China sent a Beidou-2 backup navigation satellite into orbit on a Long March-3A rocket from the Xichang Satellite Launch Center, in the southwestern Sichuan Province, at 4:58 a.m. on July 10, according to Xinhua.net.
China started to construct the third-generation of Beidou system in 2017, and eight Beidou-3 satellites are now in space. The satellite just launched is a second-generation Beidou-2, and the 32nd of the Beidou navigation system.
“The launch of a backup Beidou-2 satellite will ensure the system’s continuous and stable operation,” said Yang Hui, chief designer of the Beidou-2 series.
Some of the Beidou-2 satellites are nearing the end of their lives and need to be replaced by backup satellites. China launched two backup satellites on March 30 and June 12, 2016.
This new backup is not a simple repeat of previous satellites, but has been upgraded to improve its reliability, Yang said.
It carries redundant rubidium clocks, which is the key to the accuracy of its positioning and timing.
When China began reform and opening-up 40 years ago, its satellites mainly used costly imported rubidium clocks. After the launch of the Beidou program, the United States banned exports of rubidium clocks to China.
Sun Jiadong, chief designer of the Beidou system and an academician of Chinese Academy of Engineering, said China must depend on itself.
China’s first self-developed rubidium clock was tested on a satellite in September 2006. The performance of China’s rubidium clocks was improved on Beidou-2 satellites.
This year will see an intensive launch of Beidou satellites. The system is expected to provide navigation and positioning services to countries along the Belt and Road by late 2018. By around 2020, the Beidou system will go global.
Photo: Xinhua.net
The Beidou-3 satellites can send signals that are compatible with other satellite navigation systems and provide satellite-based augmentation, as well as search and rescue services in accordance with international standards. The positioning accuracy is 2.5 to 5 meters.
The Beidou system will coordinate with other technology, such as remote sensing, the Internet, big data and cloud computing, in future.
In the past five years, the system has helped rescue more than 10,000 fishermen. More than 40,000 fishing vessels and around 4.8 million commercial vehicles in China have been equipped with Beidou, said Beidou spokesperson Ran Chengqi.
China has sold more than 50 million domestically manufactured chips connected to the Beidou navigation and positioning system in the past five years.
By 2020, the value of China’s satellite navigation business is expected to surpass 400 billion yuan (about 58 billion U.S. dollars), of which 240 billion to 320 billion yuan will go to the Beidou system, Ran said.
QZS-2 L-band spectra, July 18, 2017, Weilheim, Germany. (Courtesy DLR)
Second QZSS Signal on Air
The successful launch of the Michibiki No. 2 satellite of the Quasi-Zenith Satellite System (QZSS) on June 1 has been followed by broadcast initiation. Researchers at the German Aerospace Center, Deutsches Zentrum für Luft- und Raumfahrt (DLR), have been observing the satellite from their ground station in Weilheim. They will provide a written analysis in the September issue.
The Japan Aerospace Exploration Agency launched first Michibiki satellite of the anticipated four-satellite constellation in September 2010.
Air Force to Recompete GPS III Follow-on
The U.S. Air Force will launch multibillion-dollar competition between current GPS III contractor Lockheed Martin Corp. and former GPS Block I and Block II contractor Boeing Co. for as many as 22 new GPS III satellites. At press time, an industry day in was scheduled for July 20 in El Segundo, California, to solicit company input, according to a new draft Request For Proposals.
In 2015 the Air Force undertook the first phase of a now two-year process to determine whether to put the next block of satellites up for competition. An initial review “has determined that viable, low-risk, high-confidence sources exist to conduct a full and open competition” for a second phase starting in fiscal 2018, according to the draft.
Lockheed Martin is assembling the first 10 satellites of the Block III program. Formal delivery of the first satellite was scheduled earlier this year, delayed by of a series of now-resolved problems with the navigation payload, cracked capacitors and a subcontractor gaffe last year that resulted in the wrong part being tested.
The satellite, which passed all of its qualification testing and verification, has been placed in storage pending the results of an unrelated review of the propulsion systems used to boost military satellites into orbit. The plan remains to launch the first GPS III satellite by spring of 2018.
“Lockheed Martin is working closely with the Air Force on resolving any concerns about the mission readiness of SV01’s Propulsion Subsystem,” Eschenfelder said in February. “We are confident that this review will not delay the Air Force’s planned spring 2018 Initial Launch Capability (ILC).”
NAVIC Clock Failures Resemble Galileo’s
The seven orbiting satellites of the Navigation Indian Constellation (NAVIC, formerly India’s Regional Navigation Satellite System, or IRNSS) have been hit by problems with some of their rubidium atomic clocks, similar to difficulties encountered earlier by Europe’s Galileo program.
NAVIC G-1 launch April 2017.
The Indian Space Research Organization (ISRO) had announced in July 2016 that all three atomic clocks on IRNSS-1A, launched in 2013, had malfunctioned, rendering that satellite ineffective.
Now, reports indicate that four more atomic clocks on the other six satellites launched more recently are not performing as required.
ISRO plans to launch a replacement satellite called IRNSS-1H in July-August to compensate for the loss of IRNSS-1A, although it is yet to announce the failure of more atomic clocks, which has not incapacitated the clock systems on the other six satellites.
The European Space Agency reported in January that anomalies had occurred in three of 36 Rubidium Atomic Frequency Standard (RAFS) clocks in the 18-satellite Galileo system, although none of the satellites were affected. ESA had said, “These failures all seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground.”
ISRO has nine satellites indented for IRNSS. While seven satellites make up the Indian regional navigation constellation, the other two were indented as backup in the event of failure. Each satellite has three atomic clocks, one the primary timekeeper and the other two acting as backup.
“Measures are being taken to correct the problems caused by the clocks in the launch of future satellites. The atomic clocks to be used in the other satellites have been modified to prevent malfunction,” a senior official in the programme said.
ISRO chairman Kumar has indicated the number of satellites could go up from the originally envisaged seven to 11 but it is not clear if this is a consequence of the failing clocks. “We are set to launch more navigational satellites. They are in the process of approvals and clearances,” he said recently, and added efforts were on to revive the IRNSS-1A clocks.”
In Europe, the European Space Agency and an industrial partner-supplier have agreed that “some refurbishment is required on the remaining RAFS clocks” to be used in new Galileo satellites.
Look to GSA Service Centre for Galileo Advisories
In July, a wide transfer of responsibilities for the Galileo constellation took place, from the European Space Agency (ESA) to the European Global Navigation Satellite System Agency (GSA) of the European Union. Key among these was a handover of communications responsibilities to manufacturers, users and markets.
All parties can now find updates in the form of Notice Advisory to Galileo Users (NAGUs) at the GSA’s Galileo Service Centre, www.gsc-europa.eu/system-status/user-notifications.
NAGUs are issued as new satellites are launched and when satellites become ready for service provision, or to give advance warning of signal unavailability owing to planned maintenance or testing activities, or to notify users of unplanned outages and then to inform them when satellites become active again.
“Keeping our users in the picture on planned activities that might lead to satellite unavailabilityhas helped them to plan their own test activities and to prepare future products,” said Rafael Lucas Rodriguez, ESA’s Galileo services engineering manager.
A total of 189 NAGUs were issued under ESA oversight in the last four years, as the constellation grew to its current 18 satellites. The user base increased from 86 to 774 registered users on the European GNSS Service Centre website as companies worked to prepare Galileo-ready products. In December 2016, Galileo’s Initial Services began operating.
One regular consumer of Galileo NAGUs, Broadcom, uses them to organize engineering activities and tests as well as input them into its orbit prediction engine for its Long Term Orbits products.
