According to the existing scenarios of interplanetary missions, the Moon is considered as an intermediate base on the way to deep space. The paper presents the results of a pilot study performed during a short-term space flight. A new experience of using countermeasure impacts of lower body negative pressure at the early stages of adaptation to microgravity conditions has been gained. Preparation for extravehicular activity on the Moon's surface requires milder LBNP effects in comparison with preparation for return to Earth. Regulatory mechanisms of the cardiovascular system proved to be quite effective when creating decompression up to -20 mm Hg. For the first time the dynamics of motor control system readaptation, verticalization strategy and success of dual task solution from the first to the third day after the short-term space flight is described. Unique data on rearrangements of gravity-dependent physiological systems in short-term flight have been obtained. Assessment of the state of gravity-dependent physiological systems after short-term flight indicates the decrease of functional reserves of the organism and the necessity to develop appropriate countermeasures. The study was one of the first steps in the development of new medical control operations at the stage of paradigm shift from orbital flights to deep space exploration.
Research Article
LBNP exposure - as perspective countermeasure for Moon missions
https://doi.org/10.21203/rs.3.rs-4692541/v1
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short-term spaceflight
microgravity
Lower Body Negative Pressure
Lunar Mission
countermeasures
The main trend in the roadmaps of space nations currently is the preparation for colonization of the Moon. According to the existing scenarios of interplanetary missions, the Moon is considered as an intermediate base on the way to deep space (Mulcahy et al. 2022, Grigor’ev et al. 2021, Boggs et al., 2020, Clément and Wood 2023). There are several projects to utilize the Moon's resources in technological aspect. Current scenarios of lunar exploration consider the Earth's satellite as a promising candidate for hosting an extraterrestrial colony of humans because the Moon, firstly, is a highly accurate platform for studies of reduced gravity, radiation risk and circadian disturbances, and secondly, it is an isolated, confined and extreme environment suitable as an analog for studying the psychosocial consequences of long-term human spaceflight (SF) and understanding these processes (Goswami, 2012). Crewed lunar exploration offers significant advantages in sample collection and instrument use compared to robotic lunar exploration. For example, six crewed Apollo missions collected a total of 382 kg of samples and traveled exploration distances of about 30 km on the lunar surface. The US National Aeronautics and Space Administration (NASA) announced elements of the Artemis crewed lunar exploration program as part of the Luna-Mars program. This initiative aims to land a human near the Moon's South Pole around 2027 with the strategic goal of returning 20–80 kg of samples from both the polar region and a resort basin. At the same time, China is actively considering an ILRS initiative and is planning a crewed lunar exploration by 2030 (Lin et al., 2024).
These prospects raise issues for the scientific community to develop a medical support system for safe lunar missions. Exposure to SF-factors leads to restructuring of physiological systems (Grigor’ev et al. 2021). The depth of such rearrangements is determined by the duration of negative flight factors and the effectiveness of special measures to counteract their influence. Speaking about short-term SF, orbital flights of up to two weeks duration suggest using only the mechanical occlusion cuffs (bracelets) preventing the blood redistribution as a countermeasure to prevent negative effects of microgravity (Kozlovskaya et al. 2015). The lack of necessity to apply a wide range of prophylactic measures is due to the possibility to implement a set of rehabilitation measures after returning to Earth. However, a decrease in orthostatic stability, poor gait and reduced performance have been repeatedly observed after short-term flights (Baevsky, 2010, Berry 1967, Grigoriev et al.,2011, Lee at al., 2019). Redistribution of fluids in the cranial direction plays a key role in changing the functions of gravity-dependent physiological systems during acute adaptation to microgravity conditions. The increase of venous return to the right atrium, arising due to redistribution of blood in the cranial direction, triggers the Henry-Gower reflex. This is a reflex delay in vasopressin release and, consequently, increased diuresis in response to increased blood flow to the right heart (Gauer et al. 1961) and further hypovolemia. The "Bracelet" product to some extent prevents the movement of fluid from the lower limbs and is recommended for use by cosmonauts at the initial stages of orbital flight. As previously stated, the transition to deep space exploration will require a more effective counteraction to negative changes in order to ensure a sufficient level of performance and health preservation for both crew members performing operations on the Moon surface and those remaining in orbit at that time. Unfortunately, at this stage of gravitational physiology development, knowledge about the patterns of physiological processes in the early period of adaptation remains insufficient. The main results were obtained in model experiments with dry immersion and anti-orthostatic hypokinesia (ANOG). These experiments strongly indicate significant restructuring of the functions of the cardiovascular, neuromuscular and movement control systems after a person stays in conditions that simulate the effects of microgravity in the proposed lunar missions (Navasiolava et al. 2011, Tomilovskaya et al. 2019, Tomilovskaya et al. 2021, Hoffmann et al. 2022). The lessons of real SF are most valuable for practicing the elements of medical support of safe lunar missions.
