Future Space Missions Research Articles

Temperature Influence on the Radiation Responses of Erbium‐Doped Fiber Amplifiers

The gain degradations of an Er‐doped fiber amplifier (EDFA) during the exposure of its active Er‐doped fiber to 40 keV X‐rays (≈2.7 mrad(SiO2) s−1 up to 300 krad) at three different temperatures: −40, 25, and 120 °C, are characterized. The spectral dependence of the fiber radiation‐induced attenuation (RIA) is monitored in situ in the 900–1600 nm spectral range, highlighting a combined temperature and radiation effect on the near‐infrared RIA levels and kinetics. At the system level, the kinetics of EDFA gain degradation are only slightly affected by varying the irradiation temperature for the tested backward pumping EDFA configuration. On the theoretical side, a homemade computer code based on the particle swarm optimization and the rate equations to model the radiation behavior of EDFA is used, considering only the RIA impact on its gain. Despite a good agreement between experimental and simulation results below the dose of 70 krad corresponding to current space missions, the comparison between the modeled and measured gain degradation kinetics at higher doses shows that a more precise modeling of the temperature impact on the absorption properties of the erbium ions is necessary to better reproduce the EDFA radiation behavior for future space missions.

Using supraglottic airways by paramedics for airway management in analogue microgravity increases speed and success of ventilation

In the next few years, the number of long-term space missions will significantly increase. Providing safe concepts for emergencies including airway management will be a highly challenging task. The aim of the present trial is to compare different airway management devices in simulated microgravity using a free-floating underwater scenario. Five different devices for airway management [laryngeal mask (LM), laryngeal tube (LT), I-GEL, direct laryngoscopy (DL), and video laryngoscopy (VL)] were compared by n = 20 paramedics holding a diving certificate in a randomized cross-over setting both under free-floating conditions in a submerged setting (pool, microgravity) and on ground (normogravity). The primary endpoint was the successful placement of the airway device. The secondary endpoints were the number of attempts and the time to ventilation. A total of 20 paramedics (3 female, 17 male) participated in this study. Success rate was highest for LM and LT and was 100% both during simulated microgravity and normogravity followed by the I-GEL (90% during microgravity and 95% during normogravity). However, the success rate was less for both DL (60% vs. 95%) and VL (20% vs. 60%). Fastest ventilation was performed with the LT both in normogravity (13.7 ± 5.3 s; n = 20) and microgravity (19.5 ± 6.1 s; n = 20). For the comparison of normogravity and microgravity, time to ventilation was shorter for all devices on the ground (normogravity) as compared underwater (microgravity). In the present study, airway management with supraglottic airways and laryngoscopy was shown to be feasible. Concerning the success rate and time to ventilation, the optimum were supraglottic airways (LT, LM, I-GEL) as their placement was faster and associated with a higher success rate. For future space missions, the use of supraglottic airways for airway management seems to be more promising as compared to tracheal intubation by DL or VL.

Compression algorithms for high-data-volume instruments on planetary missions: a case study for the Cassini mission

