. Safe Haven Configurations for Deep Space Transit Habitats

 
 
 

ABOVEIMAGE CREDITS: HASSELL & EOC

 Note about Videos: Atthe right, here's a little introduction to the Kalpana One space settlement, followed by a rotation and fly-past.

 
 
 
 
 
 

 
 

 
 
 
 
 
 

1955 Von Braun Space Station

Additional Findings: Every time a new study is done with internal layouts there are additional findings and inputs that warrant consideration in both the requirements and in future design iterations. Here are some of the findings from this study that are noteworthy
1) External viewing: Based on the ISS experien ce there is a preference that windows be provided for external viewing from the habitat as well as cameras for external views of the habitat and approaching vehicles. The EMC Mars transit habitats represented by configurations 1 through 3 include view ports in each of thedocking port hatches, or 5 windows when counting the forward hatch, three radial hatches, and a standard Window Observational Unit in the 4th radial port position. The remaining views were planned to be covered by high definition cameras and internal screens. Configurations 4 and 5 did not include radial ports, so one Window Observational Unit was provided in a radial position and a forward and aft view port in each docking
hatch were included. It is not clear if these provisions are sufficient for the mission duration planned, and so further consideration is recommended.
2) Propulsion systems: Habitat configurations 1 through 3 were pre-integrated with a large hybrid propulsion system for the initial transfer to cis-lunar space. The hybrid system includes a large solar electric propulsion (SEP) system,6 so some avionics and most of the power systems are on the propulsion element. Once in cislunar space the habitat is loaded with logistics and the hybrid propulsion system is re-fueled in preparation for the crew’s journey to Mars. The greater length of configurations 4 and 5 precluded the pre-integration of the hybrid system so an alternative chemical system was utilized. It includes a small integrated propulsion system for the initial transfer from Trans-Lunar Injection (TLI) to cis-lunar space where it is then loaded with logistics and berthed to chemical propulsion stages for the transfer to Mars. In Mars orbit the habitat berths with another set of propulsion stages that have been pre-deployed for the return trip. All avionics and power systems are integrated as part of the habitat element.
3) Power systems: The power requirements for all configurations were about the same since they all had similar requirements to support 4 crew for 1100 days. Habitat configurations 1 through 3 draw power from the solar arrays provided by the SEP system on the hybrid propulsion stage, whereas configurations 4 and 5 utilize a set of deployable solar arrays sized for the habitat power requirements in Mars orbit.
4) Thermal systems: The thermal requirements for all configurations were also about the same since they had similar thermal loads. Each utilized both passive and active systems with body mounted radiators. The possible exception of note is configuration 4 where the diameter of the larger module is the same as the core stage. Several options were discussed including the use of body mounted radiators with an aero shell for protection during launch, enclosure in a 10 m diameter payload fairing, or deployable radiators located inside the fairing on the smaller safe haven module.
5) Waste management: A noted benefit for the full duration safe haven is that a second waste management compartment is also included.

