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INTRODUCTION: A ccessible spaceflight may seem a distant concept. As part of a diverse European Space Agency funded Topical Team, we are working on the physiological feasibility of space missions being undertaken by people with physical disabilities. Here, the first activity of this team is presented in the form of key lessons learned from aviation to inform new work on space missions. DISCUSSION: The first lesson is agreeing on realistic expectations about impairments, their severity, and the possibility of flying independently. This is important in terms of astronaut recruitment and societal expectations. The second lesson relates to training and adjustments for people with disabilities. Flexibility is important while maintaining safety for everyone involved. The third lesson is about managing unconscious bias from the different stakeholders. We conclude by arguing that engagement with people from different backgrounds is essential for the success of the first space mission with people with physical disabilities. [ABSTRACT FROM AUTHOR]

INTRODUCTION: G tolerance has been widely assessed using Peripheral Light Loss (PLL), but this approach has several limitations and may lack sensitivity. The aim of this study was to investigate the use of a foveal visual endpoint for centrifuge research (Grating Loss; GL) and assess its repeatability, reliability, and usability with PLL as a reference. METHODS: A total of 11 subjects undertook centrifuge assessment. Gradual onset sessions (GOR; 0.1G · s−1) measured both endpoints simultaneously and were performed twice, consisting of six determinations with anti-G suits activated (GOR-On) and six without (GOR-Off). Four determinations of each endpoint were also taken during rapid onset runs (ROR; 3G · s−1). Usability was scored subjectively. RESULTS: The GL endpoint was reached 0.3–0.5 Gz lower than PLL with each endpoint correlating strongly in GOR-Off (r = 0.93), GOR-On (r = 0.95), and ROR (r = 0.86). The GL had excellent test–retest repeatability (intraclass correlation coefficient: GOR-Off/On = 0.99, ROR = 0.92) and low within-subject variability. Between-subject variance equaled PLL in all conditions. Subjective usability endpoint ratings were equal for all conditions. DISCUSSION: For the 11 individuals tested, the GL was a reliable, repeatable, and usable endpoint, with similar performance to PLL. GL may prove useful as a supplementary endpoint for human centrifuge research as a secondary data point or to reduce fatigue in repeated measurements. The foveal GL stimulus was lost before PLL, contrary to popular models of visual changes under +Gz. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Previous centrifuge research has identified that during a centrifuge simulated suborbital spaceplane launch involving +4Gz and up to +4.5Gx, -70% of individuals experienced greyout, increasing to -80% on re-entry, assuming an upright seated posture. Furthermore, blackout and G-induced loss of consciousness (G-LOC) have been observed during the same profiles. A potential means to mitigate this risk is to instruct passengers/crew to tense their legs/abdominal muscles in a similar manner to that performed during the anti-G straining maneuver. The aim of the current study was to determine whether pre-tensing of the lower body muscles can prevent visual symptoms during suborbital acceleration profiles, thereby reducing the risk of G-LOC. METHODS: 13 participants (10 males, 3 females, age range 34-82, mean age 53 (SD= 15)) who had previously experienced G-induced visual symptoms during a centrifuge suborbital spaceflight acceleration study were invited to take part. The acceleration profile used was the most provocative suborbital profile identified in a prior study, mimicking spaceplane launch and re-entry in an upright seated position. Participants experienced acceleration while relaxed and when performing lower body muscle tensing, initiated -10 seconds prior to peak acceleration. Participants were asked to depress a marker button while they experienced any visual symptoms to record onset and duration. The study had favorable opinion from the UK Ministry of Defence Research Ethics Committee. RESULTS: Pre-tensing completely prevented greyout on launch in participants who had previously experienced greyout during suborbital profiles when relaxed, and on re-entry it prevented greyout in 54% of participants. The time to onset of greyout in those who experienced re-entry symptoms was delayed by muscle tensing. The effectiveness of pre-tensing was not related to age. Pre-tensing was well tolerated. DISCUSSION: Greyout can be common during launch and re-entry phases of centrifuge-simulated suborbital spaceflight in a seated spaceplane pro- file. Pre-tensing was found to be well tolerated and feasible for suborbital spaceplane participants and should be considered as a mitigation during routine operations. Even with pre-tensing, individuals may still experience G-related visual symptoms, indicating that the risk of G-LOC remains. Learning Objectives 1. The audience will learn about the effectiveness of muscle tensing in preventing visual symptoms in a centrifuge-simulated upright seated spaceplane profile. 2. The audience will learn that the effectiveness of pre-tensing in this study and simulated spaceplane profile was not related to age. