Deep Space Applications Research Articles

Novel Composites for Lightweighting in Deep Space Applications

Abstract The evolution of carbon nanotube composites, as inspired by the Materials Genome Initiative, unlocks new potential for materials sustainability in challenging deep space applications. This article describes research and development work at the Institute for Ultra-Strong Composites by Computational Design (US-COMP), a NASA Space Technology Research Institute consortium. US-COMP has developed a novel composite material with mechanical properties per unit mass that exceed state-of-the-art structural composites.

A semi-empirical model of the calendar ageing of lithium-ion batteries aimed at automotive and deep-space applications

Lithium-ion batteries are highly affected by calendar ageing effects, which can lead to capacity loss even when the battery is not used at all. The current literature proposes plenty of semi-empirical models to predict the calendar ageing of the lithium-ion batteries, which are mostly based on Arrhenius functions for temperature dependency, exponential models for state of charge dependency and power laws for time dependency. Those models are easy to calibrate, and they provide a sufficiently precise prediction of capacity loss over time. However, it might be difficult to find a physical meaning to the parameters determined in these models, due to their lumped nature and the optimization process used. Therefore, in this work a semi-empirical model able to predict the capacity degradation over time with physically meaningful parameters is proposed. The dependency on temperature is considered by a pre-exponential factor whereas the dependency on state of charge is considered by a power law coefficient. A two-step constrained optimization process is considered to calibrate the model parameters. The model allows to predict the capacity loss over a wide range of different temperature and state of charge conditions, and it is calibrated for 4 different cell chemistries: LMO-NMC, LFP, NCA, and NMC. It was found that the worst storing condition is given by the highest temperature and state of charge conditions. The capacity degradation is provided over a period of 50 years. Two end-of-life conditions were analyzed: a loss of capacity of 20 % as representative of an end-of-life condition for automotive applications, and a loss of capacity of 50 % as an end-of-life condition for deep-space applications. In both cases, it was observed that NMC provided the best performance (the slowest ageing over time) for storing temperatures below 15 °C and storing state of charge below 10 %, whereas for temperatures higher than 15 °C and state of charge higher than 10 %, the LFP chemistry resulted to be the most longevous.

Insight into rechargeable batteries under extreme pressure and gravity for deep space exploration

This work covers recent advancements and outlooks in rechargeable batteries for deep space application, including mass transfer, reaction interface, and core component changes under extreme pressure, microgravity, and supergravity.

Circuit-level design of radiation tolerant memory cell

As transistors shrink in size, the integration density of memory circuits like Static Random Access Memory (SRAM) cells rises, making them increasingly susceptible to Single Event Effects (SEE). In the space environment, memory circuits face stability and reliability challenges due to the presence of various charged particles such as α-particles, neutrons, electrons, heavy ions, and photons. These high-energy particles create ion tracks when they strike the memory device, leading to upsets in the storage bits. Conventional 6 T SRAM cells are susceptible to these upsets. As a solution this paper proposes a new Radiation Tolerable (RT 13 T) SRAM cell that is better suited for deep-space applications compared to other memory cell. RT13T has been validated to withstand radiation hazards through Critical Charge (QCrit) analysis, which shows that it exhibits 1.17×, 1.1×, 1.94× and 1.06× highest QCritthan QUCCE 10 T/12 T,traditional 6 T and LIOR 13 T memory cells, respectively. As the comparison made, our Proposed RT 13 T saved by5.1 %,9.9 %, 20.1 % and 7 % of the power consumption compared to QUCCE10T/12 T/LIOR 13 T/SERSC-16 T SRAM cells at a nominal supply voltage of 0.7 V. It also exhibits shorter read delay (TRA) 10.6 %, 1.34 %, 9.6 %, 22.16 %compared to QUCCE 10 T/12 T,6T, SERSC-16Tmemory cells, respectively. In terms of stability,our proposed RT13T SRAM cell exhibits 2.32×/2.05×/2.9×/1.05×/1.01 × higher read stability as compared with QUCCE10T/12 T/6T/LIOR 13 T/SERSC-16 T memory cells during the read operation. The our proposed RT13T shows improvements in design metrics are at the expense of a longer write delay. To characterize the performances of the proposed RT13T, 16-nm CMOS predictive technology model and validated through extensive simulation with licensed PrimeSim HSPICE of Synopsys. The results of our proposed RT13T cell are compared with some other previously proposed memory cells such as 6 T, QUCCE 10 T, QUCCE 12 T, LIOR 13 T and SERSC-16 T memory cells. The obtained results are tabulated and plotted for graphical analysis. In terms of area consumption our proposed 13 T consumes 0.9×/0.6 × lesser area than QUCCE 12 T/SERSC-16 T memory cells but our proposed circuit consumes 3.1×/1.08×/1.05 × more area than QUCCE10T/conventional 6 T/LIOR 13 T because QUCCE10T and 6 T consist of less number of transistors in memory cells.The cell proposed in this paper demonstrates strong radiation-hardened capabilities and excellent overall performance, making it well-suited for aerospace electronic devices and ensuring stable operation in space radiation environments.

