Genesis satellite.

The combination of advanced technologies for precise orbit determination and timing, as well as the scientific exploitation of GNSS signals, opens major new opportunities for relevant, innovative in-orbit scientific experiments. These opportunities come in the fields of Earth sciences, including geodesy, geophysics and GNSS remote sensing of the atmosphere, land, ocean and ice, fundamental physics, astronomy and time metrology. They could extend some current operational applications such as precise orbit determination for geodesy and altimetry and GNSS radio occultation for meteorology and space weather.

To further enhance the benefits of combining space-based geodetic techniques, the European Space Agency (ESA) has established the Genesis mission. The mission will collocate on board a single well-calibrated satellite, the four space-based geodetic techniques: GNSS, very long baseline interferometry (VLBI), satellite laser ranging (SLR) and Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS). This first-time-ever collocation in space will establish precise and stable ties among these key techniques. The Genesis satellite will be a unique, dynamic space geodetic observatory, whose observations, combined with the measurements using geodetic collocation techniques stations on Earth, will contribute to a significant improvement of the International Terrestrial Reference Frame (ITRF).

The ITRF is recognized as the foundation for all space- and ground-based observations in Earth science and navigation, and therefore this mission will potentially have a major impact on several GNSS and Earth observation applications. It is a particular realization of the terrestrial reference system, and its history goes back to 1984 when the former Bureau International de l’Heure, which was then in charge of maintaining an accessible reference frame, established a frame using space-based geodetic techniques. The tradition was continued by the International Earth Rotation and Reference Systems Service (IERS) when it was established in 1987. The IERS has periodically updated the ITRF incorporating new systems, data sets and analysis procedures. The Genesis mission will help identify any systematic errors in the ITRF and thereby improve the accuracy and stability of the frame, particularly the origin and scale of the frame, which are the most critical parameters for scientific applications.

The Genesis mission was endorsed by the ESA Ministerial Council in November 2022. The mission will be executed under the responsibility of ESA’s Navigation Directorate as an element of the Future Navigation Program in cooperation with ESA’s Operations Directorate.

ESA performed an internal mission feasibility study (a so-called concurrent design facility) in March and April 2022. A team of more than 40 experts reviewed the mission objectives and the possible implementation, derived high-level mission requirements, assessed the necessary mission instruments and their technology readiness level and concluded that the mission is feasible and compatible with the Genesis-defined program boundaries.

GENESIS MISSION OBJECTIVES

The overall mission goal, as defined by the Global Geodetic Observing System (GGOS) initiative of the International Association of Geodesy, is to help achieve an ITRF accuracy of 1 millimeter with long-term stability of 0.1 millimeters per year, to be able to detect the smallest variations in the Earth system solid, fluid and gaseous components.

Figure 1: Genesis mission concept.

The improvements of the ITRF will impact and improve multiple geodetic and geophysical observables, as well as precise navigation and positioning, and strengthen the geodetic infrastructure, including the Galileo constellation, by reducing the systematic biases between different observing techniques.

Furthermore, the Genesis mission will allow us to improve the link between the ITRF and the International Celestial Reference Frame (ICRF) due to improvement in determining the Earth orientation parameters (EOPs). The ICRF is a realization of a quasi-inertial reference system defined by extragalactic radio sources, mostly quasars, billions of light years away. The positions of a set of globally distributed VLBI radio telescopes are determined using the difference in the arrival times of the signals at the different telescopes. The ICRF was established and is maintained through a cooperation between the International Astronomical Union and the IERS.

The ITRF and the ICRF are related through the EOPs, which include pole coordinates, the Earth’s rotation angle typically referred to as Universal Time (and the related length of day), and nutation angles and their rates.

GENESIS MISSION OVERVIEW

Figure 2 Genesis project organization.

The baseline orbit of the Genesis satellite will be circular, will have an altitude of about 6,000 kilometers and an inclination of about 95 degrees. The mass of the satellite will be on the order of 250 kilograms to 300 kilogramsg, and it will have very precise on-board metrology, through a single ultra-stable oscillator. An artist’s conception of the satellite in space is shown in the opening image. The launch is foreseen for 2028, and the baseline duration for operations is two years with an option for extension.

