Tag: Galileo 5

System of Systems: Galileo birds active, faulty launch victims still viable

Galileo birds active

Faulty launch victims still viable

Galileo orbits viewed from above.

Europe’s fifth and sixth Galileo satellites, salvaged from their faulty 2014 Soyuz launch, will begin broadcasting working navigation signals for test purposes, for the benefit of receiver manufacturers, service providers and scientific researchers. The European Commission will decide later whether the two satellites will become part of the operational Galileo constellation.

The European Space Agency performed a complex series of in-orbit maneuvers to raise and circularize the two after they arrived in space too low and too elliptical for full Galileo use. Their initial orbits dipped the satellites too close to Earth to keep their antennas properly locked on the planet.

“Once their orbits were modified, their navigation payloads could be turned on and in-orbit testing could take place,” explained Marco Falcone, head of the Galileo System Office. “The good news was their performance was excellent.

“The navigation signals will include a signal health status reading that ‘signal component currently in test’ and its navigation data validity status will be ‘working without guarantee.’ In this way, these signals will not disturb the performance of any receivers using the Galileo signals coming from the other satellites. On the user community side, some application providers are interested in harnessing as many available satellites as possible for precision applications.”

Testing will take place in two phases: initially their navigation signal will be updated via the Galileo ground segment every 14 hours or so. Later this year, the ground segment will be reconfigured to send updates more often, enhancing navigation precision, although they will remain outside the official constellation until decided otherwise.

The two satellites are also midway through an ambitious space experiment to test Einstein’s General Theory of Relativity more precisely than ever before, by measuring how their onboard time varies in accordance with their altitude and therefore gravity, known as their gravitational redshift.

New Activation. Galileo GSAT-0210 (PRN E01), one of two launched May 24, began dual-frequency broadcast on Aug. 17, transmitting E1 and E5a signals.

GPS III launch RFP

Competitive bids invited

The U.S. Air Force released a Request for Proposal (RFP) in August for GPS III-3 launch services, scheduled to begin in 2019. The contract will be a standalone for a single GPS III launch.The United Launch Alliance (ULA) and Space Exploration Technologies (SpaceX) are expected to compete for the contract. In April, SpaceX was chosen to launch the GPS III-2 satellite in May 2018. ULA chose not to compete.

The RFP seeks an Evolved Expendable Launch Vehicle (EELV) Launch Service. The Air Force’s acquisition strategy seeks a balance between mission success/operational needs and lowering launch costs, reintroducing competition for national security space missions.

This is the second competitive launch service solicitation under the current procurement strategy. Previously, ULA was the only certified launch provider. In 2013, ULA was awarded a sole-source contract for launch services as part of an Air Force Block Buy of 36 rocket cores. In May 2015, SpaceX was certified for EELV launches, yielding two qualified launch service providers.

M-code, OCX updates

The Air Force awarded a $52.6 million contract to Raytheon for modernization of the Miniature Airborne GPS receiver 2000 (MAGR-2K): test and delivery of an M-code automatic dependent surveillance and broadcast-capable system. Congress has mandated the military buy only M-code GPS equipment by 2018. Last year, Rockwell Collins received a $36.6 million contract for such equipment.

OCX. Raytheon is implementing changes to its GPS Next-Generation Operational Control System (OCX). “Momentum is very good” towards a December 2020 deadline for software delivery, said the program manager. A Pentagon review in July followed breach of a critical cost-growth cap. The complexity of cyber security requirements contributed to delays to date. The company expects to deliver Block 0 software in 2017, in conjunction with plans to launch GPS III satellites. However, the capability will not be turned on until 2018, when an OCX Block 0 launch-and-checkout capability for GPS III launches is to begin.

August 23, 2016
Galileo satellites set for year-long Einstein experiment

News from the European Space Agency

Europe’s fifth and sixth Galileo satellites — subject to complex salvage maneuvers following their launch in 2014 into incorrect orbits — will help to perform an ambitious year-long test of Einstein’s most famous theory.

