With the leap from 5G to 6G, however, the data rate is expected to increase by a factor of 100. The sixth generation (6G) is now expected for 2030. With 5G, the focus was on implementing networks with the shortest possible delay (latency) for industry. With 6G, on the other hand, global network coverage will have an even more significant role. A mainstay of 6G will therefore probably be constellations of small satellites in low earth orbit to be able to communicate with each other even when terrestrial networks are not available. Other technologies that can develop their full potential through use in 6G are Joint Communication and Sensing, Machine Learning and Artificial Intelligence, and Quantum Communication strial networks are unavailable.

As part of the 6G research field, a terrestrial mobile radio network is being set up for research purposes on the campus of the Universität der Bundeswehr München. In the process, the end devices will be able to communicate with each other via the SeRANIS satellite ATHENE1. The network will be expanded in three phases over the entire campus. The university campus is particularly suitable because of the realistic building structure. Thus, there are areas with urban development and with rural characteristics on the site. This enables particularly realistic measurements.

The campus also has a research ground station for satellite communication that is unique in Europe. In the course of the SeRANIS project, this will be equipped with a laser communication terminal which, in combination with the ATHENE1 satellite, will then extend the test mobile communication network into space. The satellite itself will act either as a relay station in space or directly as a base station. Within the framework of the small satellite mission, parts of the future mobile radio protocols will be operated in space for the first time, bringing the “flying cell tower” in space a little closer to reality.

As part of the IoT research area, a test environment is being created for the use of miniaturized transmitter and receiver devices that can communicate directly with a satellite. Our aim is to show that our technology, which already works in Geostationary Earth Orbit (GEO), can also work in Low Earth Orbit (LEO). The SeRANIS satellite ATHENE1 will be able to communicate with tiny battery-operated devices on earth. Such devices can transmit small data packages with emergency messages, sensor values, positions or other information.

CORE OBJECTIVES AND UNIQUE FEATURE

One of our objectives is to create the smallest possible innovative sensor approximately the size of a watch that can be read worldwide via the satellite. To this end, we want to develop, test, verify and compare transmission technologies (including waveforms, algorithms and protocols) in the IoT. These technologies will be more efficient, robust and secure than the status quo.
We also want to be in a position to use existing satellites to test the robustness and safety of IoT systems that are available on the market. In doing so, we will be looking at the systems’ hardware and transmission technology. In particular, we hope to prove their operability, feasibility, efficiency and safety for LEO satellites in real conditions.

These are the result of radiation influences, high variations in temperature, and the risk of collisions with meteoroids or space debris. Global commercialization of space (New Space) involves additional challenges such as high development speeds and the demand for lower costs.

Suitable experiments are being developed for the SeRANIS satellite ATHENE1 and verified in orbit. Due to their high technological maturity level at the end of the mission and having been tested in space, the technologies will be available for application in future missions.

Lightweight designs, materials and resilience are key research topics in modern satellite structures. As part of our development and testing efforts in the research field, a substantial contribution to the further progress of spacecraft structures shall be achieved:

• Integration of mechanical metamaterials and active control concepts into optical benches for high-performance instruments
• Additive manufacturing for space technology applications
• Structural Event Monitoring System (SEM) for in-orbit detection of singular events (collisions with micrometeoroids and space debris)
• New approaches for shielding space radiation by integrating functional layers into load-bearing satellite structures
• Integration of functional layers in a linerless, carbon-fibre-reinforced fuel tank to guarantee that the structure is leak-proof and burns up completely on re-entering the earth’s atmosphere

Mechanical metamaterials have a specially designed mesostructure with which specific required macroscopic material properties (e.g. heat expansion or heat conductivity) can be created. In this way, materials can also be functionalized (smart structures), thus enabling structural actuators and control concepts to be implemented.

In order to be able to counter this problem in future, a customized nadir-oriented antenna for receiving signals in L band and a signal recording unit are being developed and installed in the SeRANIS satellite.

Special requirements are also placed on the necessary complex analysis software which is done in post-processing on the ground with dedicated software tools. This software has to be highly sensitive so that it can detect even very low-powered ground-based interference sources. The analysis software will also be able to geo-localize the emitters by means of using frequency-of-arrival and time-of-arrival measurements of the receiving signal at the satellite.

The payload is being developed in close cooperation with other laboratory units because there are many synergies with the GNSS reflectometry and with other satellite communication experiments. As soon as ATHENE1 is in space, we will be testing the satellite together with the software by deliberately inducing GNSS signal interferences from the Universität der Bundeswehr München campus.

CORE OBJECTIVES AND UNIQUE FEATURE

In addition to developing the hardware, we aim to implement innovative software with the abovementioned requirements. We are tackling the complex task of synchronizing the many individual elements and proving the technology’s ability to function in orbit.

