Mars Gravity Research Articles

Acceleration inside an aircraft in parabolic flight

This paper aims to present and analyse the acceleration data inside an aircraft during a parabolic flight. The data used were obtained during the flight from the automatic recordings of the aircraft and from a portable data logger with a built-in 3-axis accelerometer connected to a graphic calculator. There is good agreement between the accelerations obtained by the two methods. Based on the altitude data collected during each parabolic manoeuvre performed by the aircraft, it was possible to estimate the gravity of Mars and the Moon, as well as the values of the acceleration of gravity during the moments of microgravity. The analysis presented can also help to improve the understanding of the concepts of inertial forces and the equivalence between gravity and acceleration.

Lost in Space? Unmasking the T Cell Reaction to Simulated Space Stressors

The space environment will expose astronauts to stressors like ionizing radiation, altered gravity fields and elevated cortisol levels, which pose a health risk. Understanding how the interplay between these stressors changes T cells’ response is important to better characterize space-related immune dysfunction. We have exposed stimulated Jurkat cells to simulated space stressors (1 Gy, carbon ions/1 Gy photons, 1 µM hydrocortisone (HC), Mars, moon, and microgravity) in a single or combined manner. Pro-inflammatory cytokine IL-2 was measured in the supernatant of Jurkat cells and at the mRNA level. Results show that alone, HC, Mars gravity and microgravity significantly decrease IL-2 presence in the supernatant. 1 Gy carbon ion irradiation showed a smaller impact on IL-2 levels than photon irradiation. Combining exposure to different simulated space stressors seems to have less immunosuppressive effects. Gene expression was less impacted at the time-point collected. These findings showcase a complex T cell response to different conditions and suggest the importance of elevated cortisol levels in the context of space flight, also highlighting the need to use simulated partial gravity technologies to better understand the immune system’s response to the space environment.

An Independent Degree-eight Mars Gravity Field Model and the Expected Results from the Tianwen-1 Mission

Tianwen-1 is China’s first independent interplanetary exploration mission, targeting Mars, and includes orbiting, landing, and rover phases. Similar to previous Mars missions, the Tianwen-1 orbiter was designed for polar orbits during the scientific mission period but has an exceptional eccentricity of approximately 0.59. We provide the first independent eight-degree Martian gravity field model in this paper, which was developed exclusively by a team working in China with our independent software as well, based on about two months of radiometric Doppler and range data from only the Tianwen-1 mission. This model is independent from the models created by the groups at NASA Jet Propulsion Laboratory and Goddard Space Flight Center in the United States, as well as the Centre National d’Etudes Spatiales in France. Furthermore, in order to optimize the engineering and scientific benefits, we proposed a number of potential orbits for the extended Tianwen-1 mission. In order to solve a higher-degree independent Mars gravity field model, the viability of modifying the perigee height was investigated, with the priority considerations of fuel savings and implementation hazards being controlled.

Lunar and mars gravity induce similar changes in spinal motor control as microgravity.

