ISS Orbit Research Articles

Scalable and Configurable Electrical Interface Board for Bus System Development of Different CubeSat Platforms

A flight-proven electrical bus system for the 1U CubeSat platform was designed in the BIRDS satellite program at the Kyushu Institute of Technology. The bus utilizes a backplane board as the mechanical and electrical interface between the subsystems and the payloads. The electrical routes on the backplane are configured by software using a complex programmable logic device (CPLD). It allows for reusability in multiple CubeSat projects while lowering costs and development time; as a result, resources can be directed toward developing the mission payloads. Lastly, it provides more time for integration and system-level verification, which are critical for a reliable and successful mission. The current trend of CubeSat launches is focused on 3U and 6U platforms due to their capability to accommodate multiple and complex payloads. Hence, a demonstration of the electrical bus system to adapt to larger platforms is necessary. This study demonstrates the configurable electrical interface board’s scalability in two cases: the capability to accommodate (1) multiple missions and (2) complex payload requirements. In the first case, a 3U-size configurable backplane prototype was designed to handle 13 mission payloads. Four CPLDs were used to manage the limited number of digital interfaces between the existing bus system and the mission payloads. The measured transmission delay was up to 20 ns, which is acceptable for simple serial communications such as UART and SPI. Furthermore, the measured energy consumption of the backplane per ISS orbit was only 28 mWh. Lastly, the designed backplane was proven to be highly reliable as no bit errors were detected throughout the functionality tests. In the second case, a configurable backplane was implemented in a 6U CubeSat with complex payload requirements compared to the 1U CubeSat platform. The CubeSat was deployed in ISS orbit, and the initial on-orbit results indicated that the designed backplane supported missions without issues.

Onboard performance of the level 1 trigger of the mini-EUSO telescope

The Mini-EUSO telescope was launched for the International Space Station on August 22nd, 2019 to observe from the ISS orbit (∼400 km altitude) various phenomena occurring in the Earth’s atmosphere through a UV-transparent window located in the Russian Zvezda Module. Mini-EUSO is based on a set of two Fresnel lenses of 25 cm diameter each and a focal plane of 48×48 pixels, for a total field of view of 44°. Until July 2021, Mini-EUSO performed a total of 41 data acquisition sessions, obtaining UV images of the Earth in the 290 nm – 430 nm band with temporal and spatial resolution on ground of 2.5 μs and 6.3×6.3 km2, respectively. The data acquisition was performed with a 2.5 μs sampling rate, using a dedicated trigger looking for signals with a typical duration of tens of μs.In the present paper the analysis of the performance of the 2.5 μs trigger logic is presented, with a focus on the method used for the analysis and the categories of triggered events. The expected functioning of the trigger logic has been confirmed, with the trigger rate on spurious events that remains within the requirements in nominal background conditions. The trigger logic detected several different phenomena, including lightning strikes, elves, ground-based flashers and events with EAS-like characteristics.

DIEGO: A Multispectral Thermal Mission for Earth Observation on the International Space Station

ABSTRACT Observations in thermal infrared (IR) contribute substantially to the understanding of the global fluxes of energy and matter between Earth’s surface, ocean and atmosphere. Key parameters derived from such observations are Sea Surface Temperature (SST), Land Surface Temperature (LST) and Land Surface Emissivity (LSE). These variables are important for weather forecasting and climate modelling. However, satellite systems currently in orbit provide only a small number of spectral bands in the thermal region, and consequently cannot be used for temperature emissivity separation (TES) to accurately derive LST and LSE. Hence, capacities to investigate processes or phenomena where LST in high temporal and high spatial resolution (<100 m) is required, such as agricultural applications or urban heat island monitoring, are limited. Additionally, the measurement of radiative energy released from active large and small fires, which contribute significantly to greenhouse gas emissions, is still challenging with current IR systems. Here, we introduce the proposed multispectral sensor system DIEGO (Dynamic Infrared Earth Observation on the ISS Orbit) with 11 spectral bands and a ground sampling distance of less than 60 m, which aims to reduce the observation gap in the thermal infrared significantly.

