scholarly journals Thermal deformation of 3U CubeSat in low Earth orbit

2018 ◽  
Vol 158 ◽  
pp. 01013
Author(s):  
Vasily Gorev ◽  
Anatoly Pelemeshko ◽  
Alexander Zadorozhny ◽  
Aleksey Sidorchuk
Keyword(s):  
Thermal Deformation ◽  
Low Earth Orbit ◽  
Laser Communication ◽  
Earth Orbit ◽  
Small Satellite ◽  
Satellite Structure ◽  
Satellite Laser Communication ◽  
Pointing Accuracy ◽  
Uneven Heating ◽  
The Impact

The impact of uneven heating on a satellite structure in low Earth orbit has been considered using the example of 3U CubeSat. The calculations showed that the thermal deformation of CubeSat structure in orbit caused a deviation between normals to opposite small satellite sides of about 0.03°. Such a deviation is commensurate with the required satellite pointing accuracy approximately 0.1° necessary for satellite laser communication. It means that to solve similar problems in the CubeSat designing that require such or better CubeSat pointing accuracy, it is necessary to take into account the expected satellite structure thermal deformation.

scholarly journals Shipborne Acquisition, Tracking, and Pointing Experimental Verifications Towards Satellite-to-Sea Laser Communication

2019 ◽  
Vol 9 (18) ◽  
pp. 3940 ◽  
Author(s):  
He ◽  
Wang ◽  
Liu ◽  
Song ◽  
Zhou ◽  
...  
Keyword(s):  
Low Earth Orbit ◽  
Laser Communication ◽  
Earth Orbit ◽  
Tracking Accuracy ◽  
Pointing Error ◽  
Optical Links ◽  
Laser Communications ◽  
Low Earth Orbit Satellites ◽  
Pointing Accuracy ◽  
Acquisition Strategy

Acquisition, tracking, and pointing (ATP) is a key technology in free space laser communication that has a characteristically high precision. In this paper, we report the acquisition and tracking of low-Earth-orbit satellites using shipborne ATP and verify the feasibility of establishing optical links between laser communication satellites and ships in the future. In particular, we developed a shipborne ATP system for satellite-to-sea applications in laser communications. We also designed an acquisition strategy for satellite-to-sea laser communication. In addition, a method was proposed for improving shipborne ATP pointing error. We tracked some stars at sea, achieving a pointing accuracy of less than 180μrad.We then acquired and tracked some low-Earth-orbit satellites at sea, achieving a tracking accuracy of about 20μrad. The results achieved in this work experimentally demonstrate the feasibility of ATP in satellite-to-sea laser communications.

scholarly journals In Situ Measurement of Carbon Fibre/Polyether Ether Ketone Thermal Expansion in Low Earth Orbit

Aerospace ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 35 ◽  
Author(s):  
Farhan Abdullah ◽  
Kei-ichi Okuyama ◽  
Isai Fajardo ◽  
Naoya Urakami
Keyword(s):  
Thermal Expansion ◽  
Carbon Fibre ◽  
Material Science ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Small Satellite ◽  
Polyether Ether Ketone ◽  
Ether Ketone ◽  
Orbit Data

The low Earth orbit (LEO) environment exposes spacecraft to factors that can degrade the dimensional stability of the structure. Carbon Fibre/Polyether Ether Ketone (CF/PEEK) can limit such degradations. However, there are limited in-orbit data on the performance of CF/PEEK. Usage of small satellite as material science research platform can address such limitations. This paper discusses the design of a material science experiment termed material mission (MM) onboard Ten-Koh satellite, which allows in situ measurements of coefficient of thermal expansion (CTE) for CF/PEEK samples in LEO. Results from ground tests before launch demonstrated the feasibility of the MM design. Analysis of in-orbit data indicated that the CTE values exhibit a non-linear temperature dependence, and there was no shift in CTE values after four months. The acquired in-orbit data was consistent with previous ground tests and in-orbit data. The MM experiment provides data to verify the ground test of CF/PEEK performance in LEO. MM also proved the potential of small satellite as a platform for conducting meaningful material science experiments.

