STEM TODAY December 2017, No. 27
STEM TODAY December 2017, No. 27
CONTENTS SM2.1: Determine the changes in sensorimotor function over the course of a mission and during recovery after landing.
The most profound sensorimotor deficits occur during and after gravitational transitions. Given these changes there is a possibility that crew will experience impaired control of the spacecraft during landing along with impaired ability to immediately egress following a landing on a planetary surface (Earth or other) after long-duration space flight.
Editorial Editor: Mr. Abhishek Kumar Sinha Editor / Technical Advisor: Mr. Martin Cabaniss
STEM Today, December 2017, No.27
Disclaimer ( Non-Commercial Research and Educational Use ) STEM Today is dedicated to STEM Education and Human Spaceflight. This newsletter is designed for Teachers and Students with interests in Human Spaceflight and learning about NASA’s Human Research Roadmap. The opinion expressed in this newsletter is the opinion based on fact or knowledge gathered from various research articles. The results or information included in this newsletter are from various research articles and appropriate credits are added. The citation of articles is included in Reference Section. The newsletter is not sold for a profit or included in another media or publication that is sold for a profit. Cover Page The Voyager spacecraft showcasing where the Golden Record is mounted Voyager 1 Fires Up Thrusters After 37 Years
Image Credit: NASA/JPL
Back Cover Golden Record This image highlights the special cargo onboard NASA’s Voyager spacecraft: the Golden Record. Each of the two Voyager spacecraft launched in 1977 carry a 12-inch gold-plated phonograph record with images and sounds from Earth. An artist’s rendering of the Voyager spacecraft is shown at bottom right, with a yellow circle denoting the location of the Golden Record. The cover of the Golden Record, shown on upper right, carries directions explaining how to play the record, a diagram showing the location of our sun and the two lowest states of the hydrogen atom as a fundamental clock reference. The larger image to the left is a magnified picture of the record inside. The Voyagers were built by NASA’s Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft. JPL is a division of the California Institute of Technology in Pasadena. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate. Image Credit: NASA/JPL-Caltech
STEM Today , December 2017
Editorial Dear Reader
STEM Today, December 2017, No.27
All young people should be prepared to think deeply and to think well so that they have the chance to become the innovators, educators, researchers, and leaders who can solve the most pressing challenges facing our world, both today and tomorrow. But, right now, not enough of our youth have access to quality STEM learning opportunities and too few students see these disciplines as springboards for their careers. According to Marillyn Hewson, "Our children - the elementary, middle and high school students of today - make up a generation that will change our universe forever. This is the generation that will walk on Mars, explore deep space and unlock mysteries that we can’t yet imagine". "They won’t get there alone. It is our job to prepare, inspire and equip them to build the future - and that’s exactly what Generation Beyond is designed to do." STEM Today will inspire and educate people about Spaceflight and effects of Spaceflight on Astronauts. Editor Mr. Abhishek Kumar Sinha
Editorial Dear Reader The Science, Technology, Engineering and Math (STEM) program is designed to inspire the next generation of innovators, explorers, inventors and pioneers to pursue STEM careers. According to former President Barack Obama, " Science is more than a school subject, or the periodic table, or the properties of waves. It is an approach to the world, a critical way to understand and explore and engage with the world, and then have the capacity to change that world..." STEM Today addresses the inadequate number of teachers skilled to educate in Human Spaceflight. It will prepare , inspire and educate teachers about Spaceflight. STEM Today will focus on NASA’S Human Research Roadmap. It will research on long duration spaceflight and put together latest research in Human Spaceflight in its monthly newsletter. Editor / Technical Advisor Mr. Martin Cabaniss
STEM Today, December 2017, No.27
Human Health Countermeasures (HHC) SM2.1: Determine the changes in sensorimotor function over the course of a mission and during recovery after landing
The most profound sensorimotor de cits occur during and after gravitational transitions. Given these changes there is a possibility that crew will experience impaired control of the spacecraft during landing along with impaired ability to immediately egress following a landing on a planetary surface (Earth or other) after long-duration space ight.
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Spatial Disorientation and Sensory-motor problems in Mir
A top priority in the U.S. space program is assuring crew and vehicle safety. This priority gained significant focus in June 1997 following the collision of the Progress 234 resupply ship with the Mir space station during a manual docking practice session. There were two separate attempts to dock the Progress with the Mir that day. In the first attempt, docking was aborted after the radar used for range calculations apparently interfered with a camera view of the Progress. In the second, near fatal attempt, mission managers decided to turn the radar off and leave the camera on. For this arrangement to work the Mir commander asked his two crewmates to look for the Progress approach through a porthole, and once sighted, to provide range information with handheld range instruments. Trouble began when neither the camera view nor the visual spotters could locate the Progress as it closed on the station. When spotters moved between modules to obtain a better view, they lost their frame of reference, and were uncertain which direction to look.
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Once spotted, the Progress’ speed was above an acceptable rate, and it was very close to the Mir. Braking rockets on the Progress, fired by the Mir commander, failed to slow the velocity of the approaching spacecraft. No range information or other position data were available to assist the commander. To complicate matters, one of the other crewmembers may have bumped into the commander as he attempted to make last second inputs to the approaching Progress via joystick. The resulting collision tore a portion of the solar panel on the Mir, punched a hole in the Spektr module, and caused a decompression of the station. Loss of situational awareness, spatial disorientation, and sensory-motor problems, including difficulties with vision, head-hand-eye coordination, and an inability to judge distance and velocity with limited feedback likely contributed to this outcome. Target acquisition studies have shown dramatic changes in the speed at which target visualization can be achieved, delaying response time by as much as a 1000 msec. Eye-hand response could take as long as another full second. A delay of two seconds is a lifetime when a spacecraft is closing, and not responding to joystick commands intended to decrease forward velocity. Members of the Russian Institute of Biomedical Problems (IBMP) believe that the collision between Mir and Progress was caused by poor situational awareness, spatial disorientation, and sensorymotor problems (I.B. Kozlovskaya, personal communication). After the fact, Ellis.et.al. performed a rigorous, quantitative analysis of the available visual and non-visual information and suggested a number of potential sensory-motor and cognitive/psychophysical contributions to the crash. To avoid human factors contributions to future crashes such rigorous analyses should be performed well before attempting any three-dimensional visual-motor control task.