Introduction: Once more, plans are underway to send humans to the Moon or possibly even to Mars. It is therefore, important to know potential physiological effects of a prolonged stay in space and to minimize possible health risks to astronauts. It has been shown that spinal motor control strategies change during microgravity induced by parabolic flight. The way in which spinal motor control strategies change during partial microgravity, such as that encountered on the Moon and on Mars, is not known. Methods: Spinal motor control measurements were performed during Earth, lunar, Mars, and micro-gravity conditions and two hypergravity conditions of a parabola. Three proxy measures of spinal motor control were recorded: spinal stiffness of lumbar L3 vertebra using the impulse response, muscle activity of lumbar flexors and extensors using surface electromyography, and lumbar curvature using two curvature distance sensors placed at the upper and lower lumbar spine. The participants were six females and six males, with a mean age of 33years (standard deviation: 7years). Results: Gravity condition had a statistically significant (Friedmann tests) effect spinal stiffness (p < 0.001); on EMG measures (multifidus (p = 0.047), transversus abdominis (p < 0.001), and psoas (p < 0.001) muscles) and on upper lumbar curvature sensor (p < 0.001). No effect was found on the erector spinae muscle (p = 0.063) or lower curvature sensor (p = 0.170). Post hoc tests revealed a significant increase in stiffness under micro-, lunar-, and Martian gravity conditions (all p's < 0.034). Spinal stiffness decreased under both hypergravity conditions (all p's ≤ 0.012) and decreased during the second hypergravity compared to the first hypergravity condition (p = 0.012). Discussion: Micro-, lunar-, and Martian gravity conditions resulted in similar increases in spinal stiffness, a decrease in transversus abdominis muscle activity, with no change in psoas muscle activity and thus modulation of spinal motor stabilization strategy compared to those observed under Earth's gravity. These findings suggest that the spine is highly sensitive to gravity transitions but that Lunar and Martian gravity are below that required for normal modulation of spinal motor stabilization strategy and thus may be associated with LBP and/or IVD risk without the definition of countermeasures.

Widespread impact-generated porosity in early planetary crusts

NASA’s Gravity Recovery and Interior Laboratory (GRAIL) spacecraft revealed the crust of the Moon is highly porous, with ~4% porosity at 20 km deep. The deep lying porosity discovered by GRAIL has been difficult to explain, with most current models only able to explain high porosity near the lunar surface (first few kilometers) or inside complex craters. Using hydrocode routines we simulated fracturing and generation of porosity by large impacts in lunar, martian, and Earth crust. Our simulations indicate impacts that produce 100–1000 km scale basins alone are capable of producing all observed porosity within the lunar crust. Simulations under the higher surface gravity of Mars and Earth suggest basin forming impacts can be a primary source of porosity and fracturing of ancient planetary crusts. Thus, we show that impacts could have supported widespread crustal fluid circulation, with important implications for subsurface habitable environments on early Earth and Mars.

An alternative opportunity of future Psyche mission using differential evolution and gravity assists

&lt;abstract&gt;&lt;p&gt;NASA's Psyche mission will launch in August 2022 and begin a journey of 3.6 years to the metallic asteroid: Psyche, where it will orbits and examine this unique body. This paper presents an alternative opportunity of the Psyche mission as well as the return opportunity to the Earth. It uses Mars's gravity assists to rendezvous with and orbits to the largest metal asteroid in the solar system. The spacecraft orbits around Psyche for approximately 1710 solar days, then starts its return journey. In the outer layer of the proposed methodology, the differential evolution algorithm is used to find the optimal launch, flyby and arrival date. In the inner layer, Lambert's algorithm is used for finding the feasible and optimal space trajectories solution. Considering gravity assists, before the gravity assists impulse, an optimal thrust impulse has been calculated at periapsis of the fly-by planet that gives the maximum $ \Delta\nu_2 $ to the spacecraft.&lt;/p&gt;&lt;/abstract&gt;

Plant Gravitropism and Signal Conversion under a Stress Environment of Altered Gravity.

Humans have been committed to space exploration and to find the next planet suitable for human survival. The construction of an ecosystem that adapts to the long-term survival of human beings in space stations or other planets would be the first step. The space plant cultivation system is the key component of an ecosystem, which will produce food, fiber, edible oil and oxygen for future space inhabitants. Many plant experiments have been carried out under a stimulated or real environment of altered gravity, including at microgravity (0 g), Moon gravity (0.17 g) and Mars gravity (0.38 g). How plants sense gravity and change under stress environment of altered gravity were summarized in this review. However, many challenges remain regarding human missions to the Moon or Mars. Our group conducted the first plant experiment under real Moon gravity (0.17 g) in 2019. One of the cotton seeds successfully germinated and produced a green seedling, which represents the first green leaf produced by mankind on the Moon.

