System-Scenario Methodology to Design a Highly Reliable Radiation-Hardened Memory for Space Applications

Cache memory circuits are one of the concerns of computing systems, especially in terms of power consumption, reliability, and high performance. Voltage-scaling techniques can be used to reduce the total power consumption of the caches. However, aggressive voltage scaling significantly increases the probability of memory failure, especially in environments with high radiation levels, such as space. It is, therefore, important to deploy techniques to deal with reliability issues along with voltage scaling. In this chapter, we present a system-scenario methodology for radiation-hardened memory design to keep the reliability during voltage scaling. Although any SRAM array can benefit from the design, we frame our study on the recently proposed radiation-hardened cell, Nwise, which provides high level of tolerance against single event and multi event upsets in memories. To reduce the power consumption while upholding reliability, we leverage the system-scenario-based design methodology to optimize the energy consumption in applications, where system requirements vary dynamically at run time. We demonstrate the use of the methodology with a use case related to satellite systems and solar activity. Our simulations show that we achieve up to 49.3% power consumption saving compared to using a cache design with a fixed nominal power supply level

An SDR Mission Measuring UHF Signal Propagation and Interference between Small Satellites in LEO and Arctic Sensors

Enabling communication to sensor systems in the Arctic is a challenge due to the harsh climate, limited infrastructure and its remote location. In this paper a communication system for Arctic back-haul serving low- power devices to complement existing services is discussed and two small satellite missions are defined. The communication mission objective is to provide Arctic researchers with faster access to scientific data. However, a precursor mission is needed to gather data about the UHF communication channel and interference in the Arctic to design a reliable communication system between Arctic sensors and LEO (Low Earth Orbit) satellites. An SDR (Software Defined Radio) payload is proposed to fly on a small satellite as a secondary payload in order to carry out the radio measurements in a flexible way. The challenges of being a secondary payload are also outlined

HYPSO-1 CubeSat: First Images and In-Orbit Characterization

The HYPSO-1 satellite, a 6U CubeSat carrying a hyperspectral imager, was launched on 13 January 2022, with the Goal of imaging ocean color in support of marine research. This article describes the development and current status of the mission and payload operations, including examples of agile planning, captures with low revisit time and time series acquired during a campaign. The in-orbit performance of the hyperspectral instrument is also characterized. The usable spectral range of the instrument is in the range of 430 nm to 800 nm over 120 bands after binning during nominal captures. The spatial resolvability is found empirically to be below 2.2 pixels in terms of Full-Width at Half-Maximum (FWHM) at 565 nm. This measure corresponds to an inherent ground resolvable resolution of 142 m across-track for close to nadir capture. In the across-track direction, there are 1216 pixels available, which gives a swath width of 70 km. However, the 684 center pixels are used for nominal captures. With the nominal pixels used in the across-track direction, the nadir swath-width is 40 km. The spectral resolution in terms of FWHM is estimated to be close to 5 nm at the center wavelength of 600 nm, and the Signal-to-Noise Ratio (SNR) is evaluated to be greater than 300 at 450 nm to 500 nm for Top-of-Atmosphere (ToA) signals. Examples of images from the first months of operations are also shown.publishedVersio

Study of a 145 MHz Tranceiver

After the planning phase autumn 2006, the work with the student satellite project evolved into sub-system design and prototyping. The work presented in this report considers a proposal for a VHF radio system intended for a small student satellite. The design process started on scratch, not looking much at earlier ncube designs, almost no documentation is to be found about actual construction and final measurements. Three design concepts where developed, one featuring an integrated transceiver, one as a self-designed FSK radio and the last one uses a GMSK-modem to solve modulation and de-modulation issues. As the design was chosen and the work of selecting components commenced, it became clear the chosen design would become not unlike the receiver proposed for ncube. The reason for this is component availability, especially the SA606 IF-sub-system and the GMSK-modem. During test and measurement, a few issues were discovered. The proposed low noise amplifiers seems to be a dead end for this frequencies, and alternatives must be found. The layout for the SA606 is improved and seems to function as required. Since the chosen layout is quite similar to the previous ncube 145 MHz receiver, it shows that the components selected for this designs are a good solution. However, the design is so extensive more work is required before a prototype is ready. It can be questioned if the first design proposal would have been less extensive and could have lead to a finished prototype withing the assigned time frame. Anyway, link budgets and power estimates shows that it is possible to build such a system within the defined limits