A Pulsar Vector Observation-Based Link Acquisition Method for X-Ray Communications

X-ray communication (XCOM) is an emerging laser communication technique for deep space applications. Traditional link acquisition of laser communications depends significantly on Earth support and shows little autonomy. For XCOM, a pulsar vector observation-based link acquisition method is proposed, which utilizes noncooperative pulsars in deep space as beacons to acquire absolute attitude information and accomplish link acquisition. Firstly, a pulsar vector observation model was established based on the coordinate definition of the X-ray detector and X-ray collimator model. Secondly, a modified “success-failure” pulsar vector search algorithm with two degrees of freedom was proposed to acquire the pulsar vector. With the pulsar vector and the relative attitude obtained from inertial sensors, the link acquisition pointing vector could be determined. Finally, the performance of the proposed method was evaluated using numerical experiments, and factors that influence the performance are discussed and analyzed.

Nanocomposite physics and structure considerations in MCNP proton shielding models

Background Deep space crewed missions require unique radiation shielding considerations. Due to mission duration and the heavy, high-energy nature of deep space radiation, the aluminum alloys that have historically been used for spacecrafts do not provide sufficient protection for crew members. Polymer-based nanocomposites have been proposed as potential radiation shielding materials for deep space applications; however, the high tunability of nanocomposites and the limited number of facilities able to produce representative radiation energies presents barriers to nanocomposite testing. Computational approaches may allow for preliminary investigation and discrimination of nanocomposite parameters like polymer and filler composition, loading percentage, and filler size and structure. Methods This work aims to investigate several modeling methods to perform radiation transport simulations for a nanocomposite, particularly with regards to modeling the filler nanostructure and the involved physics. Published experiments of a polydimethylsiloxane-carbon nanotube nanocomposite in 63 MeV and 105 MeV proton beams were digitally recreated in MCNP6.2 with three different nanocomposite structures. Additionally, several simulations were performed under various physics assumptions. The computationally determined water equivalent thicknesses are compared between modeling methods, as well as between the computational and the published experimental work. Results Nanostructure model complexity had no impact on the computed water equivalent thickness, with <1% difference between the three modeling methods. The inclusion of delta ray production and tracking physics produced a slight decrease in the computed water equivalent thickness and significantly increased the computational time for a single simulation by a factor of 35.7. Computationally determined water equivalent thicknesses are within 5% of published experimentally determined values. Conclusions Shielding capabilities of a polymer/carbon nanotube nanocomposite estimated using Monte Carlo radiation transport models agree well with published experimental results, even with a simplistic representation of the nanocomposite material. Radiation transport settings influenced the resulting water equivalent thickness as well as computational resource needs.

Radiation hardness evaluation of ε-Ga2O3 thin-film devices under swift heavy ion irradiation

The ultra-wide band gap (∼4.9 eV) and extremely large breakdown field strength (∼8 MV/cm) enable ε-Ga2O3 as an ideal materials candidate for high-performance power devices and solar-blind photodetectors. For the purpose of deep space applications explorations, comprehensive study of the effects of particle irradiation on the lattice stability and electronic properties of ε-Ga2O3 are of pivotal importance. In this work, leveraging a unique Ta radiation source, we interrogate the radiation hardness of ε-Ga2O3 thin films after 1907 MeV Ta swift heavy ion (SHI) irradiation. Detailed characterizations of the structural and optical properties show that the morphology and lattice structure are disrupted, with an increase of the band gap. Additionally, X-ray photoelectron spectroscopy experiments combining density functional theory calculations corroborate extrinsic flux-induced high concentration defects in the film, which lead to truncated photo-response performance of the device. However, even upon irradiation with a fluence of 5 × 1010 cm−2, the overall performance of the device remains robust and substantial. This outstanding radiation hardness of ε-Ga2O3 thin films rationalizes their potential usage for space applications.