Understanding Reduced Gravity Effects on Early Plant Development Before Attempting Life-Support Farming in the Moon and Mars

Plants are a necessary component of any system of bioregenerative life-support for human space exploration. For this purpose, plants must be capable of surviving and adapting to gravity levels different from the Earth gravity, namely microgravity, as it exists on board of spacecrafts orbiting the Earth, and partial-g,as it exists on the surface of the Moon or Mars. Gravity is a fundamental environmental factor for driving plant growth and development through gravitropism. Exposure to real or simulated microgravity produces a stress response in plants, which show cellular alterations and gene expression reprogramming. Partial-gstudies have been performed in the ISS using centrifuges and in ground based facilities, by implementing adaptations in them. Seedlings and cell cultures were used in these studies. The Mars gravity level is capable of stimulating the gravitropic response of the roots and preserving the auxin polar transport. Furthermore, whereas Moon gravity produces alterations comparable, or even stronger than microgravity, the intensity of the alterations found at Mars gravity was milder. An adaptive response has been found in these experiments, showing upregulation of WRKY transcription factors involved in acclimation. This knowledge must be improved by incorporating plants to the coming projects of Moon exploration.

Three-dimensional analysis of a counterweight type space elevator

Space elevators studied thus far have been mainly the climber type, in which a cable connects the ground to a space station and the payload is transported by climbers ascending and descending along the cable. However, this type of system has problems, such as the difficulty of supplying energy to climbers and a short lifespan owing to the abrasion of the cable and climber wheels during operation. To avoid these problems, in this study, we investigate a novel counterweight-type space elevator. This system consists of two cables: a guide cable that withstands the tension applied to the structure and a moving cable that connects two gondolas, one at either end of the cable, attaches to a driving wheel in the space station, and transports the payload in the gondolas by driving the wheel. In this study, we analyzed the cable dynamics by using the point mass cable model developed by our group when the counterweight type is applied between the station and the ground, and we calculated the energy necessary for actual operation. As a result, when the counterweight type is applied between the Mars gravity center (altitude 3900 km) and the ground, while the climber type is applied at altitudes above that, the system uses less energy than conventional climber-type space elevators.

Microbially-Enhanced Vanadium Mining and Bioremediation Under Micro- and Mars Gravity on the International Space Station.

As humans explore and settle in space, they will need to mine elements to support industries such as manufacturing and construction. In preparation for the establishment of permanent human settlements across the Solar System, we conducted the ESA BioRock experiment on board the International Space Station to investigate whether biological mining could be accomplished under extraterrestrial gravity conditions. We tested the hypothesis that the gravity (g) level influenced the efficacy with which biomining could be achieved from basalt, an abundant material on the Moon and Mars, by quantifying bioleaching by three different microorganisms under microgravity, simulated Mars and Earth gravitational conditions. One element of interest in mining is vanadium (V), which is added to steel to fabricate high strength, corrosion-resistant structural materials for buildings, transportation, tools and other applications. The results showed that Sphingomonas desiccabilis and Bacillus subtilis enhanced the leaching of vanadium under the three gravity conditions compared to sterile controls by 184.92 to 283.22%, respectively. Gravity did not have a significant effect on mean leaching, thus showing the potential for biomining on Solar System objects with diverse gravitational conditions. Our results demonstrate the potential to use microorganisms to conduct elemental mining and other bioindustrial processes in space locations with non-1 × g gravity. These same principles apply to extraterrestrial bioremediation and elemental recycling beyond Earth.

From Spaceflight to Mars g-Levels: Adaptive Response of A. Thaliana Seedlings in a Reduced Gravity Environment Is Enhanced by Red-Light Photostimulation.

