CubeSat Research Articles

Usage of Light Emitting Diodes (LEDs) for improved satellite tracking

With the increasing number of satellite launches, especially in Low Earth Orbit (LEO), optical tracking can offer a convenient enhancement of tracking precision and availability. Spaceborne active illumination devices, such as LED payloads, can offer a significant improvement to optical observations, extending the observability interval to the whole eclipse time and performing optimized flash sequences for identification, orbit determination, attitude reconstruction or low data rate communication. The main features of LED panels for optical tracking mounted on small satellites platforms (and with particular regards to nano-satellite platforms) are outlined in this paper, along with the description of the design drivers. The analysis of the performance is referred to Sun-Synchronous (at 700 km of altitude) and International Space Station (400 km) orbits, while the ground segment and the optical link budget reference design relies on a standard university space debris observation station architecture. The paper also outlines the advantages of using different observation techniques and the variety of flashing patterns. The LEDSAT 1U CubeSat, aiming at demonstrating the effectiveness of an LED-based payload for observation and tracking, is used as a study case for examples of the LED payloads and related operations that are reported and described in this paper.

Introduction: The history of the CubeSat by Bob Twiggs and Jordi Puig-Suari

Introduction: The history of the CubeSat by Bob Twiggs and Jordi Puig-Suari

Design and Implementation of High Reliability Electrical Power System for 2U NutSat

This article proposes the design and implementation of an electrical power system (EPS) for 2U CubeSat using a single-ended primary-inductor converter (SEPIC) along with the perturbed and observe method for the maximum power point tracking (MPPT). SEPIC converters have the advantages of input current continuity, voltage boosting and bucking, short-circuit protection, low-side driver, and noninverted input and output voltages. When the battery voltage is too low, by adding a low power consumption latching relay to develop a novel topology, the battery can be directly charged with solar panels without the MPPT algorithm and to improve the system reliability. In addition to the on-board computer subsystem, we can independently control whether to turn on the power according to the battery capacity and importance priority for each subsystem of CubeSat. The satellite is operated in outer space that the environment is wide temperature variation, vacuum, and high electromagnetic radiation. Therefore, the satellite was subjected to various types of tests, such as vacuum, thermal cycling, and radiation tests, to verify the system's capacity for enduring the aforementioned environmental changes. Finally, implementations and various tests were carried out to verify the viability and the accuracy, and reliability of the EPS of the satellite.

Morphing lattice boom for space applications

Structures used in space applications demand the highest levels of stiffness for their mass whilst also performing in a hostile environment. To partly address these requirements and so as to also pack efficiently for stowage during launch we propose a new type of compact telescopic morphing lattice space boom. This boom stows within a 1U CubeSat volume and is lightweight being only 0.4 kg. The boom has a total length of 2 m in its deployed state which is 20 times its stowed height. The device comprises two multi-stable cylindrical composite lattices that are joined telescopically. These lattices nest inside one another in the stowed configuration, with the objective of improving packaging efficiency. Notably, prestress and lamina orientation are used to smoothly change shape from being compact when stowed to being extended when deployed. The lattices in the boom have been designed to maximise deployment force and to be self-deploying by tuning manufacturing parameters. As a result, only a small, lightweight mechanism is required to regulate deployment speed of the lattice boom. By reversing its direction, this mechanism can be used to retract the lattice boom to its stowed configuration, thereby enabling two-way reconfigurability.

Modeling and attitude control of CubeSat utilizing moving mass actuators

Any vehicle propelled by solid rocket motors (SRMs) must include an attitude control system capable of dealing with the torque generated by thrust misalignment. In order to expand the application of SRMs on CubeSats, an attitude control system utilizing moving mass actuators is discussed. The present research develops an eight-degree-of-freedom simulation model of a 2U CubeSat with two moving mass actuators. That model also considers the influence of propellant combustion processes. By analyzing the model disturbance source and systematic coupling, the key layout parameters are designed and a simplified control model is proposed. The controller is derived based on a combination of backstepping and sliding mode techniques. An orbit maneuver from 300 km circular orbit to 300 and 500 km elliptical orbit using this attitude control system is verified.