On the Use of Micro Satellites as Communication Nodes - in an Arctic Sensor Network

Arktis og verdsrommet er to konsept som er kjelder til fascinasjon og undring for mange av oss. Begge stadane verkar fjerne og ugjestmilde, men samstundes er dei vakre og spanande. Saman utgjer dei ein del av verda som er full av utfordringar, samstundes som dei står for store moglegheiter for vitskap, rekreasjon, kunnskap, undring og inspirasjon. Mange forskarar ynskjer meir og jamnleg oppdatert informasjon om miljøet i dei arktiske områda. I dag eksisterar det ikkje gode kommunikasjonssystem, heller ikkje satellittkommunikasjonssystem, som gjer det mogleg å enkelt hente ut sensordata utan å reise dit sjølv. Gjennom dette arbeidet ynskjer eg å bygge ei bru mellom delar av Arktis til verdsrommet. Resultata frå denne systemstudia kan bringe Arktis nærare oss gjennom eit satellittkommunikasjonssystem, slik at sensorar i Arktis kan nåast av folk som held til i meir sentrale delar av verda. Hovudmotivasjonen for oppgåva var å finne ut om eit kommunikasjonssystem basert på små satellittar kan vere eit brukbart alternativ for å tilby kommunikasjonsløysingar i Arktis. Hovudkonklusjonen viser at det ser ut til å vere mogleg. Småsatellittar har fleire utfordringar og avgrensingar, men ved å designe eit godt system kan dette ha ei yting samanliknbar med andre system, både når ein ser på nytte og på kostnad. Eit av dei viktigaste bidraga i dette arbeidet er studiet av svermar av små satellittar, og korleis ein kan få til desse svermane. Med slike svermar kan ein oppnå god og hyppig dekning, utan å måtte nytte satellittar som har framdriftssystem. Ved å kutte ut framdriftssystemet, vert både kostnad, masse og volum redusert. Dette bidreg også til å redusere oppskytingskostnaden. Det å sende svermen av satellittar ut i bane, ser også mogleg ut, både frå ein teknisk ståstad og frå eit økonomisk perspektiv. Ein av eigenskapane til satellittsvermar er at dekninga ein oppnår på bakken ikkje er konstant. På grunn av at satellittane endrar innbyrdes avstand heile tida, vil dei ved somme tidspunkt sjå ut til å overlappe, og ein mister difor litt kapasitet samanlikna med ein konstellasjon med like mange satellittar. I ein slik konstellasjon held satellittane deira innbyrdes avstand til kvarandre, men då er det naudsynt med eit framdriftssystem for å få dette til. Likevel, for dei fleste tenestene som er diskutert i dette arbeidet handlar det om å flytte informasjon som ikkje er tidskritisk. Difor er det at dekninga endrar seg mindre viktig. Når ein uansett ikkje treng dekning heile tida, spelar variasjon i dekning, samt kor lang tid det tek å flytte informasjonen frå sensor til sluttbrukar ei mindre rolle. Eit anna bidrag frå dette arbeidet er ei systemanalyse om korleis ein heterogen kommunikasjonsarkitektur kan verte definert. Ulike nettverk kan koplast saman gjennom standard internettprotokollar tilpassa Internet of Things (IoT). Slik kan sensorar som står på aude stadar koplast saman med ein sluttbrukar, gjennom internett. Ved bruk av dei vanlege internettprotokollane, sikrar ein at ulike typar utstyr og ulike typar nettverk kan snakke saman. Desse nettverka kan vere lokale linkar i grupper av sensorar, det kan vere satellittlinkar mellom sensorar og ein satellitt, eller mellom satellitt og ein bakkestasjon. I tillegg kan andre bemanna eller ubemanna fartøy frakte data frå ein del av eit nettverk til ein annan del. Desse fartøya kan vere anten i lufta, på eller i sjøen, alt etter som kvar sensoren er plassert. Når ein skal lage eit system for radiokommunikasjon er linkbudsjettet eit av dei viktigaste elementa som må studerast. Her har ein studert forskjellige fenomen som alle har ein innverknad på linkbudsjettet, og ei mogleg løysing er presentert. Likevel, ein må oppfylle fleire føresetnader for at linkbudsjettet skal vere nyttig. For å kunne lage eit system som har ei stor nok datarate til at det blir brukbart, må satellitten verte bygd for å kompensere for nokre av avgrensingane som vil finnast i ein typisk sensor i Arktis. Om ein ynskjer ei enno høgare datarate i systemet, treng også sensoren på bakken ei antenne med ei viss vinning. Dette er eit av fleire spennande tema som er føreslått som vidare arbeid. Kostnaden ved å ta fram eit slikt system er også studert. Her er satellittsystemet samanlikna med eit system som bygger på bruk av ubemanna flygande fartøy, og eit system som nyttar eit fly til å samle inn data frå sensorane. Satellittsystemet vil kunne gi dekning mykje oftare, og vil vere i stand til å hente inn ei samanliknbar mengde data, til ein samanliknbar kostnad. For å summere opp, så viser dette arbeidet at eit eige satellittsystem er ei god løysing på utfordringa det er å skaffe vitskaplege data frå sensorsystem i Arktis, og få dette levert til vitskapsfolk her heime. Arbeidet er basert på etablerte arbeidsmetodar for design og analyse av romprosjekt