Galileos 5 and 6 were launched together by a Soyuz rocket on August 22, 2014. But the faulty upper stage stranded them in elongated orbits that blocked their use for navigation.

ESA’s specialists moved into action and oversaw a demanding set of maneuvers to raise the low points of their orbits and make them more circular. “The satellites can now reliably operate their navigation payloads continuously, and the European Commission, with the support of ESA, is assessing their eventual operational use,” explained ESA’s senior satnav advisor Javier Ventura-Traveset. “In the meantime, the satellites have accidentally become extremely useful scientifically, as tools to test Einstein’s General Theory of Relativity by measuring more accurately than ever before the way that gravity affects the passing of time.”

The original (in red) and corrected (in blue) orbits of the fifth and sixth Galileo satellites, along with that of the first four satellites (green).

Although the satellites’ orbits have been adjusted, they remain elliptical, with each satellite climbing and falling some 8500 km twice per day. It is those regular shifts in height, and therefore gravity levels, that are valuable to researchers.

Albert Einstein predicted a century ago that time would pass more slowly close to a massive object. It has been verified experimentally, most significantly in 1976 when a hydrogen maser atomic clock on Gravity Probe A was launched 10,000 km into space, confirming the prediction to within 140 parts in a million.

Passive hydrogen maser atomic clock of the type flown on Galileo, accurate to one second in three million years. (Photo: ESA)

Atomic clocks on navigation satellites have to take into account they run faster in orbit than on the ground — a few tenths of a microsecond per day, which would give us navigation errors of around 10 km per day.

“Now, for the first time since Gravity Probe A, we have the opportunity to improve the precision and confirm Einstein’s theory to a higher degree,” comments Javier.

This new effort takes advantage of the passive hydrogen maser atomic clock aboard each Galileo, the elongated orbits creating varying time dilation, and the continuous monitoring thanks to the global network of ground stations.

The Gravity Probe A payload of 1976, flown in a highly elliptic single orbit to measure the “gravitational redshift” of Einstein’s Theory of General Relativity more accurately than ever before, seen with its designers Robert Vessot and Martin Levine of the Smithsonian Astrophysical Observatory. The experiment compared a hydrogen maser clock on Earth with its replica in space as it ascended to about 10,000 km, and confirmed theoretical expectations to an accuracy of 0.02%. (ESA file photo)

“Moreover, while the Gravity Probe A experiment involved a single orbit of Earth, we will be able to monitor hundreds of orbits over the course of a year,” explained Javier. “This opens up the prospect of gradually refining our measurements by identifying and removing systematic errors. Eliminating those errors is actually one of the big challenges. For that we count on the support of Europe’s best experts plus precise tracking from the International Global Navigation Satellite System Service, along with tracking to centimeter accuracy by laser.”

The results are expected in about one year, projected to quadruple the accuracy on the Gravity Probe A results.

The two teams devising the experiments are Germany’s ZARM Center of Applied Space Technology and Microgravity, and France’s SYRTE Systèmes de Référence Temps-Espace, both specialists in fundamental physics research.

ESA’s forthcoming Atomic Clock Ensemble in Space experiment, planned to fly on the International Space Station in 2017, will go on to test Einstein’s theory down to 2–3 parts per million.

November 9, 2015
Latest Galileo Satellites Will Head to Plane A

The Soyuz launcher is transferred to the launch pad. (Credit: Arianespace)

I had the honour of the first question at today’s Galileo press conference hosted by the European Space Agency (ESA), and it was about the status of the satellites launched last March. The answer to that question and others are below.

The satellites being launched this evening are destined for Plane A and will be its first occupants. They will occupy slots 5 and 8 in the plane. They will undergo a 76-day-long in-orbit test procedure before being made available to users.

The satellites launched in March, Galileo satellites 7 and 8 (a.k.a. FOC-FM3 or GSAT0203 and FOC-FM4 or GSAT0204 using PRNs 26 and 22, respectively), have essentially completed in-orbit testing and should be available to users sometime this month.