6) Stowage systems: Long-term stowage of food is a concern in the radiation environment of space and may require greater utilization of refrigeration and freezer units than currently planned. In addition, the impact on food packaging and life support consumables if exposed to vacuum is not fully understood. Duplicate stowage was not considered in the mass estimates for these safe haven configurations and so additional research is needed to confirm that packaging and food stores can survive the potential for explosive decompression and cold when going to vacuum. All configurations were found to have limited packaging volume except configuration 4. Configurations 1 through 3 and 5 required a higher packaging density than currently used on ISS. Acceptable packaging densities need to be confirmed.
7) Research systems: All configurations used a reduced mass and only one research station in the layout for
research systems. Concern over the reduction of research equipment and associated volume along with the packaging density concerns for stowage are among the reasons for exploring the larger volumes shown in
configurations 4 and 5.
8) Concept of operations: A detailed concept of operations for safe havens is needed to examine a variety of scenarios where their use might be required to prevent loss of mission and/or loss of life. Going through the concept of operations analysis should help generate better requirements that can be applied to more detailed design solutions.9) Interior layouts: Configuration 1 uses a vertical layout on two deck levels with open circulation between levels similar to the way Skylab was designed. Large crew quarters are provided in a horizontal orientation for the bunk area with the intent of applying this design towards surface habitats and artificial-g configurations. Configurations 2 and 3 are the same, but the open space is restricted by the addition of a bulkhead/dome and an IVA airlock. Configurations 4 and 5 use a horizontal layout on three deck levels with vertical circulation through each end dome. The layout is intended for in-space use only so the crew quarters
are in a vertical orientation with sleeping bags on the walls as done in the ISS crew quarters. In general, the
vertical layout appears to provide more open public space for the small volume provided, whereas the
horizontal layouts appear to provide more private spaces and improved packaging efficiency. The packaging efficiency improvements include opportunities for additional workstations, easier access to stowage along the outside walls, and a separate utility room as opposed to packaging utilities under the floor in the end domes. In addition, the vertical layouts locate the crew quarters around the perimeter whereas the horizontal layouts locate the crew quarters in the center of the module providing the possibility for maximizing radiation protection using stowage and habitation systems.

 Structures: The internal bulk shown in Configuration 2 was found to be nearly three times more massive than a standard end dome due to the requirement for supporting pressure loads from either side which places the dome in a possible tension or compression load. As a result, it was found that there is little mass difference between a pressure vessel with an internal bulkhead and two separate pressure vessels. The bulkhead design provided a more compact solution but requires an additional airlock for EVA access outside the habitat. The dual pressure vessel solution offers simpler manufacturing, possible use of the IVA airlock for EVA access too, but is much longer and less compact. In total, the additional structures mass was found to be around 1700 kg for both bulkhead and dual pressure vessel options.

Avionics: Most of the internal avionics, consisting primarily of communications and data handling equipment, was duplicated to provide a complete system inside each pressure vessel. It was noted that the highest risk for pressure loss would be from collision during docking operations when communications, data handling, and vehicle controls would be critical. In total, the additional avionics mass was found to be around 742 kg.

 
 

Findings and Recommendations

The primary mass drivers for the safe haven were found to be in structures, avionics, and the life support system, which totaled about 3000 kg for a 30-day safe haven and about 5000 kg to 6000 kg for a full duration safe haven.

Safe Haven Configurations for Deep Space Transit Habitats

Smoke, fire on board, as well as pressure loss or a collision with another spacecraft during docking or undocking operations could provide For Mars missions, ground operations will be limited, quick return impossible.

So, the risk of a collision during deep space missions could yield disastrous results, such a loss of mission and a loss of crew for transit habitat designs without safe haven capabilities.

The safe haven concept was inspired to help to resolve these issues by determining the mass impact for providing a second pressure vessel that the crew could move into to give them time to recover from a mishap, and designed in a configuration that could be launched efficiently on the Space Launch systems (SLS).

Configurations considered included a single pressure vessel with an internal bulkhead, dual pressure vessels of the same size, and a primary pressure vessel with a second smaller unit for the safe haven. 

Life support options included duplicate closed loop life support systems for full duration in either volume, and a single closed loop life support system in the primary volume with an open loop life support for 30-day duration in a smaller secondary volume.

The concept study start with the Mars Transit Habitat base-lined in the Advanced Exploration Systems, the Evolvable Mars Campaign.

The Configuration A (CA) is the standard single volume monolithic habitat planned for Mars missions in the 2030s, which includes an advanced closed loop life support system designed to support 4 crew for 1100 days. In the Configuration B, it is an upgraded version of CA, which required a little more volume for stowage, uses structures and end domes based on current SLS manufacturing standards, and uses current life support systems from the International Space Station (ISS).  

The interior layout for the monolithic design is arranged in a vertical orientation on two deck levels. The lower deck includes all of the crew systems for research, vehicle controls, galley, exercise, and waste management. The life support systems are located below the floor in the lower end dome. Translation from the lower deck to the upper deck is through a large opening in the center of the module providing a more open layout approach. The upper deck includes the four crew quarters with stowage packed in between and around the quarters to further enhance radiation protection for the crew. 