Measurement of cosmic radiation in LEO by 1U CubeSat

CubeSats are inexpensive tools for studying cosmic radiation. The paper presents an architecture and measurement of Lucky 7 1U CubeSat, which was launched to the quasi-synchronous polar orbit with an altitude of 520 km on June 27, 2019. The satellite is equipped with a scintillator detector whose luminescence emission is measured by a PIN diode and a space GPS receiver that labels the radiation measurement with a precise time and position. The cosmic radiation data were collected since summer 2019. The obtained measurement results are in good conformity with model calculations of the fluxes of the radiation components in Low Earth Orbit (LEO). During the performed pilot experiment, the objectives are to test a simple and inexpensive system providing input data for numerical models together with precise time and position data; and measure count rate data, which are compared with the models.

Glacial Lakes Mapping Using Multi Satellite PlanetScope Imagery and Deep Learning

Glacial lakes mapping using satellite remote sensing data are important for studying the effects of climate change as well as for the mitigation and risk assessment of a Glacial Lake Outburst Flood (GLOF). The 3U cubesat constellation of Planet Labs offers the capability of imaging the whole Earth landmass everyday at 3–4 m spatial resolution. The higher spatial, as well as temporal resolution of PlanetScope imagery in comparison with Landsat-8 and Sentinel-2, makes it a valuable data source for monitoring the glacial lakes. Therefore, this paper explores the potential of the PlanetScope imagery for glacial lakes mapping with a focus on the Hindu Kush, Karakoram and Himalaya (HKKH) region. Though the revisit time of the PlanetScope imagery is short, courtesy of 130+ small satellites, this imagery contains only four bands and the imaging sensors in these small satellites exhibit varying spectral responses as well as lower dynamic range. Furthermore, the presence of cast shadows in the mountainous regions and varying spectral signature of the water pixels due to differences in composition, turbidity and depth makes it challenging to automatically and reliably extract surface water in PlanetScope imagery. Keeping in view these challenges, this work uses state of the art deep learning models for pixel-wise classification of PlanetScope imagery into the water and background pixels and compares the results with Random Forest and Support Vector Machine classifiers. The deep learning model is based on the popular U-Net architecture. We evaluate U-Net architecture similar to the original U-Net as well as a U-Net with a pre-trained EfficientNet backbone. In order to train the deep neural network, ground truth data are generated by manual digitization of the surface water in PlanetScope imagery with the aid of Very High Resolution Satellite (VHRS) imagery. The created dataset consists of more than 5000 water bodies having an area of approx. 71km2 in eight different sites in the HKKH region. The evaluation of the test data show that the U-Net with EfficientNet backbone achieved the highest F1 Score of 0.936. A visual comparison with the existing glacial lake inventories is then performed over the Baltoro glacier in the Karakoram range. The results show that the deep learning model detected significantly more lakes than the existing inventories, which have been derived from Landsat OLI imagery. The trained model is further evaluated on the time series PlanetScope imagery of two glacial lakes, which have resulted in an outburst flood. The output of the U-Net is also compared with the GLakeMap data. The results show that the higher spatial and temporal resolution of PlanetScope imagery is a significant advantage in the context of glacial lakes mapping and monitoring.

Nanosatellite electrical power system architectures: Models, simulations, and tests

SummaryThis paper presents four of the most employed nanosatellite's Electrical Power System (EPS) architectures, comparing their efficiency through simulations and experiments. Every circuit architecture has been mathematically modeled in order to discuss the solar panel control technique and the overall architecture efficiency. Solar panels and EPS components have been analytically modeled and tested in order to comprehend their impact on the EPS efficiency. A test stand has been proposed to evaluate the circuits, emulating the solar irradiance and the nanosatellite power consumption. The following electrical power systems have been designed, implemented, and tested: the directly coupled architecture, the very low dropout (VLDO) voltage regulator architecture, the maximum power point tracking (MPPT) with an integrated circuit, and the MPPT architecture with a discrete boost regulator. A case study has been presented, testing all the EPS architectures according to the Floripa‐Sat I (1U CubeSat) power consumption profile. Experiments results have shown that, although the MPPT boost regulator architecture harvest more energy, it is the VLDO architecture that presents the best overall efficiency.

