Characterizing Cosmic-Ray Nuclei with the RadMap Telescope using Neural Networks

Comparison of dose and risk estimates between ISS Partner Agencies for a 30-day lunar mission

Unlike the low-Earth orbit (LEO) project, space radiation, mainly coming from galactic cosmic radiation (GCR) and solar particle event (SPE), has been generally considered to be one of the most important health risk factors for astronauts in manned deep space exploration missions. In fact, space radiation environment in deep space is substantially different from that in low Earth orbit, in which high-energy protons and heavy nuclei provide the main contribution to the equivalent dose and health risk. Both the total equivalent dose and health risk in deep space are significantly higher than those in LEO missions, which may exceed the permissible radiation exposure limits in the career of astronauts. And, health risks from space radiation exposure remain a primary concern for manned deep space explorations. Space radiation protection is an important strategy to reduce astronauts’ risks of damage and disease induced by space radiation and ensure their health and safety in manned deep space exploration missions. Therefore, space radiation protection is considered to be an important technical problem to be solved in the further manned spaceflight project. However, the complexity and particularity of space radiation environment in manned deep space exploration missions make space radiation protection extremely difficult. Based on the analysis of space radiation environment characteristics in manned deep space exploration missions, this review systematically summarizes and analyzes the current research progresses of space radiation protection, including physical protection and biomedical protection. In general, the physical protection refers to the passive shielding and acitve shielding. The passive shielding of materials with different thickness is the simplest and feasible physical countermeasure to deal with deep space radiation, especially in the case of SPE occurrences. The passive shielding technologies were raised and reviewed from four aspects, including radiation shielding performance indexes and their applications in new material selections, manned spacecraft radiation shielding, personal radiation shielding, and astral surface soil radiation shielding. However, the passive shielding is problematic for GCR due to the penetration of primary high-energy particles, the production of secondary radiation and the mass constraints of manned spacecraft. While, active shielding, involving the generation of electromagnetic fields to deflect space radiation, is a promising and interesting technical improvement to overcome challenging technical hindrance to prevent GCR. But different kinds of active shielding technologies, such as electrostatic shielding, plasma shielding, confined and unconfined magnetic field shielding, have not been applicable in practical cases. Moreover, a series of radioprotectors and radiomitigators in the biomedical protection, including (1) antioxidants, (2) inhibitors of various pathways, (3) cytokines, chemokines, growth factors and hormones, (4) protein molecules, (5) cellular therapeutic agents, and (6) plant derived products, were also summarized and reviewed. Most radioprotectors and radiomitigators are currently being researched and developed under early preclinical phase, and have not been approved by the food and drug administrations. At the same time, the deficiency of some present radioprotectors and radiomitigators, such as the unclear biomedical mechanisms and unavoidable side-effects, limited the popularity in actual applications. In a word, the review points out that the current space radiation protection technologies still face a series of problems and challenges, and puts forward the key technologies and countermeasures of the current space radiation protection. The summary and analysis of the critical challenges and key countermeasures of space radiation protection are of great significance for the follow-up researches and provide a theoretical basis and a solution for the implementation of manned deep space exploration mission.

This paper presents a general approach to solve multi-client space logistics path optimization problems in the case of low-thrust propulsion. The methodology accounts for key time-dependent factors, including secular J 2 and drag perturbations, eclipse propulsion constraints, and servicer fuel mass depletion. A low-thrust transfer strategy, consisting of three phases (thrust-coast-thrust), is employed, utilizing a drift orbit to correct the difference in Right Ascension of the Ascending Node. The drift orbit parameters are optimized by using a nonlinear programming algorithm to minimize the fuel cost associated with the transfer while satisfying a maximum time of flight constraint. An optimization is conducted for all possible transfers between the satellites of a dataset on a two-dimensional discrete grid of initial servicer mass and departure time. This procedure creates two four-variable arrays representing the cost of each possible visitation in terms of fuel consumption and time of flight. The arrays are then interpolated to efficiently solve a general path optimization problem by using a genetic algorithm. Two test cases are analyzed for datasets consisting of 12 and 20 satellites in low Earth orbit, respectively. The first addresses an optimal open tour problem where the servicer must visit all satellites once while minimizing total fuel consumption. The second addresses an on-orbit refueling problem where the servicer must refuel as many satellites as possible. The mission scenario is generalized to consider a priority index associated with each client; servicing time and fuel mass constraints are also taken into account.