Configuration 2, shown in Fig. 2, has the same exterior appearance as configuration 1b but creates a safe haven by installation of an internal bulkhead between the upper and lower decks with an intra-vehicular activity (IVA) airlock, and a duplicate closed loop life support system that provides for full duration capability in either volume. The crew systems are split between the two deck levels to minimize loss if evacuation from one side is required. Each level includes two crew quarters and about half the stowage, a split in the crew systems functions, and a complete life support systems packaged in the decks over the dome and bulkhead for each level.

In the event of pressure loss in one side, duplicate life support and avionics are provided on each side to sustain life for the full duration and provide communications and vehicle control systems on each side. In concept, the IVA airlock provides passage through the bulkhead for transfer of stowage and equipment needed for the duration of the flight. Conveniences like research equipment, hygiene, and exercise, might be lost or downgraded in one side or the other, but with access to the unpressurized volume it is believed that operational workarounds can be found to resolve life sustaining issues.

Internal and external repairs might be possible so the habitat is designed for both internal and external access to the pressure vessel walls. The interior uses a modular pallet system that can tilt up from the floors above the domes and away from the walls. An external inflatable airlock is also available at one of the radial hatches (not shown), to provide EVA crew access to the entire pressure shell for repair operations.

When configurations 1b and 2 are compared the basic increase in mass for a full duration safe haven can be found. It came to 5,969 kg, which included 1700 kg for the additional structure required for the internal bulkhead and airlock, 742 kg for the duplicate avionics required for each volume, and 3,527 kg for the duplicate life support system. So, for around 6,000 kg it seems reasonable to assume that a full duration safe haven can be provided in most Mars transit habitat designs that will protect the crew from smoke, fire, and pressure loss for the duration of their mission. The advanced life support system planned for the 2030s included in the EMCs Configuration 1a is about 1000 kg lower in mass, which would bring the total impact of the safe haven mass down to only 5,000 kg.

These estimates do not include duplicate food stowage systems. It is assumed that the crew will be able to pass through the internal airlock to collect the supplies they need. Which, also assumes that the stowed provisions are not permanently damaged by exposure to smoke, fire, or vacuum. These operational details and concerns are part of the recommendations for further analysis of safe haven concepts.

Configuration 3 shown in Fig. 3 is the same as configuration 2, but uses two pressure vessels of equal volume. When configuration 3 is compared to configuration 2 it was found to be about 300 kg more massive, all attributable to the additional structures mass. This comparison indicates that manufacturing simplifications for configuration 3 may be worth further investigation for the dual pressure vessel option.

 

Configuration 4 shown in Fig. 4 is a new concept utilizing the pressure vessel volumes planned for the Exploration Upper Stage (EUS), which yielded a convenient large volume habitat with a closed loop system paired with a smaller volume using a 30-day open loop system. The concept is similar to ideas where any attached pressure vessel for logistics could be used as a temporary safe haven if attached to an airlock that permits IVA transfers between volumes. The findings yielded the same basic difference in structures and avionics mass as the full duration habitat, with a much lower mass for the open loop life support system of about 629 kg. The total additional mass for the 30-day safe haven is about 3,071 kg. There is additional risk for this approach over the full duration safe haven configurations, because the crew would have only 30-days to make repairs to the primary volume. Regardless, it is still an improvement that could mitigate some risks. In addition, if a separable logistics module were utilized, disposal could occur in Mars orbit prior to return but after all of the Mars orbital docking operations have passed.

Several additional differences should be noted in the configuration 4 design. The structures using the basic EUS design will yield simplification in overall manufacturing, but the design is optimized for habitat loads. This yielded a lower loading case which permitted a reduced pressure vessel mass of about 2900 kg lower than the original EUS designed for propellant loads. In addition, the volume available between the two pressure vessels makes it possible to build in an airlock that can be utilized for both IVA transfers and EVA access too. This finding yielded an additional benefit by eliminating the attached airlock required for configurations 1 through 3.