Numerical Simulations of Space Charge Waves Amplification Using Negative Differential Conductance in Strained Si/SiGe at 4.2 K

This paper introduces a two-dimensional (2D) numerical simulation of the amplification of space charge waves using negative differential conductance in a typical MOS silicon–germanium (SiGe)-based field-effect transistors (FET) and complementary metal oxide semiconductor (CMOS) technology at 4.2 K. The hydrodynamic model of electron transport was applied to describe the amplification of space charge waves in this nonlinear medium (i.e., the negative differential conductance). This phenomenon shows up in GaAs thin films at room temperature. However, this can be also observed in a strained Si/SiGe heterostructure at very low temperatures (T < 77 K) and at high electric fields (E > 10 KV/cm). The results show the amplification and non-linear interaction of space charge waves in a strained Si/SiGe heterostructure occurs for frequencies up to approximately 60 GHz at T = 1.3 K, 47 GHz at T = 4.2 K, and 40 GHz at T = 77 K. The variation of concentration and electric field in the Z and Y directions are calculated at 4.2 K. The electric field in the Z direction is greater than in the Y direction. This is due to the fact that this is the direction of electron motion. In addition to deep space applications, these types of devices have potential uses in terrestrial applications which include magnetic levitation transportation systems, medical diagnostics, cryogenic instrumentation, and superconducting magnetic energy storage systems.

Mars mission capabilities enabled by nuclear thermal propulsion

As part of the Artemis era of space exploration, space agencies will be working together with their industry partners to establish systems and infrastructure that enable sustained Lunar missions and develop capabilities for Mars. Lockheed Martin has a longstanding history of designing, building, and operating systems for deep space applications, from Viking to Orion. Lockheed Martin develops concepts, trades, and early system designs for Moon and Mars exploration to enable future missions. In 2016, Lockheed Martin presented a vision for achieving crewed exploration of Mars. Known as Mars Base Camp (MBC), this design reference mission envisioned a crewed vehicle in Martian orbit from which astronauts could perform excursions to Phobos and Deimos and perform telerobotic exploration of the Martian surface, including sample return. This concept served as an “existence proof” for a novel, practical, and affordable path to enable human exploration of the Martian system. In 2017, an update was published that included the production of propellant from water and a single-stage fully reusable Mars lander concept. Then in 2021, Lockheed Martin introduced a nuclear thermal propulsion (NTP) configuration of Mars Base Camp, a technology that will be greatly enabling for crewed missions to Mars. This paper matures the design of the NTP configuration of Mars Base Camp and explores the Mars mission capabilities that the NTP technology will enable. These investigations include optimized trajectories for faster transit to Mars and an analysis of abort scenarios that are made possible by the high thrust and performance of NTP. The results provide insight into the performance and capabilities that are realized when NTP technology is matured and integrated into a Mars transit vehicle. The paper will also describe initial surface infrastructure capabilities that significantly enhance sortie science operations, including mobility and power. The resulting updated Mars Base Camp serves as an example of what is possible with current technologies and technologies under development. The MBC reference mission builds on the capabilities that will be developed and demonstrated through Artemis missions, enabling a viable, sustainable long-term Mars exploration program, with the first crewed Mars mission possible in the 2030s.