Calibration and Validation of the TEMPEST-D CubeSat Radiometer

Temporal Experiment for Storms and Tropical Systems-Demonstration (TEMPEST-D) is a 6U CubeSat satellite with a cross-track scanning millimeter-wave radiometer measuring at five frequencies from 87 to 181 GHz. It employs a direct-detection architecture with InP HEMT monolithic microwave integrated circuit (MMIC) low-noise amplifiers and related new technologies. An end-to-end two-point external calibration is performed every 2-s rotation of the scanning mirror, based on observations of the cosmic microwave background and an internal blackbody calibration target, with three thermistors to monitor the target physical temperature. Corrections for antenna pattern effects and cross-scan biases based on prelaunch measured values were updated using data from an on-orbit calibration pitch maneuver. Validation of the observed brightness temperatures ( T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> ) is performed by comparing to coincident nonprecipitating ocean observations from five well-calibrated on-orbit instruments, including Global Precipitation Measurement (GPM) mission Microwave Imager (GMI) and four Microwave Humidity Sounder (MHS) sensors on board NOAA-19, MetOp-A, MetOp-B, and MetOp-C satellites. Absolute calibration accuracy is within 1 K for all channels, well within the 4-K requirement. Calibration precision, or stability over time, is within 0.6 K for all channels, also well within the 2-K requirement. The intrinsic noise of TEMPEST-D is lower than MHS, resulting in similar on-orbit noise equivalent differential temperatures (NEDTs), even though TEMPEST-D has a much shorter integration time of 5 ms as compared to 18 ms for MHS. As a result, although the TEMPEST-D radiometer is substantially smaller, lower power, and lower cost than similar current operational radiometers, it has comparable or better performance in terms of instrument noise, calibration accuracy, and calibration stability or precision.

Challenges in LICIA Cubesat trajectory design to support DART mission science

In 2021, the DART spacecraft will be launched by NASA to intercept the binary system Didymos and impact the moonlet (Dimorphos), to test the effectiveness of kinetic impactors for the deviation of hazardous asteroids’ trajectories. The impact is expected to generate a cloud of particles, whose study could provide valuable data about asteroid’s properties and impact models. Observations from ground to characterize ejecta and plume evolution after impact would be possible, but the resulting quality would be significantly lower than a short-range imaging. In this framework, ASI (Italian Space Agency) and NASA started a collaboration to embark on the US DART vehicle the LICIA (Light Italian CubeSat for Imaging Asteroid) 6U CubeSat as a piggyback payload. LICIA is devoted to grasp science data by imaging the ejecta plume after the impact, and observe Dimorphos surface while flying by the binary system. The Italian consortium involved in the mission sees ARGOTEC for the platform development, and INAF, Politecnico di Milano and Università di Bologna to cover the mission science, trajectory design and orbit de-termination tasks, respectively. The paper focuses on the mission analysis and maneuvers design, strongly driven by the science return, under the tight constraints enforced by the platform. In particular, it describes the preliminary procedure followed to derive trajectory constraints and to select the best option for the flyby. Despite the mission is still under development, and subjected to frequent updates of several parameters, the final performances derived in this paper maintain their validity as they represent the desired target values for the mission.

CubeSatNet: Ultralight Convolutional Neural Network designed for on-orbit binary image classification on a 1U CubeSat

A 1U CubeSat has severe limitations on size, power and downlink capabilities. Transferring images taken by imaging payload from orbit can be a challenging. To save time and effort in downlinking and post-processing, a mechanism must be in place to sort quality data before transmitting it to the ground station. This paper presents an innovative approach combining a novel CubeSat image dataset and a lightweight Convolutional Neural Network architecture for automatically selecting images for downlink on a 1U CubeSat. Coined as CubeSatNet, the neural network is trained on 60,000 augmented images, is tiny enough to run on an ARM Cortex MCU and is tested on on-orbit data from Kyushu Institute of Technology’s BIRDS-3 CubeSats with an accuracy of 90% and F1 score of 0.92. CubeSatNet outperformed SVM, DBN and AE trained to classify CubeSat images. If implemented, the CNN could cut down operation time by about 2/3 while significantly improving the quality of received data.

Spacecraft Attitude Control: A Consideration of Thrust Uncertainty

To account for torque disturbances and control trajectory error, a model of a spacecraft attitude system is presented that replicates uncertainty in the class of continuous low-thrust systems. The generated uncertainty from each thruster is modeled as a Gaussian white noise process, multiplicative in control. An optimal stochastic control law is derived for precision pointing and three-axis stabilization. To derive the optimal control, a Hamilton–Jacobi–Bellman equation is formulated, and a power series-based method is employed to approximate the optimal control. The derived nonlinear control minimizes the objective function of the Lagrange problem in an infinite horizon setting. Stability and existence conditions of control are provided. The nonlinear stochastic optimal controller is compared to its deterministic counterpart for a 6U CubeSat model.

