International Space Station Orbit Research Articles

Textrm{O}^+ density distribution in the nightside ionosphere reconstructed from ISS-IMAP/EUVI data

The textrm{O}^+ density distribution in the nightside ionosphere has been reconstructed from extreme ultraviolet (EUV) images taken by the EUVI-B imager of the International Space Station Ionosphere, Mesosphere, upper Atmosphere, and Plasmasphere mapping (ISS-IMAP) cameras. The EUVI-B imager covers the wavelength range from about 70 nm to 110 nm and mainly observes the 91.1 nm emission from the recombination of textrm{O}^+ ions and electrons. Assuming that the electron density is equal to the textrm{O}^+ density in the F-region where the imager observes, the EUV intensity observed by EUVI-B is approximately proportional to the line-of-sight integral of the square of the textrm{O}^+ density. This enables us to estimate the textrm{O}^+ density distribution in the F-region from a sequence of EUVI-B data in each International Space Station (ISS) orbit with a Bayesian method. We demonstrate the reconstruction of the textrm{O}^+ distribution. In particular, the textrm{O}^+ density structure of the equatorial ionization anomaly (EIA) in the vicinity of an ISS orbit is obtained.Graphical

Active radiation measurements over one solar cycle with two DOSTEL instruments in the Columbus laboratory of the International Space Station

Two DOSimetry TELescopes (DOSTELs) have been measuring the radiation environment in the Columbus module of the International Space Station (ISS) since 2009 in the frame of the DOSIS and DOSIS 3D projects. Both instruments have measured the charged particle flux rate and dose rates in a telescope geometry of two planar silicon detectors. The radiation environment in the ISS orbit is mostly composed by galactic cosmic radiation (GCR) and its secondary radiation and protons from the inner radiation belt in the South Atlantic Anomaly (SAA) with sporadic contributions of solar energetic particles at high latitudes. The data presented in this work cover two solar activity minima and corresponding GCR intensity maxima in 2009 and 2020 and the solar activity maximum and corresponding GCR intensity minimum in 2014/2015. Average dose rates measured in the Columbus laboratory in the ISS orbit from GCR and SAA are presented separately. The data is analyzed with respect to the effective magnetic shielding and grouped into different cut-off rigidity intervals. Using only measurements in magnetically unshielded regions at low cut-off rigidity and applying a factor for the geometrical shielding of the Earth, absorbed dose rates and dose equivalent rates in near-Earth interplanetary space are estimated for the years 2009 to 2022.

Effect of electron beam improved dielectric function on optical properties of sol-gel derived CuIn1-XGaXSe2 thin-film

Electron beam has been applied as a practical posttreatment process for the surface modification at the CuIn1-XGaXSe2 thin film. The rise of the film thickness indicated the advantages of the modified surface-related properties (such as the optical parameters to develop an optimum optical model) via enriching the microstructure with the negative charged beta particles by using Sr-90 radioisotope. The effect of negatively charged beta particles on dielectric constants was examined at two different dose levels (3 and 9.1 Gy) by using Sr-90 radioisotope. The application of the electron beam to the thin film surface caused the slight changes in refractive index (n), extinction coefficient (k) and optical absorption coefficient. The increase of refractive index and the improvement of absorption coefficient provided to distinguish clearly the decrease in extinction coefficient and the decline in energy band gap as the result of the rise of the beta dose at the thin-film. The slight variations in dielectric constants were performed by encouraging more dense structure to form the optimum crystalline network at the thin film (applied beta dose). The application of beta dose favoured inventive variations in the refractive index. The applied two different beta dose levels were below ∼3.1 Gy and above ∼9 Gy. The beta dose level at ∼9 Gy was ∼3 times dose value of 3.1 Gy (applied as a security value for the utilization of this thin film at the extreme environments such as international space station orbit). The refractive index stated its importance specifying the rise of the bending of light in the thin film structure.