Temperature Analysis of DMGC CGAA FET for Future Deep Space and Military Applications: An Insight into Analog/RF/Self-Heating/Linearity

This manuscript introduces a pioneering investigation on the temperature effects of Dual Material Graded Channel (DMGC) Cylindrical Gate All Around (CGAA) FET by outlining its significance in various aspects such as analog/RF, self-heating, and linearity performance metrics. For this analysis, we have proposed a DMGC CGAA FET by amalgamating the gate and channel engineering techniques and the temperature is varied from 250 K to 450 K. A significant improvement in Ion/Ioff, SS, and DIBL by an amount of 96.98%, 19.49%, and 51.26% is obtained respectively for the proposed DMGC CGAA FET as compared to the single material graded channel (SMGC) CGAA FET. As the temperature is reduced from 450 K to 250 K, a noticeable improvement in analog/RF figure of merits and delay is obtained. Further, the self-heating effect (SHE) analysis revealed that the utilization of lower Rth is preferrable to minimize SHE in the device. Moreover, linearity parameters like gm2, gm3, VIP2, VIP3, IIP3 and IMD3 are noticed to be better for lower temperatures at higher VGS indicating good linearity. The obtained results make proposed device an ideal choice for various applications especially that operate in low temperature environments such as deep space, military, and RF applications.

Control strategy study for a heat pipe cooled nuclear reactor

The heat pipe cooled nuclear reactor (HPR) features simple structure, high safety, low noise, compact structure and long working time. HPR is therefore a better candidate energy source for deep space and underwater applications. Due to the unique features, the dynamics of HPR are different from conventional nuclear reactors. It is necessary to investigate the control strategy. In this study, an HPR system code HEART is coupled with 3KeyMaster to build the HPR simulation platform using the shared memory technology. Steady state and transient characteristics of HPR are obtained in the platform and analyzed. The control strategy with reactor power, heat pipe temperature and electric power controlled is proposed. The control systems are built and tuned on the simulation platform. Typical transient tests are performed to evaluate the performance of the control systems. The simulation results demonstrate that the proposed control strategy can meet control requirements on the power maneuvering and reactor startup.

Low-intensity low-temperature analysis of perovskite solar cells for deep space applications

Perovskite solar cells (PSCs) are studied in low-intensity low-temperature (LILT) conditions before and after low energy proton irradiation to characterize device performance at deep space mission-relevant light intensities and temperatures.

On line-of-sight navigation for deep-space applications: A performance analysis

Line-of-Sight (LoS) navigation is an optical navigation technique that exploits the direction to visible celestial bodies, obtained from an onboard imaging system, to estimate the position and velocity of a spacecraft. The directions are fed to an estimation filter, where they are matched with the actual position of the observed bodies, retrieved from onboard stored ephemerides. As LoS navigation represents a really promising option for the next-generation deep-space spacecraft, the objective of this work is to provide new insights into the performance. First, the information matrix is analyzed to show the influence of the geometry between the spacecraft and the observed planet(s). Then, a Monte Carlo approach is used to investigate the influence of measurement error (ranging from 0.1 to 100 arcsec), and tracking frequency (ranging from four observations per day to one observation every two days). The effect on navigation performance is quantified by two indicators. The first is the 3D position and velocity Root-Mean-Square-Errors, computed once the estimation is considered to be steady-state. The second is the convergence time, which quantifies the required time for the estimation to reach the steady-state behaviour. The simulation is based on a set of four planets, which do not follow the common heliocentric dynamics but rotate around the Sun with the same (distance-independent) angular velocity of the spacecraft. This approach allows the separation of scenario-dependent behaviours from navigation intrinsic properties, as the same relative geometry between observer and observed objects is maintained during the whole simulation. The results provide a useful guide for the next-generation autonomous navigation system, for both the definition of hardware requirements and the design of an appropriate navigation strategy. Considerations are then applied to Near-Earth Asteroid fly-by mission scenarios for the definition of the navigation strategy and hardware requirements. It is shown the importance of relative angles between the spacecraft and the planets. In the single-planet observation scenario, when the angle between the position vectors of the spacecraft and planet approaches a null value, the estimation error decreases. In the double-planets observation scenario, when the separation angle between the two LoS directions gets close to 90°, the estimation error decreases. The main influence on the performance is driven by the measurement error, which with current technologies is shown to be able to provide a position error in the order of a few hundred kilometers, while with a lower measurement error (0.1 arcsec) it would be possible to have a position error below 100 km. Finally, it is demonstrated that tracking frequency plays a secondary role in the performance, and only influences tangibly the convergence time.