The Genesis mission architecture will consist of the Genesis satellite, a ground control segment constituted by a mission control center and a (network of) ground station(s), a data processing center (including a global GNSS sensor station network), a data archiving and distribution center, and the required ground infrastructure for the VLBI, SLR and DORIS campaigns (See FIGURE 1). The scope of the procurement for this mission is the Genesis satellite, the ground control segment, the launch service and two years of operations with the option for extension.

As previously mentioned, the satellite will be launched as the first with all four space-based geodetic techniques on board — namely GNSS, VLBI, SLR and DORIS:

• GNSS receiver. This will be a high-quality multi-constellation (Galileo and GPS) and multi-frequency space receiver. The GNSS observations will be of very high quality and will allow multi-GNSS integer ambiguity resolution for the carrier phase with a very high success rate. This instrument is crucial for the very precise orbit determination of the Genesis satellite.
• VLBI. This instrument will transmit radio signals compatible with receivers at each observing VLBI station. To eliminate the ionospheric dispersive delay along the paths to each station, different frequency bands will be used. The signals will also comply with the evolving observation procedures at all VLBI stations. The signals will be observed by all geodetic VLBI antennas, including the new VLBI Global Observing System (VGOS) fast slewing stations, in their standard geodetic receiver setups. The transmitter currently under development is designed to transmit at different frequencies between 2 GHz and 14 GHz, but also higher frequency bands can be considered. The present setup for regular VGOS observations use four 1-GHz-wide bands within the S, C and X frequency bands. The unit is designed to transmit both pseudo-noise and random noise. The random noise signal mimics the broader-band noise emitted by quasar radio sources routinely observed by VLBI, and hence can be processed essentially by the usual station and correlator software. VLBI observations of Genesis will enable VLBI stations to be accurately located within the ITRF consistently with the other geodetic techniques, enable a frame tie between the celestial frame and the dynamic reference frames of satellite orbits as well as a frame tie between the ITRF and the extremely accurate and stable ICRF.
• SLR. A passive SLR retro-reflector (LRR) will be attached to the satellite in such a way to ensure an adequate field of view when the satellite is in Earth-pointing mode. The SLR observable is the round-trip time of flight of a laser pulse between a ground station and the LLR. Currently, the ITRF long-term origin is defined by SLR, and this is the most accurate satellite technique in sensing the Earth’s center of mass.
• DORIS. Genesis will include a DORIS receiver instrument. DORIS is based on the principle of the Doppler effect between a network of transmitting terrestrial beacons and the on-board instrument. DORIS was first featured on the SPOT-2 satellite launched in 1990. Since then, DORIS receivers have been featured on multiple satellites. The integration of the DORIS receiver on Genesis, given the high-precision knowledge of the Genesis orbit, will benefit other space geodetic techniques from the global DORIS network distribution.

All active instruments will rely on a single high-precision compact frequency standard payload, termed the ultra-stable oscillator.

GENESIS PROJECT ORGANIZATION

The Genesis mission is being procured in an end-to-end approach, meaning that the industry prime is responsible for the development of the satellite, including the payload instruments, the launch services and the satellite operations. For this reason, the following approach has been applied: contract signature was in March 2024. Design, development, validation and acceptance will take place between 2024 and 2027, leading up to a planned launch in 2028.

The contract for Genesis amounts to € 76.6 million. A consortium of 14 entities led by OHB Italia S.p.A. has been tasked with developing, manufacturing, qualifying, calibrating, launching and operating the Genesis satellite, including all its payloads. The mission is supported by Italy, Belgium, France, Switzerland, Hungary and the United Kingdom.

Figure 3 Processing, archiving and distribution of Genesis data and products.

The overall project organization is outlined in FIGURE 2. The ESA Genesis project team, led by the project manager, will manage and coordinate the work of all interfaces among i) the industrial consortium, ii) ESA in its role of handling data processing, archiving and operating the distribution center, iii) the scientific community for whatever the necessary interface is required for the preparation of scientific exploitation and coherency between the project development and the scientific mission objectives.

