. Torpor Habitat Concept
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SpaceX/Dragon Arrives at the Space Station
On July 20, two days after its launch from the Complex 40 at Cape Canaveral - Air Force Station (CCAFS) in Florida, the SpaceX Dragon cargo spacecraft arrived at the ISS, carrying science research, crew supplies and hardware in support to the station’s Expedition 48 and 49 crews. Credit: NASA
NASA EMC Habitat Concept Using Torpor
The motivation for this design effort was to characterize the impact of implementing torpor into an existing transit habitat design. In the creation of this habitat design, only those systems directly impacted by the inclusion of the torpor concept of operations and supporting subsystems were changed.
In this concept, the majority of the standard dehydrated space food is replaced with liquid enteral nutrition formula.
The crew is also provided with two weeks of solid (normal) food stores for each period of transition into and out of torpor operations, or eight weeks’ worth in total. The replacement of solid food with liquid nutrition formula yields significant reduction in total food mass because of the mass-efficiency of the formula relative to solid food. The quantity of housekeeping and other habitat consumables was also reduced to capture the impact of 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
The motivation for this design was to fully characterize the impact of implementing torpor in a new habitat design, primarily by taking advantage of the reduced consumables and supplies storage volume, and to reduce the quantity of equipment spares required based on lower ECLSS demands during torpor period.
As with the previous concept, the majority of the standard dehydrated space food is replaced with dehydrated enteral nutrition formula. The crew is provided with two weeks of solid food for each period of transition into and out of torpor operations, or eight weeks’ worth in total. As before, the replacement of solid food with nutrition formula yields significant reduction in total food mass because of the mass-efficiency of the formula relative to solid food. Comparedto the reference habitat, the quantity of housekeeping and other habitat consumables was also reduced to capture the
impact of reduced crew activity on habitat outfitting requirements. This reduced food and consumables mass translatesto reduced consumables volume.
Similarly, because the crew spends the majority of the transit phase in torpor, the scientific payloads and payload provisions are not included. 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 Mass Breakdown Statement
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.
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.
Advancing Torpor Inducing Transfer Habitats for Human Stasis to Mars
SpaceWorks Enterprises, Inc. (SEI) proposes the development of an advanced habitat system for transporting crews between the Earth and deep space destinations. This new and innovative habitat design is capable of cycling the crew through inactive, noncryonic torpor sleep states for the duration of the in-space mission segments.
Recent medical advancements in Therapeutic Hypothermia (TH) have demonstrated our ability to induce deep sleep states (i.e. torpor) with significantly reduced metabolic rates for humans over extended periods of time with moderate reductions in core body temperature.
The innovative adaptation of TH to spaceflight is an opportunity to realize a game changing technology.
Cycling the crew in and out of the torpor state further reduces the burden on fully autonomous systems, ensures crew cognitive abilities are maintained, and enables use by NASA on early Mars missions. Over time, it is reasonable to assume this capability can be further extended to periods of months to offer additional benefits.
Advanced Habitat Designs
The crew habitat is designed to support a complement of 4 during the transit phases of missions to Mars and/or theMartian moons of Phobos and Deimos. The habitat is sized for 1100 days of crewed duration during the Mars 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. Where possible, existing and near-term technologies used on the ISS were selected in the design of this system to minimize risk associated with development. The ECLSS for the torpor habitat 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 (driven by passenger breathing and sweat) using the Temperature and Humidity Control (THC) subsystem and collected from passenger urine in the Urine Processor Assembly; a vacuum distillation process is used to recover water from urine. All water collected is sent to a Water Processor for treatment.
In the ARS, the first step of the oxygen recovery process is to remove the carbon dioxide from the cabin atmosphere using a Carbon Dioxide Removal Assembly (CDRA). The ARS also includes a Trace Contaminant Control Subsystem (TCCS) to filter particulates and remove volatile organic trace gases from the air.
Once collected the carbon dioxide is passed OPS, specifically to the Carbon Dioxide Reduction Assembly (CReA) for processing. The CReA uses a Sabatier reaction to convert carbon dioxide and hydrogen into methane and water. The water is sent on to the final step of this process, the Oxygen Generation Assembly (OGA). The OGA uses electrolysis to break the water into hydrogen and oxygen gas. The oxygen is fed back into the cabin atmosphere, while the hydrogen is sent back into the CReA to support the Sabatier reaction.
The additional hydrogen required to maintain the CReA is recovered from its methane exhaust. Excess oxygen in the system, introduced from the food solids and recovered via the OGA, is reacted with the methane exhaust to produce carbon dioxide and water. The water is sent to the OGA for electrolysis, while the carbon dioxide and remaining methane are vented from the habitat. A small amount of hydrogen gas is included in the system outfitting to initiate this process.
For torpor-enabled habitats, the required crew support systems and body interfaces are identified in the Figure below. When thetorpor is utilized, the maximum duration is nominally 14 days. The crew schedule, generated by the Bio-Simulator tool, is set such that there is always at least one active crew member. This yields active periods between cycles of 2-3 days, depending on the total number of crew members
Torpor Pod and Crew System Implementation
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. A factor of safety of 2.0 on ultimate loads was selected to comply with JSC 65828 "Structural Design Requirements and Factors of Safety for Spaceflight Hardware".
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.
Micrometeoroid Orbital Debris (MMOD) protection is sized to be sufficient for the 15-year lifetime in a deep space
environment. The transit habitat does not carry dedicated GCR and SPE protection beyond that provided by the habitat structure, internal subsystems, and consumables. Internal layout of consumables is therefore driven by the desire to maximize passive GCR and SPE protection.
The habitat does not contain any power generation systems. Instead, it receives power generation located on the propulsive element(s) of the combined transfer vehicle stack. The habitat does include internal power management and distribution systems and batteries to provide 72-hours of power in emergency scenarios.
The habitat internal atmosphere is a 101.3 kPa (14.7 psia), with 21% O2 nominal atmosphere. The habitat contains a
fully 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
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.
NASA EMC Reference Habitat Lower Level (left) and Upper Level (right) Overhead Views