Neutronics analysis of a 200 kWe space nuclear reactor with an integrated honeycomb core design

Heat pipe cooled nuclear reactor has been a very attractive technical solution to provide the power for deep space applications. In this paper, a 200 kWe space nuclear reactor power design has been proposed based on the combination of an integrated UN ceramic fuel, a heat pipe cooling system and the Stirling power generators. Neutronics and thermal analysis have been performed on the space nuclear reactor. It was found that the entire reactor core has at least 3.9 $ subcritical even under the worst-case submersion accident superimposed a single safety drum failure, and results from fuel temperature coefficient, neutron spectrum and power distribution analysis also showed that this reactor design satisfies the neutronics requirements. Thermal analysis showed that the power in the core can be successfully removed both in normal operation or under one or more heat pipes failure scenarios.

A highly reliable radiation tolerant 13T SRAM cell for deep space applications

This paper proposes a highly reliable radiation-tolerant 13T (HRRT 13T) SRAM cell for deep-space applications. The proposed SRAM cell design can effectively tolerate radiation events. The design metrics of the proposed SRAM cell are compared with conventionally used SRAM cells like QUCCE 10T, QUCCE 12T and standard 6T SRAM cells. The proposed SRAM cell consumes 9.4% and 14% lesser hold power (HPWR) compared to QUCCE 10T and QUCCE 12T SRAM cells, respectively. The proposed SRAM cell exhibits 12.7%, 3.63% and 11.7% shorter read access time (TRA) compared to QUCCE 10T, QUCCE 12T and 6T SRAM cells, respectively at a nominal supply voltage (VDD) of 0.7 V. The proposed HRRT 13T SRAM cell exhibits higher read stability compared to other conventionally used SRAM cells. This has been validated by 2.92×, 2.33× and 2.06× higher read static noise margin (RSNM) exhibited by the proposed cell compared to the 6T, QUCCE 10T and QUCCE 12T SRAM cells, respectively at VDD = 0.7 V. The proposed SRAM cell exhibits high radiation tolerance capability compared to the conventionally used SRAM cells. This has been proved by 94.1%, 17.8% and 10.0% higher critical charge (QC) of the proposed cell compared to 6T, QUCCE 10T and QUCCE 12T SRAM cells, respectively at VDD = 0.7 V. The proposed cell achieves all these improvements at the expense of 1.05×, 1.38× and 1.36× longer write delay (TWA) compared to QUCCE 10T, QUCCE 12T and 6T SRAM cells, respectively at VDD = 0.7 V. Extensive simulations on SPICE using 16-nm CMOS technology are performed to validate the theoretical design of the proposed SRAM cell.

The Short‐Time Prediction of the Energetic Electron Flux in the Planetary Radiation Belt Based on Stacking Ensemble‐Learning Algorithm

AbstractHigh energy electrons in planetary radiation belts are a major threat to satellites and communications in deep space applications. In order to predict the variations of energetic electron fluxes for different energy channels, we proposed a new ensemble machine leaning model for differential electron flux from 30 keV to 4 MeV in the Earth's radiation belts based on the RBSP‐A observation data from March 2013 to December 2017. The deep neural network (DNN), the convolutional neural network (CNN), the combination of CNN and DNN (CNN&DNN), the linear regression (LR), and the light gradient boosting machine (LightGBM) are among the machine learning models chosen. We carefully compared the electron flux predictions for 20 energy levels and all five models can present valid short‐time flux forecasts. The DNN model has the poorest result. The LR model is good for short‐term forecasting but not so good for long‐term forecasting. The LightGBM ensemble model is highly stable, and it has always outperformed other independent models in terms of forecast accuracy. Then the comparison by adding AE and SYM‐H indexes is given and the influence of geomagnetic activity conditions can be negligible for this short‐time prediction. Furthermore, we applied these five models on Saturn and finally got very similar prediction results. Our results will be significantly useful in instrument designs and system control of future scientific satellites in deep space explorations.