For the data processing, exploitation, archiving and dissemination of data to the scientific community, the PROcessing, Archiving, exploitation and Dissemination Centre (PROAD) has been set up, (See FIGURE 3), using the European Space Operations Centre (ESOC) Navigation Support Office facilities and the GNSS Science Support Centre (GSSC) of the European Space Astronomy Centre (ESAC).

For the data processing required in advance of scientific exploitation of the data, the ESOC Navigation Support Office facilities will be used. The data processing includes the precise orbit determination for the GENESIS satellite.

Figure 4 Genesis science team.

Furthermore, after the processing performed by ESOC, ESAC’s GSSC will be used for data archiving and data distribution for scientific exploitation. The PROAD will be set up and coordinated internally in ESA.

The setup and coordination of the required ground infrastructure, VLBI and SLR campaigns, the DORIS network and so on, will be managed by ESA’s Genesis project team together with a Genesis science team (See FIGURE 4).

The science team will also support ESA’s Genesis project team as required in the reviews and follow-up activities, especially with respect to compliance with the mission objectives.

SUMMARY

The Genesis mission is a very challenging one, which has been made possible by the combined effort from the scientific community, ESA member states, industry and ESA itself. The success of Genesis will strongly depend on the interaction, cooperation and support of the international scientific community. The mission objectives of Genesis address core scientific as well as societal aspects. Above all, the Genesis mission is at the foundation level of all positioning and navigation.

ACKNOWLEDGEMENTS

This article has drawn, in part, on the multi-author paper “GENESIS: co-location of geodetic techniques in space,” Earth, Planets and Space (2023), Vol. 75, No. 5, https://doi.org/10.1186/s40623-022-01752-w

<p>The post Innovation: ESA’s multi-modal space mission to improve geodetic applications first appeared on GPS World.</p>

Photo: ESA

The European Space Agency (ESA) has upgraded the ground segment of the Galileo satellite navigation system, without any disruption to its users. This update enhances the Galileo Control Segment responsible for managing the constellation of orbiting satellites.

The upgrade involved a series of improvements to both the operational control centers and the extensive network of ground stations. These enhancements are designed to boost the robustness and reliability of the Galileo system, which is crucial to critical applications such as navigation, timing services and emergency response.

With Galileo’s First Generation close to completion, the ground segment required an upgrade to System Build 2.0 to bring critical enhancements to the system, especially for the roll-out of the Public Regulated Service (PRS), which provides highly accurate and robust encrypted signals for authorized governmental users

With the cooperation of the European Union Space Programme Agency (EUSPA) and key industrial partners, ESA ensured a seamless transition, highlighting the effectiveness of international collaboration in advancing satellite navigation technologies.

Click here to visit the official ESA blog and learn more.

<p>The post Galileo ground segment updates first appeared on GPS World.</p>

Photo: Grimaldi

The Grimaldi Satellite Autonomous Berthing (GSAB) project, funded by the European Space Agency (ESA) Navigation Innovation and Support Program (NAVISP) program, has developed a system for automatic, high-precision port berthing operations in large (200m) carrier ships. The system offers ship captains and crew with an overview of ship conditions in real time port settings, including detailed information on maneuvering operations.

Project leader Grimaldi Euromed, in collaboration with two divisions of Kongsberg, conducted the research and development of the new system, including integrating various sensors to provide accurate positioning and ranging data with high integrity. The GSAB system suggests the best path for berthing based on all available and relevant information sources, while augmented reality (AR) goggles provide an intuitive method of visualizing critical berthing information.

System subcomponents include an inertial navigation system (INS) where GNSS measurements are fused with motion/attitude data from the Kongsberg motion gyro compass (MGC). This allows the system to deliver robust and precise data on vessel location, velocities and acceleration. A perception system includes a camera-based sensor for determining steel-to-steel distances from the vessel to any obstruction and quays.

Kongsberg illustrated increased efficiency using to the new system, including a clear reduction in the time required to enter and exit from a port, and a corresponding decrease of emitted pollutants.