Results of long-term radiation environment monitoring by the Russian RMS system on board Zvezda module of the ISS

The Radiation monitoring system (RMS) continuously operated in various configurations since the launch of the Zvezda module of the International Space Station (ISS). The RMS consisted of 7 units, namely: the R-16 dosimeter, 4 DB-8 dosimeters, utility and data collection units. The obtained data covers a time of 22 years. This paper analyses the radiation environment variations on board the “Zvezda” module. Variations of the onboard daily dose rate associated with changes of ISS altitude and 11-year cycle galactic cosmic rays’ variations are analyzed and discussed. It is shown that the observed increase in the daily dose from 0.20 - 0.25 to 0.35 - 0.50 mGy/day is mostly due to the increase of ISS orbit altitude, resulting in a substantial increase of the dose contribution from the South Atlantic Anomaly (SAA) Region. Dose rate variations in the SAA as well as latitude and longitude dose rate distributions are discussed in detail. Analysis confirms that the well-known westward drift effect of the SAA is clearly visible from radiation dose measurements on the ISS.

Development of CubeSat Magnetic Torquer Testing System in a Vacuum Environment

This paper discusses the development and instrumentation of an integrated facility based on an air-bearing table to test small ADCS actuators such as electric propulsion devices, reaction wheels, and magnetic torquers for CubeSats. It includes an automatic balancing system that corrects the center of mass of the testing platform and a Helmholtz cage for the simulation of the in-orbit geomagnetic environment inside the vacuum environment. Through experimental tests, it was observed that the attitude disturbances due to the aerodynamic drag and the viscous rotational friction in atmospheric conditions (~5×10-6 Nm) can be significantly decreased when the testing platform is placed inside a vacuum environment (~5×10-7 Nm). It was also observed that the vacuum condition facilitates the verification test of attitude control maneuvers using small magnetic torquers for CubeSats whose control torque is smaller than the attitude disturbance torque in atmospheric conditions. A demonstration test was performed to verify the attitude stabilization control by the magnetic torquers in vacuum conditions under a simulated geomagnetic field as in the International Space Station orbit using this integrated testing facility.

Active Tissue Equivalent Dosimeter: A Tissue Equivalent Proportional Counter flown onboard the International Space Station

The Active Tissue Equivalent Dosimeter (ATED) is a low-cost, easy-to-use and compact tissue equivalent proportional counter designed for use aboard spacecraft, satellites, aircraft, unmanned aerial vehicles and high-altitude balloons. ATED was rigorously tested at particle accelerator facilities utilizing heavy ions of charge and energy similar to Galactic Cosmic Rays (GCRs). Upon completion of the ground-based testing and calibration, the ATED was operated aboard the International Space Station (ISS) during July–August of 2018. ATED measurements from the ISS were then analyzed in terms of time, latitude, longitude, and altitude in order to correlate with the radiation fields in the ISS orbit. When ATED measurements were correlated with orbital position, elevated absorbed dose rates due to the South Atlantic Anomaly (SAA) were clearly evident. ATED measurements were also separated based on their orbital location into three different regions. The results from the July–August 2018 flight show that ATED functioned as designed while onboard the ISS. The hypothesis that lineal energy and linear energy transfer can be used interchangeably with measurements by a TEPC in Low Earth Orbit (LEO) was tested by ATED measurements. Lastly, a direct comparison was made between linear energy transfer (LET) converted from lineal energy spectra from a spherical TEPC in LEO and model-calculated LET values. Such a comparison is highly challenging with the TEPCs with cylindrical geometry previously used in space.

Эффективные методы и алгоритмы синтеза видео 360 градусов на основе кубической проекции виртуального окружения

The paper deals with the task of creation and playback of panoramic video with 360-degree overview, which allows the researcher to be immersed in virtual medium outside parent virtual environment system (VES). To solve the task, the extension of the method is proposed, in which resolution is determined taking into account viewer camera field of view and screen resolution (Adequate Cubemap Projection, ACMP). The paper studies the influence of the camera orientation inside the cube on the cubemap pixel / screen pixel ratio determining panorama visualization quality. Based on this, a method to calculate resolution for high-quality panorama visualization for all possible camera orientations is proposed. The paper considers an efficient method and algorithm to create ACMP-video on the GPU using render-to-texture technology, which allow to synthesize panoramas with constant orientation or bound to the observer's view direction. In the research efficient methods and algorithms to play ACMP-video are also proposed, which are based on the visualization of visible cube faces and adaptive frame buffering. The obtained methods and algorithms are implemented in ACMP-video synthesis program complex (С++, OpenGL, FFmpeg) including frame capture module (embeddable into VES) and the player. The developed solution was tested in system «Virtual Earth» designed for training to observe Earth objects from the International Space Station (ISS). Using the capture module, an ACMP-video of the flight along the ISS orbit track was created. When playing this video, the trainee flies in orbit above virtual 3D surface of the Earth and can explore it by means of camera rotation. Testing of the complex confirmed the adequacy of the developed methods and algorithms to the task. The obtained scientific and practical results expand the capabilities and scope of application of VES, scientific visualization systems, video simulators and virtual laboratories; provide effective exchange of experience between researchers, etc.