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Incidents due to situational awareness during EVA
The International Space Station (ISS) teleoperation system was heavily used during construction, and it will continue to be used to support extravehicular activities (EVA) operations, as well as in grappling/docking of rendezvousing cargo vehicles. Training and operating the Shuttle and ISS telerobotic manipulator systems as well as telerobotically controlled surface rovers presents significant sensorimotor challenges . These systems are usually controlled using separate rotational and translational hand controllers, requiring bimanual coordination skills and the ability to plan trajectories and control the arm in some combination of end-effector or world reference frames. The abilities to visualize and anticipate the three-dimensional position, motion, clearance, and mechanical singularities of the arm and moving base are critical. Thus, operators must have the cognitive abilities to integrate visual spatial information from several different reference frames. Often the video cameras are not ideally placed, and in some situations (e.g. ISS operations) the views may actually be inverted with respect to one another, so cognitive mental rotation and perspective taking skills are also important . Teleoperation is sufficiently difficult that several hundred hours of training are required to qualify, and all operations are monitored by a second qualified operator, backed up by a team of trainers and engineers on the ground. Recency is important, so ISS astronauts perform on-orbit refresher training. Despite all the training and precautions, however, there have been four-five significant ISS teleoperation in-
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cidents (e.g., collisions with a payload bay door, significant violations, or close calls) over the course of the first 16 ISS increments. Procedures are updated after each incident, but there are generic common factors relating to spatial visualization skills, misperception of camera views, timeline pressures, and fatigue.
MSS Close Call Flight Incidents
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PDGF "Stiction" Problem Situation: Crew was releasing and backing off a grapple fixture. The normal method for this is to send an auto release command and the system relieves tension, opens the snares and extends the carriage forward. After the snares are opened, the operator starts backing off the grapple fixture so the carriage does not bump the fixture and pin. During this release the Latching End Effector (LEE) became stuck in the grapple fixture. Operator observed no motion so input higher hand controller command (building up forces in the arm). As the carriage moved forward it pushed the LEE off of the grapple fixture. The arm sprang off the fixture due to the force buildup and recoiled back striking the grapple fixture and lab (actual contact made and heard by crew inside). Contributing factors: Situational Awareness - Loss of Situational Awareness of overlays and video. Not sure if crew noticed the overlay data indicating high command inputs but no actual motion. Video also showed no motion. If the crew noticed they did not react in time to prevent hitting. Operational Changes: Situational Awareness: Education of crew on stiction problem - Train the crew on the signatures of a sticky grapple fixture. Overlay will indicate high level of commanded input but little to no actual FOR motion. Video will not show motion. Input should be removed immediately to limit arm force build up. Changes to release technique - After this incident the ground team investigated causes of the stiction. No root cause has been determined but for expected grapple fixtures and scenarios a "push-off" technique is used to release. This technique allows the carriage to extend and "push" the LEE off the grapple fixture.
MSS Close Call Flight Incidents
ISS-7A / STS-104 Close Call Space Station Remote Manipulator System (SSRMS) to Ultra High Frequency (UHF) Antenna Close Call Situation: • The crew got ahead in the timeline and decision was made to install a third oxygen/nitrogen tank (ONTO). Tank was grappled by the SSRMS and handed off to EV crew at the airlock. At the end of the handoff the crew was asked to park the arm at a known location but the trajectory to get there was unfamiliar since the crew had not trained flying to a park position from the third tank install location. • The big picture camera (Camera C on the Orbiter) was zoomed in on EV crew installing the ONTO tank while the arm was being maneuvered to park. This stage of assembly utilized station crewmembers for robotics operations and all three crewmembers were trained on the tasks. This maneuver was very late in the crew day and the "least" trained operator was performing this "simple" maneuver. The arm was maneuvered well away from structure and hit a six-degree of freedom (6 DOF) singularity causing the elbow to swing toward the UHF antenna. Eventually the camera C view was zoomed out to see whole arm, but elbow to UHF clearance not
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discernable. Good orthogonal camera views did not exist due to station configuration (no outboard structure yet to house a camera). Ground made a call to stop the arm and the Lab window was utilized to view actual clearance between arm and antenna. The ground tools showed 2 inches of clearance between arm and antenna when the arm stopped. • The arm was maneuvered using a joint held algorithm. If a singularity was encountered, the arm would release the held joint and manage the singularity. This was identified by sluggish FOR motion, moving joint indication and pitch plane change (elbow joint swing) of the arm.
Contributing Factors • Situational Awareness - Poor camera views - Crew had no big picture view. What had been a big picture view earlier, Cam C was left zoomed in on the ONTO. Crew was reluctant to ask shuttle crew to adjust cam C. Also the lack of cameras at this stage of assembly limited visibility into some clearances.
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• Long Day, Tired Crew - The nominal plan for the day was to do two tanks, but they were ahead in the timeline and crew agreed to press with the third tank. After the mission, the crew reported that the arm ops were both physically and mentally draining. • Unscripted Task/Unscripted Operator - There was never a plan or procedure to go from the 3rd ONTO to Lab FRGF. Therefore, this trajectory was never evaluated on the ground for clearance or singularities. This took them into the SY or WY singularity. Although the SSMRS Operator was fully certified on SSRMS, they had no experience operating in this area of the ISS. The operator that flew this last maneuver of the day was not the same operator that flew the EVA task just prior (the crew switched off operators). • No Full-Time M2 - Because the day was longer than expected, the M2 was trying to do two jobs: M2 role and helping with IV Ops as EVA crew were ingressing the Airlock. M2 was not fully engaged in the final task. • Crew was unaware of singularity indications - Crew was never trained to identify a singularity condition based on "sluggish" FOR motion, joint release and elbow swing. Generic Robotics Training and Spec Skills flow did not exist in this timeframe.