Changes in the cardiovascular system when assessing orthostatic stability in cosmonauts have been described based on the results of short-term flights on the Vostok and Voskhod spacecrafts (Baevsky 2010) and in astronauts after short-term flights on the Gemini and Apollo programs (Berry 1967, Hoffler and Johnson 1975). The changes were manifested by increased heart rate (HR), decreased systolic and pulse pressure, and increased susceptibility to fainting when attempting to hold an upright posture (Gazenko et al., 1981). Biomedical studies within the framework of the Shuttle program showed a decrease in the strength of the carotid baroreflex manifestation after short-term SF, which directly contributed to the development of post-flight orthostatic intolerance (Fritsch at al. 1992). The hypothesis of our study was that it is possible to mitigate the negative effects of the acute period of cardiovascular system adaptation to microgravity conditions by creating negative pressure on the lower part of the body (LBNP). LBNP is a well-established method of preventing negative effects of weightlessness based on artificial deposition of circulating blood volume below the zone of exposure and reduction of venous return to the heart, which therefore leads to a decrease in blood flow in the vascular system of the head and chest organs (Goswami et al. 2019).
A 60-minute application of mild LBNP during prolonged spaceflight can attenuate cardiovascular effects, particularly fluid shifts to the head (Evans et al. 2018).
In a study (Petersen et al. 2019), LBNP from 0 to 40 mmHg was used to create the effects of hypovolemia induced by acute hemorrhagic shock and to study the effects of cardiovascular mechanisms during aerobic exercise. To compensate for blood movement, baroreflexes and neuroendocrine mechanisms are activated to maintain mean arterial pressure and protect tissue oxygenation (Petersen et al. 2019). In a model of intracranial hypertension, LBNP displaces fluid from cranial compartments, subsequently reducing intracranial pressure in the brain parenchyma and ventricles (Petersen et al. 2019). With gradual application of LBNP, LBNP 20 mmHg was found to be the optimal level to reduce intracranial pressure without worsening cerebral perfusion or cardiac stroke volume.
Neurohumoral mechanisms triggered by LBNP exposure are caused by decreased parasympathetic influences on the heart and increased sympathetic influences on blood vessels due to decreased blood volume in the vessels of the upper part of the body, which is caused by decreased impulse from receptors located in the aortic arch and carotid sinus zone. As a result, there is an increase in HR and a 30–40% decrease in blood flow in the skin and abdominal organs. Reflex tachycardia and increased vascular resistance in skeletal muscles occur due to decreased impulse from cardiac stretch receptors. Unloading of low-pressure baroreceptors is manifested by an increase in the level of antidiuretic hormone and activation of the renin-aldosterone system, which leads to a decrease in diuresis and retention of water and sodium in the body (Campbell et al. 2015, Charles and Lathers 1994). A decrease in systolic blood pressure and an increase in hemoglobin level in the thigh muscles under the influence of LBNP training have been observed (Hachiya et al. 2004).
During the short-term SF it was anticipated to confirm the possibility of using preventive LBNP effects corresponding in magnitude to the preparation for the lunar landing. One of the objectives of the experiment was to assess the dynamics of re-adaptation of gravity-dependent physiological systems to the Earth conditions. The paper presents the results of a pilot study.
The experiment was carried out in SF with a duration of 12 days. The study was approved by the Bioethical Commission of the State Research Centre of the Russian Federation – IMBP RAS (Protocol No. 657 of 16.01.2024) and the Human Research Multilateral Review Board (HRMRB (Protocol No. 24 − 005 of 24.01.2024)).
According to the study design, baseline examinations of the state of gravity-dependent systems were performed 30 days prior to SF, including assessment of the tolerance of the cardiovascular system to LBNP exposure. Several LBNP exposures were planned during SF; their magnitude, frequency and number were determined according to medical conditions. After the flight, the dynamics of readaptation to Earth conditions was assessed. The overall study design is shown in Fig. 1.