Body pointing, acquisition and tracking for small satellite laser communication

2019 ◽  
Author(s):  
Jessica Chang ◽  
Curt M. Schieler ◽  
Kathleen M. Riesing ◽  
Jamie W. Burnside ◽  
Kenneth Aquino ◽  
...  
Keyword(s):  
Laser Communication ◽  
Small Satellite ◽  
Satellite Laser Communication

scholarly journals Atmospheric drag effects on modelled low Earth orbit (LEO) satellites during the July 2000 Bastille Day event in contrast to an interval of geomagnetically quiet conditions

2021 ◽  
Vol 39 (3) ◽  
pp. 397-412
Author(s):  
Victor U. J. Nwankwo ◽  
William Denig ◽  
Sandip K. Chakrabarti ◽  
Muyiwa P. Ajakaiye ◽  
Johnson Fatokun ◽  
...  
Keyword(s):  
Geomagnetic Activity ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Satellite Orbits ◽  
Percentage Increase ◽  
Atmospheric Drag ◽  
Drag Effect ◽  
Satellite Drag ◽  
Ballistic Coefficient ◽  
The Impact

Abstract. In this work, we simulated the atmospheric drag effect on two model SmallSats (small satellites) in low Earth orbit (LEO) with different ballistic coefficients during 1-month intervals of solar–geomagnetic quiet and perturbed conditions. The goal of this effort was to quantify how solar–geomagnetic activity influences atmospheric drag and perturbs satellite orbits, with particular emphasis on the Bastille Day event. Atmospheric drag compromises satellite operations due to increased ephemeris errors, attitude positional uncertainties and premature satellite re-entry. During a 1-month interval of generally quiescent solar–geomagnetic activity (July 2006), the decay in altitude (h) was a modest 0.53 km (0.66 km) for the satellite with the smaller (larger) ballistic coefficient of 2.2×10-3 m2 kg−1 (3.03×10-3 m2 kg−1). The associated orbital decay rates (ODRs) during this quiet interval ranged from 13 to 23 m per day (from 16 to 29 m per day). For the disturbed interval of July 2000 the significantly increased altitude loss and range of ODRs were 2.77 km (3.09 km) and 65 to 120 m per day (78 to 142 m per day), respectively. Within the two periods, more detailed analyses over 12 d intervals of extremely quiet and disturbed conditions revealed respective orbital decays of 0.16 km (0.20 km) and 1.14 km (1.27 km) for the satellite with the smaller (larger) ballistic coefficient. In essence, the model results show that there was a 6- to 7-fold increase in the deleterious impacts of satellite drag between the quiet and disturbed periods. We also estimated the enhanced atmospheric drag effect on the satellites' parameters caused by the July 2000 Bastille Day event (in contrast to the interval of geomagnetically quiet conditions). The additional percentage increase, due to the Bastille Day event, to the monthly mean values of h and ODR are 34.69 % and 50.13 % for Sat-A and 36.45 % and 68.95 % for Sat-B. These simulations confirmed (i) the dependence of atmospheric drag force on a satellite's ballistic coefficient, and (ii) that increased solar–geomagnetic activity substantially raises the degrading effect of satellite drag. In addition, the results indicate that the impact of short-duration geomagnetic transients (such as the Bastille Day storm) can have a further deleterious effect on normal satellite operations. Thus, this work increases the visibility and contributes to the scientific knowledge surrounding the Bastille Day event and also motivates the introduction of new indices used to describe and estimate the atmospheric drag effect when comparing regimes of varying solar–geomagnetic activity. We suggest that a model of satellite drag, when combined with a high-fidelity atmospheric specification as was done here, can lead to improved satellite ephemeris estimates.

Gynecologic Risk Mitigation Considerations for Long-Duration Spaceflight

2020 ◽  
Vol 91 (7) ◽  
pp. 543-564
Author(s):  
Jon G. Steller ◽  
Rebecca S. Blue ◽  
Roshan Burns ◽  
Tina M. Bayuse ◽  
Erik L. Antonsen ◽  
...  
Keyword(s):  
Risk Mitigation ◽  
Low Earth Orbit ◽  
Space Environment ◽  
Earth Orbit ◽  
Mineral Density ◽  
Management Options ◽  
Health Maintenance ◽  
Medical Risk ◽  
Long Duration ◽  
The Impact