The ground segment is to be modified to enable the production of navigation messages for satellites 5 and 6 (a.k.a. FOC-FM1 or GSAT0201 and FOC-FM2 or GSAT0202 using PRNs 18 and 14, respectively) launched in August 2014 into wrong orbits (a “kind of Plane D” according to one of the ESA officials at the press conference). This will occur by the beginning of 2016 when these satellites will then be available for testing in navigation and positioning applications. They will not be included in the broadcast almanac as the orbits are too far from nominal to be represented by the standard almanac format. But the signals should be fully usable by those receivers and chipsets that can acquire and track Galileo satellites without an almanac. Testing will be carried out to see if the satellites can become part of the operational constellation.

IOV-4 (a.k.a. FM4 or GSAT0104 using PRN 20), the in-orbit validation satellite that suffered a power failure in May 2014 and is only broadcasting on the E1 frequency, may become operational for single-frequency use if suitable ground segment modifications can be made.

The next Galileo launch after this evening’s will be in December on a Soyuz launcher when another two satellites will be placed into orbit.

In 2016, there will be one launch but using, for the first time, the Ariane 5 launcher, to place four satellites into orbit.

In 2017, there will be two launches: a Soyuz launch orbiting two satellites, and an Ariane 5 launch, orbiting four satellites.

A 30-satellite constellation will be in place by 2020, following ESA’s slogan “30 satellites by 2020,” with 10 satellites per plane with each plane having two spare satellites. This should be feasible as two satellites are now being manufactured every three months. Twenty-four satellites is the minimum for Galileo operational capability.

September 10, 2015
ESA Releases Guide on Galileo 5 and 6 Recovery

The European Space Agency has published a short guide on the recovery of Galileo satellites 5 and 6. The PDF of “Salvage in Space: Recovering Galileo 5 and 6” can be downloaded.

The four-page guide, written for a non-technical audience, describes the root cause of the anomaly that placed the two satellites into the wrong orbit, and the solution used to correct the orbits.

July 8, 2015
Sixth Galileo Satellite Reaches Corrected Orbit

The original (in red) and corrected (in blue) orbits of the fifth and sixth Galileo satellites, along with that of the first four satellites (green). Photo: European Space Agency

By the European Space Agency

The sixth Galileo satellite of Europe’s navigation system has entered its corrected target orbit, which will allow detailed testing to assess the performance of its navigation payload.

Launched with the fifth Galileo last August, its initial elongated orbit saw it traveling as high as 25,900 km above Earth and down to a low point of 13,713 km — confusing the Earth sensor used to point its navigation antennas at the ground.

A recovery plan was devised between ESA’s Galileo team, flight dynamics specialists at ESA’s ESOC operations centre and France’s CNES space agency, as well as satellite operator SpaceOpal and manufacturer OHB. This involved gradually raising the lowest point of the satellites’ orbits more than 3500 km while also making them more circular.

The fifth Galileo entered its corrected orbit at the end of November 2014. Both its navigation and search and rescue payloads were switched on the following month to begin testing. Now the sixth satellite has reached the same orbit, too.

This latest salvage operation began in mid-January and concluded six weeks later, with 14 maneuvers performed in total. Its corrected position is effectively a mirror image of the fifth satellite’s, placing the pair on opposite sides of the planet. The exposure of the two to the harmful Van Allen Belt radiation has been greatly reduced, helping to ensure future reliability.

Significantly, the corrected orbit means they will overfly the same location on the ground every 20 days. This compares with a standard Galileo repeat pattern of every 10 days, helping to synchronize their ground tracks with the rest of the constellation.

The test results from Galileo 5 proved positive, with the same test campaign for the sixth satellite due to begin shortly, overseen by ESA’s Redu centre in Belgium. A 20 m-diameter antenna will study the strength and shape of the navigation signals at high resolution.

“I am very proud of what our teams at ESA and industry have achieved,” says Marco Falcone, head of Galileo system office. “Our intention was to recover this mission from the very early days after the wrong orbit injection. This is what we are made for at ESA.”