Operational Changes: • Improvements in Communication - "All stop on the arm" voice protocol implemented - The call to crew was not very clean nor quick. A formalized method for declaring and implementing an All Stop was developed for both the Station and Shuttle Arm. Caution was taken to make the call and response similar for each system so cross trained crews would not be confused. New method has the person identifying the emergency issue declare all stop three times (All Stop, All Stop, All Stop). If heard the operator releases the hand controllers and safes the system. If called during a docked mission both the Shuttle and Station arms react to the same call so there is no reason to discern between the systems in trouble. • Tight clearance scenarios implemented in Generic simulations & MSS lessons - The training team developed a series of scenarios and lessons to exercise tight clearance situations and unscheduled trajectory flying. • Improvements in Situational Awareness - "Joint release" computation developed for the Mission Control Center (MCC) - The ground created an indication that the held joint had released. This would alert the ground team to possible elbow swing and they could make the call to crew.
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MSS Close Call Flight Incidents
ISS-8A / STS-110 Operational Changes: No issues occurred during this mission that were SFRM errors. The arm did have a joint failure prior to flight, which was worked around using procedures and software changes. Operational changes came during training. The areas the arm was operating for the flight had numerous 6 DOF singularity zones. To avoid the earlier issues the community decided to start locking joints, which disabled the singularity management. If a singularity was encountered, the arm would simply stop and the team could decide how to continue with the task. Also in this timeframe the software was updated to include crew annunciations of 6 DOF singularities and enhancements to the Dynamic Onboard Ubiquitous Graphics (DOUG) tool provided better Situational awareness to the crews.
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MSS Close Call Flight Incidents
ISS-UF2 / STS-111 Close Call SRMS to SSRMS Close Call Situation: During a scheduled EVA activity, both the Shuttle and Station robotic arms were being used in close proximity to each other. The EV crews were directing the motion of both arms (called Ground Control Assist or GCA). At one point the two arms were moving at the same time toward each other. The ground called to have motion stopped (new All stop protocol was still being worked out so not utilized). Actual arm-to-arm distance is unknown but inside of desirable 5 feet. Contributing Factors: • Communication - Shuttle and Station arm operators were not coordinating motion. Communication between Shuttle and Station operators and ground teams not ideal in this scenario. There was no documented rules stating how to handle this situation. • Situational Awareness - M1 not familiar with procedure. At this stage in assembly the Station crew was still utilized for arm operations and often times paired with a shuttle crewmember. Since Station crews could launch months ahead of the Shuttle mission, training the M1 and M2 together for tasks was very difficult to schedule. Many times the procedure would change after the Station crew had launched and they would have to adapt to those changes in real time. • Communication and Situational Awareness - EV providing GCA to both arms. EVA tasks were happening in parallel and neither EV crew was very aware of the arm locations.
Operational Changes: • Improvements in Situational Awareness - Ground developed a flight rule to minimize dual arm motion when in close proximity to each other. The flight rule (FR C12-7) states that simultaneous motion is allowed if 5 feet between the arms is maintained. • Camera conflicts are minimized pre-flight since the Station and Shuttle arm operators can and do share cameras.
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• Improvements in Communication - Shuttle and Station ground teams work together to develop a choreographed plan for arm motion. Procedures now contain callouts and sync points between the arms to minimized unnecessary dual motion. An example would be a callout in the Station procedure that says "give a go to the SRMS to maneuver to Install viewing position". The Shuttle procedure would then say "Notify Station when at Install viewing position".
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MSS Close Call Flight Incidents
ISS-9A / STS-112 Close Call SSRMS Elbow to PLB Door Close Call Situation: During an EVA task the arm was in a closed configuration (not ideal). The EV crew was giving GCA calls to maneuver the arm and was helping some with helmet video views of clearances. This particular maneuver required rotation and translation commands in a particular sequence to limit the elbow swing of the arm. This swing was due to arm configuration (closed up so a very small angle between the tip and base booms) and not singularities. The crew was aware of the elbow swing from training. They had notes indicating how to avoid this effect. During the maneuver the prime camera for the elbow (Camera C from the Orbiter) got washed out with sunlight. Crew switched to a backup camera but mistook a box on the arm for the elbow so lost sight of closest object. The maneuver was flown as trained but response was not as expected and the elbow started to swing toward the Orbiter payload bay door. The All Stop was called by the ground and the proper response was issued. When the arm came to stop the ground tools indicated contact but no evidence of this was seen onboard (i.e. no damage to arm or door). Actual distance is unknown. Contributing Factors: • Situational Awareness - Poor camera views. Crew lost the big picture view when Camera C was washed out. The backup view was misused when they thought they had the elbow in one of their scenes but the object turned out to be a box on the arm. • Maneuver known to potentially cause large Elbow Pitch joint motion due to proximity of the tip of the SSRMS to its base. Crew was aware of the issue through training and had details in their crew notes concerning this maneuver. • The technique used for the maneuver was not performing as expected. Crew made simultaneous translation and rotation inputs. Performing the rotation corrections first, minimizes the unwanted elbow joint motion. Crew commented that the on-orbit rotation response seemed less than what they had experienced during training.
Operational Changes: • Improvements to Situational Awareness - Ground now has camera pan/tilt data which can be sent to their clearance monitoring tool. This will help identify what the crew is watching and the ground team can direct them if they are watching something incorrectly. Crew is now provided with pan and tilt data in procedures so they can know they are looking at the proper things. • Limit unscripted manual mode use. The arm is now maneuvered primarily by auto sequences or single joint mode. The manual operations are reserved for small EVA maneuvers to final worksite and grapples. This
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allows the ground to evaluate issues and contingencies from known positions. The ground also designs better arm configurations for tasks to avoid having the arm closed up on itself. • Improvements to Communication - Established sync points for communicating with EV crew and ground.