Control of a Thrust-Vectoring CubeSat Using a Single Variable-Speed Control Moment Gyroscope

A minimal actuator design is proposed for orbit-attitude control of a spacecraft. The actuator design includes a single thruster, fixed in the body frame, and a variable-speed control moment gyroscope (VSCMG) used for thrust vectoring. It is known that the full attitude cannot be controlled using a single VSCMG, but that a single axis is controllable. This paper develops a nonlinear control that is able to vector the thruster at discrete intervals or continuously. The closed-loop stability of the system is proved using Lyapunov stability theory for each control law. These control laws could enable high maneuverability of CubeSats, using either a single chemical (impulsive) or electric thruster (continuous). The controls are demonstrated, in simulation, with an application to a 12U CubeSat rendezvous using a single throttable electric thruster.

Initial Radiance Validation of the Microsized Microwave Atmospheric Satellite-2A

The Microsized Microwave Atmospheric Satellite (MicroMAS-2A) is a 3U CubeSat that was launched in January 2018 as a technology demonstration for future microwave sounding constellation missions, such as the NASA Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission now in development. MicroMAS-2A has a miniaturized 1U ten-channel passive microwave radiometer with channels near 90, 118, 183, and 206 GHz for moisture and temperature profiling and precipitation imaging [4]. MicroMAS-2A provided the first CubeSat atmospheric vertical sounding data from orbit, and to date it is the only CubeSat to provide temperature and moisture sounding and surface imaging. In this article, we analyze six segments of data collected from MicroMAS-2A in April 2018 and compare them to ERA5 reanalysis fields coupled with the Community Radiative Transfer Model (CRTM). This initial assessment of CubeSat radiometric accuracy shows biases relative to ERA5 with magnitudes ranging from 0.4 to 2.2 K (with standard deviations ranging from 0.7 to 1.2 K) for the four mid-tropospheric temperature channels and biases of 2.2 and 2.8 K (standard deviations 1.8 and 2.6 K) for the two lower tropospheric water vapor channels.

UWE-4: First Electric Propulsion on a 1U CubeSat—In-Orbit Experiments and Characterization

The electric propulsion system NanoFEEP was integrated and tested in orbit on the UWE-4 satellite, which marks the first successful demonstration of an electric propulsion system on board a 1U CubeSat. In-orbit characterization measurements of the heating process of the propellant and the power consumption of the propulsion system at different thrust levels are presented. Furthermore, an analysis of the thrust vector direction based on its effect on the attitude of the spacecraft is described. The employed heater liquefies the propellant for a duration of 30 min per orbit and consumes 103 ± 4 mW. During this time, the respective thruster can be activated. The propulsion system including one thruster head, its corresponding heater, the neutralizer and the digital components of the power processing unit consume 8.5 ± 0.1 mW · μ A−1 + 184 ± 8.5 mW and scales with the emitter current. The estimated thrust directions of two thruster heads are at angles of 15.7 ± 7.6∘ and 13.2 ± 5.5∘ relative to their mounting direction in the CubeSat structure. In light of the very limited power on a 1U CubeSat, the NanoFEEP propulsion system renders a very viable option. The heater of subsequent NanoFEEP thrusters was already improved, such that the system can be activated during the whole orbit period.

Feasibility of Observing Gamma-Ray Polarization from Cygnus X-1 Using a CubeSat

Abstract Instruments flown on CubeSats are small. Meaningful applications of CubeSats in astronomical observations rely on the choice of a particular subject that is feasible for CubeSats. Here we report the result of a feasibility study for observing gamma-ray polarization from Cygnus X-1 using a small Compton polarimeter on board a 3U CubeSat. Silicon detectors and cerium bromide scintillators were employed in the instrument models that we discuss in this study. Through Monte Carlo simulations with a Geant4-based MEGAlib package, we found that, with a 10 Ms on-axis, zenith-direction observation in a low-inclination, low-altitude, Earth-orbit radiation background environment, the minimum detectable polarization degree can be down to about 10% in 160–250 keV, 20% in 250–400 keV, and 65% in 400–2000 keV. A 3U CubeSat dedicated to observing Cygnus X-1 can therefore yield useful information on the polarization state of gamma-ray emissions from the brightest persistent X-ray black hole binary in the sky.