We investigated data compression algorithms to boost science data return from high-data-volume instruments on planetary missions, particularly outer solar system missions where every bit of data represents an engineering triumph of over severe constraints on mass (limiting antenna size) and power (limiting signal strength). We developed a methodology to (1) investigate algorithms to improve compression and (2) to work with the science teams to evaluate the effects on the science. Our algorithm for compressing the Cassini Radio Plasma Wave Science (RPWS) data achieved a factor of 5 improvement in data compression (relative to what the RPWS team was using), and our algorithm for the Cassini Ultraviolet Imaging Spectrograph (UVIS) Saturn data set achieved a much higher factor (∼70). In both cases, the investigators on the science teams who evaluated our results reported that the science goals were not compromised. Our compression algorithm for Imaging Science Subsystem images achieved on average a factor of ∼1.7 improvement in lossless compression compared to the original algorithm. We also evaluated the compression effectiveness of JPL’s Fast Lossless EXtended (FLEX) hyperspectral/multispectral image compressor on Cassini’s Visible and Infrared Mapping Spectrometer data. FLEX lossless compression provides a factor of 2 improvement over the original compression. We also explore a different range of lossy compression, which can achieve an additional factor 2 to 5 depending on the fidelity required. Our findings have implications for the design of future space missions, particularly with respect to antenna size and overall size, weight, and power budgets, by demonstrating strategies to implement better data compression. In addition to improved algorithms, we show that an iterative process involving real-time science team evaluation and feedback to update the onboard compression algorithm is both essential and feasible. We make the case that a spacecraft facility compressor hosting a toolbox of compression algorithms, available to all of the science instruments and supported by a team of compression experts, convey significant benefits. Beyond the obvious benefits of increased science return and faster playback, better data compression enables design trades between antenna size and number of science instruments on the payload.

Potential of commercial SiN MPW platforms for developing mid/high-resolution integrated photonic spectrographs for astronomy.

Integrated photonic spectrographs offer an avenue to extreme miniaturization of astronomical instruments, which would greatly benefit extremely large telescopes and future space missions. These devices first require optimization for astronomical applications, which includes design, fabrication, and field testing. Given the high costs of photonic fabrication, multi-project wafer (MPW) silicon nitride (SiN) offerings, where a user purchases a portion of a wafer, provide a convenient and affordable avenue to develop this technology. In this work, we study the potential of two commonly used SiN waveguide geometries by MPW foundries, i.e., square and rectangular profiles, to determine how they affect the performance of mid/high-resolution arrayed waveguide grating (AWG) spectrometers around 1.5 µm. Specifically, we present results from detailed simulations on the mode sizes, shapes, and polarization properties, and on the impact of phase errors on the throughput and cross talk as well as some laboratory results of coupling and propagation losses. From the MPW run tolerances and our phase-error study, we estimate that an AWG with R ∼10,000 can be developed with the MPW runs, and even greater resolving power is achievable with more reliable, dedicated fabrication runs. Depending on the fabrication and design optimizations, it is possible to achieve throughputs ∼60% using the SiN platform. Thus, we show that SiN MPW offerings are highly promising and will play a key role in integrated photonic spectrograph developments for astronomy.

Imprints of the secondary interstellar hydrogen atoms at 1 au

ABSTRACT In this paper, we search for the possible imprints of the secondary interstellar hydrogen atoms created at the heliospheric boundary in the full-sky maps of the hydrogen fluxes at the Earth orbit. By using our three-dimensional time-dependent kinetic model, the maps of the hydrogen fluxes are calculated for different phases of the solar cycle and different energy ranges. It is shown that the flux maps obtained during the solar minimum conditions for the energy range 1–20 eV have specific features such as blobs and tails, which are pronounced due to a signal of the secondary component of the interstellar atoms. We investigate how these features depend on parameters of the secondary atoms far away from the Sun and found that the geometry and shape of the tails depend on the averaged velocity and kinetic temperatures of the secondary population. The results of the paper provide a strategy where and when we need to look in order to detect the secondary component of the interstellar hydrogen separately from the primary component at 1 au. This can be important for future space missions devoted to the exploration of the heliospheric boundary.

