TORPOR HABITAT CONCEPT
FOR HUMAN STASIS TO MARS
SpaceWorks Enterprises, Inc. (SEI) proposes an advanced habitat system for transporting crews between the Earth and deep space destinations. During the in-space mission segments or travel, their innovative habitat design will be capable of cycling them through inactive, non-cryonic torpor sleep states. This is the Therapeutic Hypothermia (TH), a concept that reduce metabolic rates of humans over extended periods of time.
The torpor habitat consists mostly of sleep chambers, or pods. Here, shortly after departure from Earth or after leaving their destination for the return, crewmembers enter into for stasis.
Initiated during transit phases, this approach could solve a myriad of medical and engineering challenges associated with long human spaceflight missions. Cycling the crew in and out of the torpor state further reduces the burden on fully autonomous systems, and ensures crew cognitive abilities are maintained.
Sleep disruption, monotony and boredom are the most frequent complaints of individuals in an integrated collaboration environment such as space flight. With requirements for high degrees of alertness and penalties for errors seen as especially stressful.Today, these conditions are not a big medical emergencies and are adequately treated by taking medications carried on board. Routinely, astronauts take medication against these conditions such as motion sickness, headache, sleeplessness, and back pain.
The current approach envisions the use of a combination of passive cooling systems, minimal dosage suppressive drugs, and an adenosine A1AR agonist pharmaceutical, to initiate and sustain the torpor state. This process allows the crew metabolic rates to be reduced relative to the standard basal metabolic rate (BMR). It results of that a reducing demand of oxygen and nutrient requirements. The body’s core temperature need only to be reduced to 89o at 93oF to enable this process. In stasis, body hydration and nutritional needs are then provided enterally via all-liquid solutions.
The baseline crew operations approach is referred to as a “sentry protocol”. This protocol puts each crew member in a rotation sequence of being active for a brief period of a few days followed by a 10-14 days of an inactive, torpor phase.
Example, for four crewmembers, three would be placed in a torpor state with the assistance of the fourth one. Through the cycle, alternating crew members would be woken at about every 14-days by the current sentinel crew. After 2-3-day period of non torpor activity, the first crew is assisted in its two-week torpor phase with the help of the second.
The sentinel protocol allows for one member of the mission crew to be fully awake and active at all times. The process gives preventive and corrective maintenance of equipment and, daily communication with mission control during the outbound and return phases of the mission.
Another benefit is that the fourth one provides an onboard assistant to the medical team. Then, it assists with the monitoring and wakening of the other crew members thereby minimizing some of the dependency on automation systems.
For the transit habitat design, based on the standard used by NASA, only systems and supporting subsystems directly impacted by the torpor concept were changed.
Then, the majority of the standard dehydrated space food is replaced with liquid enteral nutrition formula. In add, two weeks of solid food stores for each period of transition into and out of torpor operations, or eight weeks’ worth in total, is provided.
The replacement of solid food with liquid nutrition formula yields significant reduction in total food mass. The quantity of housekeeping and other habitat consumables is also reduced because the reduced crew activity on habitat outfitting requirements.
Because the crew spends the majority of the transit phase in torpor, the scientific payloads and payload provisions were removed. The on-duty crewmembers will spend the majority of their time tending to those crewmembers in torpor and maintaining spacecraft operations. Payload storage is still available for sample return to Earth.
SpaceWorks Torpor-Enabled Habitat Designs
A new habitat layout was conceived to take full advantage of the reduced consumables and supplies volumes. It was decided that, because only one crewmember is active for the majority of the mission, the habitable volume per crewmember can be reduced below 25 m3. This allowed for a significant reduction in overall habitat size. Subsystems, equipment, and accommodations were repackaged into the smaller volume. This allowed the pressure vessel, structures, and MMOD protection masses to be reduced based on the smaller habitat geometry.
The reduced habitable volume can also be propagated into the sizing of the ECLSS systems. With smaller ECLSS systems, the power requirements of the habitat are also reduced, thus reducing the mass of the power distribution and thermal management systems.
SpaceWorks Torpor-Enabled Habitat Mass Breakdown Statement
The SpaceWorks torpor-enabled habitat geometry is shown in the Figures belows. Similar to the EMC Reference design, the habitat is divided into two levels. The lower level serves as the crew living area and workspace. The upper level houses consumables and spares, as well as crew torpor modules. Life support subsystems are housed in the deck
beneath the lower level.