Prior to the flight, the following techniques were performed:
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a test on a treadmill BD-2 in the motorized mode of the track web movement, further the "Individual Strategies" (TIS);
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a test on the VB-3M bicycle simulator according to the protocol used by ISS partners, further "Velotest";
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a comprehensive test for screening assessment of physical performance and the state of the movement control system, further "Express test";
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assessment of tolerance to the impact of negative pressure on the lower part of the body with a value corresponding to the preparation of the cardiovascular system for staying in the conditions of the Moon, further "LBNP test".
Individual Strategy Test (TIS) (Fig. 2) was performed in the motorized mode of treadmill “BD-2” surface movement. TIS includes determination of physical performance at standard load and cardiorespiratory kinetics. During the TIS, gas analysis data (before and after the flight – on the ergospirometer “Cosmed K5, Italy”) and electrocardiogram (ECG) were recorded.
This test was developed by Prof. Hoffmann et al. at the University of Sports Sciences, Cologne, and involves the determination of cardiorespiratory kinetics – the speed of the cardiovascular system's response to changes in exercise intensity (Hoffman et al., 2016). The test consists of two parts. The first part of the test involves alternating walking intervals at 3 km/h and 6 km/h in the form of a pseudo-random binary sequence and is designed to determine the cross-correlation of locomotion speed with the measured physiological parameters. A high and quickly achieved peak of the cross-correlation function indicates a rapid response of a particular physiological parameter to changes in the speed of locomotion, which may signal a more optimal regulation of the cardiovascular system. The second part of the TIS is a stepwise increasing load from 3 to 15 km/h with a speed increase of 1 km/h every 30 s. Based on the obtained data on cardiorespiratory kinetics, a transfer function was calculated to predict the physiological response to a step-increasing load.
"Velotest" was conducted on a cycle ergometer VB-3M and included 5 minutes of rest, pedaling at 50 W power ("idle power") for 3 minutes, then, starting from 100 W, a step-increasing load was started with an increase in power by 25 W every minute with approximately 60–70 rotations per minute. The gradual workload was continued until the subject refused to continue further work due to fatigue, followed by 1 minute of pedaling at 50 W and then 5 minutes of recovery at rest. Power of the VB-3M and HR were recorded throughout the test. BP was measured at each stage of exercise (Fig. 3).
"Express test" included assessment of the hand movement control system, the Romberg test (Jenek and Skorupińska 2018), verticalization strategies from supine positions, collection of weights around the perimeter of the marked area, assessment of the weight and accuracy of throwing three different weights, success of the dual task - timing of covering a standard distance (3 meters) with simultaneous counting back by triples from a given number when walking in tandem (heel to toe), push-ups from the floor from prone position (number of times in 10 s) and squats from standing to a right angle in the knee joint (number of times in 10 s) (Fig. 4).
The cardiovascular response to exercise was assessed based on HR recording, with the start and end events of each Express test task noted. The set of tests was developed taking into account the experience of the Russian-American experiment "Field Test" (Reschke et al. 2022).
Under SF conditions on the 3rd day of stay on the ISS, daily ECG registration in V2, V5, aVF leads («Myocard-Holter", Sarov) and LBNP test were performed. LBNP test was performed using a “Chibis” suit with continuous ECG recording and minute-by-minute BP measurement. The duration of the test was 18 minutes, the maximum decompression achieved was − 15 mmHg. During the period from the 4th to the 6th day of stay on the ISS, LBNP exercises were performed daily. Decompression from − 10 to -20 mmHg was created with a step of 5 mmHg, each step lasted 5 minutes. ECG was continuously recorded and BP was measured every minute.
In-flight tests
The sessions of LBNP effects conducted under short-term flight conditions proved the possibility of using this method during the acute period of adaptation to microgravity conditions. The LBNP test performed on the 3rd day of stay at the station showed that it was possible to safely reach the decompression value of -15 mm Hg. Further increase of exposure was not performed due to technical reasons. Preparation for return to Earth at the final stage of the flight is usually performed using LBNP − 45 mmHg. We assumed that a LBNP of -10 mmHg would be sufficient to prepare for extravehicular activities on the lunar surface given the reduced gravity. During the LBNP test no arrhythmias and ectopic activity of the cardiac conduction system were registered on the electrocardiogram. There were no subjective complaints about well-being during the LBNP test.