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MSS Close Call Flight Incidents
ISS-11A / STS-113 Incident Mobile Transporter hit the stowed P1 UHF Antenna Situation: During this mission the Mobile Transporter (MT) was timelined to translate after the deployment of the antenna. The EVA to deploy the antenna got behind and the deploy was delayed. The decision to translate was not altered and during the maneuver the MT ran over the antenna. When it hit, the ground didn’t know what was going wrong. An EVA Crew inspection determined a box on the MT was hitting the UHF antenna on P1. The EV crew deployed the UHF antenna so the MT translation path was clear. Analysis failed to realize the antenna in its stowed state was in the translation corridor for the MT. There was some damage to the MT box but the antenna was fine. Contributing Factors: • Situational Awareness - Camera views were not required for the maneuver. Translation analysis had been done with P1 UHF antenna deployed since this was the expected configuration. During the fit test at Cape Canaveral, the UHF antenna was deployed, and they didn’t check to see if the MT would fit past the antenna if it was stowed. • P1 UHF antenna deployment was delayed because the EVA activity ran long. Failure of the ground team to determine the impact this might have on the translation.
Operational Changes: Improvements to Situational Awareness - A flight rule now exists (FR B12-5) that states a CCTV survey of MT translation path is required before motion.
MSS Close Call Flight Incidents
Other Onboard Events Situation: There have been several events where operators have made input errors in typing auto sequence numbers. All but one was caught prior to motion. The event where motion occurred was minor since only the wrist roll joint moved. Typically there are several checks in place to assure proper entry of numbers. Breakdown in these checks have led to the mistakes. Breakdowns include having solo operators (no second set of eyes to verify what was entered or what should be entered), Crew fatigue (performing operations late in a crew’s day) and
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improper mismatch or use of the M1 and M2. Contributing Factors: • Situational Awareness - Crew fatigue can lead to omitting or adding a sign change in the typed number. Can also lead to moving a decimal place or transposing numbers. • Communication - Solo operations (without an M2) has led to issues. • Leadership - Improper use of an M2 can lead to problems.
Operational Changes:
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• Improvements in Situational Awareness - Educating the crew on when they are fatigued and steps they should take when they are in this state. Training touches on this by putting crews in timed situations adding pressure and trying to overload the operator. Educating the ground to be aware of what they are asking the crew to perform and the timing of the request (i.e. don’t schedule tasks very late in the day without taking extra precautions). • Improvements in Communication - New Ground rules and constraints are being generated to indicate the types of operations that can be done solo and which ones require an M2. There are also rules being generated to detail what steps should be taken if an M2 is not available. This includes more sync points with the ground and possible communication with station requirements for the operation to proceed. • Improvements in Leadership - Steps are being taken to properly match skill levels of M1 and M2 operators. Keeping skill levels the same minimizes the chances that one operator will get ahead or behind the other. Training has developed a lesson to educate operators on proper M1 and M2 habits and roles. All arm operators take this class.
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Driving Performance
Adaptive changes in sensorimotor function during space flight can compromise a crewmember’s ability to optimize multi-sensory integration, leading to perceptual illusions that further compromise the ability to drive under challenging conditions. During the June 2006 Apollo Medical Operations Summit in Houston, TX, Apollo crewmembers reported that rover operations posed the greatest risk for injury among lunar surface EVA activities. During rover operations, crewmembers often misperceived the angles of sloped terrain, and the bouncing from craters at times caused a feeling of nearly overturning while traveling cross-slope, causing the crewmembers to reduce their rover speed as a result (Apollo 15 report). This is not surprising given the evidence of tilt-translation disturbances following G-transitions, as incorrect perceptions of vehicle accelerations, tilted terrain, and uneven (bumpy) surfaces may cause inappropriate responsive actions. While automatic control systems can compensate for some deficiencies in performance, lessons learned from the Apollo missions (Mindell 2008) suggest that manual takeover is required as a minimum safe guard, and therefore countermeasures must concentrate on mitigating risks associated with crewmembers in the control loop for rover operations. Risk factors for injuries identified [NASA/TM-2007-214755] The Apollo astronauts were queried about risky behaviors on the lunar surface or conditions that could predispose them to injuries. Overall, the crews felt the injury risk was low due to the partial gravity providing considerable time to react to a fall and the relatively short distance to fall considering their lunar weight was
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1/6 their Earth weight. They were quick to mention that the videos of their falls on the moon were misleading, and that it did not hurt to fall. However, the crews pointed out that their inertial mass did not change on the moon. Given the EVA suit/PLSS (∼ 194 lbs. on Earth) and crewmember mass and right set of circumstances listed below, sufficient energy could be applied to a joint or extremity to cause injury.
• Navigation into terrain or craters with slopes > 20-26◦ A fall on sloped terrain may be well tolerated unless the crew was moving or carrying an external load, such as equipment or rock samples. Although the exact angle of the slope was an estimate, the crews remarked that stable footing was limited and leg fatigue would become more pronounced in terrain steeper than approximately 26◦ . Lack of suit mobility, primarily at the hips, made getting in and out of steep terrain difficult. Another concern was the lack of peripheral vision in the suit and the inability to see where an outstretched hand might land. Hand or wrist injuries were more of a concern for some of the crewmembers than lower extremity injuries. The ability to estimate crater dimensions was compromised as mentioned by one crewmember in the following statement: "Reflective light in the shadows isn’t as evident as on Earth. Craters did appear steeper visually. But we knew we had to go down into that crater, so it gave us concern."
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• Rover activities The safety harness took roughly three minutes to fasten and some crews opted not to engage the buckle. The astronauts stated that the lunar module pilot in the right seat was at particular risk of falling out due to the undulating terrain and often being tilted downward and out the vehicle. • Falling from a height Falling from the rim of a steep crater was a concern in some instances. Ladder height on the LM was less that six feet, but it became a concern with the poor glove grip mechanics. Mention of the proposed LSAM ladder height ranging from 20-28 feet drew sighs from astronauts and obvious concern for injury.