The response of plants to the spaceflight environment and microgravity is still not well understood, although research has increased in this area. Even less is known about plants’ response to partial or reduced gravity levels. In the absence of the directional cues provided by the gravity vector, the plant is especially perceptive to other cues such as light. Here, we investigate the response of Arabidopsis thaliana 6-day-old seedlings to microgravity and the Mars partial gravity level during spaceflight, as well as the effects of red-light photostimulation by determining meristematic cell growth and proliferation. These experiments involve microscopic techniques together with transcriptomic studies. We demonstrate that microgravity and partial gravity trigger differential responses. The microgravity environment activates hormonal routes responsible for proliferation/growth and upregulates plastid/mitochondrial-encoded transcripts, even in the dark. In contrast, the Mars gravity level inhibits these routes and activates responses to stress factors to restore cell growth parameters only when red photostimulation is provided. This response is accompanied by upregulation of numerous transcription factors such as the environmental acclimation-related WRKY-domain family. In the long term, these discoveries can be applied in the design of bioregenerative life support systems and space farming.

Space station biomining experiment demonstrates rare earth element extraction in microgravity and Mars gravity

Microorganisms are employed to mine economically important elements from rocks, including the rare earth elements (REEs), used in electronic industries and alloy production. We carried out a mining experiment on the International Space Station to test hypotheses on the bioleaching of REEs from basaltic rock in microgravity and simulated Mars and Earth gravities using three microorganisms and a purposely designed biomining reactor. Sphingomonas desiccabilis enhanced mean leached concentrations of REEs compared to non-biological controls in all gravity conditions. No significant difference in final yields was observed between gravity conditions, showing the efficacy of the process under different gravity regimens. Bacillus subtilis exhibited a reduction in bioleaching efficacy and Cupriavidus metallidurans showed no difference compared to non-biological controls, showing the microbial specificity of the process, as on Earth. These data demonstrate the potential for space biomining and the principles of a reactor to advance human industry and mining beyond Earth.

Combined Environment Simulator for Low-Dose-Rate Radiation and Partial Gravity of Moon and Mars.

Deep space exploration by humans has become more realistic, with planned returns to the Moon, travel to Mars, and beyond. Space radiation with a low dose rate would be a constant risk for space travelers. The combined effects of space radiation and partial gravity such as on the Moon and Mars are unknown. The difficulty for such research is that there are no good simulating systems on the ground to investigate these combined effects. To address this knowledge gap, we developed the Simulator of the environments on the Moon and Mars with Neutron irradiation and Gravity change (SwiNG) for in vitro experiments using disposable closed cell culture chambers. The device simulates partial gravity using a centrifuge in a three-dimensional clinostat. Six samples are exposed at once to neutrons at a low dose rate (1 mGy/day) using Californium-252 in the center of the centrifuge. The system is compact including two SwiNG devices in the incubator, one with and one without radiation source, with a cooling function. This simulator is highly convenient for ground-based biological experiments because of limited access to spaceflight experiments. SwiNG can contribute significantly to research on the combined effects of space radiation and partial gravity.

The Eu:CROPIS Mass Property Campaign: Trimming a Spin-Stabilized Compact Satellite for a Long-Term Artificial Gravity Experiment

Eu:CROPIS (Euglena Combined Regenerative Organic Food Production in Space) is the first mission of DLR’s compact satellite program. The launch of Eu:CROPIS took place on December 3rd in 2018 on-board the Falcon 9 SSO-A mission. The satellite’s primary payload Eu:CROPIS features a biological experiment in the context of closed loop coupled life support systems. The Eu:CROPIS satellite mission uses spin stabilization along its Z -axis to provide defined acceleration levels for the primary and secondary payloads to simulate either a Moon or Mars gravity environment. For the payload performance, it is vital to achieve a minimum deviation between spacecraft Z -axis and the major moment of inertia (MoI) axis to minimize the offset of the envisaged acceleration levels. Specific moment of inertia ratios between the spin- and minor axes had to be maintained to allow the attitude control system to keep the satellite at a stable rotation despite environmental disturbances. This paper presents the adaptive and flexible trimming strategy applied during the flight model production, as well as the mass property measurement acceptance campaign and the respective results.