Configuration 5 shown in Fig. 5 matches the total volume of configuration 4 using two equal pressure vessels and duplicate closed loop life support systems for full duration in either volume. When these two configurations are compared, the results are only about 1500 kg more for configuration 5, indicating that further optimization of the EUS structural design in configuration 4 may be possible because theoretically the difference should only be the additional 3000 kg required for the duplicate life support system.

Configuration 1 shown in Fig. 1 represents the baseline approach from the EMC’s Mars transit habitat. The modifications made from configuration 1a to configurations 1b and 2 for utilization of standard end domes and increasing volume to accommodate current packaging efficiencies, increased the overall habitat module length by 1.6m. Configuration 3 grew an additional 1.4m with the dual pressure vessel approach. All of these configurations appear to package in the standard shroud currently planned for SLS payload flights. It should be noted however, that growth in the habitat length will place limitations on growth of the hybrid propulsion stage.
Configuration 4 using the EUS manufacturing capabilities is a unique option. Its overall length grew about 6.3m beyond the original 1a configuration, which precluded packaging with the hybrid propulsion stage, even though part of the habitat could be extended into the nose cone volume. In addition, a section of the habitat is the same diameter as the core stage and will be exposed to aero loads during launch. This section will likely require aero shell panels to protect the surface of the habitat module where surface mounted radiator panels are likely. Another alternative wouldbe to utilize a 10m diameter payload fairing to completely encapsulate this habitat configuration.
Configuration 5 is about 5.7m longer than configuration 1a, which also precluded use of the hybrid propulsion system. So, like configuration 4, a separate propulsion element was planned.

Credit: David Smitherman* Tara Polsgrove†, and Justin Rowe‡ NASA Marshall Space Flight Center, Huntsville, AL, 35812 and, Matthew Simon, PhD§ NASA Langley Research Center, Hampton, VA, 23681

Life Support Systems: Two life support systems were investigated to provide a 30-day safe haven using an open loop life support system and a full duration safe haven using a duplicate closed loop life support system. Several options are possible for each approach. The 30-day open loop system has an overall mass of about 629 kg for hardware and consumables to support a crew of four. Options available include increasing the duration up to 60 days, although this would be approaching the breakeven point for going with a closed loop life support system. The full duration closed loop life support systems has an overall mass of about 3,527 kg based on current ISS technologies. The benefit for using this system is that it has a known reliability for long term use, so planning for maintenance, repair, sparing of components, supplying of filters and consumables is understood. The primary issue is that it is over sized with capabilities to support a crew of 11. An alternative is to down size the system to support a crew of 4 with more advanced technology. This approach is believed to save about 1000 kg or more in hardware mass and consumables yielding the variation stated above for full duration safe havens in the 5000 kg to 6000 kg range.

HISTORICAL TRAVEL OF THE RUSSIA INTO THE SPACE

In the Earth orbit from 1973 to 1979, Skylab was the first space station launched and operated by NASA. The module of 77 t has been launched unmanned on a modified Saturn V rocket. To complete the assembly, three manned missions with three-astronaut crew each has been conducted between 1973 and 1974. To make the work well, crew using the Apollo Command/Service Module (CSM) placed atop the smaller Saturn IB. On the last two manned missions, an additional Apollo / Saturn IB stood by ready to rescue the crew in orbit if it was needed.

Skylab included the Apollo Telescope Mount, which was a multi-spectral solar observatory, Multiple Docking Adapter (with two docking ports), Airlock Module with EVA hatches, and the Orbital Workshop, the main habitable volume. Electrical power came from solar arrays, as well as fuel cells in the docked Apollo CSM. The rear of the station included a large waste tank, propellant tanks for maneuvering jets, and a heat radiator.