Precise real‐time navigation of LEO satellites using GNSS broadcast ephemerides

The availability of orbit information with high precision and low latency is a key requirement for many Earth-observation missions, predominantly in the field of radio occultation. Traditionally, precise orbit determination solutions of low-Earth orbit (LEO) satellites are obtained offline on ground after downloading GNSS measurements and auxiliary spacecraft data to the processing center. The latency of this processing depends on the frequency of LEO downlink contacts and the availability of precise GNSS orbit and clock products required for the orbit determination process. These dependencies can be removed by computing the precise orbit determination solution on board the satellite using GNSS broadcast ephemerides. In this study, both real data and simulated measurements from a representative LEO satellite are processed in a flight-proven Kalman-filter algorithm. The paper studies the use of GPS, Galileo and BeiDou-3 for real-time orbit determination in different combinations with simulated measurements. Results show that use of dual-frequency observations and broadcast ephemerides of Galileo and BeiDou-3 leads to a significant reduction of 3D rms orbit errors compared to GPS-only processing. An onboard navigation accuracy of about one decimeter can be achieved without external augmentation data, which opens up new prospects for conducting relevant parts of the science data processing in future space missions directly on board a LEO satellite.

The Impact of Spaceflight and Microgravity on the Human Islet-1+ Cardiovascular Progenitor Cell Transcriptome.

Understanding the transcriptomic impact of microgravity and the spaceflight environment is relevant for future missions in space and microgravity-based applications designed to benefit life on Earth. Here, we investigated the transcriptome of adult and neonatal cardiovascular progenitors following culture aboard the International Space Station for 30 days and compared it to the transcriptome of clonally identical cells cultured on Earth. Cardiovascular progenitors acquire a gene expression profile representative of an early-stage, dedifferentiated, stem-like state, regardless of age. Signaling pathways that support cell proliferation and survival were induced by spaceflight along with transcripts related to cell cycle re-entry, cardiovascular development, and oxidative stress. These findings contribute new insight into the multifaceted influence of reduced gravitational environments.

Laboratory demonstration of space experiment for spectrometry of planetary gamma-rays with tags of Galactic Cosmic Rays producing them

The laboratory demonstration of a space experiment implementing spectrometry of planetary gamma-rays with tags of Galactic Cosmic Rays (GCR) was conducted at Joint Institute for Nuclear Research. The main objective of these efforts was to study the capability of this method to search for heterogeneities in the analog of planetary soil and to compare it with capability of the standard gamma-ray spectroscopy. It was experimentally shown that the method of spectroscopy of gamma-rays with tags demonstrates much higher confidence to search variations of amounts of the most widespread metals, like Al, Fe and Ti, in the planetary regoliths. The numerical simulation of the laboratory experiment shows a very good agreement with observations. It is proved that gamma-ray spectrometry with tags is a perspective method for future space missions to explore the Moon, Mars and another celestial bodies with thin atmosphere or without it.

Prototype of a monolithic cavity-based ultrastable optical reference for space applications.

We present a compact, monolithic optical reference for the frequency stabilized laser of future inter-satellite laser interferometer missions. A prototype based on the integration of a high-finesse cavity and associate optics has been designed to be space compatible while maintaining sufficient stability. The prototype has then been developed with a space-qualified bonding technique, and an in situ multi-degree-of-freedom alignment method. The performances of the optical reference have been studied by beat note analysis with another frequency stabilized laser, and the preliminary results are in agreement with the potential requirements of future space missions.

Effects of Low Dose Space Radiation Exposures on the Splenic Metabolome.

Future space missions will include a return to the Moon and long duration deep space roundtrip missions to Mars. Leaving the protection that Low Earth Orbit provides will unavoidably expose astronauts to higher cumulative doses of space radiation, in addition to other stressors, e.g., microgravity. Immune regulation is known to be impacted by both radiation and spaceflight and it remains to be seen whether prolonged effects that will be encountered in deep space can have an adverse impact on health. In this study, we investigated the effects in the overall metabolism of three different low dose radiation exposures (γ-rays, 16O, and 56Fe) in spleens from male C57BL/6 mice at 1, 2, and 4 months after exposure. Forty metabolites were identified with significant enrichment in purine metabolism, tricarboxylic acid cycle, fatty acids, acylcarnitines, and amino acids. Early perturbations were more prominent in the γ irradiated samples, while later responses shifted towards more prominent responses in groups with high energy particle irradiations. Regression analysis showed a positive correlation of the abundance of identified fatty acids with time and a negative association with γ-rays, while the degradation pathway of purines was positively associated with time. Taken together, there is a strong suggestion of mitochondrial implication and the possibility of long-term effects on DNA repair and nucleotide pools following radiation exposure.

