NASA is planning to send people to Mars by 2033. NASA is not alone in having Mars Ambitions. . China has announced plans to build a manned moon base which will explore lunar resources and act as a launchpad for missions to Mars. A number of companies in the telecom sector are taking various initiatives to launch constellations of nanosatellites and microsatellites to offer their users faster internet services and additional bandwidth. Defense organizations have been launching communication nanosatellites and microsatellites to provide communication signals to soldiers stationed in remote locations or in dense forests.
Deep-space and long-duration missions, where both crew members and spacecraft no longer benefit from the protection of Earth’s magnetic fields, are considered high risk for adverse radiation impacts. Aircraft flying at altitude, at about 30,000 feet and above, also are starting to experience radiation-induced effects. “There are 500 times more neutrons at 30,000 feet than there are on the ground,” points out Aitech’s Romaniuk. Long term exposure of astronauts to radiation is problematic and the effect that space radiation has on spacecraft electronics and software is equally challenging.
Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. For modern weather, communications and surveillance satellites to be cost-effective, they need to be operational for at least 10 to 15 years. Onboard electronic equipment failures are a common reason for early satellite failure. But with extended space missions comes the requirement for flawless performance by on-board equipment over a period of years, in a very harsh environment. Ensuring the reliable operation of microcircuits in outer space is an important scientific and economic objective.
Breakthrough Initiatives established by Yuri Milner , in 2017 conducted a successful test flight of its first spacecraft known as “Sprites”, the credit card sized smallest spacecraft ever launched, By leveraging recent developments in computing and miniaturization, spacecraft would be capable of carrying all the necessary sensors, microprocessors and microthrusters, but would be so small and light that it would take much less energy to accelerate them to relativistic speeds – in the case of Starshot, up to 20 percent the speed of light.
“The launch of the Sprite satellites marks the first demonstration that miniaturized electronics on small chips can be launched without damage, survive the harsh environment of space and communicate successfully with earth. The Starshot Initiative aims to launch similar chips attached to a lightweight sail that it being pushed by a laser beam to a fifth of the speed of light, so that its camera, communication and navigation devices (whose total weight is of order a gram) will reach the nearest planet outside the solar System within our generation.”
Challenges of Space Electronics
The first hurdle for space electronics to overcome is the vibration imposed by the launch vehicle. Rocket launchers generate extreme noise and vibration. When a satellite separates from the rocket in space, large shocks occur in the satellite’s body structure.
Pyrotechnic shock is the dynamic structural shock that occurs when an explosion occurs on a structure. Pyroshock is the response of the structure to high frequency, high magnitude stress waves that propagate throughout the structure as a result of an explosive charge, like the ones used in a satellite ejection or the separation of two stages of a multistage rocket. Pyroshock exposure can damage circuit boards, short electrical components, or cause all sorts of other issues.
Outgassing is another major concern. Plastics, glues, and adhesives can and do outgas. V apor coming off of plastic devices can deposit material on optical devices, thereby degrading their performance.
High levels of contamination on surfaces can contribute to electrostatic discharge. Satellites are vulnerable to charging and discharging. Discharges as high as 20,000 V have been known to occur on satellites in geosynchronous orbits. If protective design measures are not taken, electrostatic discharge, a buildup of energy from the space environment, can damage the devices. A design solution used in geosynchronous Earth orbit (GEO) is to coat all the outside surfaces of the satellite with a conducting material.
The atmosphere in LEO is comprised of about 96% atomic oxygen. Atomic oxygen can react with organic materials on spacecraft exteriors and gradually damage themPlastics are considerably sensitive to atomic oxygen and ionizing radiation. Coatings resistant to atomic oxygen are a common protection method for plastics.
Another obstacle is the very high temperature fluctuations encountered by a spacecraft. Because it is closer to the Sun, the temperature fluctuations on a satellite in GEO stationary orbit will be much greater than the temperature variations on a satellite in LEO. Here again, ceramic packages can withstand repeated temperature fluctuations, provide a greater level of hermeticity , and remain functional at higher power levels and temperatures. Ceramic packages provide higher reliability in harsh environments.
New space system implementations require the use of advanced microelectronic devices as well as reduction of mass, power and volume make the situation more challenging. However, newly developed advanced microelectronic devices lack the traditional reliability and characterization data necessary for qualification for insertion into space systems.
RF Payload Systems deals with not only the specific radio technologies, equipments (low and high power amplifiers, filters, frequency converters) and systems aboard a spacecraft tasked with delivering mission objectives, but also the supporting ground equipment and telecommunication systems through which spacecraft payloads are controlled and results communicated to mission control.