LBNP training were conducted on the 4th, 5th and 6th days of staying on the ISS (Table 1). The decompression value of -20 mm Hg was achieved. On the 6th day of stay on the ISS in LBNP-training there was a slight decrease in systolic, diastolic and pulse blood pressure (SBP − 102/68, pulse pressure (PP) − 34 mmHg), as well as an increase in HR (84 beats/min) on the step with decompression − 20 mmHg. In LBNP training on the 5th and 6th days, no significant changes in cardiovascular system were observed. There were no subjective complaints about well-being during LBNP training.
Table 1. Physiological parameters during LBNP training.
Post-flight results
The TIS was conducted 25 days before the flight and on the 13th day after the flight and was not fully performed due to the failure of the test participant. Before the flight the planned speed of 15 km/h was achieved, after the flight - only 13 km/h (13% less than the pre-flight value). Running at 13 km/h after SF was accompanied by a slight increase in HR compared to pre-flight values: 174 beats per minute versus 171. At the same time, oxygen consumption decreased from 33.3 to 31.5 ml/kg/min (by 5%), respiratory rate and pulmonary ventilation remained the same. Thus, the changes in physiological parameters at the standard stage of running were minor. However, there was a noticeable increase in resting and walking HR. The resting HR after flight was higher by an average of 28 beats/min (41%), and while walking - by 13 beats/min (13%) compared to the pre-flight values. With increasing load, the differences in pre- and postflight HR values leveled off and were less than 5%. Considering also the reduction of the maximum achieved speed from 15 km/h to 13 km/h, it is important to take into account that the level of physical performance has decreased even on the 13th day after the short-term flight, which confirms the necessity to search for measures to counteract the reduction of physical performance.
Mathematical processing of pseudo-randomised walking intervals showed a decrease and lag of the peak of the cross-correlation function of HR and walking speed on the 13th day after flight (Fig. 5). In other words, post-flight HR in response to changes in walking speed increased longer and slower than pre-flight values, while the HR values themselves were higher than pre-flight values. This change may indicate a decrease in the functions of the cardiovascular system.
The prediction of peak HR when running at 15 km/h before SF was accurate to 1 bpm (Fig. 6). After the flight, the accuracy of the predictive algorithm was reduced, the predicted HR values were lower than the real ones, the peak value differed by 16 beats/min (Fig. 7). This may indicate rearrangements in the regulation of the cardiovascular system, which were not taken into account in prognostic algorithm.
The decrease in HR kinetics in an astronaut after a short flight is consistent with the results obtained by Hoffmann et al. (2016) in a study involving 10 astronauts on long-duration space flights. The authors showed that after a six-month space flight with the use of prophylaxis, there was a statistically significant decrease in oxygen consumption kinetics during exercise testing on a bicycle ergometer compared to pre-flight values. There was a statistically significant correlation between HR kinetics and peak oxygen consumption in the step-increasing test. The changes persisted up to 21 days after the return to the Earth gravity conditions. A study involving 5 Russian cosmonauts (Koschate et al. 2021) showed a significant decrease in HR kinetics after a six-month space flight with the use of countermeasures. During spaceflight, based on analysis of data from three cosmonauts, a decrease in physical performance was observed by the third quarter of spaceflight, similar to changes in annual flight, despite the difference in flight duration by a factor of two.
"Velotest" was performed 36 days before the flight and on the 12th day after the flight. The maximum power achieved did not change and equaled 175 W. The peak HR at the 175 W step was 10% higher after SF compared to baseline (Fig. 8). The results indicate an increase in the physiological value of standard exercise. An increase in cardiovascular response was observed already from the minimum loading step of 50 W.
“Express test”' was conducted from the 1st to the 3rd day after SF. In the task of hand movement control under conditions of visual deprivation, an increase in the accuracy of movements of the left (non-leading) hand was observed from the first to the third day of readaptation to Earth conditions. Movement control of the right (leading) hand was performed quite successfully from the first day of readaptation to the Earth conditions (Fig. 9).
The success rate of performing the Romberg test did not change after the flight.
The strategy of lifting from the supine position, in contrast to long flights, did not change after a short-term flight. On the first day after the flight the lifting was performed with support on both arms, on the third day - with support on one arm. From the prone position the lifting strategy did not change from the first day to the third day.