Precise relative GPS navigation is essential technology for rendezvous and formation flying of spacecraft in Low Earth Orbit. Key design issues of precise relative GPS navigation software are studied and a novel formulation is proposed for the mission which requires high accuracy when the separation distance is up to several km. The navigation filter estimates float navigation solutions by extended Kalman filter with elaborate dynamics models, and resolves ambiguities of integer carrier phase biases to achieve high accuracy fix navigation solutions. A relative navigation software with the proposed formulation is implemented and evaluated in two different ways. One is a test using spacebourne GPS receivers and a GPS signal simulator to evaluate the performance and sensitivity of the software against variation of parameters. The other is a test using actual telemetry data from Gravity Recovery and Climate Experiment (GRACE) to demonstrate the software performance. The design, implementation, and results of the evaluation are presented and discussed on this paper.

Robust and precise baseline determination of distributed spacecraft in LEO

The PROBA-2 microsatellite of the European Space Agency (ESA) is equipped with a novel single frequency global positioning system (GPS) receiver, which combines low resource requirements with a high navigation performance. Aside from supporting the spacecraft and mission operations, the Phoenix GPS receiver on PROBA-2 is used to study realtime and offline navigation using single-frequency GPS measurements. A 1 m accuracy is targeted for both applications which has so far been the domain of dual-frequency receivers. Following a mission overview, the achievable performance for ground-based orbit determination and real-time onboard navigation is discussed for different processing concepts based on flight data collected during the first half year of mission operations. It is shown that a 1 m or better accuracy can be achieved in either case, despite sub-optimal GPS tracking conditions induced by the mission specific attitude profile. Besides self-consistency checks and comparisons with independent GPS based orbit determination solutions, the accuracy is evaluated using satellite laser ranging (SLR) measurements as an external reference. The results show that single-frequency GPS tracking is sufficient to meet the navigation requirements of even advanced remote sensing missions in low Earth orbit, if their accuracy potential is properly exploited.

THERE is a growing trend toward distributed missions for scientific and remote sensing applications where large\nnumbers of satellites are required. Analogous to proliferating terrestrial wireless sensor networks, space sensor\nnetworks could provide an unprecedented capability to investigate widespread phenomena. For example, several\nimportant space weather missions have yet to be realized due to the present inability to take simultaneous\nmeasurements of a phenomenon over a large volume. Space economics and environmental concerns dictate a costeffective mass-producible low-mass satellite for such massively distributed missions in low Earth orbit (LEO).\nAn investigation of very small (sub-kilogram) satellite miniaturization techniques has been undertaken, focusing\non enabling technologies targeted at space sensor network applications. Existing and emerging very small satellite\ntechnologies have been assessed and compared with power generation and payload volume being the key\nperformance metrics. Two novel design methodologies have been developed, simulated, and verified through\nfunctional and environmental testing of hardware prototypes. SpaceChip, inspired by the satellite-on-a-chip vision,\nis a monolithic heterogeneous system-on-a-chip (SoC) integration approach.\n1,2 PCBSat is a proposed miniaturization\napproach, which is based on printed circuit board (PCB) substrates.\n3\nPCBSat is focused on deriving the smallest\npractical satellite within the context of space sensor networks, and constrained to the use of commercial off the shelf\n(COTS) components, processes, and deployment systems.

ESA's current approaches to end-of-life strategies for HEO missions

Respecting the requirements of lightweight, small size, low power consumption and especially low cost, commercial off-the-shelf (COTS) analog-to-digital converters (ADCs) are gradually being used to replace specifically designed aerospace -grade ones in space-borne miniature interferometric fiber-optic gyroscopes (IFOGs). However, the total ionizing dose (TID) effect of $\gamma $ -ray radiation in the space environment may cause the damage of COTS ADCs, and lead to performance degradation and even the failure. In order to measure the safety of COTS ADCs in IFOGs under the TID effect, the radiation-induced degradation model and the corresponding reliability model are proposed in this work. First of all, the relationship between the degradation of COTS ADCs and the IFOG's angular random walk (ARW) is deduced. Then, a radiation accelerated test is designed and performed, with a real-time, dynamic data acquisition method based on the first-input-first-output (FIFO) memories to determine the degradation of COTS ADCs. Finally, a degradation path model is established based on the degradation data, and the reliability of COTS ADCs used for space-borne IFOGs is further obtained by using the Monte Carlo method. An engineering application is introduced to show the effectiveness of the proposed model, and the results show that the reliability of the experimental COTS ADCs makes them usable for the space-borne miniature IFOGs in low-earth orbit (LEO) and geostationary earth orbit (GEO) space missions.