The decision whether to use the two satellites for navigation and search-and-rescue purposes will be ultimately taken by the European Commission, as the system owner, based on the in-orbit test results and the system’s ability to provide navigation data from the improved orbits.

The next pair of satellites is due for launch on March 27.

The Galileo operations team, joined by Director General Jean-Jacques Dordain, Director of Human Spaceflight and Operations Thomas Reiter and experts from European industry, in the Main Control Room at ESA’s Space Operations Centre, ESOC, in Darmstadt, Germany, August 28, 2014. (Photo courtesy of ESA)

March 13, 2015
Orbit of Second Wayward Galileo Satellite Adjusted

Editor’s Note: See the report from the European Space Agency here.

An official with the European Space Agency has confirmed that the sequence of maneuvers to adjust the orbit of the second of two Galileo satellites launched into a wrong orbit in August 2014 has been completed.

The orbit of the first satellite, known variously as GSAT0201, Galileo FOC-FM1 or Galileo 5 (with COSPAR ID 2014-050A and NORAD ID 40128) was raised during operations carried out in November, and the satellite began transmitting L-band signals on Nov. 29.

Maneuvering of the second satellite (GSAT0202, Galileo FOC-FM2 or Galileo 6, with COSPAR ID 2014-050B and NORAD ID 40129) began around Jan. 15. The procedure took somewhat longer than that for the first satellite as it also involved changing the mean anomaly of the satellite to be about 180° away from that of the first satellite.

The locations of the satellites in the Galileo constellation are shown in the accompanying figure. Satellites in green are transmitting a full complement of L-band signals. Galileo 4 (GSAT0104), one of the in-orbit validation satellites, suffered a power anomaly and only transmits on the E1 frequency. Galileo 5 is transmitting L-band signals but its orbit cannot be properly represented in the Galileo broadcast almanac. Galileo 6 has not started transmitting valid L-band signals yet.

Officially, all Galileo signals are currently declared unavailable during an extended period of testing following ground segment upgrades. However, signals continue to be monitored by stations participating in the International GNSS Service Multi-GNSS Experiment.

March 11, 2015
First Galileo FOC Satellite on the Air

Will Be Employable for Surveying, Precise Positioning, and Geodesy

By Peter Steigenberger and André Hauschild, German Aerospace Center (DLR) / German Space Operations Center

The first Full Operational Capability (FOC) Galileo satellite started transmitting L-band navigation signals on November 29, 2014. Based on data collected by a global network of GNSS tracking stations of the Cooperative Network for GNSS Observation (CONGO) and the Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS), we determined that an E1 signal with pseudorandom noise code (PRN) E18 was first tracked at the station LLAG (La Laguna, Tenerife, Canary Islands) at 06:08 UTC. A few moments later, the satellite’s transmissions were also tracked at other MGEX stations including the E5a, E5b, and E5 AltBOC signals. Based on the computed satellite visibility at various tracking stations, the satellite could be positively identified as GSAT0201, also known as Galileo FOC-FM1 or Galileo 5 with COSPAR ID 2014-050A and NORAD ID 40128.

FIGURE 1 shows the carrier-to-noise-density ratio (C/N₀) of the E18 signals tracked at the CONGO/MGEX station SIN1 (Singapore, using a Trimble NetR9 receiver with a Leica AR25.3 antenna). We selected the signals from this station for analysis due to an E18 pass occurring close to the zenith and covering almost the full range of elevation angles. The E5a and E5b signals (S5X and S7X RINEX identifiers) show very similar performance, whereas the C/N₀ values of the E1 signal are 1–2 dB-Hz higher. The C/N₀ values of the E5 AltBOC signal (S8X) reach 60 dB-Hz at high elevation angles, which is about 6 dB-Hz higher than the other signals.

Figure 1. Galileo E18 carrier-to-noise-density ratio for the CONGO/MGEX station SIN1 (Singapore).