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pilots in high-performance aircraft are exposed to acceleration in the +Gz (Head-to-foot) axis which can result in G-induced Loss of consciousness (G-LOC). Breathing elevated levels of CO2 have been reported to increase Systolic Blood Pressure (SBP) and Middle Cerebral Artery Velocity (MCAv) and therefore may potentially be used to improve G tolerance. Lower body negative pressure (LBNP) has been used as a tool to investigate responses to central hypovolemia and as a surrogate of hypergravity. The present study aimed to determine whether breathing 5% CO2 increased cerebral blood flow and blood pressure during LBNP. METHODS: 15 subjects (9 M/6 F, 31±8 yr) undertook the experiment which involved breathing either room air or a mix of 5% CO2, 21% oxygen, balance nitrogen for 3 mins followed by a 2 min period of -60mmHg LBNP. There was a 2-minute washout period between trials. We measured middle cerebral artery velocity (MCAv) with transcranial Doppler ultrasound. Continuous, non-invasive blood pressure was measured using finger plethysmograph with mean arterial pressure (MAP), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) determined. We corrected MCAv for blood pressure (MAP) and present it as cerebrovascular conductance index (CVCi). RESULTS: LBNP caused an increase in heart rate and TPR while SV and CO significantly decreased (p < 0.05, main effect of LBNP) with each of these changes being similar between breathing gas conditions. MCAv, MAP, and CVCi were all greater during the 5% inspired CO2 trials (p < 0.05, main effect of gas), irrespective of exposure to LBNP. DISCUSSION: Breathing a mixture of 5% CO2 increased cerebral blood flow and blood pressure with these increases remaining during an analogue of hypergravity. While technical challenges exist in integrating CO2 breathing inflight, increasing inspired CO2 could contribute to better G-tolerance. Learning Objectives 1. The audience will note that breathing a mixture of 5% CO2 increased cerebral blood flow and blood pressure, and these increases were demonstrated in an analogue of hypergravity. 2. The audience will learn that increasing inspired CO2 could contribute to better G tolerance. [ABSTRACT FROM AUTHOR]

BACKGROUND: One in 5 people worldwide lives with a disability, frequently facing challenges in aviation. This makes accessible space flight seem like a distant dream. Recently, ESA selected the first astronaut with a physical disability. Our ESA Topical Team supports this opportunity by reviewing the existing literature and lived experience in the field, to investigate the physical and physiological challenges and also the potential advantages of astronauts with disabilities. OVERVIEW: Given the overlap between the medical standards required for pilot medical certification and those for astronaut selection, we started by examining the experience of a disabled flying charity, Aerobility. Three key lessons were learned from this review which will support the collaboration between stakeholders when working with astronauts with physical impairments.The first lesson was to recognise that not everyone will meet the standards for aeromedical certification. Astronauts face similar requirements and a transparent approach to assessment is required. However, these criteria can evolve over time, as advancements in both medical and technological fields may mitigate the impact of physical impairments on an individual's ability to participate in space missions. The second lesson was that people with disabilities can meet the requirements for flying with adapted training and technical modifications. In this context, flexibility and open discussions are needed to understand individual needs and find optimal solutions. Likewise, considering astronauts, dedicated efforts are required to adapt systems and procedures, ensuring accessibility. The third lesson highlighted the significance of involving different stakeholders when reviewing recruitment, training, adaptations, and operations. Unconscious bias remains a challenge in the field. Without scientific evidence demonstrating the suitability of candidates with physical disabilities, space accessibility would remain partial. DISCUSSION: We reviewed the experience of a leading flying charity to define key lessons from aviation that could be translated and adapted for space flight. Our overarching goal is to evaluate the physiological considerations for people with physical disabilities in order to support ESA's team and space missions. This work will become even more relevant with the emergence of space tourism, and the need for accommodating a diverse array of candidates for both short-term and extended space flights. Learning Objectives 1. To discuss the requirements and adjustments for people with disabilities in aviation and how they can inform space missions. 2. To identify the needs and adjustments for astronauts with a physical disability. [ABSTRACT FROM AUTHOR]

BACKGROUND: Anti-G Suits provide protection against +Gz acceleration through several physiological mechanisms. The contribution of each of these mechanisms to improving G-tolerance, and how each relate to the degree of protection provided, is not fully understood. This study investigates the cardiovascular response to three levels of G-protection: No (NP), Moderate (MP; 5-Bladder Anti-G Trousers) and Improved (IP; Full Coverage Anti-G Trousers) protection. METHODS: 11 subjects undertook a series of rapid onset (3 G/sec; 15 sec plateau) runs in a human centrifuge with target +Gz increased until Peripheral Light Loss (PLL) was reached. Impedance plethysmography (IPG) assessed blood volume changes in the whole lower body (Total), Abdomen, Thigh and Calf. Non-invasive pressure waveform monitoring was used to calculate Blood Pressure (BP), Cardiac Output (CO), Stroke Volume (SV) and Total Peripheral Resistance (TPR). Heart Rate (HR) was calculated from 3-lead ECG. For each variable, changes between preceding baseline and the +Gz plateau at PLL were analysed using repeated measures analysis and post-hoc pairwise comparisons. A comparison between MP and IP at +3.2 Gz was also performed. RESULTS: +Gz at PLL increased with increasing protection (mean ± SD: NP; +3.4 ± 0.5 Gz, MP; +4.5 ± 0.6, IP; +5.0 ± 1.0 Gz). At PLL, there was no difference in the change in eye-level BP, SV or CO between conditions. However, the increase in TPR was greater for IP than MP. At +3.2 Gz, eye-level ΔBP was the same for MP and IP, but ΔHR was higher in MP, whilst ΔTPR was higher in IP. At PLL, Total ΔIPG decreased (i.e blood volume increased) for NP, but