Data Products, Quality and Validation of the DLR Earth Sensing Imaging Spectrometer (DESIS).

Imaging spectrometry from aerial or spaceborne platforms, also known as hyperspectral remote sensing, provides dense sampled and fine structured spectral information for each image pixel, allowing the user to identify and characterize Earth surface materials such as minerals in rocks and soils, vegetation types and stress indicators, and water constituents. The recently launched DLR Earth Sensing Imaging Spectrometer (DESIS) installed on the International Space Station (ISS) closes the long-term gap of sparsely available spaceborne imaging spectrometry data and will be part of the upcoming fleet of such new instruments in orbit. DESIS measures in the spectral range from 400 and 1000 nm with a spectral sampling distance of 2.55 nm and a Full Width Half Maximum (FWHM) of about 3.5 nm. The ground sample distance is 30 m with 1024 pixels across track. In this article, a detailed review is given on the applicability of DESIS data based on the specifics of the instrument, the characteristics of the ISS orbit, and the methods applied to generate products. The various DESIS data products available for users are described with the focus on specific processing steps. The results of the data quality and product validation studies show that top-of-atmosphere radiance, geometrically corrected, and bottom-of-atmosphere reflectance products meet the mission requirements. The limitations of the DESIS data products are also subject to a critical examination.

Optimal Transport Based Tracking of Space Objects in Cylindrical Manifolds

In this paper, we examine the performance of satellite state estimation algorithms in the modified equinoctial coordinate system, defined on the cylindrical manifold of $\mathbb {R}^{5}\times \mathbb {S}$, where $\mathbb {R}$ is the space of reals and $\mathbb {S}$ denotes circular space. A comparison is made between an optimal transport based filter and ensemble Kalman filter algorithm in the context of satellite state estimation. The initial state joint probability density function is modeled in $\mathbb {R}^{5}\times \mathbb {S}$ using the Gauss von Mises distribution. The sensor noise for optimal transport filtering is modeled in the same manifold. The ensemble Kalman filter, by definition, requires the sensor noise to be Gaussian and is modeled in $\mathbb {R}^{6}$ for this problem. We observe that there is a clear advantage in using an optimal transport based filtering algorithm where we represent the initial condition uncertainty and sensor noise, in the cylindrical manifold. These two filtering algorithms are implemented on a simulated International Space Station orbit, with measurement at equal intervals. We compare two distinct scenarios in this simulation based study. In the first one, sensor noise characteristics are assumed to be known. For the second one, we present a new algorithm within the optimal transport framework with unknown sensor noise characteristics, a practical and relevant issue in the space-tracking problems. The optimal transport based algorithm provides more consistent and robust estimates compared to that of ensemble Kalman filter, in each of these scenarios.