Anomaly in Lunar Roving Vehicle [Apollo 15 Mission Report]
Deployment Saddle Difficult To Release From Vehicle The lunar roving vehicle deployment saddle was difficult to release from the vehicle during the final stage of deployment operations. The causes of this problem are two fold and interrelated. • The saddle-to-vehicle connection has close-tolerance interfaces to provide the rigidity required to prevent release-pin distortion and permanent binding. This design requires the vehicle/saddle interface to be completely free of stress to permit easy separation. • The tilt of the lunar module to the rear and sideways, together with an uneven lunar surface, provided some stress preloading of the vehicle/saddle interface. Attempts by the crew to improve the rover position by moving and pulling on it may have aggravated this situation. The crew was aware that the interface had to be free of stress, and when this was accomplished, the saddle separated. Ground tests have shown that if the partially deployed lunar roving vehicle resting on the surface but not yet detached from the saddle and lunar module, is rolled either to the left or right, the saddle/rover chassis interface will bind. The interface can be released, and the saddle dropped to the ground by one crewman adjusting the roll back to zero while the other taps the saddle with a hand tool. The corrective action is to insure adequate crew training.
Volt/Ammeter Inoperative The lunar roving vehicle battery 2 volt/ammeter was inoperative upon vehicle activation, and remained inoperative throughout the traverses. Problems with the meter were experienced during its initial development;
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however, after a more rigid acceptance test program was implemented, the earlier problems were cleared. The flight problem was not duplicated during any of the ground tests. Since the instrument is not essential for the operation of the vehicle, no further action is being taken. Front steering System Inoperative During initial lunar roving vehicle activation, the front steering was inoperative. Electrical checks were made which verified that electrical power was being supplied to the front steering system. Unsuccessful attempts were made to manually rotate the wheels about their steering axes and to detect steering motor stall current on the ammeter. The forward steering circuit breaker and switch were cycled without any apparent effect. Consequently, the front steering was switched off for the first traverse. During preparations for the second traverse, the forward steering circuit breaker and switch were cycled and front steering was operative; however, the time that front steering capability was restored is unknown. Front-wheel wandering did not occur during the first traverse, indicating a mechanical problem. The steering continued to function properly for the second and third traverses. During the second traverse, the rear steering was turned off temporarily and wandering of the rear wheels occurred.
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The most likely cause of this anomaly is motor and/or gear train binding, as indicated by the inability to drive back through the linkage and gear train by manually pushing against the wheels. Electrical causes are possible, but less likely. The front steering system of the Apollo 16 lunar roving vehicle is currently being analyzed because of an intermittent failure of a similar nature. Manually pushing against the wheels would not always drive back through the linkage and gear train and the motor stalled at limit current for 0.8 second during a test of this condition. Lunar Roving Vehicle Seat Belt Problems The following seat belt problems were experienced throughout all traverses • The crew was trained to stow the belts, prior to egress, on the inboard handholds. However, during egress and ingress, the belt hooks would slip through the handholds to the floor area. Finding the belts after ingress was difficult because of their displacement from the proper stowage location. • The belts snagged repeatedly on the ground Support equipment connector on the console support structure when displaced from the proper stowage locations. • The belts were not of sufficient length to secure the hooks to the outboard handholds easily. This resulted primarily from an unexpected decrease in suit contour conformance to the seated position in 1/6g. Consequently, the crewmen’s laps were several inches higher than had been anticipated. The main causes of these problems, in addition to insufficient belt length, were insufficient belt rigidity and lack of visibility of the securing operation. New, stiffer seatbelts with an over-center tightening mechanism will be provided for Apollo 16 to eliminate adjustment after each ingress and to provide more tightening capability.
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3D Space - Mental Representation of Spatial Cues During Space Flight
The purpose of the Mental Representation of Spatial Cues During Space Flight (3D-Space) experiment is to investigate the effects of exposure to microgravity on the mental representation of spatial cues by astronauts during and after space flight. The absence of the gravitational frame of reference during spaceflight could be responsible for disturbances in the mental representation of spatial cues, such as the perception of horizontal and vertical lines, the perception of objects’ depth, and the perception of targets’ distance. The results of this study could have important consequences for human performance during space flight. This experiment involves comparisons of preflight, inflight, and postflight perceptions and mental imagery, STEM Today Page 12
with special reference to spaceflight-related decreases in the vertical component of percepts. There are two methodological foci: The first uses multiple measures, stimulus production and stimulus evaluation, to disentangle perceptual and motor contributions. The second is use of a digitizing tablet for subject written input. Virtual reality is used for information display and presentation of perceptual stimulus. • Handwriting and drawing tasks in the Mental Representation of Spatial Cues During Space Flight (3DSpace) investigation will be used to compare the mental representation of the horizontal versus vertical components of layouts of letters and two-dimensional and three-dimensional objects. • 3D-Space will investigate if depth perception is altered during space flight by analyzing the strength of geometric optical illusions based on perspective. Subjects will also be asked to indicate which of normal, elongated, or shrunk three-dimesional objects look normal while in microgravity and after return to Earth.
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• 3D-SPACE will investigate distance perception in microgravity by comparing the judgments of relative distance between three-dimesional objects and landmarks on three-dimesional natural scenes, as well as absolute distance between self and one landmark.
The results show that astronauts on board the International Space Station exhibit biases in the perception of their environment. Objects’ heights and depths were perceived as taller and shallower, respectively, and distances were generally underestimated in orbit compared to Earth. These changes may occur because the perspective cues for depth are less salient in microgravity or the eye-height scaling of size is different when an observer is not standing on the ground. This finding has operational implications for human space exploration missions. The main results of 3D Space are: • Visual illusions based on perspective are less intense in 0 g. This suggests that the perspective cue is less salient for depth perception. • When a subject in 0 g adjusts the dimensions of a 3D cube so that it looks normal, its height is shorter and its depth is larger than when performing this test in 1g; when a subject in 0 g draws a Necker cube with the eyes closed, its height is shorter and its depth is larger. This indicates that the cognitive and the sensory-motor representations of 3D objects both adapt to 0 g. • It is well know that perception of size and distance are usually related. When you underestimate the distance of an object, you tend to attribute a small size to this object. In agreement with this, we observed that subjects indeed underestimate distance in 0 g. Note that egocentric distance is underestimated in 1 g, but it is even more underestimated in 0g (by up to 20%). • These results indicate that the visual space of the astronauts (i.e. the visual component of the perceptual representation of the world around them) is distorted in 0 g. Interestingly, similar effects have been recently reported in spatial neglect and vestibular-defective patients. • The speed of drawing and writing is smaller in 0 g compared to 1 g. The asymmetry between up and down vertical motion also tends to disappear in 0 g. These results confirm those obtained previously in pointing experiments.
