Qualification and Flight of a Cutting Edge Sunsensor for Constellation Applications

Satellites for a constellation can be build in a significantly more cost-effective way because the Non-recurring Engineering charges (NRE) can be spread over multiple units. A further significant cost reduction can be achieved if the units and subsystems are optimized for volume production and the units are produced in a continuous production line with a sustainable throughput. Though this optimized production can lead to significant improvement in cost effectiveness, this should in no way impair the reliability of the products. It can be reasoned that the approach implemented by Lens R&D will even increase the reliability of production as it allows for statistical process monitor and control of the product quality. As reliability and cost effectiveness in volume production are core to the Return On Investment (ROI) for constellation owners, these properties have been core design drivers for the BiSon Sunsensors discussed in this paper. After a design change that led to the development of an automated assembly robot, the cutting edge BiSon64-ET and BiSon64-ET-B Sunsensors developed by Lens R&D went through a full ESA qualification program. This means that for the first time ever, a Sunsensor optimized for volume manufacturing has finished a full ESA qualification program. A flight contract has been signed to fly 20 sensors on the two ESA science satellites making up the Proba-3mission. Flight data however already will be received earlier, through a precursor 3U Cubesat mission, flown through the Dutch company Innovative Solutions In Space (ISIS). This paper focusses on the novel manufacturing approach used, the qualification performed and the processes needed to cost effectively produce large quantities of Sunsensors for constellation applications

Measurements on an autonomous wireless payload at 635 km distance using a sensitive radio telescope

The Delfi-C3 spacecraft carries the first autonomous wireless payload in space. This payload is a wireless sun sensor developed by TNO in the Netherlands. The data captured by the sensor is wirelessly transported to the central computer system inside the spacecraft. Since no additional power supply is needed, this sensor is fully autonomous. The radio link is a FSK link at 915 MHz using a standard Nordic Chipset. At the Delfi C3 spacecraft two of these autonomous sun sensors are mounted. Unfortunately only one is operational. Using the Westerbork Synthesis Radio Telescope we tried to detect the 915 MHz signal from the sun sensor to the internal receiver. Before the measurements could be done, the effects of the shielding of the spacecraft case were measured using a spare spacecraft. The final obtained link budget showed a 10 dB SNR when using a 25 meter single dish telescope. Measurements were performed at the WSRT by using multiple radio telescopes placed in the orbit direction. The downlink signal of Delfi C3 was detected, but the 915 MHz signal was not as it should be. We conclude that the sun sensor is malfunctioning

LEO and the Big Blue Marble, a Bad Combination for Albedo Errors

Almost all satellites fly Sunsensors for launch and early orbit (LEOP) and safe mode operations. More than 90% of these are analogue Sunsensors with either an analogue or digital interface. The later are quite often referred to as digital Sunsensors but contrary to a true digital Sunsensor, analogue Sunsensors with a digital interface are still largely affected by albedo generated error signals. Depending on the positioning of the sensor on the satellite, the satellites altitude, and the local node time, albedo errors can lead to significant measurement inaccuracies. This paper describes some research into albedo induced errors in analogue fine Sunsensors as performed while using the data generated by the NAPA-2 satellite. This Satellite was built and is operated by ISISpace. This 6 unit Cubesat has one Auriga startracker and three MAUS Sunsensors on board allowing to compare the startracker determined attitude with the Sunsensor determined attitude. Although the study results are far from complete, preliminary results shown a strong influence of the Earth’s albedo on the measurement accuracy of the Sunsensor

The time for SCOTS has come

With all major European primes starting to work on programs \u3e100 satellites in 2015 the time for Space grade Commercial Off The Shelf components has come. For many years there have been discussions on costs savings by offering COTS components and especially the cubesat community knows several vendors that offer space systems in a COTS fashion. None of these component however qualify for the extreme requirements posed by the current constellations under design as most of them have to operate above 1000 km and are preferred to have a 10 to 15 year lifetime. This leads to several megarads of total dose en 15 years at 1400 km will require the ability to withstand some 65.000 thermal cycles. In order to fulfil these requirements full space grade true high reliability components will be needed where on the other hand the financial constraints are very strong. This is bound to lead to a completely new generation of real high reliability Space grade Commercial Off The Shelf (SCOTS) components. Without knowing these constellations would come, Lens R&D has been focussing on recurring production of true high reliability sensors and now has several sensors in final stage of optimisation which will be offered in a SCOTS approach. The presentation will focus on the mega constellation market, the issues faced when developing SCOTS components and current state of development of our BiSon series of sunsensors

Towards a Scalable Sun Position Sensor with Monolithic Integration of the 3d Optics for Miniaturized Satellite Attitude Control