The first pair of Galileo FOC spacecraft was launched on August 22 with a Soyuz launcher from the Guiana Space Centre, Kourou, French Guyana. Due to a malfunction of the Fregat upper stage, the satellites were injected into elliptical orbits with an inclination of about 49° instead of near circular orbits with 55° inclination. In November, the perigee of the first FOC satellite was raised by about 3,500 kilometers by a series of 11 maneuvers with a corresponding reduction in orbit eccentricity from 0.23 to 0.16.

E18 has been included in the precise orbit and clock solutions of the MGEX analysis center at Technische Universität München (TUM) in Munich, Germany, since December 5. FIGURE 2 shows the detrended estimates of the active Galileo E18 clock for December 7. The presence of a pronounced quadratic term as well the large drift of 33.9 microseconds per day indicate that the active clock is a rubidium atomic frequency standard rather than a more precise passive hydrogen maser. The FOC satellites carry two of each kind of clock.

Figure 2. Galileo E18 clock estimates for December 7, 2014, with respect to the hydrogen maser at the Ottawa IGS station (NRC1) after removing an offset and drift (blue) or a second order polynomial (red).

The TUM orbit and clock product allows researchers to again compute dual-frequency positioning solutions using only Galileo observations, as the In-Orbit Validation satellite E20 has not transmitted an E5 signal since May, when a power anomaly left the satellite with the capability to only transmit an E1 signal. Furthermore, E20 currently does not transmit a navigation message.

TABLE 1 shows the scatter of single-point positioning using pseudorange (code) observations from the MGEX station MAS1 (Maspalomas, Gran Canaria, Canary Islands) for a Galileo-only, a GPS-only, and a combined Galileo+GPS solution for December 6. At an elevation cut-off angle of 10°, four Galileo satellites were visible from 10:15 until 12:25 UTC (see FIGURE 3). The GPS-only solution covers the same time interval. The start time is not limited by the cut-off angle but an E18 transmission outage from 3:45–10:15 UTC.

TABLE 1. Single point positioning results for the MGEX station MAS1 (Maspalomas) for December 6, 2014.

Figure 3. Galileo visibility at the MGEX station MAS1 (Maspalomas) on December 6, 2014. The time period considered in the single-point positioning is indicated by vertical lines.

We used an ionosphere-free linear combination of Galileo E1 and E5 AltBOC code observations and GPS L1 and L2 code observations with a 30-second sampling interval. As the Galileo-only solution suffered from position dilution of precision (PDOP) values of up to 830, a total of 32 epochs with PDOP values greater than 25 were excluded. The geometry of the remaining epochs is still pretty unfavorable. At a mean PDOP value of 7.4, the standalone position solution exhibits a 3D standard deviation (STD) error of 3.4 meters. Use of the Galileo satellites in a combined GPS+ Galileo solution improves the positioning performance. In particular, the height component benefits from the inclusion of the four Galileo satellites with a standard deviation improvement of 25 percent.

Despite the orbit injection error, the new Galileo FOC satellite has now been successfully activated and added to the Galileo constellation. Unfortunately, the current orbit is incompatible with the standard Galileo almanac format, which may cause restrictions for some commercial receiver types.

Nevertheless, the satellite can already be tracked by a wide range of geodetic receivers with existing firmware versions and it will, in fact, be possible to use the new satellite for diverse applications in surveying, precise positioning, and geodesy, as well as in general multi-GNSS studies. We now look forward to the activation of the second FOC satellite, which can be expected in early 2015 and will, for the first time, offer multi-frequency signals from a total of five Galileo satellites.

December 18, 2014
The System: eLoran Operational on Eastern UK Coast

Bridge of the Galatea, a GLA vessel that carries a eLoran receiver and conducted tests of the new system. Photo: GLA

Back-up to Vulnerable GPS Signals Required for Busy Shipping Lanes

The General Lighthouse Authorities (GLAs) of the UK and Ireland announced October 31 the initial operational capability of UK maritime eLoran. Seven differential reference stations now provide additional position, navigation, and timing (PNT) information via low-frequency pulses to ships fitted with eLoran receivers. The service will help ensure they can navigate safely in the event of GPS failure in one of the busiest shipping regions in the world, with expected annual traffic of 200,000 vessels by 2020.