On-orbit operations and offline data processing of CALET onboard the ISS

The CALorimetric Electron Telescope (CALET), launched for installation on the International Space Station (ISS) in August, 2015, has been accumulating scientific data since October, 2015. CALET is intended to perform long-duration observations of high-energy cosmic rays onboard the ISS. CALET directly measures the cosmic-ray electron spectrum in the energy range of 1 GeV to 20 TeV with a 2% energy resolution above 30 GeV. In addition, the instrument can measure the spectrum of gamma rays well into the TeV range, and the spectra of protons and nuclei up to a PeV.In order to operate the CALET onboard ISS, JAXA Ground Support Equipment (JAXA-GSE) and the Waseda CALET Operations Center (WCOC) have been established at JAXA and Waseda University, respectively. Scientific operations using CALET are planned at WCOC, taking into account orbital variations of geomagnetic rigidity cutoff. Scheduled command sequences are used to control the CALET observation modes on orbit. Calibration data acquisition by, for example, recording pedestal and penetrating particle events, a low-energy electron trigger mode operating at high geomagnetic latitude, a low-energy gamma-ray trigger mode operating at low geomagnetic latitude, and an ultra heavy trigger mode, are scheduled around the ISS orbit while maintaining maximum exposure to high-energy electrons and other high-energy shower events by always having the high-energy trigger mode active. The WCOC also prepares and distributes CALET flight data to collaborators in Italy and the United States.As of August 31, 2017, the total observation time is 689 days with a live time fraction of the total time of ∼ 84%. Nearly 450 million events are collected with a high-energy (E > 10 GeV) trigger. In addition, calibration data acquisition and low-energy trigger modes, as well as an ultra-heavy trigger mode, are consistently scheduled around the ISS orbit. By combining all operation modes with the excellent-quality on-orbit data collected thus far, it is expected that a five-year observation period will provide a wealth of new and interesting results.

Have rocket...will travel

IN THE PAST 45 years, no-one has ventured further from the Earth's surface than the average height of the International Space Station's orbit (about 400km), which critics have characterised as being 'stuck in low-Earth orbit'. Well-publicised announcements on Mars colonisation from SpaceX CEO Musk suggest that NewSpace entrepreneurs are ready to pick up the space travel baton, but to some this is still science-fiction. Space policy expert and professor emeritus of political science at George Washington University, John Logsdon, says: Elon Musk's suggestion of a million-person city on Mars is almost pure fantasy. Why would that many people want to immigrate to a hostile environment? What would be the basis for a Martian economy to sustain them? Would they eat more than potatoes? Would there be good wine to drink?

Atomic clock ensemble in space (ACES) data analysis

The Atomic Clocks Ensemble in Space (ACES/PHARAO mission, ESA & CNES) will be installed on board the International Space Station (ISS) next year. A crucial part of this experiment is its two-way microwave link (MWL), which will compare the timescale generated on board with those provided by several ground stations disseminated on the Earth. A dedicated data analysis center is being implemented at SYRTE—Observatoire de Paris, where our team currently develops theoretical modelling, numerical simulations and the data analysis software itself.In this paper, we present some key aspects of the MWL measurement method and the associated algorithms for simulations and data analysis. We show the results of tests using simulated data with fully realistic effects such as fundamental measurement noise, Doppler, atmospheric delays, or cycle ambiguities. We demonstrate satisfactory performance of the software with respect to the specifications of the ACES mission. The main scientific product of our analysis is the clock desynchronisation between ground and space clocks, i.e. the difference of proper times between the space clocks and ground clocks at participating institutes. While in flight, this measurement will allow for tests of general relativity and Lorentz invariance at unprecedented levels, e.g. measurement of the gravitational redshift at the level.As a specific example, we use real ISS orbit data with estimated errors at the 10 m level to study the effect of such errors on the clock desynchronisation obtained from MWL data. We demonstrate that the resulting effects are totally negligible.

Single Event Upset Analysis: On-orbit performance of the Alpha Magnetic Spectrometer Digital Signal Processor Memory aboard the International Space Station

Based on the collection of error data from the Alpha Magnetic Spectrometer (AMS) Digital Signal Processors (DSP), on-orbit Single Event Upsets (SEUs) of the DSP program memory are analyzed. The daily error distribution and time intervals between errors are calculated to evaluate the reliability of the system. The particle density distribution of International Space Station (ISS) orbit is presented and the effects from the South Atlantic Anomaly (SAA) and the geomagnetic poles are analyzed. The impact of solar events on the DSP program memory is carried out combining data analysis and Monte Carlo simulation (MC). From the analysis and simulation results, it is concluded that the area corresponding to the SAA is the main source of errors on the ISS orbit. Solar events can also cause errors on DSP program memory, but the effect depends on the on-orbit particle density.

