Abstract Single event upset （SEU） effect, caused by highly energized particles in aerospace, threatens the reliability and security of small satellites composed of commercialofftheshelves （COTS）. SEU induced contr...Abstract Single event upset （SEU） effect, caused by highly energized particles in aerospace, threatens the reliability and security of small satellites composed of commercialofftheshelves （COTS）. SEU induced control flow errors （CFEs） may cause unpredictable behavior or crashes of COTSbased small satellites. This paper proposes a generic softwarebased control flow checking technique （CFC） and bipartite graphbased control flow checking （BGCFC）. To simplify the types of illegal branches, it transforms the conventional control flow graph into the equivalent bipartite graph. It checks the legal ity of control flow at runtime by comparing a global signature with the expected value and introduces consecutive IDs and bitmaps to reduce the time and memory overhead. Theoretical analysis shows that BGCFC can detect all types of internode CFEs with constant time and memory overhead. Practical tests verify the result of theoretical analysis. Compared with previous techniques, BGCFC achieves the highest error detection rate, lower time and memory overhead; the composite result in evaluation fac tor shows that BGCFC is the most effective one among all these techniques. The results in both theory and practice verify the applicability of BGCFC for COTSbased small satellites.展开更多
The full constellation of Chinese Global Navigation Satellite System(GNSS)Bei Dou-3 has been deployed completely and started fully operational service.In addition to providing global Positioning,Navigation and Timing(...The full constellation of Chinese Global Navigation Satellite System(GNSS)Bei Dou-3 has been deployed completely and started fully operational service.In addition to providing global Positioning,Navigation and Timing(PNT)services,the Bei Dou-3 satellites transmissions can also be used as the sources of illumination for Earth Observation(EO)with a bistatic radar configuration.This innovative EO concept,known as GNSS reflectometry(GNSS-R),allows to measure the Earth surface characteristics at high resolution via the reflected L-band radar signals collected by a constellation of small,low cost and low Earth orbiting satellites.For the first time in orbit,earth reflected Bei Dou-3 signal has been detected from the limited sets of raw data collected by the NASA’s Cyclone GNSS(CYGNSS)constellation.The feasibility of spaceborne Bei Dou-3 reflections on two typical applications,including sea surface wind and flooding inundation detection,has been demonstrated.The methodology and results give new strength to the prospect of new spaceborne GNSS-R instruments and missions,which can make multi-GNSS reflectometry observations available to better capture rapidly changing weather systems at better spatio-temporal scales.展开更多
Earth off\|nadir pointing technology can be used on a small satellite to provide larger nadir earth surface imaging coverage. In this paper, the satellite attitude dynamics equations including the gravity\|gradient ...Earth off\|nadir pointing technology can be used on a small satellite to provide larger nadir earth surface imaging coverage. In this paper, the satellite attitude dynamics equations including the gravity\|gradient torque and wheel motor torque are derived using Euler parameters. The necessary conditions for optimum solutions subject to the performance index are obtained via Pontryagin's principle. The resulting two\|point boundary value problem is solved numerically with an optimal slew illustrated by example. 展开更多
基金support from the National Natural Science Foundation of Chinathe Fundamental Research Funds for the Central Universities of China
文摘Abstract Single event upset （SEU） effect, caused by highly energized particles in aerospace, threatens the reliability and security of small satellites composed of commercialofftheshelves （COTS）. SEU induced control flow errors （CFEs） may cause unpredictable behavior or crashes of COTSbased small satellites. This paper proposes a generic softwarebased control flow checking technique （CFC） and bipartite graphbased control flow checking （BGCFC）. To simplify the types of illegal branches, it transforms the conventional control flow graph into the equivalent bipartite graph. It checks the legal ity of control flow at runtime by comparing a global signature with the expected value and introduces consecutive IDs and bitmaps to reduce the time and memory overhead. Theoretical analysis shows that BGCFC can detect all types of internode CFEs with constant time and memory overhead. Practical tests verify the result of theoretical analysis. Compared with previous techniques, BGCFC achieves the highest error detection rate, lower time and memory overhead; the composite result in evaluation fac tor shows that BGCFC is the most effective one among all these techniques. The results in both theory and practice verify the applicability of BGCFC for COTSbased small satellites.
基金supported in part by the Spanish Ministry of Economy and Competitiveness and EU/FEDER(ESP201570014-C2-2-R)the International Science and Technology Cooperation Projects of Shanghai(No.17220730600)the ESA-MOST China Dragon5 Program(ID.58070)。
文摘The full constellation of Chinese Global Navigation Satellite System(GNSS)Bei Dou-3 has been deployed completely and started fully operational service.In addition to providing global Positioning,Navigation and Timing(PNT)services,the Bei Dou-3 satellites transmissions can also be used as the sources of illumination for Earth Observation(EO)with a bistatic radar configuration.This innovative EO concept,known as GNSS reflectometry(GNSS-R),allows to measure the Earth surface characteristics at high resolution via the reflected L-band radar signals collected by a constellation of small,low cost and low Earth orbiting satellites.For the first time in orbit,earth reflected Bei Dou-3 signal has been detected from the limited sets of raw data collected by the NASA’s Cyclone GNSS(CYGNSS)constellation.The feasibility of spaceborne Bei Dou-3 reflections on two typical applications,including sea surface wind and flooding inundation detection,has been demonstrated.The methodology and results give new strength to the prospect of new spaceborne GNSS-R instruments and missions,which can make multi-GNSS reflectometry observations available to better capture rapidly changing weather systems at better spatio-temporal scales.
文摘Earth off\|nadir pointing technology can be used on a small satellite to provide larger nadir earth surface imaging coverage. In this paper, the satellite attitude dynamics equations including the gravity\|gradient torque and wheel motor torque are derived using Euler parameters. The necessary conditions for optimum solutions subject to the performance index are obtained via Pontryagin's principle. The resulting two\|point boundary value problem is solved numerically with an optimal slew illustrated by example.