Radiation effects (total dose, latchup, single event upsets) are one of the main concerns for space microelectronics. The design of radiation-hardened integrated circuits ( RHlCs ) involves four primary efforts. First is the selection of a technology and process which are relatively insensitive to the projected application environment of the IC.
Second, parts representative of the selected technology must be characterized in a simulated environment that models the RHIC’s application environment in order to quantify the effects of the environment on material and device characteristics. In the third phase, the circuit design techniques which make device responses most insensitive to the radiation are selected based on the technology analyses, and implemented in an IC design. The fourth phase actually occurs throughout the design process. Computer simulations of the chip response in pertinent environments should be performed as a part of each cycle of the design, manufacture, and testing processes, write Sherra E. Kerns, Senior Member, IEEE, And B. D. Shafer, Department of Electrical Engineering, Vanderbilt University, Nashville, TN 37235, USA.
Space Electronics and Microelectronics
The basic elements of a spacecraft are divided into two sections: the platform or bus and the payload. The platform consists of the five basic subsystems that support the payload: the structural subsystem, the telemetry subsystem, tracking and command subsystems, the electric power and distribution subsystem, the thermal control subsystem, and the attitude and velocity control subsystem.
The payload is the equipment in support of the primary mission. For GPS navigation satellites, this would include atomic clocks, navigation signal generators, and high power RF amplifiers and antennas. For telecommunications systems, the payload would include antennas, transmitters and receivers, low noise amplifiers, mixers and local oscillators, demodulator and modulators, and power amplifiers. Earth observation payloads would include microwave and infrared sounding instruments for weather forecasting, visible infrared imaging radiometers, ozone mapping instruments, visible and infrared cameras, and sensor.
Microengineering is a discipline dealing with the design, materials synthesis, micro-machining, assembly, integration and packaging of miniature 2-D and 3-D sensors, actuators, microelectronics and microelectro-mechanical systems.
Designing and developing new components for specific space projects will often require engineers to expand the applications of existing devices. Leti’s RF MEMS switches, for example, which had been previously studied for land-based operations, have been adapted to the specific requirements of space missions.
One of the main tasks of the Microelectronics Section is to ensure the availability of suitable FPGA and ASIC technologies for users in the space community. The specific constraints of space projects (e.g. radiation environment, high reliability, low order quantities, long product lifetimes and long development cycles) have to be considered.
Reprogrammable (SRAM based) FPGA (RFPGA), featuring high flexibility, combined with high performance and complexity become increasingly important also for space applications. Reprogrammable FPGAs allow modification of the unit depending on the mission phases, replacing several units by a single one which can be reconfigured accordingly. With satellite lifetimes increased far beyond 10 years, much longer than the validity of telecom standards, reprogrammability in flight becomes a stringent requirement.
Advanced ASIC and FPGA technologies allow to integrate complex systems on a single chip, embedding standard processor devices, dedicated processing blocks, interfaces to various peripherals, on-chip bus structures in a SOC, or even analog blocks in a mixed-signal device. Moving away from the use of traditional components towards SOC technology will help to satisfy the ever-increasing demands for high processing performance, while reducing mass and power consumption.
With increasing complexity, the design methodology has changed from being gate-level oriented to the integration of complex building blocks (IP-cores). Tasks, which traditionally are considered as ‘system-design’, such as interface specification, bus throughput assessment etc. are now part of the chip design. But different IP-blocks from various origins imply different coding styles, documentation and verification levels. Their interoperability and compliance to the overall SOC specification ultimately has to be verified on chip level.
Analogue and Mixed-Signal IPs for Space
The functionality and performance of the satellites is heavily constrained by Mass, Size and Power. The development is in turn heavily constrained by Costs.
Technology downscaling has allowed to increase processing power of digital electronics, at relatively constant mass, size and power. Analogue circuits have to deal with increased data rates from the digital and the number of analogue interfaces, types and required accuracy in satellites is slowly rising. Unfortunately analogue circuits usually suffer from technology downscaling.
Taking the example of analogue-to-digital and digital-to-analogue converters, bandwidth can only be increased for converters at constant Mass, Size and Power consumption by reducing sensitivity. For increased sensitivity only integration offers the means to meet increased bandwidth at constant Mass and Size.
Consequently, new circuit designs and processes are required to increase performance and reduce the Power consumption. Analogue and Mixed-Signal IP-Cores are required to facilitate integration and keep development Cost within bounds. The availability of qualified IP mixed-signal blocks is also a key element to reduce development risk of integrated ASICs. Therefore, and in accordance to its mission “to provide and promote, for exclusively peaceful purposes, cooperation among European states in space research and technology and their space applications”, Says ESA
In the space domain, the FPGA as well as other electronic devices suffer from radiation-induced faults and for that reason space-qualified FPGAs are protected. Protection is added in electronics technology as hardened by design processes or in the firmware design as a fault-tolerant functional architecture implementation. One example of European high-performance and radiation-hardened FPGAs are the NG-MEDIUM and NG-LARGE devices from NanoXplore, which GMV developed in the QUEENS-FPGA ESA project for deep analysis and evaluation, including a high-performance computer-vision implementation for the satellite capture phase of the Active Debris Removal scenario.