ISS as a Platform for Optical Remote Sensing of Ecosystem Carbon Fluxes: A Case Study Using HICO

Data from the hyperspectral imager for coastal ocean (HICO), mounted on the International Space Station (ISS), were used to develop and test algorithms for remotely retrieving ecosystem productivity. Twenty-six HICO images were used from four study sites representing different vegetation types: grasslands, shrubland, and forest. Gross ecosystem production (GEP) data from eddy covariance were matched with HICO-derived spectra. Multiple algorithms were successful relating spectral reflectance with GEP, including: spectral vegetation indices (SVI), SVI in a light-use efficiency model framework, spectral shape characteristics through spectral derivatives and absorption feature analysis, and statistical models leading to multiband hyperspectral indices from stepwise regressions and partial least squares regression. Successful algorithms were able to achieve r 2 better than 0.7 for both GEP at the overpass time and daily GEP. These algorithms were successful using a diverse set of observations combining data from multiple years, multiple times during growing season, different times of day, with different view angles, and different vegetation types. The demonstrated robustness of the algorithms presented in this study over these conditions provides some confidence in mapping spatial patterns of GEP, describing variability within fields, as well as the regional patterns. The ISS orbit provides periods with multiple observations collected at different times of the day within a period of a few days. Diurnal GEP patterns were estimated comparing the half-hourly average GEP from the flux tower against HICO estimates of GEP ( r 2 = 0.87) if morning, midday, and afternoon observations were available.

Transient Floating Potential Variations Attributed to High-Voltage Solar Array Operations

The International Space Station continues to be a productive space research laboratory after over 15 years of operations, and it has proven to be a valuable resource for observing spacecraft floating potential variations related to high-voltage solar array operations in low Earth orbit. Measurements of the ionospheric electron density and temperature along the International Space Station orbit and variations in the International Space Station floating potential are obtained from the floating potential measurement unit. In particular, rapid variations in the International Space Station floating potential during solar array operations on timescales of tens of milliseconds can be recorded due to the 128 Hz sample rate of the floating potential probe, providing insight into high-voltage solar array interaction with the space plasma environment. Comparing the floating potential measurement unit data with the International Space Station operations’ timeline and solar array data provides a means for correlating some of the more complex transient floating potential variations with mission operations. These complex variations are not reproduced by current models and require further study to understand the underlying physical processes. In this paper is presented some of the floating potential transients observed over the past few years along with the relevant space environment parameters and solar array operations data.

Radiation Hard Contactless Angular Position Sensor Based on Hall Effect

The results of the total ionizing dose (TID) and single event effect (SEE) tests on the contactless angular position sensor based on Hall effect are presented. The TID testing reveals that the devices are resistant to the gamma radiation exhibiting only a slight increase in the supply current, not more than 1 % of the initial values. In general, both the serial peripheral interface (SPI) output errors and analog output errors have recovered to their initial values after annealing at high temperatures. Only the biased sample with magnet showed a significant increase of the analog output error at higher radiation levels and did not return to its initial value, it remained about a 56 % higher. Nevertheless, the error is still within the limits for space application of the sensor. SEE tests were performed up to linear energy transfer (LET) levels of 67.7 MeV $\cdot $ cm2/mg and the sensors experienced neither single event latch-up (SEL) nor single event transient (SET). The upper limit of cross section for single event functional interrupt (SEFI) was found by Weibull fit as being $3.53\cdot 10^{\mathrm {-6}}$ cm2 and the LET threshold was 15.1 MeV $\cdot $ cm2/mg. The SEFI rates were calculated by means of the CREME96 for geostationary orbit (GEO) and the orbit of the International Space Station (ISS). Calculations were performed for minimum solar and peak 5 minutes environment, and in the case of the ISS orbit also trapped particles and magnetic weather conditions were included.

Calibration and Validation of the RapidScat Scatterometer Using Tropical Rainforests

Launched in September2014, RapidScat is currently operating on the International Space Station (ISS). RapidScat estimates ocean vector winds via the measurement of the normalized radar coefficient (σ 0 ) of the ocean's surface. Measurements are also collected over land. The ISS orbit permits, for the first time, the observation of the diurnal variation in Ku-band σ 0 at midto high-incidence angles. To complement calibration efforts over the ocean, in this paper the calibration and validation of the σ 0 measurements are performed using natural land targets, namely the Amazon and Congo rainforests. The diurnal σ 0 cycle of the targets is estimated with respect to incidence angle, azimuth angle, and season using measurements from previous sensors. Understanding this diurnal backscatter response enables the comparison of RapidScat measurements with measurements from the QuikSCAT, NASA Scatterometer, SeaWinds, and Oceansat-II scatterometers. RapidScat σ 0 measurements are found to be consistent but biased low compared to those of QuikSCAT by up to 0.3 dB. The effectiveness of slice balancing is evaluated and found to be dependent on the pitch of the ISS. Extreme pitches of the ISS are also found to introduce azimuth dependencies in egg measurements. By accounting for seasonal and diurnal cycles, we find that the rainforests are well suited for scatterometer sensor cross-calibration, even for disjoint years.