The lower level is divided into five areas as shown in Figure 20. The top area contains storage for medical supplies and habitat cleaning supplies. The upper left area is the command station with interfaces and displays for the onboard computer systems. The upper right area contains crew exercise equipment and medical equipment. The lower left area contains the shower and hygiene station. The lower right area contains the toilet and storage for crew hygiene supplies.
The bottom area is the galley, which includes food rehydration and warming stations, and a foldable table and chairs for mealtimes.
SpaceWorks Torpor Habitat Concept Views (4 Crew)
SpaceWorks Torpor Habitat Concept Lower Level Design (4 Crew)
The upper level, as shown in Figure 21, has four torpor modules containing all of the torpor support subsystems, one for each crewmember. The torpor modules are surrounded on all sides by ISS-style cargo transfer bags (CTBs) containing all of the life support system consumables: 60 days of food and 1100 days of enteral nutrition; 30 days of emergency water, oxygen, and lithium hydroxide canisters; and contingency oxygen and nitrogen to re-pressurize the cabin in case of depressurization. Equipment spares are also carried in CTBs.
The radiation protection provided by the consumables allows this area to also serve as a storm shelter during SPEs.
Crew total GCR exposure is significantly reduced because the crew spends the majority of the mission in torpor withinthis protected area.
SpaceWorks Torpor Habitat Concept Upper Level Design (4 Crew)
The two levels are connected by a central hatch. Three of the four docking hatches are located in the lower level alongthe walls. The fourth docking hatch is location in the upper level in the center of the ceiling.
Mupirocin 2% ointment: Mupirocin is an antibiotic that prevents bacteria from growing on your skin. Mupirocin topical (for use on the skin) is used to treat skin infections such as impetigo (IM-pe-TYE-go) or a "Staph" infection of the skin.
chlorhexidine gluconate (CHG) alcohol wipes: Indicated for skin antisepsis prior to invasive procedures, this product helps reduce bacteria on skin to diminish the risk of surgical site infection.
SPACE LAUNCH SYSTEM (SLS)
The habitat is designed to fit within the 8.4 meter diameter shroud for Space Launch System (SLS) which corresponds to a 7.5 meter diameter usable envelope that limits the habitat diameter to less than 7.5 meters when stowed. This diameter maintains flexibility to use the 8.4 or 10 meter diameter SLS shrouds.
The habitat length limit is set by the 8.4 meter diameter shroud usable envelope when co-manifested with a hybrid propulsive stage (HPS) for LDRO insertion. The transit habitat is launched with the HPS, with the habitat on the top of the propulsion stage. These launch vehicles are packaged with adaptors such that neither payload carries the loads of the other.
The habitat structure is sized to provide sufficient load bearing interfaces for integration with propulsion stages or other elements above or below the habitat in the launch-vehicle stack.
HOW THE TORPOR WORK?
It is divided into five stages: Pre-Flight, Preparation, Initiation, Maintenance, and Reversal. The current protocol utilizes adenosine receptor agonist compounds with minimal sedation combined with ambient air cooling. Long-term IV access would be provided through a preplaced Port catheter. Nutrition would be provided through enteral feeding via a preplaced PEG tube during torpor cycles, with an option for normal oral hydration and nutrition while active. Waste collection during torpor would be accomplished through Foley catheter and fecal waste collection systems.
FIRST STAGE: PRE-FLIGHT
The first Stage is the Pre-Flight that begin approximately six (6) months before the crew mission is launched. During this time, crew members makes some training on the catheterization of the bladder, application and removal of fecal collection systems and competency in venous access. This latter includes the access and maintenance of the Porta Cath®.
Port-A-Cath® Device for Central Vein Access (Credit: PM Solutions)
Port catheters are small medical appliances that are surgically installed beneath the skin, usually in the upper chest just below the clavicle or collar bone. A catheter then connects the port to an underlying vein. Sitting directly under the skin, the port provides direct venous access via a septum through which medications and IV fluids can be administered and blood samples can be drawn.