Radiolabs, a non-profit research organization, recently joined the GSAB consortium. It focuses on investigating and prototyping a new ground truth reference system, which integrates and fuses GNSS, IMU, and lidar-derived data to provide highly accurate positioning and ranging.

At the recent final presentation of the GSAB project, hosted by ESA, Federica Pascucci of Radiolabs described the results of the project, based in part on previous work in the automotive sector. She said the GSAB work was promising, having verified the effectiveness of Radiolabs’ lidar-based system for positioning, with adaptations necessary for application in maritime scenarios.

The GSAB project demonstrated significant potential cost and time savings benefits and improved safety and environmental performance. The partners will continue their work in the framework of a new ESA NAVISP-funded project, GSAB2, to demonstrate the system’s use in increasingly autonomous vessels and apply newly developed, advanced algorithms based on artificial intelligence.

<p>The post GSAB project showcases assisted port operations solution first appeared on GPS World.</p>

Photo: ESA

The European Space Agency (ESA) has selected Syntony GNSS to supply user demonstration receivers for its low-Earth orbit positioning, navigation and timing (LEO-PNT) project.

Led by Thales Alenia Space and funded by ESA, the first European LEO-PNT project aims to enhance PNT services from LEO. This initiative is expected to improve the accuracy and reliability of navigation systems, serving a wide range of applications, from critical emergency services to everyday technologies.

Syntony will provide its ground receivers, compatible with the new LEO/PNT signals, as well as with GPS and Galileo systems. These receivers will initially assess the performance of signals from the constellation, which will start with fewer than 10 satellites. There will be 100 to 600 satellites when the constellation is complete, according to Syntony.

Although the receivers may not always be able to calculate position, velocity, and time (PVT) due to the lack of available satellites, they will be essential in evaluating signal performance when at least four satellites are visible. This allows for PVT calculations and performance comparisons with existing GNSS systems.

Syntony’s software-defined radio (SDR) receivers enable real-time adjustments to the receiver settings to evaluate the constellation’s performance. This can be achieved without any hardware changes, as the LEO-PNT constellation uses frequencies similar to those used by the medium-Earth orbit (MEO) GNSS systems.

Syntony’s Constellator GNSS Simulator will be updated to incorporate the constellation’s signals as soon as they are available. This process is similar to how the signals from Xona Space Systems’ PULSAR constellation were integrated as early as 2022.

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Photo: Government of Japan

In early 2015, the Navigation Support Office of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) began a collaboration. At its core, the ESA-JAXA collaboration is designed to cross-validate Japan’s Quasi-Zenith Satellite System (QZSS) Precise Orbit Determination (POD) results and share expertise to improve the POD accuracy of QZSS.

The cross-validation of the QZSS POD performance was implemented by jointly analyzing QZSS observations and validating the POD results of the QZSS satellites. As a result of this joint activity, ESA and JAXA have significantly improved the robustness and accuracy of their respective POD products. This collaborative approach not only ensures the continuous improvement of QZSS force modeling and precise orbit determination performance but also demonstrates the effectiveness of international cooperation in advancing the field of space navigation, especially as the benefits of GNSS interoperability become very evident.

An important milestone in this collaboration was ESA’s role in supporting the In-Orbit Testing (IOT) activities for QZS-1R towards the end of 2021. The successful execution of these tests demonstrated the practical results of the ESA-JAXA partnership and further solidified the commitment of both agencies to enhance their capabilities for QZSS POD and associated products.

FIGURE 1 ESA’s Solar Radiation Pressure (SRP) model output in satellite-Sun frame.

The benefits of this collaboration extend beyond the agencies to the entire scientific community. Notable achievements include the revision of metadata for the QZSS constellation, such as the optical properties of the QZS-1 solar arrays, which have been refined and improved through shared expertise, while simultaneously releasing the satellite mass and attitude mode history in a machine-readable file format for easy access and adoption by the users.