Considerations for Implementing Presidential Memorandum-20 Guidelines for Nuclear Safety Launch Authorization for Future Civil Space Missions

National Security Presidential Memorandum-20 (NSPM-20) (Launch of Spacecraft Containing Space Nuclear Systems) provides updated guidelines for launch authorization for three categories of proposed launches of spacecraft with space nuclear systems: Federal government civil space including the National Aeronautics and Space Administration (NASA), Federal government defense and intelligence, and commercial. These space nuclear systems provide power, heat, and/or propulsion to the spacecraft. NSPM-20 requires a rigorous, risk-informed safety analysis and launch authorization process. The launch approval process of previous NASA missions each took several years and cost multimillion dollars. NSPM-20 provides guidelines to potentially streamline the process and improve cost and schedule. This technical note examines three NSPM-20 guidelines on a future example interplanetary mission (EIM) as to their potential implementation feasibility for three accident categories: Earth gravity assist reentry, solid propellant fires, and flight termination system design. It is found that the safety technology for these accidents were constantly improved over the last several missions, but in some cases may not be adequate for direct use in the EIM’s launch authorization process.

Possibilities of Studying the Operator Qualities of a Cosmonaut with the Help a Helicopter for the Benefit of Future Manned Space Programs.

The paper investigates the methodical and organizational issues of the use of existing helicopters in order to evaluate cosmonauts’ operator qualities for the benefit future manned space missions. The methodology for studying the ef-fects of long-duration staying in space on the quality of activity of a cosmo-naut-operator who controls a complex dynamic human-machine system has been designed and tested. The paper offers the system of objective indications for the evaluation of cosmonauts’ operator qualities according to the results of a series of preliminary experiments.

Calibration of a radiation quality model for sparse and uncertain data

This article proposes chance-constrained formulations for the calibration of computational models given data subject to uncertainty. The uncertainty might be caused by a poor metrology system, measurement noise, model-form uncertainty or by the inability to directly measure the inputs and/or outputs of the model. The formulations developed, called Forward Maximum Likelihood and Inverse Maximum Likelihood, are applicable to datasets with and without uncertainty. The forward approach performs the calibration in the space of the model’s output thereby requiring repeated model simulations. Conversely, the inverse approach leverages an ensemble of solutions to an inverse problem in order to perform the calibration in the space of the model’s parameters. The potential loss of performance incurred by this approach is often justified by a sizable reduction in computational cost. The ideas proposed are applied to the calibration of a radiation quality model used by NASA to assess cancer risk in future deep space missions. We calibrate several models in order to evaluate the extent by which data uncertainty, outliers, and the commonly made assumption of parameter independence cause conservatism in the resulting model prediction.

Development of an indirect thrust stand based on a cantilever beam

There is a large number of missions that have been or will be launched soon that utilize the electric propulsion (EP), which is considered a key technology for applications in present and future space missions. Accomplishing an accurate measure of the thrust is a key aspect of the laboratory verification of EP systems. In the case of ground conditions and direct measurements, it is complicated to verify the thrusters, especially for some high power (>5 kW) thrusters. For this reason, we have developed an indirect method for measuring thrust. We have carried out an experiment with a Hall effect thruster (operated in the 250 W power range) and compared results against direct thrust measurements. The difficulties in the indirect measurement are analyzed, which provides a basis for the development of indirect thrust measurement.

Head-Down Tilt Position, but Not the Duration of Bed Rest Affects Resting State Electrocortical Activity.