Energy spectra of low-energy solar iron particles measured in the orbit of the international space station in the period 2002–2004

The energy spectrum of iron is measured over the range of 30–150 MeV/nucleon using the PLATAN-M chamber consisting of solid-state track detectors mounted on the external surface of the International Space Station (ISS) in the period 2002–2004. The spectra of solar and galactic cosmic rays (SCRs and GCRs) are compared to the data from the SIS instrument on board the ACE spacecraft, transformed to the ISS orbit. Compared to the SIS data, the energy resolution of the PLATAN-M spectrum is twice better and the spread of experimental points is 50% lower.

ORDEM 3.0 and MASTER-2009 modeled debris population comparison

The latest versions of the two premier orbital debris engineering models, NASA׳s ORDEM 3.0 and ESA׳s MASTER-2009, have been publically released. Both models have gone through significant advancements since inception, and now represent the state-of-the-art in orbital debris knowledge of their respective agencies. The purpose of these models is to provide satellite designers/operators and debris researchers with reliable, and timely, estimates of the artificial debris environment in -Earth orbit, from about 200 km through about 40,000 km. The small debris environment within the “critical size range” of 1cm to 1mm is of particular interest to both human and robotic spacecraft programs. These objects are much more numerous than larger trackable debris and are still large enough to cause significant, if not catastrophic, damage to spacecraft upon impact. They are also small enough to elude routine detection by existing observation systems. Without reliable detection the modeling of these populations has always coupled theoretical origins with supporting observational data in different degrees.This paper offers the first cooperative comparison of the latest versions of the two models. No attempt to review model internal populations, or compare subsystems, or supporting data sets is made at this time. The models are simply run in the “Spacecraft Mode” for four test cases representing four orbital regimes, ISS (International Space Station orbit), SSO (sun synchronous orbit), GTO (geosynchronous transfer orbit), and GEO (geosynchronous orbit). Specific satellites are chosen within those categories for the analysis. Debris cumulative fluxes at three debris sizes (1m, 10cm, and the critical size range of 1cm to 1mm) are compared. At 1m there is a very good match between ORDEM 3.0 and MASTER-2009 fluxes in the non-GEO orbits, less so in the GEO orbit. The 10cm fluxes do not match as well, indicating possibly different treatment of uncatalogued objects. Within the critical size range it is noted that ORDEM 3.0 flux overtakes that of MASTER-2009 as debris size decreases in all test cases.In the analysis of separate model populations, the disparate usage of debris source populations (MASTER-2009) versus debris material density populations (ORDEM 3.0) is presently unresolved. MASTER-2009 populations of SRM (solid rocket motor) slag and explosion and collision fragments dominate with lower populations of ejecta debris. ORDEM 3.0 populations are dominated by medium and high density material with minor low density material populations. Undoubtedly, more in-depth collaborations will follow to hone in on population differences and sources.

The JEM-EUSO observation in cloudy conditions

The JEM-EUSO (Extreme Universe Space Observatory on-board the Japanese Experiment Module) mission will conduct extensive air shower (EAS) observations on the International Space Station (ISS). Following the ISS orbit, JEM-EUSO will experience continuous changes in the atmospheric conditions, including cloud presence. The influence of clouds on space-based observation is, therefore, an important topic to investigate from both EAS property and cloud climatology points of view. In the present work, the impact of clouds on the apparent profile of EAS is demonstrated through the simulation studies, taking into account the JEM-EUSO instrument and properties of the clouds. These results show a dependence on the cloud-top altitude and optical depth of the cloud. The analyses of satellite measurements on the cloud distribution indicate that more than 60 % of the cases allow for conventional EAS observation, and an additional ∼20 % with reduced quality. The combination of the relevant factors results in an effective trigger aperture of EAS observation ∼72 %, compared to the one in the clear atmosphere condition.