Galactic cosmic rays and solar energetic particles (SEPs) present formidable radiation hazards [e.g., Cucinotta et al., 2010] for human and robotic operations beyond low Earth orbit (LEO). As new plans are conceived for human exploration beyond LEO, these space radiation hazards create critical needs for accurate situational awareness. A new near-real-time tool called PREDICCS (Predictions of Radiation From REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and Other SEP Measurements, http://prediccs.sr.unh.edu) provides the first online system for predicting and forecasting the radiation environment in near-Earth, lunar, and Martian space environments. PREDICCS integrates a host of near-real-time measurements being made by satellites currently in space with numerical models (e.g., EMMREM [Schwadron et al., 2010]) to determine radiation doses and dose equivalents that characterize biological impacts and energetic particle propagation codes that can accurately project radiation levels through the inner solar system and out to Mars. PREDICCS provides updates of the radiation environment on an hourly basis and archives the data weekly, monthly, and yearly to provide a clear historical record of the space radiation environment. The PREDICCS tool provides in-depth data to characterize how hazardous SEP events are throughout the solar cycle, provides detailed information on how often large events that have significant risk associated with them are likely to be observed, and facilitates comparison of the near-Earth and lunar radiation environments to that near Mars. As an example, Table 1 shows the lens doses (in centigrays; 1 centigray = 1 rad) and dose equivalents (in centisieverts; 1 centisievert = 1 rem) for full-sphere radiation exposure from PREDICCS over the last 12 months. The PREDICCS lens dose quantifies the energy per mass deposited in 1 gram per square centimeter of water, which is a proxy for the biological impact to the human eye. Large SEP events on 23 January 2012, on 27 March 2012, and in the summer of 2012 contributed significantly to the hazards of the space environment over this interval. We observe that the dose rate limit of 200 centigrays for the lens dose [Cucinotta et al., 2010] is exceeded for nominal spacecraft shielding. Among the satellite measurements used by PREDICCS are data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument on NASA's Lunar Reconnaissance Orbiter [Spence et al., 2010]. For the SEP events of 23 January (Figure 1) and 27 March 2012, PREDICCS results are typically within 20%-30% of what CRaTER observed. These highly accurate comparisons have never before been available over such long periods of time. CRaTER not only provides validation that PREDICCS models are accurate but also directly measures the biological impacts of radiation by observing linear energy transfer spectra behind different thicknesses of tissue-equivalent plastic [Spence et al., 2010]. Accurate assessment of the biological impacts of space radiation is vital to fully characterizing the radiation hazards of the space environment. The near-real-time situational awareness provided by PREDICCs will help to enable future human space exploration endeavors, including a return to the Moon and possible missions to Mars. Nathan Schwadron is an associate professor at the University of New Hampshire and the Institute for the Study of Earth, Oceans and Space. His email is n.schwadron@unh.edu.

BackgroundThe Inspiration4 (I4) mission, the first all-civilian orbital flight mission, investigated the physiological effects of short-duration spaceflight through a multi-omic approach. Despite advances, there remains much to learn about human adaptation to spaceflight's unique challenges, including microgravity, immune system perturbations, and radiation exposure.MethodsTo provide a detailed genetics analysis of the mission, we collected dried blood spots pre-, during, and post-flight for DNA extraction. Telomere length was measured by quantitative PCR, while whole genome and cfDNA sequencing provided insight into genomic stability and immune adaptations. A robust bioinformatic pipeline was used for data analysis, including variant calling to assess mutational burden.ResultTelomere elongation occurred during spaceflight and shortened after return to Earth. Cell-free DNA analysis revealed increased immune cell signatures post-flight. No significant clonal hematopoiesis of indeterminate potential (CHIP) or whole-genome instability was observed. The long-term gene expression changes across immune cells suggested cellular adaptations to the space environment persisting months post-flight.ConclusionOur findings provide valuable insights into the physiological consequences of short-duration spaceflight, with telomere dynamics and immune cell gene expression adapting to spaceflight and persisting after return to Earth. CHIP sequencing data will serve as a reference point for studying the early development of CHIP in astronauts, an understudied phenomenon as previous studies have focused on career astronauts. This study will serve as a reference point for future commercial and non-commercial spaceflight, low Earth orbit (LEO) missions, and deep-space exploration.