Ships carry 95 percent of UK trade, accounting for its strongly expressed concerns regarding GPS vulnerability to jamming and spoofing, and the leadership role it has taken in eLoran research and testing. The UK is the first country in the world to deploy the technology along its coastline, thronged with both passenger and cargo services. Deployment involved replacing the existing radio receiver equipment in two prototype reference stations at Dover and Harwich, and the creation of five new reference stations in the Thames, Humber, Middlesbrough, and Firth of Forth and Aberdeen in Scotland, on the North Sea where oil-laden vessels come from deep-sea drilling rigs.

Entirely independent of GPS, eLoran can provide navigation information for vessels as well as the timing data necessary to maintain the power grid, cell phones, financial networks, and the Internet in the event of an outage. Unlike space-based navigation, eLoran signals can also reach inside buildings, underground, and underwater.

Captain Ian McNaught, deputy master of Trinity House, commented, “eLoran provides a signal around 1 million times more powerful than those from satellite signals, providing resilience from interference and attack. The achievement of initial operational capability for the system at Dover and along the east coast of the UK is a significant milestone, providing for improved safety aboard appropriately equipped vessels. The maritime industry would now benefit from the installation of eLoran receivers on more vessels to take advantage of improved navigational safety.”

“Telecoms, finance, energy, and other industries, which are subject to significant issues caused by the loss of timing signal provided by GPS, are recommended to take advantage of the enhanced reliability now available to address the over-dependence of key national infrastructure on vulnerable satellite systems,” McNaught said.

eLoran technology is based on longwave radio signals and is independent and complementary to GPS.

Several other nations are consulting with the UK GLAs on eLoran. South Korea wants to establish an eLoran alliance with the UK while it pursues its own rollout of differential eLoran reference stations and new eLoran transmitters based on the latest technology. In 2012, South Korea was the victim of a 16-day GPS jamming attack by North Korea.

Full operational capability covering all major UK ports is expected by 2019.

Galileo Roving High

The fifth Galileo navigation satellite, one of two left in the wrong orbit in August, made a series of November maneuvers as a prelude to its health being confirmed. The aim was to raise the lowest point of its orbit — its perigee — to reduce the radiation exposure from the Van Allen radiation belts surrounding Earth, as well as to put it into a more useful orbit for navigation purposes.

Should the two-week operation prove successful, the sixth Galileo satellite will follow the same route, according to the European Space Agency (ESA).

The Galileo pair, launched together on a Soyuz rocket on August 22, ended up in an elongated orbit traveling out to 25,900 kilometers (km) above Earth and back down to 13,713 km. The target orbit was a purely circular one at an altitude of 23,222 km. Also, the orbits are angled relative to the Equator less than originally planned.

The two satellites have only enough fuel to lift their altitude by about 4,000 km — insufficient to correct their orbits entirely. But the move will take the fifth satellite into a more circular orbit than before, with a higher perigee of 17,339 km.

“The new orbit will fly over the same location every 20 days,” said Daniel Navarro-Reyes, ESA Galileo mission analyst. “The standard Galileo repeat pattern is every 10 days, so achieving this will synchronize the ground track with the rest of the Galileo satellites.”

“In addition, from a user receiver point of view, the revised orbit will reduce the variation in signal levels, reduce the Doppler shift of the signal, and increase the satellite’s visibility,” Navarro-Reyes said. “For the satellite, reducing its radiation exposure in the Van Allen radiation belts will protect it from further exposure to charged particles. The orbit will also allow Galileo’s Earth Sensor to hold a stable direction for the satellite’s main antenna to point at Earth. Right now, when the satellite dips to its lowest point, Earth appears so large that the sensor is unusable. The satellite relies on gyroscopes alone, degrading its attitude precision.”

The recovery is being overseen from the Galileo Control Centre in Oberpfaffenhofen, Germany, with the assistance of ESA’s Space Operations Centre, ESOC, in Darmstadt, Germany. France’s CNES space agency is providing additional ground stations so that contact can be maintained with the satellite as needed, ESA said.