Enabling the Internet of Arctic Things with Freely-Drifting Small-Satellite Swarms

The widespread deployment of Internet-capable devices, also known as the Internet of Things (IoT), reaches even the most remote areas of the planet, including the Arctic. However, and despite the vast scientific and economic interest in this area, communication infrastructures are scarce. Nowadays, existing options rely on solutions such as Iridium, which can be limited and too costly. This paper proposes and evaluates an alternative to existing solutions, using small satellites deployed as a freely-drifting swarm. By combining these simpler and more affordable satellites with standard protocols, we show how IoT can be supported in the Arctic. Networking protocols and link characteristics are emulated for 3 different satellite orbits and 4 ground nodes. The impact of different protocols and communication conditions is assessed over a period of 49 days and a cross-layer routing approach proposed. The obtained results reveal that a communication overhead bellow 27 % can be achieved and that the implemented satellite-aware route selection allows reducing the end-to-end time of a request up to 93 min on average. This confirms that freely-drifting small-satellite swarms may enable the Internet of Things even in the most remote areas

Freely-Drifting Small-Satellite Swarms for Sensor Networks in the Arctic

Satellite communications have been widely used to provide connectivity around the world. However, regions such as the Arctic still have limited coverage, despite the need to monitor this region. Currently, several sensors are deployed in the Arctic, but are limited by poor and costly connectivity. Constellations of small satellites, or CubeSats, have been proposed in order to overcome this lack of connectivity, offering an alternative to typical satellite solutions. However, these constellations face challenges in their deployment and in orbital station keeping. In this paper, we propose a simpler deployment of small satellites, in the form of a drifting swarm, integrated with networking protocols widely used in the Internet of Things (IoT). A realistic setup is considered, evaluating this solution taking into account the position of sensor nodes, ground stations and the dynamics of such a drifting swarm. The topology evolution of the small-satellite swarm is studied and all its link characteristics are emulated using a real network stack and protocols. The obtained results prove the feasibility of the proposed solution and show that a freely drifting satellite swarm, with three small satellites, outperforms more costly solutions. Our results also show that by using standardised networking protocols, a satellite architecture with two ground stations connected over the Internet, can reduce the average end-to-end time of a request from 88 to 38 min. The obtained results motivate the use of freely drifting swarms of small satellites for reaching sensor nodes in remote locations, as well as the use of IoT protocols for improved performance

Digital Engineering Management in an Academic CubeSat Project

Digital engineering is increasingly introduced for managing and supporting the development of systems for space. However, few academic teams have the competency needed to manage projects using digital engineering and systems engineering. The subject of this paper is an academic CubeSat project in which a variety of digital engineering techniques are used. The tailoring that has been applied to fit the academic environment including students from different disciplines and levels of maturity is described. This paper shows how a customized Scrum methodology for hardware and software integrated with a workflow in a digital tool environment has given positive results for both the team and the system development. This paper also discusses how to introduce new members to the team and how to train them to work with digital engineering as a multidisciplinary team. This paper presents how the systems engineering and project management activities have been integrated into the academic CubeSat project, evaluate how well this fusion worked, and estimate its potential to be used as a guide for other digital engineering projects