A review on developments of deployable membrane-based reflector antennas

The gossamer space structures are very large and ultra-lightweight structures. A large aperture-based space structure is highly efficient in capturing signals from a wide coverage area. However, their deployment in space has been a critical challenge to date. Extensive research has been carried out on various types of gossamer structures used for earth exploration and deep space applications. Space antenna, in general, should have a large electrical aperture, be light in weight with small stowage volume, be easily deployable in space, and thermally stable. The antenna consists mainly of a reflector as a major part and a torus for supporting the reflector, electronic control unit, and struts. This paper covers an extensive review of gossamer space structure considering different categories of large deployable antennas. More attention has been given to a large membrane-based antenna having a parabolic reflector. This work includes the study of designs, analyses, and development of prototypes and successful deployment of space structures in orbit. We emphasize understanding the behaviour of thin membrane, their static and dynamic characteristics, wrinkling control, shape control of thin membrane reflector, and recent advances in deployment techniques of large deployable antenna structures.

Space time clock: An on-chip clock with 10−12 instability

High precision and stable clock is extremely important in communication and navigation. The miniaturization of the clocks is considered to be the trend to satisfy the demand for 5G and the next generation communications. Based on the concept of meter bar and the principle of the constancy of light velocity, we designed a micro clock, Space Time Clock (STC), with the size smaller than 1 mm × 1 mm and the power dissipation less than 2 mW. Designed in integrated circuit of 0.18 μm technology, the instability of STC is assessed to be 2.23 × 10−12 and the trend of the instability is reversely proportional to τ. With the potential ability to reach the level of 10−16 instability on chip in the future, the period of the STC’s signal is locked on the delay time defined by the meter bar which keeps the time reference constant. Because of its superior performance, the STC is more suitable for mobile communication, PNT (Positioning, Navigation and Timing), embedded processor and deep space application, and becomes the main payload of the ASRTU satellite scheduled to launch next year and investigate in space environment.

Dislocations Stabilized by Point Defects Increase Brittleness in PbTe

AbstractDislocations and the residual strain they produce are instrumental for the high thermoelectric figure of merit, zT ≈ 2, in lead chalcogenides. However, these materials tend to be brittle, barring them from practical green energy and deep space applications. Nonetheless, the bulk of thermoelectrics research focuses on increasing zT without considering mechanical performance. Optimized thermoelectric materials always involve high point defect concentrations for doping and solid solution alloying. Brittle materials show limited plasticity (dislocation motion), yet clear links between crystallographic defects and embrittlement are hitherto unestablished in PbTe. This study identifies connections between dislocations, point defects, and the brittleness (correlated with Vickers hardness) in single crystal and polycrystalline PbTe with various n‐ and p‐type dopants. Speed of sound measurements show a lack of electronic bond stiffening in p‐type PbTe, contrary to the previous speculation. Instead, varied routes of point defect–dislocation interaction restrict dislocation motion and drive embrittlement: dopants with low doping efficiency cause high defect concentrations, interstitial n‐type dopants (Ag and Cu) create highly strained obstacles to dislocation motion, and highly mobile dopants can distribute inhomogeneously or segregate to dislocations. These results illustrate the consequences of excessive defect engineering and the necessity to consider both mechanical and thermoelectric performance when researching thermoelectric materials for practical applications.

Refractive index and extinction coefficient of hollow microspheres for solar reflection

While hollow microspheres and various porous structures have received much attention for solar reflection in the recent literature, their fundamental determinants of optical properties and material selection criteria are relatively little known. Here, we study hollow microspheres with varying refractive index and extinction coefficient and identify their role in determining the solar reflectivity. Our simulations based on finite-difference time-domain method show the effects of refractive index between 1.5 and 100 and extinction coefficient between 10−6–100 in the wavelength region of 0.2–2.4 μm and explain how the reflectivity of hollow microspheres is attributed to a combination of strong backscattering and limited absorption. Our analysis indicates that ceramic materials with a high refractive index and a low extinction coefficient such as Y2O3 are promising. When Y2O3 hollow microspheres are randomly distributed with the diameter ranging from 0.5 to 1 μm, our simulation shows the solar reflectivity reaches 0.97 even at 300 μm thickness, and a diffusion theory-based model predicts the solar reflectivity to exceed 0.98 at 500 μm or 0.99 at 1 mm thickness. Our findings can guide optimal designs of hollow microspheres and related porous structures toward complete solar reflection and enable breakthroughs in thermal management and deep-space applications.