Once in place, these devices require no special maintenance or care, and usually do not limit any physical activities, including weightlifting and swimming. Ports can remain in place as long as required.
A Percutaneous Endoscopic Gastrostomy (PEG) tube will also be surgical placed via a combined laparoscopic and endoscopic approach. This will allow adequate time for surgical recovery and to identify postsurgical complications.
A Percutaneous Endoscopic Gastrostomy (PEG) is a tube inserted through a small incision in the abdomen and into the stomach and is intended for long-term enteral nutrition (with a median use of 6 months, but with well documented extended use for over 4 years)
The training is also about the inspection, the maintenance, and the use of the PEG tube and alternate nasogastric (NG)/orogastric (OG) tubes. Through this, they learn the basic interpretation of altered vital signs such as the level of consciousness, the heart rate, the blood pressure, the respiratory rate and the urine output. As a big concern for the habitat, the end-tidal carbon dioxide output must be learned to assist the medical staff evaluation of torpor induced crew members.
Core body temperature is measured either directly via the esophagus, bladder, rectum, tunneled catheter, or wirelessly via an ingestible capsule to monitor cooling rates and steady state cooling levels.
Finally, the crew must familiarize with the operation and maintenance of basic life support monitoring systems. These latter systems include the EKG pulse oximeter, the automatic blood pressure device and the end-tidal carbon dioxide capnography. Important concern will be do to the torpor specific systems, such as the gas delivery and the nutritional support.
PEG Tube for Delivery of Liquid Nutrition and Hydration Fluids (Credit: Cancer Research UK)
Exposure to Torpor Cycles
To allow the crew to experience and prepare for the physical and psychological effects associated with the torpor initiation and waking process, they will undergo short duration cycles of torpor of 24 to 48 hour. With this implication, medical team will identify which one is the best to tolerate the temperature and pharmacological aspects of torpor. In the same goal, they can also assist the medical team in torpor initiation and recovery steps, increasing their knowledge and application of induction protocols.
Establish Permanent IV and Nutritional Access
Approximately 12 weeks prior to the flight, a central venous catheter, 9 Fr single lumen silicone catheter with Titanium portal (Porta Cath®) will be inserted in the left subclavian vein for right-handed subjects and in the right subclavian vein for left-handed subjects. (Showing above)
SECOND STAGE: CREW PREPARATION
Beginning approximately one (1) week before torpor induction (likely post-Earth departure), we proceed to the skin preparation of crew members. They will apply Mupirocin 2% ointment to each nostril twice a day until the induction of torpor.
Three days prior to induction, the skin will be cleaned with chlorhexidine gluconate (CHG) alcohol wipes, twice a day, paying attention to axillae, groin, and rectal regions.
Most nosocomial infections in prolonged bedridden patients are from the patients’ own endogenous flora found in the skin, mucus membrane, respiratory tract, and gastrointestinal tract.
Reducing the surface bacterial flora appears to mitigate the risk of local and post-site skin infection. Once torpor cycling has been initiated, this procedure will be repeated daily during any active, non-torpor periods for the crew members until the last torpor cycle.
Bowel Preparation with enteral feeding through PEG or NG/OG tube
Two days prior to torpor crew members will start a clear liquid diet. Twelve hours prior to torpor they should take two bisacodyl tablets (common stool softener) and they will continue to consume oral liquids until two hours prior to the induction of torpor.
As bowel movements, passage of flatus, and defecation are decreased under moderate sedation and hypothermia, this will transition waste to a more mobile form that is more conducive to the proposed waste collection systems.
Perform Systems Test on Torpor Induction Systems
One day prior to torpor induction the crew, in conjunction with mission control support teams, shall perform operational tests on all torpor-based electronics and mechanical equipment systems.
Test Access to Port-a-Cath and PEG Tube
Prior to induction of torpor, the crew shall access the Porta Cath and initiate maintenance infusion of Lactated Ringers 40 ml/hr. The PEG tube line will be flushed with 100-200 ml of sterile water or saline to ensure patency.