Welcome IIF-8

The U.S. Air Force launched the eighth GPS IIF satellite on October 29, aboard an Atlas V 401 rocket. With this new arrival on orbit, only four more Block IIF satellites remain to be placed aloft. Three are in storage awaiting launch, and one is in production.

The Boeing-built GPS IIF-8 (SVN-69/PRN-03) will replace SVN-51 in the E plane slot 1. SVN-51 will be re-phased from E1 to an auxiliary node at E7 somewhere around SVN-54 currently on station at E4, according to the Air Force Second Space Operations Squadron (2 SOPS). SVN-38/PRN-08 will be taken out of the operational constellation prior to SVN-69 payload initialization and sent to Launch, Anomaly Resolution and Disposal Operations (LADO). PRN-08 will be assigned initially to SVN-49 and set to test.

SVN-51 will remain in an auxiliary node once it completes its re-phase journey. The SVN-51 re-phase will take about six months after the initial burn occurs.

December 1, 2014
First Navigation Signal from Galileo 5 Received

News courtesy of CANSPACE Listserv.

The first navigation signal transmission from the fifth Galileo satellite, one of two Full Operational Capability satellites launched into wrong orbits on August 22, was received today.

Stations of the Cooperative Network for GNSS Observation (CONGO) and the International GNSS Service Multi-GNSS Experiment (MGEX) network tracked an E1 signal with a PRN code of E18 this morning. The signal was first tracked at the La Laguna station (LLAG, Tenerife, Canary Islands) at 06:08:00 UTC.

A few moments later, the satellite was also tracked at the Geodetic Observatory Wettzell (WTZ3, Wettzell, Germany) and at the University of New Brunswick (UNBD, Fredericton, Canada). The receivers at all three stations are JAVAD GNSS Triumph receivers.

Analysis of current Galileo satellite visibility at various tracking stations confirms that the active satellite is GSAT0201, also known as Galileo FOC-FM1 or Galileo 5, with COSPAR ID 2014-050A and NORAD ID 40128.

As reported earlier, the perigee of Galileo 5’s orbit was raised in an effort to make the satellite usable for research, at least, and potentially for positioning and navigation.

December 1, 2014
Orbit of One Wayward Galileo Satellite Raised

The orbit of one of the two Galileo satellites launched into incorrect orbits on August 22 is being adjusted. Tracking data supplied by the North American Aerospace Defense Command (NORAD) and the U.S. Joint Space Operations Center (JSpOC) has confirmed the change.

Also, the first navigation signal from Galileo 5 has been received.

The satellites were supposed to go into circular orbits with an inclination to the equator of 56 degrees and with a semi-major axis of about 29,600 km. They ended up in eccentric orbits with semi-major axes more than 3,300 km shorter and with an inclination of about 49.7 degrees.

Instead of an orbital height of 23,222 km above the surface of the Earth, they were moving between apogee heights of about 25,900 km and perigee heights of about 13,800 km, perilously close to the most dangerous regions of the Van Allen radiation belts.

The European Space Agency announced on November 10 that the orbit of one of the two wayward satellites, Galileo 5, would have its perigee raised to 17,339 km through a series of 15 orbital maneuvers. This orbital adjustment would put the satellite into a safer orbit and potentially make it useable for positioning and navigation. If the operation is successful, Galileo 6 will follow suit.

These maneuvers likely started on or shortly after November 8. After the maneuvers began, NORAD/JSpOC temporarily “lost” the satellite as often happens when satellites undergo unpredicted Delta-V operations. NORAD/JSpOC recovered the satellite after about 18 days and issued new orbital elements for the satellite on November 25.

The new elements show that (so far) the perigee of Galileo 5 has been raised from about 13,820 km to 17,230 km with a corresponding change in the orbital eccentricity from about 0.23053 to 0.15619. The apogee height is virtually the same as that immediately after launch. Also, the inclination is not and will not be materially changed.

An animation, produced using the NORAD/JSpOC orbital element sets and the XEphem software, compares Galileo 5’s old and new orbits:

December 1, 2014