The number of push-ups and squats performed after the flight did not decrease compared to the pre-flight results.
The success of double task performance decreased on the 1st day after the flight compared to the pre-flight values, but on the 2nd and 3rd days it was already in line with the pre-flight results.
The estimation of cargo weight with the highest accuracy was performed on the 3rd day after the flight (Fig. 10).
The performance of the "express test" tasks basically shows a tendency for improvement from the 1st to the 3rd day after the flight.
According to our hypothesis, LBNP exposures are a promising tool for lunar missions. To present day, the system of counteraction to the rearrangements of gravity-dependent physiological systems functioning for SFs lasting up to two weeks includes only the use of occlusion cuffs (Hamilton et al. 2012).
The countermeasure program for long SF includes physical training on a treadmill, bicycle trainer, strength training machine. At the final stage of the flight the use of LBNP is added to the above-mentioned means.
The first work devoted to the study of the effect of LBNP on the cardiovascular system was published in 1965 and mainly showed that LBNP test can serve as a more informative test for orthostatic stability in comparison with passive orthostatic test. At that time, similar physiological responses were recorded at a decompression value of -60 mmHg and testing with a 90° table tilt (Stevens and Lamb 1965).
Further studies of LBNP have shown its effectiveness as a method that largely prevents orthostatic instability after different durations of stay in ANOG conditions as one of the SF models (Pestov and Asyamolov 1972, Watenpaugh et al. 2007).
In the Apollo program (missions 7–9, 15–17), LBNP exposure was used as a test of orthostatic stability before and after SF. In response to LBNP, an increase in HR to 109 beats/min post-flight compared to pre-flight values of 70 beats/min was recorded (Berry 1973). The first application of LBNP directly in weightlessness was performed in 1971 on the Salyut-1 spacecraft. LBNP device " Veter" was the first device of this type, used by Soviet cosmonauts in flight conditions two years earlier than in the framework of the "Skylab" program. Subsequent flights on Salyut-4, Salyut-5, and Salyut-6, in which LBNP effects were used weekly, made it possible to record in-flight increases in HR, total peripheral resistance, and left ventricular ejection time compared to preflight values (Gazenko et al. 1981).
The Skylab program provided an opportunity to obtain a large amount of data on the use of LBNP. Nine astronauts on three different missions performed a large number of LBNP exercise sessions, starting in the fourth day of flight every 3–4 days. The decrease in orthostatic stability during the first days of the 28-day Skylab 2 mission was primarily manifested by early cessation of LBNP training at low exposure levels. The increase in HR in response to LBNP reached its maximum after 5–10 days of flight. During the flights "Skylab-3" and "Skylab-4" with duration of 59 and 84 days, respectively, it was found that the adaptation of the astronauts' cardiovascular system to orthostatic stress caused by LBNP exposure occurred after about 4 weeks of flight (Thornton and Ord 1977).
LBNP was also used on some Shuttle flights as a test procedure and preventive measure. In the final days of the mission, LBNP exposure of -30 mmHg for 4 hours was used. This had a pronounced prophylactic effect, manifested by a decrease in HR in response to the next day's 40-minute LBNP test protocol with a stepwise increase in decompression by 10 mmHg until − 50 mmHg was reached (Sawin 2022).
In the Russian system of prevention of negative effects of weightlessness LBNP-exposure has been included since the Salyut-4 orbital station. LBNP-exercises with decompression modes from − 10 mmHg to -45 mmHg with a step of 5 mmHg and exposure time of each mode of 5 minutes are used every 3–4 days at the final stage of the flight in order to prepare the cardiovascular system for the return to the Earth gravity conditions. We have suggested that LBNP may be a promising method of preventing the negative effects of weightlessness on the cardiovascular system for a mission to the Moon.
The results of measuring the cardiothoracic index, i.e. the ratio of the transverse size of the heart to the transverse size of the thorax, are interesting in relation to the prevention of the negative effects of weightlessness in the lunar mission. The cardiothoracic index in Apollo astronauts indicates pathological changes only in crew members who did not participate in extravehicular activities. In other words, even short-term exposure to 1/6 of Earth's gravity had a "preventive" effect on the cardiovascular system (Hoffler and Johnson 1975, Hoffler and Wolthuis 1974).