A catheter is a flexible tube placed in your bladder. An "indwelling" catheter stays in your bladder all day and night. There are two types of indwelling catheters. Indwelling "Foley" catheters are placed in your urethra. Indwelling "suprapubic" catheters go above your pubic bone through a small surgical cut in the belly. With both types, a balloon holds the tube in your bladder. They both also drain urine into a bag outside the body. Credit: urologyhealth
STAGE 3: INITIATION TO TORPOR HABITAT
Crew members will maximize skin exposure to facilitate heat transfer from the body. If glabrous skin surface cooling is utilized, then hand and feet heat-exchange garments will be donned. If heat exchange through ambient cooling is utilized, then crew torpor habitat cooling will be commenced at this time and cabin temperature reduced to <10 degrees Celsius.
Place Foley Catheter, Fecal Collection system, and OG/NG Tube
At this time, fecal collection system placement is required if enteral feeding is selected, and OG/NG tube placement would be required if a PEG tube is not utilized.
Urination continues whether TPN or enteral feeding is utilized. Foley collection systems therefore must be placed as the drainage of the bladder is necessary to maintain renal function and measure the adequacy of tissue perfusion. The bladder temperature obtained through Foley catheter will also provide a measure of core body temperature.
Cooling catheters are closed loop intravenous lines that are inserted into the femoral or subclavian vein. Cooled saline solution is then circulated through the closed loop portion (commonly composed of either a metal coated tube or balloon) which uses convection cooling to lower the temperature of a patient’s blood. This method is both safe and effective, and allows for the tightest level of control over steady state temperature as well as cooling and rewarming rates.
During torpor cycles, a enteral feeding via a temporary nasogastric (NG)/orogastric feeding line or Percutaneous Endoscopic Gastrostomy (PEG) tube will be used. The nutritional solutions is consisted of water and all the necessary nutriments, microelements and electrolytes for healthy physiologic function, such about 0.5 to 2 kcal/ml. The preparations have storage capabilities of at least 2 years for unopened containers at room temperature.
SpaceWorks supports the use of enteral feeding via NG/OG tube or PEG tube during torpor cycles, with a PEG tube as the baseline approach.
The total caloric needs for crewmembers in Torpor will be approximately 25-35 kcal/kg/day, with a protein component of 1.2 – 2.0 gm/kg/day. No more than 20% of the calories will come from lipid emulsions, with fish oil fat emulsion like Omegaven® instead of egg-based formulas utilized as they help prevent/reverse liver disease and cholestasis. Micronutrients will be adjusted as needed based on the type of solution utilized.
For urine collection, the most common indwelling bladder catheter is the Foley catheter, a flexible tube which a clinician passes through the urethra and into the bladder to drain urine. The catheter is secured in place with a balloon that s inflated with sterile water once inside the bladder.
While most catheters are intended for short-term use (1-7 days), newer catheters created from PTFE, hydrogel or a silicon elastomer make catheters suitable for 28 days to three months indwelling duration. As with enteral feeding tubes, Foley catheters are easy to insert, remove and maintain, with even children easily able to master the process with simple training.
Complications associated with prolonged catheter use include equipment failure and malfunction, irritation to the urethra, and bladder infection. However, the implementation of multifaceted intervention plans (i.e. sterile insertion, prophylactic antibiotics, and advanced materials) has reduced the risk of infection by 3-fold.
There are multiple fecal collectors available, the newest of which are external collection systems that consist of a self-adhering skin barrier and attached pouch. These fecal collectors are a closed system and the pouch is entirely external and non-invasive, meaning patients using fecal collectors do not encounter the same risks to the internal anal sphincter and rectal mucosa that can accompany internal devices that pass through the anal sphincter and dwell in the rectum. Fecal collectors are also classified as Class I medical devices (considered as presenting minimal potential for harm). In addition, with training a well positioned and adhered fecal collector can provide up to 30 days of extended wear.
Possible complications associated with use include skin irritation caused by the adhesives on skin, leakage, and blockage. Overall, fecal collectors are a user-friendly, cost-effective, efficient tool to contain solid waste for extended periods of time.
Induce Moderate Sedation
Moderate sedation will be induced and maintained for the duration of the torpor using a balanced anesthetic technique. Then, a combination of intravenous medication is used to achieve hypnosis, analgesia, and depression of the nervous system. With this medication, we suppress the shivering response and help the crew tolerate the cooling process until core body temperature is reduced past the “shivering threshold”, approximately 35 °C/ 95 °F.