changes in individual segments were not significant. Total and Abdominal ΔIPG increased equally with both MP and IP. Thigh ΔIPG increased significantly with IP but was unchanged in the other conditions. Calf ΔIPG was unchanged from baseline in all conditions. At +3.2 Gz, Abdominal ΔIPG was increased more by IP than MP. DISCUSSION: At PLL, regardless of the level of protection, key measures of cardiovascular physiology were similar. Greater protection allowed these physiological changes to occur at higher +Gz. Both Anti-G suits reduced blood volume re-distribution to the lower body. The main difference with improved protection was a greater blood volume shift from the thigh. Thigh and abdominal compression appear key to the level of G-protection, whilst calf compression appears less critical. Learning Objectives 1. The audience will learn about the differences in cardiovascular response between exposures to +Gz with and without G-protection. 2. The audience will learn about how differences in cardiovascular response reflect changes in G-tolerance. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Aircrew physiological monitoring (PHYSMON) is an area of increasing interest, but published research in general aviation related to this topic is limited. This study held two aims; to describe the heart rate (HR) response of inexperienced fliers to the general aviation environment and investigate the viability of two PHYSMON technologies to measure HR accurately and reliably in general aviation (including aerobatic flight). METHODS: 14 subjects with <5 hrs of light aircraft flight experience were passengers during a varied flight profile, including aerobatic manoeuvres, in a T67 Firefly with a flight instructor as pilot in command. Subjects HR was measured by two independent devices; a Garmin Fenix 6 Pro smartwatch utilising photoplethysmography (PPG) and Polar H10 chest strap using electrocardiography (ECG), the latter of which being treated as the reference device. The data was synchronised against cockpit video and analysed for agreement and variance in discrete phases of flight, categorised as either aerobatic or non-aerobatic. RESULTS: The two devices were largely in agreement during nonaerobatic flight (bias = 0.2031 with SD = 4.234, LoA -8.501 to 8.095). In aerobatic manoeuvres, the agreement between the two devices decreased (bias = 3.364 with SD = 5.371, LoA -7.163 to 13.89). Short (<10 seconds) duration increases in HR detected by the H10 were often not detected by the Garmin watch, reflected in a higher variance in HR from the H10 during these phases of flight. DISCUSSION: The agreement between the H10 and Fenix 6 suggests that PPG technologies work in the assessment of heart rate during non-aerobatic flight. The increasing disparity between chest-strap and smartwatch values for HR in the aerobatic phase suggests that ECG-based devices are more appropriate for use in aerobatic flight. This study highlights the need for PHYSMON devices to be validated in the flight setting to ensure the collected data reflects the physiological reality and suggests that PPG may be unreliable for use in the dynamic flight environment of aerobatics. Alternative technologies may exist for this role that pose novel solutions. Learning Objectives 1. The audience will learn about the difference in performance between ECG and PPG-based physiological monitoring devices when used in the dynamic flight environment. 2. The audience will learn about the heart rate response to civilian aerobatics. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of the study?The aim was to determine the effects of duration of acceleration in the cranial–caudal direction (+Gz) on acceleration atelectasis and identify measurement techniques that can be used to assess it.What is the main finding and its importance?Non‐invasive measurement of acceleration atelectasis using electrical impedance tomography and estimates of pulmonary shunt provide more detailed assessment of acceleration atelectasis than traditional forced vital capacity measures. Using these techniques, it was found that as little as 30 s of exposure to +Gz acceleration can cause acceleration atelectasis. The results of the present study will allow a more accurate and detailed assessment of acceleration atelectasis in the future. Recently, there have been reports of acceleration atelectasis during fast jet flight despite the use of systems designed to minimize this. Before further investigation of this, indices suitable for use in applied settings and identification of acceleration durations that elicit it are required. Fifteen non‐aircrew subjects underwented five centrifuge exposures lasting 15, 30, 60 and 2 × 90 s with a plateau of +5 Gz (acceleration in the cranial‐caudal direction) while breathing 94% O2 during all but one control exposure (21% O2). Lung volumes and gas exchange limitation were assessed after each exposure. Regional lung impedance and compliance were measured after Gz exposure using electrical impedance tomography and the forced oscillatory technique, respectively. The presence of acceleration atelectasis was confirmed by reductions of 10–17% in vital and inspiratory capacity after 60 and 90 s Gz exposures (P < 0.05) and resulted in reduced regional lung impedance and a gas exchange limitation of 8.1 and 12.5%, respectively (P < 0.05). There was also a small but significant decrease in regional lung impedance after 30 s exposures. Functional residual capacity and lung compliance were unchanged in atelectatic lungs (P > 0.05). In the majority of individuals, >60 s of Gz exposure while breathing 94% O2 causes acceleration atelectasis. Electrical impedance tomography and the measurement of gas exchange limitation provide useful indicators of acceleration atelectasis. Acceleration atelectasis exerts its effects primarily through basal lung closure and reflex inspiratory limitation, both of which can be reversed by performing three maximal inspiratory breathing manoeuvres. [ABSTRACT FROM AUTHOR]