Adverse cognitive and behavioral conditions and psychiatric disorders are considered a critical and unmitigated risk during future long-duration space missions (LDSM). Monitoring and mitigating crew health and performance risks during these missions will require tools and technologies that allow to reliably assess cognitive performance and mental well-being. Electroencephalography (EEG) has the potential to meet the technical requirements for the non-invasive and objective monitoring of neurobehavioral conditions during LDSM. Weightlessness is associated with fluid and brain shifts, and these effects could potentially challenge the interpretation of resting state EEG recordings. Head-down tilt bed rest (HDBR) provides a unique spaceflight analog to study these effects on Earth. Here, we present data from two long-duration HDBR experiments, which were used to systematically investigate the time course of resting state electrocortical activity during prolonged HDBR. EEG spectral power significantly reduced within the delta, theta, alpha, and beta frequency bands. Likewise, EEG source localization revealed significantly lower activity in a broad range of centroparietal and occipital areas within the alpha and beta frequency domains. These changes were observed shortly after the onset of HDBR, did not change throughout HDBR, and returned to baseline after the cessation of bed rest. EEG resting state functional connectivity was not affected by HDBR. The results provide evidence for a postural effect on resting state brain activity that persists throughout long-duration HDBR, indicating that immobilization and inactivity per se do not affect resting state electrocortical activity during HDBR. Our findings raise an important issue on the validity of EEG to identify the time course of changes in brain function during prolonged HBDR, and highlight the importance to maintain a consistent body posture during all testing sessions, including data collections at baseline and recovery.

Current status of space gravitational wave antenna DECIGO and B-DECIGO

Abstract The Deci-hertz Interferometer Gravitational Wave Observatory (DECIGO) is a future Japanese space mission with a frequency band of 0.1 Hz to 10 Hz. DECIGO aims at the detection of primordial gravitational waves, which could have been produced during the inflationary period right after the birth of the Universe. There are many other scientific objectives of DECIGO, including the direct measurement of the acceleration of the expansion of the Universe, and reliable and accurate predictions of the timing and locations of neutron star/black hole binary coalescences. DECIGO consists of four clusters of observatories placed in heliocentric orbit. Each cluster consists of three spacecraft, which form three Fabry–Pérot Michelson interferometers with an arm length of 1000 km. Three DECIGO clusters will be placed far from each other, and the fourth will be placed in the same position as one of the other three to obtain correlation signals for the detection of primordial gravitational waves. We plan to launch B-DECIGO, which is a scientific pathfinder for DECIGO, before DECIGO in the 2030s to demonstrate the technologies required for DECIGO, as well as to obtain fruitful scientific results to further expand multi-messenger astronomy.

The concept of a long-term service station to increase the life duration of some satellites or to remove space debris

Every year the concentration of space debris is steadily growing, which significantly complicates the conduct of both modern and future space missions using automatic, and especially manned space vehicles. To date, over 18,000 artificial objects and fragments recorded in near-Earth space. Therefore, the issues of cleansing outer space of space debris of various sizes are quite relevant. In this article, the concept of a multirole station is studied. For the successful design of such a station that could serve spacecraft in space and successfully cope with space debris, it is necessary to consider and necessarily take into account in its further work the ballistic aspects of the orbital motion of spacecraft and the logistics of building such a station. This station could be a maintenance hub for satellites or a space debris collector. Because some satellites have very precious instruments onboard, it could be a loose of money to launch a new satellite if the first one is out of service because of a system failure or a lack of fuel. In this perspective, an orbital maintenance hub would enable to fix the failure (batteries replacement, refueling, mechanical maintenance) and to give to the satellites a new life. In this article, we also study the possibility of using such a hub to remove space debris from their orbit and to collect them until they can be deorbiting.