The Dexmedetomidine is the current preferred sedation medication because it provide analgesia, amnesia, and abolish spontaneous movements. In the same time, crewmembers should be able to maintain a patent airway, adequate minute ventilation, and satisfactory hemodynamic parameters.
Specifically, the Dexmedetomidine is an alpha 2 adrenergic receptor agonist, even ten times more selective than clonidine. It is a very versatile drug in anaesthesia practice, finding place in increasing number of clinical scenarios and is no more limited to intensive care unit (ICU) sedation. It is analgesic, has anaesthetic sparing effect, sympatholytic property, useful in other procedural sedation and also has cardiovascular stabilizing property. It reduces delirium and preserves respiratory function which adds benefits to its uses. Source: US National Library of Medicine National Institutes of Health
To set the core body temperature to the torpor target levels, we uses a combination of CHA and 8-SPT. This latter maintain the cardiovascular system at a level that is in safe physiologic ranges.
The synthetic adenosine receptor agonist used by Dr. Kelly Drew, N6- Cyclohexyl Adenosine (called CHA), is a pharmacological agent that has shown the ability to spontaneously initiate a torpor state with the associated decrease in metabolic rate in rats. Drew’s research team has also been conducting experiments on another chemical compound, 8 – Sulphophenyl Theophylline (called 8-SPT). 8-SPT acts as A1AR Adenosine Receptor Antagonist, which means that it is a counter to the CHA discussed above.
CHA and 8-SPT torpor induction would be initiated through IV infusion through the Port-a-Cath per research study verified weight-based calculations. Current estimates are 4.2 mg bolus with a 0.1 mg/kg/h maintenance infusion rate for CHA, with 8-SPT administered per research study verified weight-based calculations as needed to maintain normal blood pressure.
This medication has been used by her research team to counteract episodes of bradycardia (or a lowered heart rate), and hypotension (or low blood pressure) which can accompany induced hypothermia in rat studies.
As visualized on this chart, there is a significant effect on both heart rate and blood pressure of the test subjects when CHA is initially administered. However, a single dose of 8-SPT (time denoted as ‘S’) restored cardiovascular levels to normal without countering the CHA cooling process. This is because 8-SPT does not cross the blood-brain barrier, meaning it does not affect the brain or the hypothalamus, which is the thermoregulatory center for the body.
The level of sedation should be such that the crew will not respond to verbal commands but should respond to noxious stimuli.
The need for sedation would be reduced and may potentially be avoided with CHA torpor induction as CHA not only resets thermogenesis threshold but also suppresses the shivering response.
Induction of Hypothermia
Ambient cooling of the torpor habitat would be continued, resulting in hypothermia through direct conduction and convection from the skin to the surrounding air. Alternately, cooling could be limited to glabrous skin surfaces (namely the hands and feet). Core temperature would be regulated by either further cooling the ambient environment, or through active warming by convection air or through a heating pad or blanket.
Again, as 0.5 degrees Celsius is the well-established rewarming rate, the SpaceWorks Torpor protocol would utilize the same guidelines for normal torpor cycles. However, by employing the higher 1.5-degree Celsius rewarming rate crewmembers could be recalled from the torpor state rapidly and be available to provide assistance to the sentinel crew member during emergency situations.
STAGE 4: TORPOR MAINTENANCE
Continuous vital signs evaluation would be performed using current NASA approved monitoring systems.
The collection and processing of laboratory testing to evaluate system electrolytes, basic body chemistry, red and white blood cell levels, and the presence and identification of any systemic body infection can be conducted by programmable automated systems or by sentinel crew member.
Laboratory testing, including urinalysis from Foley catheter samples, would be conducted at scheduled intervals and as per crew member vital signs or physical symptoms dictate.
Enteral feeding via temporary NG/OG feeding line or PEG tube would be initiated through gravity drainage or lower pressure pump assistance. Prepared solutions consisting of water and all the necessary nutrients, microelements and electrolytes necessary for healthy physiologic function would be administered in a single feeding of 2 kcal/ml nutrient solution.
To minimize the risk of infections, broad spectrum antibiotics (Ciprofloxacin at ~400 mg every 12 hours) will be started and continued for the duration of hypothermic torpor. Broad spectrum antibiotic ointment should be instilled in both eyes, with lids closed. The inside of the mouth and gum lines should be periodically swiped with chlorhexidine gel swabs.