No Effect of Microgravity and Simulated Mars Gravity on Final Bacterial Cell Concentrations on the International Space Station: Applications to Space Bioproduction.

Microorganisms perform countless tasks on Earth and they are expected to be essential for human space exploration. Despite the interest in the responses of bacteria to space conditions, the findings on the effects of microgravity have been contradictory, while the effects of Martian gravity are nearly unknown. We performed the ESA BioRock experiment on the International Space Station to study microbe-mineral interactions in microgravity, simulated Mars gravity and simulated Earth gravity, as well as in ground gravity controls, with three bacterial species: Sphingomonas desiccabilis, Bacillus subtilis, and Cupriavidus metallidurans. To our knowledge, this was the first experiment to study simulated Martian gravity on bacteria using a space platform. Here, we tested the hypothesis that different gravity regimens can influence the final cell concentrations achieved after a multi-week period in space. Despite the different sedimentation rates predicted, we found no significant differences in final cell counts and optical densities between the three gravity regimens on the ISS. This suggests that possible gravity-related effects on bacterial growth were overcome by the end of the experiment. The results indicate that microbial-supported bioproduction and life support systems can be effectively performed in space (e.g., Mars), as on Earth.

Wheels' performance of Mars exploration rovers: Experimental study from the perspective of terramechanics and structural mechanics

The soft ground and stones on the surface of Mars may cause sinkage of and damage to the wheels of a Mars rover. Therefore, we analyzed the performance of a wheel-step Mars rover from the perspective of terramechanics and structural mechanics. Using China’s Mars rover wheel prototype and wheel-soil interaction testbed, we obtained the driving performance of the wheels of a Mars rover under various conditions, including full skidding conditions. The vertical load set in the tests was determined using the gravity of Mars and the mass of the wheel-step Mars rover. The results indicate that the driving torque, sinkage, and resistance coefficient have a linear relationship with the wheel vertical load. An analysis of the structural mechanical characteristics of the wheel of the Mars rover was conducted by testing the radial, axial, torsional, and deflection stiffness. We found that the wheel ribs can improve the stiffness of the wheel but may reduce its driving performance. The analysis methods and evaluation indices can be used to analyze the performance of the wheels of other Mars rovers. Furthermore, the findings of this study can be used to optimize wheel design and motion control of wheel-step Mars exploration rovers.

Analysis of Phobos’ dynamical environment considering effects of ephemerides and physical libration

ABSTRACT A dynamical model is developed in the body-fixed frame of Phobos, in which the high-precision gravity field and exact physical libration of Phobos, the gravity of Mars with J2, and the gravity perturbations of the Sun, Jupiter, and Earth are considered. The JPL development ephemeris are applied to calculate the positions of celestial bodies. Phobos is considered as a homogeneous polyhedron with 16 037 vertices to characterize its irregular shape and the corresponding gravity field. The physical libration of Phobos is incorporated into its rotational motion by using the results in ‘Report of the IAU WGCCRE’. With the proposed model, equivalent gravity and slope on Phobos surface are calculated and analysed. The liftoff velocity is also computed and presented. Besides, the orbital environment is also investigated. Instantaneous equilibrium points in the Mars–Phobos system are computed and demonstrated, and the acceleration of a particle in the vicinity of Phobos is analysed to find out the main influencing factor in different regions. Quasi-satellite orbits and libration point orbits, which were determined in the circular restricted three-body problem model, are simulated in different dynamical models. The results applying the newly developed high-fidelity dynamical model have shown significant differences with respect to existing models, suggesting that dynamical models with higher accuracy are needed for close-range orbital activities.