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Visual Reorientation Illusion
The visual reorientation illusion (VRI) has been first described by astronauts on the Skylab and Spacelab-1 missions. When crew float about in the cabin, they experience a spontaneous change in the subjective identity of surrounding surfaces, such that the "surface beneath my feet seems somehow like a floor."
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Visual Reorientation Illusion in Skylab and Spacelab-1 missions
On the 41-G and Spacelab 1 missions, subjects experienced some visual illusions as they performed prescribed movement tests. Other tests measured the subjects’ changes in perception when blindfolded in weightlessness. When crewmembers viewed various targets and then pointed at them while blindfolded, their perception of target location was very inaccurate in flight compared to similar tests on the ground. In a test of the ability to perceive mass in microgravity, subjects were much more inaccurate in predicting masses in weightlessness than in predicting weights and masses in preflight tests.
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The hop and drop experiments studied the otolith-spinal reflex which normally prepares one for landing from a fall. Surface electrodes over the calf muscles recorded neuromuscular signals during simulated falls (accomplished in weightlessness by attaching elastic cords to the crewman to pull him downward). The normal reflex was inhibited when tested early in flight, declined further as the flight pro greased, but returned to normal during tests conducted immediately after landing. Again, this suggests that in microgravity the brain ignores or reinterprets otolith signals. Spacelab 1 experiments studying the vestibulo-spinal reflex mechanisms measured changes in the spinal reflexes and posture associated with the vestibular system. The subjects’ physiological responses to standard posture and reflex tests were recorded. Results of these tests indicate that posture is modified dramatically in weightlessness, and the individuals whose central nervous systems are better able to modify response patterns may experience less severe symptoms of space motion sickness. A related French experiment on the 51-G mission revealed changes in muscle movement and the role of vision during postural control. Pre- and postflight Spacelab 1 tests using a sled to accelerate subjects along a linear path indicated that subjects had an increased ability to perceive linear motion after exposure to microgravity; this seems to indicate that signals sent from the otoliths, which sense both gravity and linear acceleration, come to be interpreted by the brain as only linear motion. To increase the number of subjects for statistical studies, some of the Spacelab 1 experiments were modified and reflown aboard the Spacelab D1 mission. These included the space motion sickness studies, the rotating dome experiment, and the hop and drop experiment. Although the Spacelab D1 results are still being analyzed, they generally confirm the Spacelab 1 findings. A sled developed by the European Space Agency was flown in space for the first time on the D1 mission. When subjects were accelerated on the sled in flight, without the influence of gravity, they had smaller increases in sensitivity to linear motion than the investigators expected. Postflight D1 sled experiments confirmed the earlier Spacelab 1 postflight sled tests, with subjects continuing to show slight increases in sensitivity to linear accelerations.
Oman (2003, 2007) noted that astronauts must orient with respect to a vehicle frame of reference defined by local visual vertical cues. However, architectural symmetries of the cabin interior typically define multiple "visual vertical" directions, usually separated by 90â—Ś . The Earth can provide yet another visual reference frame when viewed through cockpit windows or while spacewalking. There is a natural tendency to perceive the subjective vertical as being aligned with the head-foot axis, generally referred to as the "idiotropic" effect. Which visual reference frame the observer adopts thus depends strongly on relative body orientation and visual attention. VRI occur when the perceived visual vertical reference frame is not aligned with the actual, so that, for example, the overhead surface is perceived as a deck. The type and magnitude of perceptual illusions may depend on whether a crewmember uses an idiotropic or visual reference frame. Individuals who are visually oriented with respect to external references perceive themselves to be inverted or sideways during flight. They report difficulty in switching rest frames and performing coordinate transformations, in addition to experiencing loss of orientation in the absence of visual cues. When an idiotropic reference frame is used, the alignment of a vertical along the longitudinal body axis allows little disorientation and an easy switch between rest frames. Forty-six percent of astronauts and 58% of cosmonauts were classified as using an idiotropic reference frame, 46% of astronauts and 34% of cosmonauts as using predominantly visual reference, and 8% of both crews were classified as using a mixed of both. Individual STEM Today Page 14
experiences with self- or surround-motion may vary, but commonly reported illusions include (a) exaggerated rate, amplitude, and positioning of body movement; (b) temporal disturbance to perception of motion; and (c) altered path perception. Data from animal experiments in parabolic and orbital flight suggest that the VRI surface identity illusion physiologically corresponds to a realignment of the two-dimensional plane that limbic neurons use to code direction and location. When VRI occur, crews lose their sense of direction with respect to the entire vehicle, and reach or look in the wrong direction for remembered objects. Susceptibility to VRI continues through the first weeks in space, and occasional illusions have been reported after many months on orbit. Strong sensations of height vertigo have been described during spacewalks. These might reflect sudden changes in the limbic horizontal frame of reference from the spacecraft to the surface of the Earth.
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VRI can also occur on Earth, but reorientations usually occur only in yaw perception about the gravitational axis, e.g., when we emerge from a subway and discover we are facing in an unexpected direction. VRI about Earth-horizontal axes have been created using tumbling rooms and virtual reality techniques. For example, investigators have shown have shown that the direction and strength of visual vertical cues depend on field of view, the relative orientation of familiar gravitationally "polarized" objects, and the orientation and symmetry of surfaces in the visual background. Single planar surfaces or the longer surface in a rectangular room interior were most frequently identified as "down". Prior visual experience and knowledge of the specific environment are also important factors. Even when VRI do not occur, the visual verticals of adjacent or docked spacecraft modules are often incongruently aligned. Astronauts typically orient to the reference frame of the local module, and significant cognitive effort is required to sort out these multiple vehicle frames of reference. Using virtual reality simulations, Oman 2007 and Aoki et al. (2006, 2007) have shown that subjects remember the interiors of each module in a canonical, visually upright orientation. When performing tasks that require subjects to interrelate different reference frames, additional time is required and workload imposed. The fastest responses occur when module verticals are congruently aligned. Significantly greater time is required to perform simulated emergency egress navigation tasks when module visual vertical reference frames are incongruently aligned.