Comparison and Time Evolution of the Geomagnetic Cutoff at the ISS Position: Internal vs External Earth’s Magnetic Field Models

AbstractOur back-tracing code (GeoMagSphere) reconstructs the cosmic ray trajectories inside the Earth’s magnetosphere. GeoMagSphere gets the incoming directions of particles entering the magnetopause and disentangles primary from secondary particles (produced in atmosphere) or even particles trapped inside the Earth’s magnetic field. The separation of these particle families allows us to evaluate the geomagnetic rigidity cutoff. The model can be used considering the internal symmetric (IGRF-12) magnetic field only, or adding the asymmetric external one (Tsyganenko models: T89, T96 or TS05). A quantitative comparison among these models is presented for quiet (solar pressure Pdyn &lt; 4 nPa) and disturbed (Pdyn &gt; 4 nPa) periods of solar activity, as well as during solar events like flares, CMEs. In this analysis we focused our attention on magnetic field data in magnetosphere, from Cluster, and simulated cosmic rays for a generic detector on the ISS as for example AMS-02. We found that high solar activity periods, like a large fraction of the period covering years 2011-2015, are better described using IGRF+TS05 model. Results, i.e. the average vertical rigidity cutoff at the ISS orbit, are shown in geographic maps of 2° × 2° cells.

Characteristics of spacecraft charging in low Earth orbit

It has been found that the DMSP spacecraft at 840 km can charge to very large negative voltages (up to −2000 V) when encountering intense precipitating electron events (auroral arcs). We present an 11‐year study of over 1600 charging events, defined as when the spacecraft charged to levels exceeding 100 V negative during an auroral crossing. The occurrence frequency of events was highly correlated with the 11‐year solar cycle with the largest number of events occurring during solar minimum. This was due to the requirement that the background thermal plasma density be low, at most 104 cm−3. During solar maximum, the plasma density is typically well above that level due to the solar EUV ionizing radiation, and although the occurrence frequency of auroral arcs is considerably greater than at solar minimum, the occurrence of high‐level charging is minimal. As a result of this study, we produced a model spectrum for precipitating electrons that can be used as a specification for the low‐altitude auroral charging environment. There are implications from this study on a number of LEO satellite programs, including the International Space Station, which does enter the auroral zone, particularly during geomagnetic activity when the auroral boundary can penetrate to very low latitudes. The plasma density in the ISS orbit is usually well above the minimum required density for charging. However, in the wake of the ISS, the plasma density can be 2 orders of magnitude or more lower than the background density and thus conditions are ripe for charging.

Distribution of secondary particles intensities over Earth’s surface: Effect of the geomagnetic field

We use the CORSIKA package (Heck et al., 1998) and AMS-01 flight data (Alcaraz et al., 2000) to evaluate the distribution of secondary particles in the Earth atmosphere. Distribution covers all longitudes and latitudes of STS-91 Space Shuttle flight trajectory to Mir Space Station. Moreover distribution covers all depth in the atmosphere in the evaluated area. We show distributions for e−, e+, μ+, μ−, gammas, hadrons and Cherenkov light from primary protons and helium component of cosmic rays flux. Our results compare favorably with other estimates made by different techniques.We also estimate an UV light production (300–400nm) by electron component of secondaries at the top of the atmosphere and at ISS orbit.

Optimization of radiation exposures during extravehicular activity using the effect of the West-East asymmetry of the fluxes of trapped protons

To estimate the protective properties of a space suit against cosmic radiation the dose rates were calculated for extravehicular activity in the ISS orbit for a number of representative points of critical organs of the human body. The screening functions of the Orlan-M space suit obtained by the authors earlier are used in the calculations. In addition, the effect of East-West asymmetry of the fluxes of high-energy protons trapped by the geomagnetic field is taken into account. It is shown that during passages through the South Atlantic Anomaly, choosing the optimal orientation of astronauts in relation to the cardinal directions, one can achieve for the most critical body organs a dose rate reduction by a factor of ∼1.5–1.8 (in the maximum of solar activity) and by a factor of ∼2–2.5 (in the solar activity minimum). The obtained results can serve for obtaining more accurate estimation of radiation risk for astronauts working in the Orlan-M space suit in the near-terrestrial orbits and for elaborating practical recommendations to reduce their radiation exposures.