FPGA hardware is a device where programmers can exploit parallelism and pipelining techniques in order to accelerate the execution of time-consuming algorithms, or to implement interface protocols and data manipulation in streaming. GMV applies this knowledge and capabilities for the selection of FPGA-based co-processors in space avionics. For instance, in the Mars Sample Return mission GMV provides the Sample Fetching Rover of the mission with a localization and mapping system based on stereo-vision images of the surface close to the rover. Complex image processing is performed in real-time with high speed requirements. An accurate and precise image-processing algorithm used for this task would not be feasible in the mission if part of this code is not re-implemented into the FPGA. Another example of image processing is the Vision-Based Navigation system for Phobos Sample Return mission guiding the Descent and Landing of the spacecraft onto the surface of Phobos at a specific design position in an autonomous way without Ground Control Center support (from Earth).
Precise algorithm-implementing feature detection and tracking, allowing control of the spacecraft, takes far more than 1 second per frame in conventionally used space-qualified processors in software. The same algorithm, re-designed and implemented in an FPGA takes less than 130 milliseconds. In the HERA mission, GMV Romania is designing an Interface Control Unit (ICU) board that gathers information from different spacecraft sensors in parallel through different types of interfaces and at different speeds. In addition, the HERA ICU provides room for the image processing acceleration needed in the Guidance, Navigation and Control functions, as well as implementing data compression of sensor data to reduce the downlink communication to Earth.
Xilinx launches industry’s first 20nm space-grade FPGA for space applications
Xilinx, Inc. (NASDAQ: XLNX), the leader in adaptive and intelligent computing, announced the industry’s first 20-nanometer (nm) space-grade FPGA, delivering full radiation tolerance and ultra-high throughput and bandwidth performance for satellite and space applications. The new 20nm Radiation Tolerant (RT) Kintex® UltraScale™ XQRKU060 FPGA provides true unlimited on-orbit reconfiguration, over a10x increase in digital signal processing (DSP) performance – ideal for payload applications – and full radiation tolerance across all orbits.
Xilinx’s 20-nanometer Radiation Tolerant Kintex UltraScale (XQRKU060) FPGA can enable the designers of high-throughput and high-bandwidth satellites to process data on board with a 10X Increase in DSP compute, compared to prior generation Xilinx Space FPGA. This offers 400 gigabits per second aggregate bandwidth with the 32 SERDES running at 12.5 gigabits per second per lane. The XQRKU060 provides true unlimited on-orbit reconfigurability and a machine learning ecosystem for high-performance edge inference in space.
Often, the task of processing raw sensor information is in-depth and requires signal-processing-intensive techniques such as non-uniformity correction, decimation, equalization, pulse compression, beamforming, and a variety of others. The task of then rendering usable images can include additional tasks such as rotation, back-projection, and ortho-rectification. Not all these tasks have traditionally been possible on-orbit, but the XQRKU060 now opens the door to making this possible.
The XQRKU060 also brings high performance machine learning (ML) to space for the first time. A diverse portfolio of ML development tools supporting industry standard frameworks, including TensorFlow and PyTorch, enable neural network inference acceleration for real-time on-board processing in space with a complete “process and analyze” solution. The XQRKU060’s dense, power-efficient compute with scalable precision and large on-chip memory provides 5.7 tera operations per second (TOPs) of peak INT8 performance optimized for deep learning, a nearly 25X increase compared to the prior generation.
Building on Xilinx’s space heritage and highly successful 65nm space-grade devices, the launch of the first 20nm part for space applications advances the space industry by three process node generations. It delivers a significant reduction in size, weight and power, and is engineered with robust radiation tolerant features. The XQRKU060 provides customers with a space-resilient device equipped to handle both short and long duration missions in harsh space environments.
“With our extensive history in developing leading-edge, radiation tolerant technology and deploying this in reliable space-grade solutions, Xilinx continues its lead with the launch of the world’s most advanced process node for space,” said Minal Sawant, system architect and space products manager, at Xilinx. “The 20nm RT Kintex UltraScale FPGA is breaking industry standards and setting a new benchmark for meeting the high compute requirements of high bandwidth payloads, space exploration and research missions.”