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Bodies In the Space Environment: Relative Contributions of Internal and External Cues to Self - Orientation, During and After Zero Gravity Exposure (BISE)
The Bodies in the Space Environment: Relative Contributions of Internal and External Cues to Self-Orientation, During and After Zero Gravity Exposure (BISE) investigation involves having subjects view a computer screen through a cylinder that blocks all other visual information. The subjects will be presented with various background images containing different up and down orientations, on top of which they’ll see a letter that could be either a "p" or a "d" depending on its orientation. Crewmembers will indicate which letter they see to determine the transition point at which they can’t recognize the letter. This BISE test will enable the researchers to measure the relative importance of visual and body cues to the subjects’ perception of "up" and measure the influence of various cues and demonstrate which ones are the most important. The scientists are also studying the process by which the brain combines multiple pieces of information about the same thing and produce the correct answer. BISE will conduct experiments during long-duration microgravity conditions on the International Space Station to better understand how humans first adapt to microgravity and then readapt to normal gravity conditions upon return to earth. BISE will also establish a relationship between different measures of orientation perception: OCHART, shape-from-shading and luminous line and whether these may be differently influenced preflight and postflight. Studies done in an aircraft that produce brief periods of microgravity suggest that, in the absence of gravity, people rely more on body cues than vision to tell them which way is up. This study will examine whether the same is true on the Space Station. Scientists noted that the Station can be "tricky" because it contains different modules that are not all in a straight line. An astronaut in one module who perceives the floor to be where their feet are may become disoriented when they float into another module. Crewmembers often go through a right angle to go between one module and another, therefore whatever corresponds to the ground in one module will not necessarily match in another module. Scientist stated that these issues may also affect astronauts during STEM Today Page 15
spacewalks. When the astronauts go outside of the spacecraft, they must adjust their orientation and use whatever visual cues they have. Laurence R. Harris and other authors published about BISE in their research paper "The effect of long-term exposure to microgravity on the perception of upright". Seven astronauts volunteered to be a part of this experiment (mean age: 49, 2 female). The astronauts had various amounts of previous experience in space (three with none, three with 11-16 days, one with 193 days, and of course represent a highly trained and rigorously selected group. Authors used a control group on earth of 14 volunteers chosen to roughly balance the age and gender distribution of the astronauts (mean age: 41, 3 females). Due to the prolonged nature of this experiment (more than a year from start to finish) three of the control group were unable to complete the schedule and were dropped from the analysis. All experiments were approved by the appropriate ethics boards.
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RESULTS For both ground-based and astronaut participants, the subjective visual vertical(SVV) and perceptual upright (PU) responses remained consistent across data collection sessions even though astronaut observers were subjected to microgravity for an average of 168 days (Figs 1 and 2). The variance of the SVV measured without visual cues while upright immediately after return to earth (BDC2) was significantly larger than before flight (BDC1) but returned to preflight levels by BDC3 (Fig. 1). Modeling individual PU responses as a weighted linear vector sum revealed a significant reduction in visual relative to body weighting between BDC1 and on first arriving in space (FLTE). This reduction was also found in BDC3, on average 130 days after return to earth (Fig. 5c).
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No change in visual effect on arrival in space The stability in the visual effect on first going into space contrasts sharply with earlier results using transient periods of microgravity created by parabolic flight in which an instant reduction in visual weighting was found. Here, authors demonstrate that astronauts adapt within the first 10 days of flight (during which time authors unfortunately did not have access to them) to their new perceptual environment such that the influence of vision in determining their perceptual upright was comparable to the visual influence they showed on earth prior to their space mission. The lack of the expected increase in visual effect for the FLTE data suggests that in space the body cue is given more weight relative to vision than it normally has on earth. It is important to note, however, that when tested in space astronauts held on to the COGNI tunnel that was attached to the ISS, which provides a tactile frame of reference. While this was the same arrangement as used in ground-based controls, it may be that tactile cues are more influential in space which may have contributed to strengthening the influence of the body cue. However this increase is achieved, it appears that astronauts adapt to a microgravity environment by adjusting the relative weights given to the visual and body cues, thus canceling the increase in visual influence on orientation that would be expected if the weights had retained their on-earth values. A tendency to rely more on the body cue for orientation has been seen in earlier microgravity experiments but has never before been quantified. In contrast to this reduced dependence on static visual cues for orientation, dynamic visual cues seem to be more effective in space, for example in evoking vection. However, these observations may be connected to misperception of static cues to distance in microgravity. Effects persist after return to earth There were no significant changes in the direction or influence of vision on the SVV following spaceflight,
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although it is possible there were changes within the first few days after return when authors did not have access to the astronauts. An unexpected finding, however, was that when the astronauts were tested many days after return (average 130 days, range 68-285 days), there was a significant reduction in the weighting placed on the visual cue relative to the body cue (v:b) in determining the PU, relative to BDC1. The reduction following spaceflight was comparable to the reduction authors observed on first going into space (Fig. 4c).
If a decline in emphasis on vision were part of adapting to microgravity, as authors postulated to explain the results found in short-duration microgravity, then authors might expect to see the reduction in the ratio of the weighting of vision relative to body to persist for some time upon return to earth. The ratio of vision to body weighting at BDC2 was unchanged relative to BDC1, but decreased over the next few months when BDC3 measurements were taken. What could have caused this long-term change and why was it not seen immediately on landing? It has been known anecdotally for some time that going into space can affect vision, especially near acuity.