Electromyography for Teleoperated Tasks in Weightlessness

The cooperation between robots and astronauts will become a core element of future space missions. This is accompanied by the demand for suitable input devices. An interface based on electromyography (EMG) represents a small, light, and wearable device to generate a continuous three-dimensional (3D) control signal from voluntarily muscle activation of the operator's arm. We analyzed the influence of microgravity on task performance during a two-dimensional (2D) task on a screen. Six subjects performed aiming and tracking tasks in parabolic flights. Three different levels of fixation-fixed feet using foot straps, semi-free by using a foot rail, and free-floating feet-are tested to investigate how much user fixation is required to operate via the interface. The user study showed that weightlessness affects the usage of the interface only to a small extent. Success rates between 89${\%}$ and 96${\%}$ are reached within all conditions during microgravity. A significant effect between 0 and 1G could not be identified for the test series of fixed and semi-free feet, while free-floating feet showed significantly worse results in fine and gross motion times in 0G compared to ground tests (with success rates of 92${\%}$ for 0G and 99${\%}$ for 1G). Further adaptation to the altered proprioception may be needed here. Hence, foot rails as already mounted in the International Space Station (ISS) would be sufficient to use the interface in weightlessness. Low impact of microgravity, high success rates, and an easy handling of the system, indicates a high potential of an EMG-based interface for teleoperation in space.

Rapid Generation of Fully Relativistic Extreme-Mass-Ratio-Inspiral Waveform Templates for LISA Data Analysis.

The future space mission LISA will observe a wealth of gravitational-wave sources at millihertz frequencies. Of these, the extreme-mass-ratio inspirals of compact objects into massive black holes are the only sources that combine the challenges of strong-field complexity with that of long-lived signals. Such signals are found and characterized by comparing them against a large number of accurate waveform templates during data analysis, but the rapid generation of templates is hindered by computing the ∼10^{3}-10^{5} harmonic modes in a fully relativistic waveform. We use order-reduction and deep-learning techniques to derive a global fit for the ≈4000 modes in the special case of an eccentric Schwarzschild orbit, and implement the fit in a complete waveform framework with hardware acceleration. Our high-fidelity waveforms can be generated in under 1s, and achieve a mismatch of ≲5×10^{-4} against reference waveforms that take ≳10^{4} times longer. This marks the first time that analysis-length waveforms with full harmonic content can be produced on timescales useful for direct implementation in LISA analysis algorithms.

A Meta-Analysis of the Effects of High-LET Ionizing Radiations in Human Gene Expression.

The use of high linear energy transfer (LET) ionizing radiation (IR) is progressively being incorporated in radiation therapy due to its precise dose localization and high relative biological effectiveness. At the same time, these benefits of particle radiation become a high risk for astronauts in the case of inevitable cosmic radiation exposure. Nonetheless, DNA Damage Response (DDR) activated via complex DNA damage in healthy tissue, occurring from such types of radiation, may be instrumental in the induction of various chronic and late effects. An approach to elucidating the possible underlying mechanisms is studying alterations in gene expression. To this end, we identified differentially expressed genes (DEGs) in high Z and high energy (HZE) particle-, γ-ray- and X-ray-exposed healthy human tissues, utilizing microarray data available in public repositories. Differential gene expression analysis (DGEA) was conducted using the R programming language. Consequently, four separate meta-analyses were conducted, after DEG lists were grouped depending on radiation type, radiation dose and time of collection post-irradiation. To highlight the biological background of each meta-analysis group, functional enrichment analysis and biological network construction were conducted. For HZE particle exposure at 8–24 h post-irradiation, the most interesting finding is the variety of DNA repair mechanisms that were downregulated, a fact that is probably correlated with complex DNA damage formation. Simultaneously, after X-ray exposure during the same hours after irradiation, DNA repair mechanisms continue to take place. Finally, in a further comparison of low- and high-LET radiation effects, the most prominent result is that autophagy mechanisms seem to persist and that adaptive immune induction seems to be present. Such bioinformatics approaches may aid in obtaining an overview of the cellular response to high-LET particles. Understanding these response mechanisms can consequently aid in the development of countermeasures for future space missions and ameliorate heavy ion treatments.