The station was damaged during launch when the micro-meteoroid shield separated from the workshop and tore away, taking one of two main solar panel arrays with it and jamming the other one so that it could not deploy. This deprived Skylab of most of its electrical power, and also removed protection from intense solar heating, threatening to make it unusable. The first crew was able to save it in the first ever in-space major repair, by deploying a replacement heat shade and freeing the jammed solar panels.

Vintage NASA documentary about Skylab. Interesting comments by the astronauts early in the film about the reasons why humans should explore space. Skylab was America's only space station. It's legacy serves as a reminder of America as a great space power.

Credit: NASA/JSC Skylab. This is the story of the three missions, the nine astronauts, and their 171 days in the manned laboratory. Crisscrossing 70 per cent of the Earth's land area, Skylab's sensors gathered information about many features of the planet. Actor E. G. Marshall is host and moderator.

Astronaut Jack Lousma takes viewers on a tour of the Skylab Space Station in this 45 minute broadcast.

Gemini 8 - We've Got Serious Problems Here (Full Mission 03) The third of four intended videos which will cover the entire flight of Gemini 8.  The mission transcript is available here http://www.jsc.nasa.gov/history/missi...

The crew perform the first docking of two spacecraft in orbit, which is followed, not long afterwards, with the near catastrophic incident. Unknown to the crew, a thruster on Gemini becomes stuck open and the docked spacecraft begin to yaw. Thinking the issue is with the Agena, the crew seperate from it, but the yaw turns into a spin as the thruster continues to spew fuel out the side of the spacecraft. As the crew regains contact with CSQ the drama unfolds.....

In the first video I added captions to the video. I have decided, due to time constraints, not to do this for subsequent videos. I hope that the viewing is not spoiled because of this. I have added in the communication from the crew at the incident point.

Orbiter Space Simulator is used where actual video is not available. The orbital inclinations and orbital burns are simulated. I do not know if these are the way the actual events were. The in between ground station HD video is from ISS.

Salyut 6 was a Soviet orbital space station, the eighth flown as part of the Salyut program. It was launched on 29 September 1977 by a Proton rocket. In comparison with the earlier Soviet space Stations, its included a second docking port, a new main propulsion system and the station's primary scientific instrument, the BST-1M multi-spectral telescope. A second docking port made crew handovers and station resupply by unmanned Progress freighters possible for the first time. The early Salyut stations had no means of resupply or removing accumulated garbage (aside from the limited amount that cosmonauts could carry in their Soyuz spacecraft), nor could the propulsion system be refueled once it exhausted its propellant supply. Consequently, once the consumables launched with the station were used up, its mission had to be concluded and as a result, manned missions had a maximum duration of three months. Progress spacecraft could now bring fresh supplies and propellant and also be used to dispose of waste, which was then destroyed once the spacecraft was de-orbited.

Five crew took place over the station's lifespan, in late 1977-early 1978, late 1978, mid-1979, mid-1980, and early 1981, including cosmonauts from Warsaw Pact countries as part of the Intercosmos programme. These crews were responsible for carrying out the primary missions of Salyut 6, including astronomy, Earth-resources observations and the study of the effect of spaceflight on the human body. Following the completion of these missions and the launch of its successor, Salyut 7, Salyut 6 was de-orbited on 29 July 1982, almost five years after its launch.

Salyut 7 was a space station in low Earth orbit from April 1982 to February 1991. It was first manned in May 1982 with two crew via Soyuz T-5, and last visited in June 1986, by Soyuz T-15. Various crew and modules were used over its lifetime, including a total of 12 manned and 15 unmanned launches. Supporting spacecraft included the Soyuz T, Progress, and TKS spacecraft.

It was part of the Soviet Salyut program, and launched on a Proton rocket from the Baikonur Cosmodrome, which become the Soviet Union. Salyut 7 was part of the transition from "monolithic" to "modular" space stations, acting as a test-bed for docking of additional modules and expanded station operations. It was the tenth space station of any kind launched. Salyut 7 was the last Space Station of the Salyut Program, which was replaced by Mir.