Impact of Low-Energy Proton Induced Upsets on Test Methods and Rate Predictions

Direct ionization from low energy protons is shown to cause upsets in a 65-nm bulk CMOS SRAM, consistent with results reported for other deep submicron technologies. The experimental data are used to calibrate a Monte Carlo rate prediction model, which is used to evaluate the importance of this upset mechanism in typical space environments. For the ISS orbit and a geosynchronous (worst day) orbit, direct ionization from protons is a major contributor to the total error rate, but for a geosynchronous (solar min) orbit, the proton flux is too low to cause a significant number of events. The implications of these results for hardness assurance are discussed.

The MAXI Mission on the ISS: Science and Instruments for Monitoring All-Sky X-Ray Images

Abstract The Monitor of All-sky X-ray Image (MAXI) mission is the first astronomical payload to be installed on the Japanese Experiment Module — Exposed Facility (JEM-EF or Kibo-EF) on the International Space Station. It has two types of X-ray slit cameras with wide FOVs and two kinds of X-ray detectors consisting of gas proportional counters covering the energy range of 2 to 30 keV and X-ray CCDs covering the energy range of 0.5 to 12 keV. MAXI will be more powerful than any previous X-ray All Sky Monitor payloads, being able to monitor hundreds of Active Galactic Nuclei. A realistic simulation under optimal observation conditions suggests that MAXI will provide all-sky images of X-ray sources of $\sim $20 mCrab ($\sim $7 $\times$ 10$^{-10} $erg cm$^{-2} $s$^{-1}$ in the energy band of 2–30 keV) from observations during one ISS orbit (90 min), $\sim $4.5 mCrab for one day, and $\sim $2 mCrab for one week. The final detectability of MAXI could be $\sim $0.2 mCrab for two years, which is comparable to the source confusion limit of the MAXI field of view (FOV). The MAXI objectives are: (1) to alert the community to X-ray novae and transient X-ray sources, (2) to monitor long-term variabilities of X-ray sources, (3) to stimulate multi-wavelength observations of variable objects, (4) to create unbiased X-ray source cataloges, and (5) to observe diffuse cosmic X-ray emissions, especially with better energy resolution for soft X-rays down to 0.5 keV.

Gamma-Ray Burst Monitor for the CALET Mission

A gamma-ray burst monitor fot the CALorimetric Electron Telescope (CALET) is under development. The aim of the CALET GRB Monitor (CALET-GBM) is to obtain a wide-band energy spectrum of GRB over an unprecedented nine decades in energy (from several keV to a few TeV) together with the CALET Imaging Calorimeter (IMC) and the Total Absorption Calorimeter (TASC). The GBM is under designing so as to have a sensitivity from several keV to 20 MeV. Furthermore our undergoing plan is to use six LaBr 3 (Ce) crystals from several keV to about 1 MeV measurement (one BGO for higher energy), in which light yield is about twice as large as that of NaI(Tl). LaBr 3 (Ce) is very attractive material, but this crystal has not been used yet as a detector for long exposure in space. Therefore its radiation hardness and proton induced background due to incoming protons are not fully understood. To evaluate its performance in high radiation environment of ISS orbit, we carried out proton beam irradiation tests. Proton-induced rad...