In the Standard-Luna experiment, a short-term flight of 12 days duration was considered as an experimental model to work out approaches to the prevention of negative effects of weightlessness in a prospective lunar mission. On the one hand, it can be said that the final stage of the flight to the Moon and preparation for extravehicular activities on the surface starts from the first days of the mission. On the other hand, the gravity of the Moon will not require activation of antigravity physiological mechanisms necessary for Earth conditions, which allows us to consider the possibility of using LBNP effects much less than those required during the final stage of a long flight. The objectives of the experiment included post-flight assessment of the success of tasks simulating extravehicular activities on the Moon surface, the limiting factor for which may be the state of physiological systems providing orthostatic stability.
Numerous model experiments confirm the feasibility of this approach. Thus, in ground-based experiments with ANOG, it was shown that daily LBNP (3 sessions per day for 20 minutes with decompression of -35 mmHg) significantly increased orthostatic resistance after ANOG (Güell et al. 1990). A comparison of different means of counteracting fluid redistribution showed the highest effectiveness of daily LBNP training of 45 minutes with decompression of -25 mmHg. (Marshall-Goebel et al. 2021). It has been shown that the use of LBNP with a decompression of -52 mmHg for training in the horizontal position of the body can simulate the kinetic and metabolic effects of training in the vertical position (Charles and Lathers 1994). The application of LBNP training 6 times a week for 45 minutes at -50 mmHg decompression not only counteracts fluid redistribution but also reduces intervertebral disc stretching, which was shown in a twin 28-day ANOG study (Cao et al. 2005).
The novelty of the approach proposed in the experiment was the daily use of LBNP during the acute period of adaptation to SF conditions with an exposure magnitude corresponding to the gravity of the Moon. So far, no experiments with daily LBNP exposures in the early period of adaptation to microgravity conditions have been performed.
Thus, priority results on possible ways to counteract the negative effects of microgravity using LBNP training were obtained in a short-term flight. Obviously, there is a need to continue the data set, and the absence of negative manifestations from the cardiovascular system in our study allows us to recommend the continuation of studies in short-term space flights.
Safety of daily LBNP exposure to -20mmHg at short-term space flight was demonstrated at experiment. LBNP exposure to -20 mmHg may be perspective as countermeasure for Moon mission. Unique data on the rearrangement of gravity-dependent physiological systems in short-term flight were obtained.
Assessment of the dynamics of re-adaptation to the Earth conditions indicates the decrease of functional reserves of the organism even after a short-term flight and the necessity to develop countermeasures at the stage of paradigm shift from orbital flights to lunar missions.
The study was one of the first steps in the development of new medical control operations for future lunar missions.
Ethical Approval: the study was approved by the Bioethical Commission of the State Research Centre of the Russian Federation – IMBP RAS (Protocol No. 657 of 16.01.2024) and the Human Research Multilateral Review Board (HRMRB (Protocol No. 24-005 of 24.01.2024)).
The subject signed written informed consent to participate in the study and consent to publication of data.
Competing interests: the authors declare, that they have no competing interests to report.
Author Contributions: Marina Vasilevskaya - participant of the spaceflight; Elena Fomina, Oleg Orlov, Irina Alferova - conception and design of the work; Pavel Romanov, Oleg Orlov, Maksim Kharlamov - project administration; Maksim Kharlamov, Alexey Grishin, Alexandr Vasin, Alexey Polyakov - organisation of pre- and postflight studies; Zhana Yarmanova - hardware; Alexandr Vasin - medical safety support, Elena Fomina, Anna Ganicheva, Natalia Senatorova, Vera Bakhtereva, Irina Alferova, Yegor Lemeshko - methodology; Pavel Romanov, Alexandr Vasin, Anna Ganicheva, Natalia Senatorova, Vera Bakhtereva, Maria Kokueva, Tatiana Shushunova and Elena Fomina - data aquisition, curation and interpretation; Elena Fomina, Anna Burakova, Pavel Romanov, Anna Ganicheva, Maria Kokueva - writing of the manuscript, Natalia Senatorova, Vera Bakhtereva, Elena Fomina, Alexandr Vasin - editing. All authors reviewed the manuscript.
Funding: this study was funded by State space corporation Roscosmos and Russian academy of Science base funding (FMFR-2024-0037).
Availability of data and materials: not applicable
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No competing interests reported.