To evaluate the spacecraft models and metadata for QZS-1R prior to their public release, ESA and JAXA conducted several comparative tests. Since both organizations use different software packages for satellite POD — ESA uses NAPEOS (Dow, Springer 2009, Enderle et al., 2019 and 2022) and JAXA uses MADOCA (Kawate et al., 2023) — their results can be considered as largely independent. One comparison involved the Solar Radiation Pressure (SRP) model results produced by both organizations. FIGURE 1 shows the accelerations in satellite-Sun frame computed by ESA’s SRP model. The comparison of the computed SRP accelerations in different reference frames, spacecraft-fixed and inertial, showed excellent agreement with differences of less than 0.1 nm/s².

FIGURE 2 One-way Satellite Laser Ranging (SLR) range residuals calculated with respect to QZS- 1R orbits generated with (green) and without (blue) a-priori radiation force models and displayed as function of the Earth-Probe-Sun angle.

In addition, pseudo-range and carrier phase dual-frequency measurement data from 200 tracking stations of the International GNSS Service (IGS) network were used to generate precise QZS-1R satellite orbits and clock offsets on a day-to-day basis over a 12-month period spanning from January to December 2022. Comparison between ESA and JAXA solutions yielded a root-mean-square (RMS) agreement of 8.6 centimeters (orbit) and 0.21 nanoseconds (clock), respectively. Analysis of Satellite Laser Ranging (SLR) data from seven stations of the International Laser Ranging Service (ILRS) suggests a radial RMS accuracy of the generated orbital trajectories of about 4 cm. Without applying the analytical models for SRP and other non-gravitational perturbation forces, such as antenna thrust (AT), the RMS accuracy decreases by a factor of five (FIGURE 2).

In conclusion, the ESA-JAXA collaboration on Japanese Quasi-Zenith Satellite System POD has been a resounding success. Through this continuous and mutual support, performance cross-validation and knowledge sharing, significant improvements related to modeling and subsequently to POD accuracy could be achieved for ESA as well as for JAXA. Additionally, the global scientific community benefitted from this ESA/JAXA collaboration via improved QZSS POD products and validated metadata.

Figure 1 and 2 courtesy of the authors

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Genesis satellite. (Image: ESA)

The European Space Agency (ESA) has initiated two navigation missions, Genesis and low-Earth-orbit positioning, navigation and timing (LEO-PNT) as part of its FutureNAV program. ESA has awarded contracts, totaling €233 million, to several European entities to begin the development of the missions. They are designed to address the growing demand for more resilient and precise navigation solutions in Europe.

Genesis, with a contract value of €76.6 million, involves a consortium led by OHB Italia, tasked with the development and operation of the Genesis satellite and its payloads, supported by contributions from Italy, Belgium, France, Switzerland, Hungary and the UK. The satellite is expected to launch in 2028, with subsequent years dedicated to scientific exploitation. Genesis aims to significantly improve the International Terrestrial Reference Frame (ITRF) and offer unprecedented precision for navigation and a myriad of Earth sciences applications.

For the LEO-PNT mission, ESA has distributed €78.4 million for each of the two contracts for the development of in-orbit demonstrators. These LEO-PNT satellites will explore new signals and frequency bands, designed to provide enhanced resilience, accuracy and speed in navigation. The projects are led by GMV Aerospace and Defense and Thales Alenia Space France and involve a broad consortium of more than 50 entities from 14 countries. The first LEO-PNT satellite is expected to launch within 20 months from the project’s commencement, with the complete constellation operational before 2027.

LEO-PNT satellite. (Image: ESA)

Genesis is designed as a flying observatory to refine the ITRF to an accuracy of 1 mm and a stability of 0.1 mm/year, serving as a crucial reference for all space- and ground-based observations. This enhanced reference frame is designed to directly benefit satellite-based systems and applications across various sectors, including aviation, traffic management and autonomous vehicles. It is intended to have have broader implications for meteorology, natural hazard prediction and climate change monitoring.