ManitobaSat-1: A Novel Approach for Technology Advancement

ManitobaSat-1 is a 3U CubeSat program that is determined to advance the edges of space technology by performing things differently from traditional design strategies (see Fig.1). This will enhance access to space through novel technology development and verification and enable smaller companies to benefit from satellite services. ManitobaSat-1 is being developed at the University of Manitoba by the Space Technologies and Advanced Research Laboratory (STARLab) in collaboration with the Center for Terrestrial and Planetary Exploration at the University of Winnipeg, York University, the Interlake School Division, and Magellan Aerospace, our industrial partner.

Designing Low-Thrust Trajectories for a SmallSat Mission to Sun–Earth L5

A small satellite deployed to Sun–Earth (SE) could serve as a low-cost platform to observe solar phenomena. However, the small satellite form factor introduces significant challenges into the trajectory design process via limited thrusting capabilities, power and operational constraints, and fixed deployment conditions. To address these challenges, a strategy employing dynamical systems theory is used to design a trajectory for a low-thrust-enabled small satellite to reach the SE region. This procedure is demonstrated for a small satellite that launches as a secondary payload with a larger spacecraft that is destined for an SE halo orbit. Low-thrust trajectories, delivering the spacecraft from a deployment condition in the Earth vicinity to an science orbit, are produced for both an 180 kg SmallSat and a 6U CubeSat. These solutions demonstrate the value of a dynamical systems approach to trajectory design, while also supporting the potential for small satellite missions to perform targeted heliophysics-based scientific observations well beyond low Earth orbit.

Deserted Medieval Village Reconstruction Using Applied Geosciences

This study presents a new way to reconstruct the extent of medieval archaeological sites by using approaches from the field of geoinformatics. Hence, we propose a combined use of non-invasive methodologies which are used for the first time to study a medieval village in Romania. The focus here will be on ground-based and satellite remote-sensing techniques. The method relies on computing vegetation indices (proxies), which have been utilized for archaeological site detection in order to detect the layout of a deserted medieval town located in southwestern Romania. The data were produced by a group of small satellites (3U CubeSats) dispatched by Planet Labs which delivered high-resolution images of the Earth’s surface. The globe is encompassed by more than 150 satellites (dimensions: 10 × 10 × 30 cm) which catch different images for the same area at moderately short intervals at a spatial resolution of 3–4 m. The four-band Planet Scope satellite images were employed to calculate a number of vegetation indices such as NDVI (Normalized Difference Vegetation Index), DVI (Difference Vegetation Index), SR (Simple Vegetation Ratio) and others. For better precision, structure from motion (SfM) techniques were applied to generate a high-resolution orthomosaic and a digital surface model in which the boundaries of the medieval village of “Șanțul Turcilor” in Mașloc, Romania, can be plainly observed. Additionally, this study contrasts the outcomes with a geophysical survey that was attempted inside the central part of the medieval settlement. The technical results of this study also provide strong evidence from an historical point of view: the first documented case of village systematization during the medieval period within Eastern Europe (particularly Romania) found through geoscientific methods.

A cutting edge 6U CubeSat ADCS design for Earth observation with sub-meter spatial resolution at 230\u2013380\xa0km altitude

A 6U CubeSat for Earth observation in 230–350 km orbits with sub-meter resolution is presented. The proposed Stable and Highly Accurate Pointing Earth-Imager (SHAPE) system’s attitude determination and control system (ADCS) is composed of a single momentum bias wheel with magnetic bearings at rotational speeds of 6000–7000 rpm and refined magnetorquers. Reaction wheels as instability source are absent. The ADCS stabilizes the spacecraft attitude by counteracting the torques from external disturbances in the thermosphere down to < 1° pointing accuracy and < 0.1° instability. The momentum wheel was sized to an angular momentum of 1 Nms based on the worst-case atmospheric density of the next solar cycle. The 0.5 Am2 magnetorquer dipole moment provides with low power consumption, mass and cost, high reliability and sufficient torque. The ADCS initialisation study revealed three stable start-up modes, while the all-spun state is achieved using a set of thrusters. De-tumbling analysis show that the magnetorquers reduce the tumbling rates with magnitudes of up to 35°/s to mean motion values in less than an orbit using a static gain B-dot controller. A 3U camera design capable of sub-meter spatial resolution at 230 km altitude is presented which complies with the SHAPE spacecraft system design. The instrument has a single deployable primary mirror enabled by a deployment hinge design with hysteresis < 0.5 μ. This payload combined with air-breathing electric propulsion technology at 230 km nominal altitude boosts the SHAPE system Earth observation potential down to sub-meter spatial resolution and enables tuning of the mission lifetime by orbit keeping.