The XQRKU060 is the industry’s only true unlimited on-orbit reconfigurable solution. The onorbit reconfiguration capabilities, together with real-time on-board processing and ML acceleration, allows satellites to update in real-time, deliver video-on-demand and perform compute “on-the-fly” to process complex algorithms. The ML capabilities are suitable to a variety of problems spanning scientific analysis, object detection, and image classification – such as cloud detection – enabling improved processing efficiency and reduced decision latency both in space and on the ground. As protocols and applications progressively change, the adaptive compute architecture of the XQRKU060 allows unlimited on-orbit reconfiguration to enable customers to perform last-minute product updates prior to launch, as well as after it has been deployed in orbit.
Performance and Resiliency for Space
The XQRKU060 offers rich DSP capabilities optimized for dense power-efficient compute. It is equipped with 2,760 UltraScale DSP slices and provides up to 1.6 TeraMACs of signal processing compute, more than a 10X increase compared to the prior generation, as well as dramatic efficiency gains for floating point computations. The increased compute capability in space is paired with massive I/O bandwidth from 32 high-speed transceivers (SerDes) that can run up to 12.5Gbps to deliver 400Gbps aggregate bandwidth.
The XQRKU060 features robust 40×40 mm ceramic packaging capable of withstanding vibrations and handling during launch as well as radiation effects in harsh orbit environments. The architecture features an innovative design for single event effects (SEE) mitigation thereby meeting the industry requirements for all orbits, including low earth orbit (LEO), medium earth orbit (MEO), geosynchronous orbit (GEO), and deep space missions.
Yuji Zhao, an expert in electrical and computer engineering at Arizona State University (ASU), noted that due to the intrinsic properties of silicon, integrated circuits (IC) based on this material malfunction at high temperature (about 300 degrees Celsius) and operate at low frequency. New materials such as SOI and GaN (gallium nitride), are leading to improved component performance for telecom satellites, embedded software on optical detectors, integrated RF amplifiers and high power computing.
Introduction of Silicon On Insulator technology into commercial product lines is driven by the need for high-performance low-power integrated devices. Moreover, SOI has been the technology of choice for many space semiconductor manufacturers where radiation requirements are critical. This technology has inherent radiation latch-up immunity built into the process, which makes it very attractive to space applications.
GaN material is thermally robust and chemically stable, good at handling high temperature and radiation environments. Moreover, the GaN high electron mobility transistor (HEMT) technology allows monolithic integration of various GaN-based devices with ultrafast frequency response (100x) due to the two-dimensional electron gas. Besides LEDs, GaN can be used in the production of semiconductor power devices as well as RF components.
“This material will be needed the most for the missions with high temperature destinations. For NASA, this project would be beneficial for numerous missions, especially for the Science Mission Directorate missions focused on destinations with high-temperature environments, such as the Venus surface, Mercury, or the deep atmosphere of gas giants,” Zhao said. Leti is also focused on developing detectors with high temporal resolution that can detect a very small number of photons operating under the hazardous conditions of deep space. Increasing the gain of avalanche photodiodes (APDs) without adding more than a negligible amount of noise boosts the sensitivity of photon detectors. Leti and CNES showed that APDs made of HgCdTe (mercury cadmium telluride) significantly outperform those based on other semiconductor materials, making it possible to greatly improve their sensitivity, while maintaining a nearly constant signal-to-noise ratio.
In 2016, Leti and CNES conducted the first space qualification tests of HgCdTe APD technology, which showed that this APD can be used for a number of space applications. More recent tests demonstrated that our HgCdTe APDs could achieve 4GHz bandwidth, confirming estimates on the response time limitations in these devices, and providing evidence that bandwidths in the order of 10GHz can be achieved with them.
HgCdTe APD is also an enabling technology for inter-satellite communications in global Internet networks, where the devices’ high sensitivity can be used to reduce the complexity of the terminals, increase bandwidth, and/or reduce emitted laser power. HgCdTe APDs’ use for deep space optical telecommunications will allow space vehicles exploring the far reaches of our solar system to send more data back to earth. The higher the data collection capacities of these explorers, the bigger the data rate they will need.
The growth and maturity of the semiconductor industry has resulted in substantial improvements in processing methods, fabrication yield, and overall quality of commercially viable semiconductor devices. This coupled with large volume production and the utilization of statistical process control has greatly reduced the infant mortality population across the industry.
However, for critical space applications where the success or failure of a mission hinges on the lifetime and performance of a single device; it is critical that all aspects of the reliability and the various known failure modes and mechanisms be addressed prior to the insertion of the component in the application. The selection and application of microelectronic components in high reliability space systems requires knowledge of the component design, fabrication process, and applicable tests. In addition, reliability analysis and detailed knowledge of the application environment is necessary in order to determine the suitability of the selected component for the application.