For long duration missions beyond LEO, as well as Mars transit missions of about 1100 days, a quick return will not be possible. For that, the mass penalty for multiple volumes and operating has been always an important concern for mission concepts. Learn More


The Skylab was a large single module habitat that provided about 555 m3 of habitable volume for about 49 metric tons (mt). This is similar to many modules on the ISS where ten times the mass at 450 mt resulted in less habitable volume at 355 m3. In examining the mass statements from the historical and new studies, it was found that the structural mass of the many connections and end domes between modules adds significantly to the total mass. In addition, there are many internal subsystems that are duplicated for each module when multiple modules are used. Then, it is easy to understand how volume can be increased and how mass can be reduced simply by reducing the number of individual elements.

Credit: Space Launch System Co-Manifested Payload Options For Habitation / David Smitherman of NASA Marshall Space Flight Center, Huntsville, AL, 35812
By its volume, the SLS' large module provides a significant mass savings per unit and, has enough space for consumable payload to accommodate long duration missions. Also, it can be lifted in one shot by SLS without the need of on-orbit assembly.

Credit: Habitation Concepts For Human Missions Beyond Low- Earth-Orbit / David V. Smitherman* NASA Marshall Space Flight Center, Huntsville, Alabama, 35802
SLS Co-Manifested And Dedicated Payload Configurations. Two co-manifested elements and one of three large habitats complete the configuration planned for the lunar DRO.
The basic formulation of the Smitherman study is the use of two Universal Stage Adapters (USA2 & 3) for an assumed 10 m long for a 10 mt payload capability on two Space Launch System 1b rockets . Two concepts were developed to package the modules utilizing these adapters as seen below.

The building sequence for the Cislunar module habitats in the lunar DRO is the same for  the 5.5 m, 7.2 m  and 8.4m diameter. Learn More
The first element to be launched is the Augmented/Service Module (ASM), which is delivered by the Orion with the crew to the Lunar DRO. The ASM provides a small additional habitable volume to the Orion with its logistics and open-loop environmental control and life support system (ECLSS). Each flight has the open-loop ECLSS provision to protect the reserves and give an approach for longer missions during the building sequence or assembly. The propulsion system provides the basic station keeping of the entire stack, where the ASM  includes a pressurized tunnel and a docking port at each end. In the event where the asteroid retrieval vehicle arrives late and/or in a different orbit, it will be possible to refuel the entire stack at an another location in the DRO. 
The Docking Module (DM) is the second element to be delivered by the Orion with the crew to the Lunar DRO. The docking module provides NASA Docking System (NDS) and Common Berthing Mechanism (CBM) ports with pressurized mating adapters similar to the ISS standards.
Once the Orion capsule docks, the crew uses a robotic arm to transfer logistics.
Adoption of the larger CBM standard with its 50 x 50 inch hatch is an important Mars-forward feature that will aid in the refurbishment of a large Mars-transit habitat between missions. Also, it will make a good  surface docking system when using the future 50 x 60 inch step-through hatch. With an EVA hatch for contingency, the DM provides another airlock if needed.
The large habitat or HAB is the third and last element to be delivered. With this payload, the Exploration Upper Stage (EUS) will bring the necessary boost to go beyond the Trans-Lunar Injection (TLI) burn. This latter thrust will provide the orbit transfer of the HAB around the lunar DRO. In the study, diameters of 5.5 m, 7.2 m, and 8.4 m were considered for the large module to support a crew of 4 for 1000 days when fully outfitted with provisions.


Skylab II is a concept using an empty SLS propellant tank as Deep Space Habitat. Similar to the original Skylab (operated between 1973-74), it is a low-cost and low-risk solution because it can be lifted by the large diameter and heavy-lift capability of the SLS. The habitat module concept can provide large enough volume for the crew and their operations.

Credit:  NASA Marshall Space Flight Center | Core Capabilities and Services / Advanced Concepts and Systems Analysis Rapid Architecture Solutions

Marshall conceived and assessed a Skylab-inspired habitat for deep space exploration using the SLS.
With the payload still attached to the EUS, the Universal Stage Adapter (USA-2) fairing is jettisoned and the Orion rotates to dock with the payload. After docking, the EUS releases the payload and the Orion Service Module delivers the payload to the Lunar DRO destination.
Orbital ATK’s vision for the next step toward human space missions to Mars employs our flight-proven Cygnus advanced maneuvering spacecraft as a human habitat in cislunar space, the region between the Moon and Earth. In the early 2020s we would launch the initial habitat on NASA’s SLS rocket. Featuring a modular design, the habitat would serve both as a destination for crewed missions and as an unmanned testbed to prove-out the technologies needed for long-duration human space missions. The habitat is also envisioned as a base for lunar missions by international partners or commercial ventures. With additional habitation and propulsion modules, the habitat could be outfitted for a Mars pathfinder mission. Credit: Orbital ATK
The SLS payload delivery flights are simpler, but each requires an attached propulsion bus with it to complete the maneuver from the end of the EUS TLI burn to the final destination in the Lunar DRO.

