a series of GLONASS-K satellites is scheduled to launch in December. The new GLONASS-K series will feature a longer lifespan of up to ten years and additional signal capacity. With a full constellation expected to be complete by the end of the year, Russia is currently promoting its GNSS technology to both foreign and domestic manufacturers of navigational receivers and related products.
On September 11, 2010, Japan launched the first in a series of three satellites that will provide enhanced navigation signals for Japan and portions of the surrounding Asia-Pacific region. The Quasi-Zenith Satellite System (QZSS) is named for the asymmetrical Figure-8 orbit that will keep at least one satellite almost directly overhead – at the zenith – at all times. For high accuracy positioning, the ideal satellite geometry is to have one satellite at the zenith and three others broadly scattered around it. The new satellite, also known as “Michbiki,” will send signals that are interchangeable with those of the United States’ GPS constellation, thus allowing the QZSS to augment the eight to eleven GPS satellites that are normally available over Japan at any given time. When fully operational in 2013, the three QZSS satellites will reduce ranging errors and increase positioning accuracy even in areas of Japan where urban canyons or mountainous terrain have previously been an issue
Even before Michibiki was launched, it had its own iPhone/iTouch application. QZ-Finder allows users to keep track of QZSS and GPS satellite positions overhead with a compass-like skyplot view as well as a world map view that shows how the satellites are distributed around the globe and even tracks the QZSS orbit trajectory. The new app also features an augmented reality view of the satellites that can be accessed through the user’s iPhone camera and even incorporated into a photograph for an image that is truly “out of this world.”
The China Academy of Launch Vehicle Technology announced the successful launch of the first geosynchronous satellite in China’s Compass constellation on July 31, 2010. China has already launched four geostationary satellites that will provide navigation coverage within the Asia-Pacific region by late 2012. The first geosynchronous satellite is part of China’s proposed plan to provide full global coverage by 2020, similar to what is currently provided by the United States’ GPS constellation.
Japan is also moving ahead with its Quasi-Zenith Satellite System (QZSS). The QZSS will provide navigation coverage for Japan and portions of the surrounding Asia-Pacific region, with full operational status anticipated in 2013. The first satellite was originally scheduled to launch on August 2, 2010, but the launch was postponed due to a suspected defect in the satellite’s reaction-wheel assembly system. The defective part has since been replaced, and the launch has been rescheduled for September 11, 2010.
The QZSS will provide high accuracy positioning to most of Japan, even where urban canyons or mountainous terrain might otherwise be an issue. Following a campaign by the Japanese Aerospace Exploration Agency (JAXA), the satellite has been nicknamed “Michibiki,” which means “guiding star” or “showing the way.” The satellite also has its own mascot as well as a dedicated website that will provide 3-D interaction and information about the satellite beginning on August 23.
The Quasi-Zenith Satellite System Orbit will keep a navigational satellite almost directly overhead at all times, providing greater positioning accuracy for GNSS users in Japan (public domain image courtesy of Wikimedia Commons).
The fourth navigation satellite in China’s Beidou or Compass constellation was successfully launched on June 2, 2010. This satellite is one of five planned geostationary satellites that will ultimately provide navigation coverage within the Asia-Pacific region. An additional thirty non-geostationary satellites are expected to be in place by 2020 in order to bring the Compass constellation to full global coverage similar to what is currently provided by the GPS constellation. China is planning to have a total of twelve satellites in orbit by the end of 2012 to provide positioning, timing and short messaging communication services for much of Asia and the Pacific region. The system is expected to provide a positioning accuracy of approximately thirty feet for civilian users. A more accurate service will be available to authorized and military users only.
Once all currently planned satellites have been deployed and added to those already in orbit in existing constellations, it is anticipated that positioning services, particularly in “urban canyons” and other locations where signal strength has previously been an issue, will be significantly enhanced for navigation system users around the world.
The Compass Navigation Satellite System will initially provide service to the Asia-Pacific region (public domain image courtesy of Wikimedia Commons).
After a week of delays caused by everything from technical malfunctions to bad weather, the first in a series of
GPS IIF satellites was
finally launched from Cape Canaveral late in the evening on May 27, 2010. A total of twelve IIF satellites are expected to launch through 2014, with the next launch tentatively scheduled for November 2010.
The IIF satellites are part of the ongoing modernization of the GPS constellation by the United States Air Force. The IIFs have improved atomic clocks used for timing and are therefore expected to provide more accurate navigation signals than those currently available from the rest of the GPS constellation. The IIFs will also broadcast the civil L5 signal for safety-of-life applications, which has the potential to enhance indoor reception with its wider bandwidth and lower frequency. The new satellites will also be compatible with the Galileo, GLONASS and QZSS constellations. In addition, the IIFs will assist the IIRM series already in orbit with military-specific M-code, a unique encryption for military users requiring secure access.
The new satellite, officially known as GPS IIF-1 SV-1, is expected to begin broadcasting its signal to GPS users following a three- to four-month testing period. In addition to being the first in the new IIF satellite series, this launch was significant for another reason as well. GPS IIF 1 SV-1 was carried into orbit on a Delta IV rocket, making it the first GPS satellite since 1985 that was not placed in orbit by an Atlas rocket.
The new IIF satellite series has finally launched. (Public domain image courtesy of http://pnt.gov/public/images/.)
Russia launched three additional GLONASS satellites on March 1, 2010. The launch was originally scheduled for September 2009, but had to be postponed when problems emerged with a similar satellite already in orbit and sent the three new satellites back to the factory for pre-launch repairs. The GLONASS constellation now includes 23 operational satellites, two of which are being used in a reserve capacity. A 21-satellite constellation provides 98.5% global availability. With three additional satellites expected to launch in August and another launch scheduled for November, the GLONASS constellation could reach 99.5% global availability by the end of 2010.
As a comparison, the current GPS constellation maintained by the United States includes 32 satellites and reached full operational capacity in 1995. It takes a minimum of 24 operational satellites to provide complete global availability.
A solar flare that occurred on February 12, 2010 may signal a return to high solar activity after several months of sustained low activity. Intense solar flares can cause temporary disruptions in GPS signals due to the high levels of radiation they release into the Earth’s atmosphere.
Solar activity generally occurs in eleven-year cycles, with the next peak expected by 2012. Increased solar activity is particularly troublesome for the navigation devices many drivers reference in their vehicles. GPS blackouts may last for a number of minutes during periods of peak solar activity and may occur several times each year. In addition to GPS blackouts, the atmospheric charge can impact the amount of time it takes for a GPS signal to make it to a GPS receiver, which causes inaccurate readings. Positioning may be off by as much as thirty feet during these periods, which will have the greatest impact on GPS survey equipment.
For iPhone users that want to keep track of solar activity, NASA has helped implement a new app called “3D Sun” that allows users to access a live global view of the sun. Data is provided in near real-time fashion by NASA’s STEREO mission, a pair of satellites that provide coverage of both sides of the sun simultaneously. More information on the app is available at http://3dsun.org/.
A high resolution 2D image of the sun taken by NASA's STEREO mission. STEREO is monitoring solar activity that may interfere with GPS and other signals. (Public domain image courtesy of NASA.)
China launched the third satellite in its Compass Navigation Satellite System on January 17, 2010. This satellite is one of five planned geostationary satellites that will ultimately provide navigation coverage within the Asia-Pacific region. An additional 30 non-geostationary satellites are expected to be in place by 2020 in order to bring the Compass constellation to full global coverage.
Also known as the Beidou system, the geostationary satellites will provide free open service within the local service area. A second level of service will provide greater accuracy to authorized users only.