In this paper we present a sun position sensor platform with a scalable approach for the 3D integration of the sensor optics. This would facilitate the sun position sensor miniaturization, reduces fabrication cost and mitigates the need for sensor calibration. The sun position sensor platform is implemented in a seven mask BICMOS technology with optical windows between the light masking layer and CMOS image sensor implemented by adhesively bonded glass windows. The CMOS sensor functionality is experimentally verified by modulation of a light spot using a laser. The proposed approach enables wafer-scale fabrication of the 3D optics that includes the wafer stepper accurate overlay alignment of the apertures. This mitigates the need for cumbersome alignment of the apertures at die or package level and facilitates further miniaturization, accuracy and sensor cost.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-careElectronic Components, Technology and Material

VMMO Lunar Volatile and Mineralogy Mapping Orbiter

Understanding the lunar near-surface distribution of relevant in-situ resources, such as ilmenite (FeTiO3), and volatiles, such as water/ice, is vital to future sustained manned bases. VMMO is a highly-capable, low-cost 12U Cubesat designed for operation in a lunar frozen orbit. It accomodates the LVMM Lunar Volatile and Mineralogy Mapper and the CLAIRE Compact LunAr Ionising Radiation Environment payloads. LVMM is a multi-wavelength Chemical Lidar using fiber lasers emitting at 532nm and 1560nm, with an optional 1064nm channel, for stand-off mapping of the lunar ice distribution using active laser illumination, with a focus on the permanently-shadowed craters in the lunar south pole. This combination of spectral channels can provide sensitive discrimination of water/ice in various regolith. The fiber-laser technology has heritage in the ongoing Fiber Sensor Demonstrator flying on ESA's Proba-2. LVMM can also be used in a low-power passive mode with an added 280nm UV channel to map the lunar mineralogy and ilmenite distribution during the lunar day using the reflected solar illumination. CLAIRE is designed to provide a highly miniaturized radiation environment and effect monitor. CLAIRE draws on heritage from the MuREM and RM payloads, flown on the UK’s TDS-1 spacecraft. The payload includes PIN-diode sensors to measure ionizing particle fluxes (protons and heavy-ions) and to record the resulting linear energy transfer (LET) energy-deposition spectra. It also includes solid-state RADFET dosimeters to measure accumulated ionizing dose, and dose-rate diode detectors, designed to respond to a Coronal Mass Ejection (CME) or Solar Particle Event (SPE). CLAIRE also includes an electronic component test board, capable of measuring SEEs and TID effects in a selected set of candidate electronics, allowing direct correlations between effects and the real measured environment

Lunar “Volatile and Mineralogy Mapping Orbiter (VMMO)” Mission

Human spaceflight to/on/from the Moon will benefit from exploitation of various in-situ resources such as water volatile and mineral. Evidence for water ice in Permanently Shadowed Regions (PSRs) on the Moon is both direct and indirect, and derives from multiple past missions including Lunar Prospector, Chandrayaan-1 and LCROSS. Recent lunar CubeSats missions proposed through the Space Launch Systems (SLS) such as Lunar Flashlight, LunaH-Map and Lunar Ice-Cube, will help improve our understanding of the spatial distribution of water ice in those lunar cold traps. However, the spatial resolution of the observations from these SLS missions is on the order of one to many kilometres. In other words, they can miss smaller (sub-km) surficial deposits or near-surface deposits of water ice. Given that future lunar landers or rovers destined for PSRs will likely have limited mobility (but improved landing precision), there is a need to improve the spatial accuracy of maps of water ice in PSRs. The VMMO (Volatiles and Mineralogy Mapping Orbiter) is a semiautonomous, low-cost 12U lunar Cubesat being developed by a multi-national team funded through European Space Agency (ESA) for mapping lunar volatiles and mineralogy at relatively high spatial resolutions. It has a potential launch in 2023 as part of the ESA/SSTL lunar communications pathfinder orbiter mission. This paper presents the work carried out so far on VMMO concept design and development including objectives, profile, operations and spacecraft payload and bus

Integrated 64 pixel UV image sensor and readout in a silicon carbide CMOS technology

This work demonstrates the first on-chip UV optoelectronic integration in 4H-SiC CMOS, which includes an image sensor with 64 active pixels and a total of 1263 transistors on a 100 mm2 chip. The reported image sensor offers serial digital, analog, and 2-bit ADC outputs and operates at 0.39 Hz with a maximum power consumption of 60 μW, which are significant improvements over previous reports. UV optoelectronics have applications in flame detection, satellites, astronomy, UV photography, and healthcare. The complexity of this optoelectronic system paves the way for new applications such harsh environment microcontrollers.MicroelectronicsElectronic Components, Technology and Material