Porta Cath access should also be inspected and cleaned with Betadine swabs. Both urethral orifice and catheter surfaces should be inspected for signs of infection or biofilm formation. If necessary, the Foley catheter should be replaced with a sterile new catheter.
Systemic intravenous anticoagulation will be started and continued for the duration of the hypothermic torpor. Periodic Heparin line flushes with Lepirudin or Rivaroxaban (once daily through enteral feeding tube) are the preferred medications for preventing blood clot formation. Mechanical pulsatile compression devices will also be utilized as well as automated pressure point modification systems.
Each crew member in torpor should be monitored daily for signs of infection, development of deep venous thrombosis, or formation of pressure ulcers. Exams should be performed in a systematic fashion from head to toe, looking for injury or infection of any kind.
Routine care such as changing the position of crewmembers, dental care, monitoring and cleaning of IV and nutritional access sites, Foley catheter and fecal collection system inspection and replacement, and auscultation of heart and lungs will also be performed.Many of these activities can occur via automated systems with robotic manipulators.
Periodic crew member inspections will be video recorded and sent to mission control based medical teams for further review and care recommendations.
STAGE 5: TORPOR REVERSAL
The ambient temperature in the hibernation pod will be increased, allowing passive rewarming to occur until core temperature has reached 36°C, at which point the infusion of CHA will be stopped. Once the core body temperature has reached 36°C, the infusion of sedatives will be stopped and the crewmember will be allowed to gradually wake up.
Monitoring should be maintained until all physiological functions have returned to normal levels. If necessary, serum chemistry, including glucose, acid-base, and electrolytes should be check prior to discontinuing the EKG. Once torpor has been reversed antibiotics can be stopped. And, finally, the anticoagulation should be stopped after the crewmember has resumed spontaneous and voluntary movements in the limbs.
Crewmembers may start on an oral liquid diet and then advance gradually to a normal solid diet. Once oral nutrient intake is adequate the temporary NG/OG tube can be removed and they will gradually increase physical and mental activities.
Minor muscle weakness, joint stiffness, and clouding of consciousness may need to be reversed through increased physical and mental activities immediately after wakening. Structured exercises to increase muscle strength and tone, such as those already instituted on current NASA missions, should be continued. Range of motion exercises may need to be added to existing exercise regimes.
Complete elimination of sedatives and other pharmaceutical agents from the body will occur naturally shortly after waking, allowing for the return of normal wellbeing.
Advanced Habitat Designs
The crew habitat is designed to support 4 crew-members during the transit phases of missions to Mars and/or the Martian moons of Phobos and Deimos. The habitat is sized for 1100 days of crewed duration during the mission, plus additional uncrewed time at a lunar Distant Retrograde Orbit (LDRO) for outfitting and checkout. The transit habitat will be reused over several missions and is assumed to last for 15 years.
Life Support Systems
The Environmental Control and Life Support System (ECLSS) for the habitat is its most important subsystem. To minimize risk associated with its development, existing and near-term technologies used on the ISS has been selected in this system. The ECLSS uses a Water Processing System (WPS) to recycle water, and the Atmosphere Revitalization System (ARS) and Oxygen Generation System (OGS) to recycle oxygen.
In the WPS, water is collected from the atmospheric humidity that uses the Temperature and Humidity Control (THC) subsystem. Also, it collect from passenger urine in the Urine Processor Assembly. To do so, a vacuum distillation process is used to recover water from urine. All water collected is sent to a Water Processor for treatment.
Impact on NASA’s Human Research Program (HRP)
In order to consider the full potential impact of torpor towards supporting future human spaceflight, the medical team reviewed all of the NASA Human Research Program (HRP) Identified Spaceflight Risks.
Each team member independently considered each risk and provided a score on its potential to positively or negatively impact each risk.
This overall results from the research team indicated that torpor could positively benefit at least 11 different HRP spaceflight risks.