In this context, active antennas – known as phased array antennas – will play a major role by making it easier to reallocate power and frequency resources in desired regions on earth via beamforming. Active beamforming is also a key functionality for information-secure satellite systems that ensures that interference and weak interception performance can be avoided. This paradigm shift brings significant design challenges in terms of hardware complexity and power management onboard the satellite payloads.

Even though advances in the domain of digital onboard processors have recently been achieved, power consumption issues do not allow the use of fully digital beamforming for active satellite antennas. For this reason, intensive research efforts have recently been done in the domain of hybrid (analogue/digital) beamforming, which allows for finding a trade-off between the power consumption of the onboard processor and the complexity of the analogue hardware. The hybrid beamforming experiment planned in the SeRANIS project will pave the way for this key technology to continue maturing.

CORE OBJECTIVES AND UNIQUE FEATURE

The aim of the hybrid beamforming experiment is to identify an optimal trade-off between beamforming performance and onboard power consumption. In this way the feasibility of the hybrid beamforming technology for highly flexible satellite systems with limited power and processing resources will be thoroughly investigated.

To do so, throughout a reflectometry experiment, a portion of the signals from the GNSS satellites are reflected off the Earth’s surface and can be recorded by a receiver on a drone, aircraft, or spacecraft. By analyzing the reflected and direct signal, conclusions can be drawn about the geophysical properties of the Earth’s surface. 

Another possibility to use the continuously transmitted and freely available signals of the GNSS satellites is the so-called occultation measurement. Here, a GNSS satellite disappears on the horizon as seen from the receiver, and in the process, the navigation signal passes through the Earth’s atmosphere. From the doubling shift of the signal as a function of time, profiles of the diffraction angle and the refractivity, respectively, pressure and temperature of the atmosphere can be determined.

CORE OBJECTIVES AND UNIQUE FEATURE

Both occultation and reflectometry measurements require a stable reference source since very small changes in phase or frequency must be measured. New developments in oscillator technology make it possible to provide new-space oscillators with small dimensions, low weight and low power consumption. Therefore, an ultra-stable new-space oscillator will be tested and characterized for the SeRANIS satellite ATHENE1, which meets the frequency stability requirements for GNSS-ROX. 

Due to the high complexity of satellites and their deployment in a difficult environment without maintenance capability or other direct intervention from the ground, various challenges must be investigated, considering the latest technological developments. Thus, an important research topic in the field of mission optimization is the question of how space missions can be designed and technically implemented in a targeted, efficient, and at the same time, highly reliable manner. Therefore, our researchers deal with more than just the classical mission and system design but here exclusively take the opportunity to investigate, develop and apply innovative solutions in all critical activities in a straightforward and practical way.

CORE OBJECTIVES AND UNIQUE FEATURE

Proper handling of unforeseen situations in the context of fault management, highly autonomous operation of payloads, and autonomous planning and execution of manoeuvres are just a few examples of goals the research team is pursuing. In space, these technical challenges are combined with “system of systems” situations, resulting in correspondingly complex solutions. It has implications for the development, verification, validation and operational processes right through to the safe and sustainable disposal of satellites after the end of the mission.

In addition to the detailed technical aspects, topics in the area of complexity management as well as the entire life cycle of satellites, such as verification and validation of AI-based software, the extension of service life (in-orbit servicing, in-orbit recycling, etc.) or safe passivation after mission end, are also considered in context.

For such purposes, electric propulsion systems have proven effective thanks to the precise adjustment options of the generated forces and due to their high efficiency. The advantage of electric spacecraft propulsion systems in comparison to other types of drive systems is their high specific impulse, which requires minimal amounts of propellant. This makes these systems, in particular with regard to attractive for long-term missions. This gives reason to explore solutions for existing problems such as grid erosion in ion thrusters or the scalability of Hall-effect thrusters but also to develop new drive concepts.

CORE OBJECTIVES AND UNIQUE FEATURE

At the Institute for Plasma Technology and Mathematics at the Universität der Bundeswehr, two drive concepts – C-Star and HERVAT – have been designed for positioning satellites and tested under laboratory conditions. The first concept is based on a capacitively-coupled radio frequency discharge, where the charged particles of a quasi-neutral plasma are accelerated by means of magnetic fields. As a result, a C-Star drive does not require any additional components that would prevent build-up of static charge on the satellite (referred to as neutralizers). The concept is scalable and has a long life due to the absence of a cathode. In addition, a C-Star drive can work with different types of fuel, which is not only more environmentally friendly but also makes it possible to reduce running costs. The second concept (HERVAT) is a vacuum discharge system that is most notably characterized by its simple structure and, like the C-Star, does not require a neutralizer. Originally developed for microsatellites (Cube Sat), this system has been tested under laboratory conditions to carry out more than 10 million position-correcting pulses with one tiny unit.