Electrostatic discharge induced by strong electromagnetic field refers to the electrostatic discharge process of spacecraft surface materials, cables, some special structural parts and other areas with low charging potential induced by strong electromagnetic field. In general, the spacecraft surface low charge potential sensitive area of the electric field is weak, and electron energy is lower than the ionization energy of molecules, atoms, collision ionization probability is low, when the strong electromagnetic field action, stimulate low-pressure gas to produce dense plasma, thereby reducing the discharge threshold and induce the generation of electrostatic charge discharge. The establishment of testing method for electrostatic discharge induced by strong electromagnetic field is the premise of research on law and protection method of electrostatic discharge induced by strong electromagnetic field. At present, there are no experimental conditions for the interaction between strong electromagnetic field and space environment in China. Therefore, this article established the strong electromagnetic radiation environment and space radiation environment at the same time, under the action of induced discharge test system, not only to be able to carry out electrostatic discharge, high power microwave, nuclear electromagnetic pulse, ultra-wideband electromagnetic pulse and continuous wave such as strong electromagnetic field radiation studies, but also need to solve the high vacuum environment at the same time for sample production and discharge, the discharge parameters and the effect of real-time monitoring, etc. For the research on the rules of space equipment of strong electromagnetic field induced electrostatic discharge is of great significance.

Radiation induced cardiovascular disease: An odyssey of bedside-bench-bedside approach

The European Space Agency’s (ESA) Space Debris Office provides a service to support operational collision avoidance activities. This support currently covers ESA’s missions Cryosat-2, Sentinel-1A and -2A, the constellation of Swarm-A/B/C in low-Earth orbit (LEO), as well as missions of third-party customers. In this work, we describe the current collision avoidance process for ESA and third-party missions in LEO. We give an overview on the upgrades developed and implemented since the advent of conjunction summary messages (CSM)/conjunction data messages (CDM), addressing conjunction event detection, collision risk assessment, orbit determination, orbit and covariance propagation, process control, and data handling. We pay special attention to the effect of warning thresholds on the risk reduction and manoeuvre rates, as they are established through risk mitigation and analysis tools, such as ESA’s Debris Risk Assessment and Mitigation Analysis (DRAMA) software suite. To handle the large number of CDMs and the associated risk analyses, a database-centric approach has been developed. All CDMs and risk analysis results are stored in a database. In this way, a temporary local “mini-catalogue” of objects close to our target spacecraft is obtained, which can be used, e.g., for manoeuvre screening and to update the risk analysis whenever a new ephemeris becomes available from the flight dynamics team. The database is also used as the backbone for a Web-based tool, which consists of the visualization component and a collaboration tool that facilitates the status monitoring and task allocation within the support team as well as communication with the control team. The visualization component further supports the information sharing by displaying target and chaser motion over time along with the involved uncertainties. The Web-based solution optimally meets the needs for a concise and easy-to-use way to obtain a situation picture in a very short time, and the support for third-party missions not operated from the European Space Operations Centre (ESOC). Finally, we provide statistics on the identified conjunction events, taking into account the known significant changes in the LEO orbital environment and share ESA’s experience along with recent examples.

Ensuring a sustainable source of nutritious food is critical for long-duration space missions. Thai landrace rice 466HM exhibits high nutritional value and stress resilience, making it a promising candidate for space cultivation, yet its response to low Earth orbit (LEO) conditions remains poorly understood. This study compared rice grains maintained under terrestrial conditions with grains stored aboard the Shijian-19 (SJ-19) reusable satellite, orbiting at ~336 km for 13.5 days under microgravity (2-7 × 10-7g) and an absorbed radiation dose of ~0.153 rad (Si). Volatile compound profiling, texture analysis of cooked grains, and simulated gastrointestinal digestion followed by peptide mass fingerprinting were performed. LEO-exposed rice grains exhibited a 1.67-fold increase in adhesiveness compared to Earth-based rice (p < 0.01), while hardness remained unchanged between the two groups (p > 0.05), alongside distinct alterations in flavor-related volatile compounds and peptide profiles. Principal component analysis revealed clear separation between Earth and LEO-exposed samples, indicating microgravity-associated shifts in digestible peptide composition. Cytotoxicity assessment using MTT assays in HT-29 and HepG2 cells confirmed the safety of both rice types. These findings demonstrate that orbital conditions influence the compositional, functional, and sensory attributes of rice, providing insights relevant to space agriculture and astronaut nutrition.