The LEO-PNT mission aims to establish a small constellation of demonstration satellites to test novel navigation signals and interoperability with GNSS to offer improved signal robustness and extended navigation services to challenging environments such as deep urban areas and indoors. This mission will explore the potential of LEO constellations in supporting a wide range of applications, from transportation and critical infrastructure to mobile devices and asset tracking using advancements in communication standards, such as 5G/6G.

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Artist impression; size of debris exaggerated as compared to Earth. (Image: ESA)

So much going on up there!

On Jan.11, speaking at a press briefing in Paris, Javier Benedicto, director of navigation for the European Space Agency (ESA), announced the agency had completed the procurement process for the low-Earth Orbit Positioning Navigation and Timing (LEO PNT) program. ESA expects to have the new LEO PNT demonstration satellites, which will broadcast signals over several frequency bands, up and running by 2026. A positive outcome will most likely lead to the procurement and deployment of a full European LEO PNT constellation for global services.

Also in January, news broke that Google and two of the largest mobile network operators in the world, AT&T and Vodafone, had invested more than $200 million in AST SpaceMobile’s cellular broadband network based on LEO satellites and accessible directly by smartphones. AST SpaceMobile already operates the largest-ever commercial communications array in LEO, the BlueWalker 3 satellite, which, due to its size and brightness, is alarming astronomers.

On Feb. 21, The New York Times reported about U.S. warnings to its allies that Russia might deploy a nuclear weapon in orbit this year. According to the paper, U.S. intelligence agencies told their closest European allies that, “if Russia is going to launch a nuclear weapon into orbit, it will probably do so this year — but that it might instead launch a harmless ‘dummy’ warhead into orbit to leave the West guessing about its capabilities.” A space weapon nested inside a satellite could destroy, jam, or otherwise disable dozens or hundreds of commercial and military satellites in LEO, such as the Starlink satellites that are revolutionizing global communications. See Dana Goward’s analysis.

The next day, Tim Crain, chief technology officer of the Houston-based company Intuitive Machines announced, “Houston, Odysseus has found its new home.” For the first time since Apollo 17 in 1972, a U.S.-built spacecraft had landed on the moon. Odysseus, described by the Times as “a bit bigger than a telephone booth,” (which most people under the age of 20 have never seen), was later confirmed to be upright and sending images. It was delivered into lunar orbit by a SpaceX rocket. NASA hopes this mission will help inaugurate a new era of economical spaceflights around the solar system. Intuitive Machines is one of several small companies the agency has hired to transport instruments to reconnoiter the surface of Earth’s only natural satellite in preparation for the return of NASA astronauts.

My highly synthetic description of the Federal Aviation Administration (FAA) aircraft tracking systems in last month’s First Fix was a bit muddled. Fortunately, I can count on our Editorial Advisory Board member Mitch Narins to clarify:

FAA systems determine an aircraft’s position using a combination of independent and dependent surveillance. Independent surveillance does not require the “cooperation” of the aircraft (e.g., primary radar), while dependent surveillance requires the aircraft to either respond to an interrogation signal or periodically transmit its position — e.g., Automatic Dependent Surveillance-broadcast (ADS-B).

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Image: ESA

The European Space Agency (ESA) and the European Commission’s Joint Research Centre (JRC) are collaborating to host the 15th edition of the International Summer School on Global Navigation Satellite Systems (GNSS).

The course is scheduled to take place in Novo Mesto, Slovenia, from July 15 to 26, 2024.

The summer school invites graduate students, Ph.D. candidates, postdoctoral researchers, engineers and academics from both the industry and agencies to attend. The wide range of attendees offers a dynamic environment conducive to learning and networking.

The deadline for registration is June 15. Those who register by April 15 will be offered reduced fees. Additionally, the ESA Education Office is offering up to four scholarships.

The comprehensive curriculum of the summer school encompasses all aspects of GNSS, starting from the fundamental principles of satellite navigation to recent advancements in positioning, navigation and timing services.

Participants will have the opportunity to learn from world-leading experts in the field, including ESA Director of Navigation, Javier Benedicto, former ESA Director General, Jean-Jacques Dordain and former ESA Director of Navigation, Paul Verhoef.

Click here to learn more and register.

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