Space explorers need to be space farmers: What we know and what we need to know about plant growth in space

Space exploration will require life support systems, in which plants can provide nutrients, oxygen, moisture, and psychological well-being and eliminate wastes. In alien environments, plants must adapt to a different gravity force, even the zero gravity of spaceflight. Under these conditions, essential cellular and molecular features related to plant development are altered and changes in gene expression occur. In lunar gravity, the effects are comparable to microgravity, while the gravity of Mars produces milder alterations. Nevertheless, it has been possible to develop and reproduce plants in space. Current research seeks to identify signals replacing gravity for driving plant growth, such as light. Counteracting gravitational stress will help in enabling agriculture in extraterrestrial habitats.

RNAseq Analysis of the Response of Arabidopsis thaliana to Fractional Gravity Under Blue-Light Stimulation During Spaceflight.

Introduction: Traveling to nearby extraterrestrial objects having a reduced gravity level (partial gravity) compared to Earth’s gravity is becoming a realistic objective for space agencies. The use of plants as part of life support systems will require a better understanding of the interactions among plant growth responses including tropisms, under partial gravity conditions.Materials and Methods: Here, we present results from our latest space experiments on the ISS, in which seeds of Arabidopsis thaliana were germinated, and seedlings grew for six days under different gravity levels, namely micro-g, several intermediate partial-g levels, and 1g, and were subjected to irradiation with blue light for the last 48 h. RNA was extracted from 20 samples for subsequent RNAseq analysis. Transcriptomic analysis was performed using the HISAT2-Stringtie-DESeq pipeline. Differentially expressed genes were further characterized for global responses using the GEDI tool, gene networks and for Gene Ontology (GO) enrichment.Results: Differential gene expression analysis revealed only one differentially expressed gene (AT4G21560, VPS28-1 a vacuolar protein) across all gravity conditions using FDR correction (q < 0.05). However, the same 14 genes appeared differentially expressed when comparing either micro-g, low-g level (< 0.1g) or the Moon g-level with 1g control conditions. Apart from these 14-shared genes, the number of differentially expressed genes was similar in microgravity and the Moon g-level and increased in the intermediate g-level (< 0.1g), but it was then progressively reduced as the difference with the Earth gravity became smaller. The GO groups were differentially affected at each g-level: light and photosynthesis GO under microgravity, genes belonged to general stress, chemical and hormone responses under low-g, and a response related to cell wall and membrane structure and function under the Moon g-level.Discussion: Transcriptional analyses of plants under blue light stimulation suggests that root blue-light phototropism may be enough to reduce the gravitational stress response caused by the lack of gravitropism in microgravity. Competition among tropisms induces an intense perturbation at the micro-g level, which shows an extensive stress response that is progressively attenuated. Our results show a major effect on cell wall/membrane remodeling (detected at the interval from the Moon to Mars gravity), which can be potentially related to graviresistance mechanisms.

Pseudostate theory based iterative preliminary design method for powered gravity-assist interplanetary trajectories

The patched conic method is usually used for preliminarily design of gravity-assist transfer trajectories. However, gravity assist is usually simplified as an instantaneous velocity impulse and the time of flight for gravity assist is ignored, which differs from actual scenarios. In this paper, gravity assist is considered as a continuous process and a novel method employing the pseudostate theory is proposed to design gravity-assist transfer trajectories. The mission trajectory is categorized as gravity-assist segments and interplanetary transfer segments. A powered gravity-assist model based on the pseudostate theory is used to solve the gravity-assist segments with the restricted three-body dynamics. Then, these gravity-assist segments thus solved are patched with the interplanetary transfer segments using an adaptive iterative patching technique, which adopts an adaptive parameter adjustment strategy to improve the efficiency and robustness. Thereafter, a consecutive interplanetary mission trajectory is finally obtained. In addition, a new estimation formula of the sweepback duration is derived according to the radius of gravity field and the excess velocity. The simulation results verify the effectiveness and accuracy of the proposed formula. The transfer trajectories to Jupiter with Venus, Earth and Mars gravity assists are respectively obtained by the proposed method. Compared with patched conic methods, the fuel optimal and more realistic trajectories are efficiently solved utilizing the proposed method for gravity-assist interplanetary mission.