- Spaceflight-Induced Intracranial Hypertension/Vision Alterations
- Inadequate Nutrition
- Adverse Cognitive or Behavioral Conditions and Psychiatric Disorders
- Performance and Behavioral Health Decrements Due to Inadequate Cooperation, Coordination, Communication, and Psychosocial Adaptation within a Team
- Performance Decrements and Adverse Health Outcomes Resulting from Sleep Loss, Circadian Desynchronization, and Work Overload
- Acute (In-flight) and Late Central Nervous System Effects from Radiation Exposure
- Impaired Control of Spacecraft/Associated Systems and Decreased Mobility Due to Vestibular/Sensorimotor Alterations Associated with Spaceflight
- Acute Radiation Syndromes Due to Solar Particle Events (SPEs)
- Cardiovascular Disease and Other Degenerative Tissue Effects from Radiation Exposure
- Performance Decrement and Crew Illness Due to an Inadequate Food System
- Impaired Performan?ce Due to Reduced Muscle Mass, Strength & Endurance
Sleep disruption, monotony and boredom are the most frequent complaints of individuals in an integrated collaboration environment such as space flight. These effetcs come from the monotonous of work with requirements for high degrees of alertness and penalties for errors seen as especially stressful.
The majority of these conditions are not big medical emergencies and could be adequately treated by taking medications carried on board. This is the reason why, astronauts take routinnely medication during missions to fight againts motion sickness, headache, sleeplessness, and back pain.
Studies on medication usage rates showed that 45% of all medications used by Space Shuttle crew members were sleep aids, and that 71% of all astronauts onboard the ISS have reported using sleep aids at least once during a mission.
Use of sleep onset medications not only affects the level of wakefulness and alertness of the crew members but can also have long-term medical complications including liver damage and withdrawal affects.
Prolonged sleep cycles of seven days and beyond could significantly reduce the use of sleep onset medication and eliminate astronaut work overload.
The crew would spend a majority of the transit time during deep space missions in a torpor state. This will mitigate most of the emotional and psychological stress associated with crew interactions, isolation, lack of sleep and the physical discomforts of space travel.
The result would be reduced incidences of depression, anxiety, sleep disruption and interpersonal conflicts during the portion of the mission where the crew has minimal mission tasks that engage their attention and promote teamwork.
NASA Reference EMC Habitat Design
For a crew of four, the habitat provides 25 m3 of habitable volume per person.
The habitat is divided into two levels. The lower level serves as the crew living area and workspace. The upper level houses consumables and spares, as well as crew sleeping quarters. Life support subsystems are housed in the deck beneath the lower level.
The habitat internal atmosphere is a 101.3 kPa (14.7 psia), with 21% O2 nominal atmosphere. The habitat contains afully closed-loop water recycling and oxygen generation life support systems, with a 30-day open-loop consumable backup for water, oxygen generation, and carbon dioxide removal. The habitat also carries logistics, spares, andmaintenance for the full crew during the entire 1100-day mission duration
The habitat provides 3 docking mechanisms with hatches, which is driven by aggregation operations requiring simultaneous docking with the Gateway habitat, logistics delivery modules, and Orion crew vehicle.
NASA EMC Reference Habitat Lower Level (left) and Upper Level (right) Overhead Views
The lower level is divided into four quadrants as shown in the above Figure . The upper left quadrant contains crew exercise equipment, medical equipment, and storage for medical supplies. The upper right quadrant contains the toilet, shower, and storage for crew hygiene supplies.
The lower right quadrant is the galley, which includes food rehydration and warming stations, a foldable table and chairs for mealtimes, and storage for habitat cleaning supplies. The lower left quadrant is the command station with interfaces and displays for the onboard computer systems.
The upper level has four private crew quarters for sleeping and relaxation, one for each crewmember. The sleeping quarters are surrounded on all sides by ISS-style cargo transfer bags (CTBs) containing all of the life support system consumables: 1100 days of food; 30 days of emergency water, oxygen, and lithium hydroxide canisters; and contingency oxygen and nitrogen to re-pressurize the cabin in case of depressurization. Equipment spares are also carried in CTBs.
The radiation protection provided by the consumables allows the crew quarters to also serve as a storm shelter during SPEs. Crew total GCR exposure is also reduced because the crew spends 7-8 hours a day resting in the protected sleeping quarters.
The two levels are connected by a central hatch. Three of the four docking hatches are located in the lower level along the walls. The fourth docking hatch is location in the upper level in the center of the ceiling.