INTRODUCTION: As NASA and its international partners, as well as the commercial spaceflight industry, prepare for missions of increasing duration and venturing outside of low-Earth orbit, mitigation of medical risk is of high priority. Gynecologic considerations constitute one facet of medical risk for female astronauts. This manuscript will review the preflight, in-flight, and postflight clinical evaluation, management, and prevention considerations for reducing gynecologic and reproductive risks in female astronauts.METHODS: Relevant gynecological articles from databases including Ovid, Medline, Web of Science, various medical libraries, and NASA archives were evaluated for this review. In particular, articles addressing preventive measures or management of conditions in resource-limited environments were evaluated for applicability to future long-duration exploration spaceflight.RESULTS: Topics including abnormal uterine bleeding, anemia, bone mineral density, ovarian cysts, venous thromboembolism, contraception, fertility, and health maintenance were reviewed. Prevention and treatment strategies are discussed with a focus on management options that consider limitations of onboard medical capabilities.DISCUSSION: Long-duration exploration spaceflight will introduce new challenges for maintenance of gynecological and reproductive health. The impact of the space environment outside of low-Earth orbit on gynecological concerns remains unknown, with factors such as increased particle radiation exposure adding complexity and potential risk. While the most effective means of minimizing the impact of gynecologic or reproductive pathology for female astronauts is screening and prevention, gynecological concerns can arise unpredictably as they do on Earth. Careful consideration of gynecological risks and potential adverse events during spaceflight is a critical component to risk analysis and preventive medicine for future exploration missions.Steller JG, Blue RS, Burns R, Bayuse TM, Antonsen EL, Jain V, Blackwell MM, Jennings RT. Gynecologic risk mitigation considerations for long-duration spaceflight. Aerosp Med Hum Perform. 2020; 91(7):543–564.

scholarly journals The Impact of Innovation in the Satellite Industry on the Telecommunications Services Market

2020 ◽  
Vol 73 ◽  
Author(s):  
Krasimir Terziev ◽  
Dimitar Karastoyanov
Keyword(s):  
Low Earth Orbit ◽  
Earth Orbit ◽  
Orbit Satellite ◽  
Leo Satellites ◽  
Different Types ◽  
Telecommunications Services ◽  
Global Communications ◽  
The Impact

The article analyses the role of the satellites in global communications. Different types of orbits and different types of satellites are described. The commercial start of low and medium orbit satellites is considered. The integration of some Low Earth Orbit (LEO) projects with Teleports is commented. Some significant LEO/MEO (Medium Earth Orbit) projects are cited. The impact of the satellite industry and the Teleport systems on the technological ecosystem is discussed. LEO satellites for monitoring the earth's surface are presented. Keywords: LEO, Orbit, Satellite, Teleport.

scholarly journals Precise Relative Orbit Determination for Chinese TH-2 Satellite Formation Using Onboard GPS and BDS2 Observations

2021 ◽  
Vol 13 (21) ◽  
pp. 4487
Author(s):  
Bin Yi ◽  
Defeng Gu ◽  
Kai Shao ◽  
Bing Ju ◽  
Houzhe Zhang ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Low Earth Orbit ◽  
Asia Pacific ◽  
Earth Orbit ◽  
Reference Orbit ◽  
Satellite Formation ◽  
Relative Orbit ◽  
Comparison Results ◽  
Geo Satellites ◽  
The Impact

TH-2 is China’s first short-range satellite formation system used to realize interferometric synthetic aperture radar (InSAR) technology. In order to achieve the mission goal of InSAR processing, the relative orbit must be determined with high accuracy. In this study, the precise relative orbit determination (PROD) for TH-2 based on global positioning system (GPS), second-generation BeiDou navagation satellite system (BDS2), and GPS + BDS2 observations was performed. First, the performance of onboard GPS and BDS2 measurements were assessed by analyzing the available data, code multipath errors and noise levels of carrier phase observations. The differences between the National University of Defense Technology (NDT) and the Xi’an Research Institute of Surveying and Mapping (CHS) baseline solutions exhibited an RMS of 1.48 mm outside maneuver periods. The GPS-based orbit was used as a reference orbit to evaluate the BDS2-based orbit and the GPS + BDS2-based orbit. It is the first time BDS2 has been applied to the PROD of low Earth orbit (LEO) satellite formation. The results showed that the root mean square (RMS) of difference between the PROD results using GPS and BDS2 measurements in 3D components was 2.89 mm in the Asia-Pacific region. We assigned different weights to geostationary Earth orbit (GEO) satellites to illustrate the impact of GEO satellites on PROD, and the accuracy of PROD was improved to 7.08 mm with the GEO weighting strategy. Finally, relative orbits were derived from the combined GPS and BDS2 data. When BDS2 was added on the basis of GPS, the average number of visible navigation satellites from TH-2A and TH-2B improved from 7.5 to 9.5. The RMS of the difference between the GPS + BDS2-based orbit and the GPS-based orbit was about 1.2 mm in 3D. The overlap comparison results showed that the combined orbit consistencies were below 1 mm in the radial (R), along-track (T), and cross-track (N) directions. Furthermore, when BDS2 co-worked with GPS, the average of the ambiguity dilution of precision (ADOP) reduced from 0.160 cycle to 0.153 cycle, which was about a 4.4% reduction. The experimental results indicate that millimeter-level PROD results for TH-2 satellite formation can be obtained by using onboard GPS and BDS2 observations, and multi-GNSS can further improve the accuracy and reliability of PROD.

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