Analysis of parking orbits and transfer trajectories for mission design of cis-lunar space stations

Future human space exploration activities will very likely incorporate space stations and platforms located in the Earth–Moon system, in particular in lunar orbit or in the Lagrange points. It is reasonable to start assembly and mission logistics from today's frequently used near-Earth orbits, such as the ISS orbit, in order to utilize common launcher systems and other infrastructure elements. This contribution deals with the conceptual design of cis-lunar space missions and presents results based on analytic analysis as well as numerical trajectory computation taking gravitational perturbations of multiple celestial bodies into account. While analytic methods generate data suitable for initial estimates and general assessments on delta-v and transfer time for rather fast trajectories, the selected approach also covers long transfer time missions and allows direct and easy access to other relevant mission parameters. The report gives an overview of the perturbation shares in various orbits and trajectories in Earth vicinity and along in and outbound lunar transfers. Then, it addresses the long-term evolution of selected Earth-bound orbits that are likely to be used as staging or parking locations (on the way to and from the Moon). A summary of results is included on how these orbits are being altered by perturbations over time and consequential impacts on mission parameters like delta-v, transfer time and periods for preferable in- and outbound transfer window periods.

Comparison of debris flux models

The availability of models to estimate the impact risk from the man-made space debris and the natural meteoroid environment is essential for both, manned and unmanned satellite missions. Various independent tools based on different approaches have been developed in the past years. Due to an increased knowledge of the debris environment and its sources, e.g. from improved measurement capabilities, these models could be updated regularly, providing more detailed and more reliable simulations. This paper addresses an in-depth, quantitative comparison of widely distributed debris flux models which were recently updated, namely ESA's MASTER model, NASA's ORDEM 2000 and the Russian SPDA 2000 model. The comparison is performed by applying the models to a large number of target orbits specified by a grid in terms of impactor size (6 gridpoints), target orbit perigee altitude (16 gridpoints), and target orbit inclination (15 gridpoints). These results provide a characteristic diagram of integral fluxes for all models, which will be compared. Further to this, the models are applied to orbits of particular interest as e.g. the ISS orbit or a sun-synchronous orbit.

Probability of cell hits in selected organs and tissues by high-let particles at the ISS orbit

The fluence of high-LET particles (HLP) with LET ∞·H 2O greater than 15 keV μm −1 in selected organs and tissues were measured with plastic nuclear track detectors using a life-size human phantom on the 9 th Shuttle-Mir Mission (STS-91). The planar-track fluence of HLP during the 9.8-day mission ranged from 1.9×10 3 n cm −2 (bladder) to 5.1×10 3 n cm −2 (brain) by a factor of 2.7. Based on these data, a probability of HLP hits to a matured cell of each organ or tissue was roughly estimated for a 90-day ISS mission. In the calculation, all cells were assumed to be spheres with a geometric cross-sectional area of 500 μm 2 and the cell-hit frequency from isotropic space radiation can be described by the Poisson-distribution function. As results, the probability of one or more than 1 hit to a single cell by HLP for 90 days ranged from 17% to 38%; that of two or more than 2 hits was estimated to be 1.3 – 8.2%.

GPS-based tomographic reconstruction of the ionosphere

Modern space navigational system GPS Navstar and its Russian analogue GLONASS allow to measure not only phase, but also group delays of the signals propagating through the ionosphere. Possibility of total electron content absolute measurements removes problem of unknown initial phase always existing for phase measurements in 150/400 MHz band but ground-based ionosphere tomography on GPS basis is impossible for realization. To remove these dificulties we offer to replace angular transmitter movement as it is in the case of radiotomography using TRANSIT system by fast moving of a receiver located on board of low-orbital satellite, thus having saved the condition of frozen ionosphere during measurements. For this purposes it is convenient to use independent compact satellites separated from space station ALFA. It is shown that equal inclinations of GPS orbits and orbital system ALFA provide ideal conditions for 2D-radiotomography application. GPS-based tomographic reconstraction provides the possibility to study the ionosphere above the ISS orbit, which is very interesting from a scientific point of view. During some ISS orbits one can map the global structure of the ionosphere which is very useful also for monitoring and forecasting of natural hazards (earthquakes).