Credit: SLS Derived Concepts - "Habitat Concepts for Deep Space Exploration" by David Smitherman, NASA Marshall Space Flight Center, Huntsville, Alabama, 35812, & Brand N. Griffin of Gray Reseach, Huntsville, Alabama, 35806.
The SLS Derived Concepts with an 8.4 m diameter core stage is similar to the concept of Skylab II. The three configurations considered, fit inside the launch vehicle's main structural load path. The module needs only to be protected with a Multi-Layer Insulation (MLI) against micro-meteoroid impacts and sun radiation.
As seen in the figure below, the Minimum (C-1) and Full (C-2) Capabilities Configurations are designed to explore the upper and lower bounds of possible missions in the Lunar vicinity. Also, when configured as a Mars Transit Habitat, it will be possible to use it for asteroid missions as well as Mars destination.

The SLS derived module in Configuration C-1 has one axial port on the Airlock aft end for the attachment of the Orion MPCV. The Airlock is also equipped with a side EVA hatch  to permit an easy access to external utility systems. An additional port is possible on the dome, at the Airlock end or forward end. The aft end supports the external propulsion system, which assists the maneuvers of a separate EUS in the Lunar DRO. The aft end is also designed for refueling vehicles in transfer between the Lunar DRO, the EML1 (Earth-Moon-Lagrange-1) and the EML2 orbits. 
The interior layout uses equipment pallets, storage compartments, and acoustical panels on all three levels. The crew quarters is located in the center of the mid-deck for maximum radiation protection from surrounding systems. Therefore, no additional mass is required from water walls or polyethylene panels, as provided in the previous ISS derived configurations or in use on the ISS.
The lower deck provides a subsystem area for pallet-mounted equipment and an exercise area. Space for the crew quarters, two workstations and a waste/hygiene management compartment are found in the mid-deck . Finally, a galley/wardroom and two additional workstations are located in the upper deck. A vertical translation zone to each deck is provided through the two end domes, as seen below.
The two SLS derived habitat configurations provide living space for three 4-crew missions of 60 days, or varying lengths for up to 180 days total. Additional missions and duration times are possible with logistic flights bringing consumable and spare resources.
With a primary destination in the Lunar DRO, the propulsion system has to permit a refueling for an orbit transfer to EML1 or EML2. The entire stack must maintain its orbit for up to 10 years. The C-1 Minimum Capability has one docking port on the end of the airlock for the Orion Multi-Purpose-Crew-Vehicle (MPCV). The C-2 Full Capability has five additional docking ports, one on the opposite end dome and four radial ports to support the logistics, FlexCraft, landers, and international elements.
The internal configuration for both C-1 and C-2 is similar with the crew quarters located in the center to maximize radiation protection.
The total mass of the C-1 Minimum Capability habitat is 21,788 kg with a pressurized volume of 496 m3 and a habitable volume of 353 m3. Unlike the ISS derived habitats, the 60-day and 180-day habitat configurations have the same mass and volume. The system is designed with a launch of all the logistics required for three 60-day missions or any combination of mission duration up to 180 days for 4-crew prior to resupply.
The total mass of the C-2 Full Capability habitat is 27,434 kg with a pressurized volume of 662 m3 and a habitable volume of 519 m3.

Configuration C-3 for Mars Transit Habitat

The C-3 Configuration for the Mars Transit Habitat launched in a single large diameter module, as shown below, is designed to support 6-crew members for 1000 days. With its additional ring section at the aft end, the C-3 can support two radial ports and an airlock at the forward end with a docking port for the Orion MPCV. The radial ports accommodate a FlexCraft vehicle (left-below) and an open port for docking the Mars lander pre-deployed in Mars orbit. The overall mission concept is similar to the current Design Reference Mission, except in this case, everything is launched from the Lunar DRO and the new "vehicle" uses a higher TRL system for its propulsion and habitation. All logistics are stored along the outer walls of the module to maximize the protection against the radiation.

External Configuration C-3 for the Mars Transit Habitat. The configuration for Mars transfer is similar to the C-2 Full Capability. The transit vehicle includes one EUS and three storable propellant stages for TMI, MOI, and TEI maneuvers. The Mars Transit Habitat and Orion MPCV are shown at the forward end of the vehicle stack.

The internal layouts for all three configurations are similar. The C-3 Mars Transit Habitat accommodates 6-crew and is extended to accommodate two radial ports.
The airlock at the forward end is equipped with a side EVA hatch for an access to the external systems . The interior of the C-3 Mars Transit Habitat uses a similar layout to the previous SLS derived habitats. A floor plan is shown above, where the only difference is the accommodations for 6-crew and additional interior volume at the aft end for the two radial ports. The total mass of the C-3 Mars Transit Habitat is 41,369 kg with a pressurized volume of 662 m3 and a habitable volume of 440 m3.




The TURBOLIFT is a Linear Sled Hybrid Artificial Gravity concept (LSH AG) thatcould be essential to enabling crewed long-duration lunar stays, cis-lunar exploration, Mars orbital missions, exploration of Martian moons, Martian landings, or any further destination in our solar system. LEARN MORE


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. LEARN MORE