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John Glenn actually kept a pair of "space anticipation glasses" onboard his capsule. Reports are emerging of visual deterioration during and following space flight although the details are still not fully understood. It is possible therefore that the reduction in weighting of the visual cue authors noticed in space is attributable to an actual deterioration of vision. Such an explanation, however, would predict an increase in variance for tasks involving vision that was not observed (upright-with-vision variances for our astronauts between BDC1, 695 Âą 363 deg2 and BDC3, 446 Âą 243 deg2 ). Also, such visual deterioration is most pronounced during microgravity exposure and seems to show STEM Today Page 19
good recovery after returning to earth (see also Chris Hadfield’s anecdotal reports (The web abounds with Chris Hadfield anecdotes, and some descriptions in his popular book "An astronaut’s guide to life on earth")). Another possibility is the phenomenon of flashbackastronauts may suddenly and unexpectedly feel that they are back in space long after they are actually safely on the ground.
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A similar phenomenon is well-documented in virtual reality users and may have been evoked in our astronauts, when they used the equipment that they were familiar with in space. While these speculations are feasible hypotheses, the data cannot specifically address them. The finding of decreased weighting of vision a few months postflight was unexpected and warrants further investigation.
SVV variance increased upon return to earth A significant increase in variance associated with the SVV in the absence of visual cues was found for upright astronauts upon return to earth (BDC2) relative to preflight (BDC1). The SVV requires participants to judge the direction of gravity explicitly, something that astronauts would not have been able to do while in space. This lack of experience may have contributed to astronauts’ difficulty in judging the SVV shortly after returning to earth. Lack of precision in judging the direction of gravity may be related to postural and gait instabilities associated with return from spaceflight. The effect of previous space experience As a group, our seven astronauts had relatively little experience in space prior to their participation in our study. Although four out of the seven had been to space before, only one had prolonged space experience (astronaut E, 193 days). Astronaut E also had the lowest visual weighting (11%) out of our astronaut population prior to launch (BDC1), which was maintained through till our final testing long after returning to earth (BDC3) (Fig. 4a). Of course authors are unable to say if this single astronaut’s low visual weighting was caused by previous space experience, but the observation is compatible with the idea that a reduced weight given to vision could be a permanent consequence of space travel as has been proposed after short-duration spaceflight, parabolic flight and during in-flight centrifugation. The effect of age Our astronauts’ ages spanned from 41 to 56 years at time-of launch. Previous studies have suggested that there might be an effect of age on the ability to use gravity in the perception of orientation and certainly on susceptibility to visual reorientation illusions suggesting progressively less reliance on gravity as one gets older. Although ours was a small population, Fig. 7 plots the reduction in visual weighting between BDC1 and BDC2, and BDC1 and BDC3 as a function of age. There was a correlation in which the younger astronauts tended to have a larger reduction in visual weighting associated with exposure to space. This could imply that younger astronauts are more flexible in adjusting to novel environments, or that they are more vulnerable to visual degradation in space. Astronauts and ground control participants Astronauts are specially chosen and meticulously trained individuals. It might then be supposed that astronaut performance on ground tasks- especially during BDC1-would be superior to the naïve ground control group. As a consequence, one might have expected that BDC1 variances for astronauts would be significantly less than those reported for ground control participants. Such an effect was not found here, and a Mann Whitney U test indicated that there was also no significant difference between the baseline visual effects in the two groups (U = 23, p > 0.5). It would seem that having ’The Right Stuff’ does not necessarily include being more precise in terms of estimating the direction of up.
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Decrements in Locomotion
Most crewmembers experience some degree of locomotor dysfunction when they return to Earth after space flight. Some of these post-flight alterations are ataxia with the sensation of turning while attempting to walk a straight path; sudden loss of postural stability when rounding corners or after unexpected perturbations; and sudden loss of orientation in unstructured visual environments. In addition, some astronauts report oscillopsia (illusory movement of the visual field) while walking. Foot contact with the ground, the transfer of weight from one foot to the other, and the pushoff with the toe from the ground are critical phases, as these interactions with the support surface result in forces that create vibrations, which if unattenuated could interfere with the visual-vestibular sensory systems in the head.
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The musculoskeletal system controls these vibrations; muscles and joints act as filters to minimize the perturbing effects of impacts with the ground and help to maintain a stable trajectory at the head. During treadmill walking after returning from long-duration space flight, astronauts’ knee flexion during the stance phase signifË? 10 days. An increase in knee flexion during locomotion icantly increased, but it returned to normal within 6U will result in reduction of the axial stiffness of the lower-limb complex during the critical stance phase following heel strike, leading to reduced perturbations being transmitted to the head during locomotion. Distinct post-flight performance decrements in gait have been observed in cosmonauts returning from Soyuz missions lasting 2 to 63 days. In most cases, the duration of post-flight effects correlated with the duration of the mission. Post-flight changes in locomotion included increased angular amplitude of motion at the knee and ankle, and increased vertical accelerations of the center of mass. Post-flight locomotor control and segmental coordination show alterations in muscle activation. The temporal relationship and relative amplitude of muscle activation are modified by space flight, particularly for the events of heel-strike and toe-off that are complementary to evidence of changes in kinematics during locomotion at these events of the gait cycle. The loss of neuromuscular coordination may cause difficulty in achieving optimal transitions between muscles while walking. This loss in coordination between muscles may also affect the ability to maintain stable head movement and are complimentary to evidence seen in alterations in head-trunk coordination during walking; reduced visual acuity during walking and impairment in the ability to coordinate effective landing strategies during jump tasks. Other neurophysiological changes including proprioceptive hyper-reactivity, such as increased Hoffman reflex amplitudes; reduced ability to perform graded muscle contractions; and decreased muscle stiffness may also have a contributory influence on muscle coordination during locomotion activity. Activation of ankle-joint muscles post-flight has been heavily investigated. The space flight-related adaptive modifications in neural processing of vestibular input could negatively influence activation of lower limbs. This change, in combination with altered strength between ankle plantar flexors and dorsiflexors , can cause difficulty in walking. Changes in ankle musculature activation are suggested to result in reinterpretation of proprioceptive input. Ankle proprioception is no longer interpreted as coding anterior-posterior body sway while upright, but instead codes either whole body axial transportation (i.e., pushing off the support surface) or foot movement exclusively. In addition, the extent of reinterpretation correlates with duration of mission. Despite being appropriate for weightlessness, these changes are maladaptive on return to Earth and may contribute to post-flight decrements in locomotion.
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