Space Habitats for Lunar Gateway

Long, box-like interior with astronauts

iHab interior (credit: Vienna Region)

Original raisons d’être for the Lunar Gateway were to study long-term human endurance and sustainable life support in a deep space environment, and prepare for missions to Mars and the asteroids. The Lunar Gateway was renamed the Deep Space Gateway as part of the big push for the Artemis program.

What is the current state of plans for life support and space habitation on the Lunar Gateway? Some background is in order. Several years ago, NASA created the NextSTEP program to support crewed space exploration. In 2014, NASA’s NextSTEP program awarded contracts to several firms to expand habitation and other capabilities of the Orion space capsule. The total amount awarded for life support and habitats was about $5.5 million. NextSTEP 2 was more ambitious, funding concept studies and the construction of entire prototypes for deep space habitats. Contracts of about $10 million per awardee were awarded for 24 months of work, for a total amount of $65 million for work over 2016-2018. Awardees (current names) were Lockheed Martin, Northrup Grumman, Bigelow Aerospace, Boeing, Sierra Nevada and Nanoracks. Their visions for space habitats are shown below. (Bigelow has substantially scaled back operations since then.)

Six proposed space habitats

NextStep 2 Contract Awardees, Proposed Habitats and Differentiators. Credit: NASA.

NextSTEP 2 was a prelude for the competition for the initial Lunar Gateway space habitat module called the Habitat And Logistics Outpost module (HALO). Then on 5 June 2020, an initial $187 million contract was awarded to Northrup Grumman for the HALO module for the Lunar Gateway, which was targeted for launch by 2023 (NASA, 2020). It was felt that Northrup Grumman’s existing Cygnus cargo vehicle (used for the International Space Station) was proven technology that would allow for faster development and an earlier launch. 

Plans for HALO have gone through several iterations. It is still a habitat, but probably now it also has broader capabilities since it may be the only crewed module for awhile. The contractor for HALO Habitat And Logistics Outpost module (HALO) will almost certainly receive considerable additional funding. A ball park estimate would be at least US $1 billion for just the habitat (even if “new space” economies are invoked) and possibly several billion. This does not include funding for the propulsion or energy systems, which have been awarded to Maxar.

Two stubby, cylindrical modules.

iHAB and HALO module concepts. Note: launch years have changed. Credit: NASA.

The HALO module is really just a place for astronauts to transfer to the Moon. It does not meet the earlier goals to test human endurance and sustainable life support in deep space. However, the Lunar Gateway is planned to have a second space citation module called iHab, which supposedly will have long-term, sustainable life support capabilities. International entities such as the ESA  and JAXA are supposed to build and pay for it, so you don’t have to hold your breath for Congress to fund it. The ESA has developed significant closed-loop life support via its MeLISSA program (covered earlier by Sustainspace), so they certainly have advanced capabilities in closed-loop life support.

Artist’s concept of the Gateway power and propulsion and HALO in orbit around the Moon. Credit: NASA

Up-to-date details on iHab are scarce. High level requirements for deep space habitats have been determined by past studies, but it is unclear which of those iHAB will contain. Based on relatively easy-to-deploy capabilities that have already been developed, is expected that, at minimum, iHAB will provide capabilities for water recycling, modest food production (including plants), partial CO2 recycling and exercise.

The construction and deployment of the HALO and iHAB modules will be a significant expansion of the anthroposphere into space, and the most durable expansion into deep space. How long the Gateway will endure and be crewed are still open questions, but it is still a concrete step towards grander visions of humanity in deep space.

Further Information

Impact of Deep Space Missions on Life Support Development

Orion capsule approaching Gateway

NASA Lunar Gateway

The reconfiguration of the Deep Space Gateway into the Lunar Gateway and the accelerated schedule to land humans on the Moon will have significant impact on the development of regenerative life support systems and the sustainability of deep space communities of humans.

The existing International Space Station (ISS) is in low Earth orbit. That orbit provides a microgravity environment, intermediate radiation and some logistic challenges. It also involves a strictly-controlled habitat and severe limitations on plant care due to the severely impacted schedule of astronauts. In contrast, the deep space environment differs from that in low Earth orbit in several ways. First, there is considerably more radiation. Second, low Earth is much better protected by the Earth’s magnetic field. Third, it is more difficult and much more expensive to re-supply deep space.

There has been much evolution of planned deep space human missions by NASA, and hence its partners. At one point, there was a plan to have astronauts visit and retrieve an asteroid. Then the plan was to have a large Deep Space Gateway station that would gain experience for deep space missions and advance life support technology. Then the plan was to place humans on the Moon in a sustainable manner. Now the plan is for a minimal Lunar Gateway and a human landing to the Moon by 2024 and worry about sustainability after that milestone.

A common denominator among the plans has been the need to use the NASA Space Launch System (SLS) rocket and the Orion crew capsule. The SLS is an extremely powerful vehicle in terms of both propulsion and political clout. It will return some of the capabilities to NASA that were lost with the discontinuation of the Saturn V system. Since NASA has been strongly encouraged by the President to land humans on the Moon by 2024, private vehicles are now under consideration as well, if they can help achieve the deadline.

The original configuration of the Deep Space Gateway included a life support module that would have allowed the gateway to support astronauts with fewer resupply missions. It probably would have included a plant growth component.

However, due to the acceleration of a manned lunar landing mission, the Deep Space Gateway reconfigured minimalist approach focuses on providing an assembly node for short manned missions to the Lunar surface. There would also be a propulsion module and possibly an airlock module. A lunar lander would be ferried to the Gateway and the an Orion capsule would take astronauts to the Gateway. The astronauts would take the lander to the Moon for a few weeks, return to the Gateway and return to the Earth via the capsule. However, there will not be an enhanced life support module (at least not until much later).

According to a NASA source, after humans return to the Moon, then the Gateway and lunar base could focus on keeping people there on a sustainable basis. So plants in a long duration life support module might have to wait until after 2024.

The bottom line is that funding for deep space life support and sustainability will be likely delayed. If there are other cost overruns, life support and the biological sciences can get cut disproportionately. Since sustainability is untimely a cost-saver, this means that deep space communities will be more expensive for the foreseeable future, due to greater resupply expenses. The only silver lining is that there will be more time to “get it right” for sustainable life support technologies.


Book Review: Revolutionary Understanding of Plants

many chili peppers

Will plant intelligence compel future spacefarers to carry chili peppers? © Tomas Castelazo. CC BY-SA 4.0.

Stefano Mancuso’s book The Revolutionary Understanding of Plants: A New Understanding of Plant Intelligence and Behavior (2017) makes the case that plants are an often ignored, under-appreciated and yet extremely intelligent life form that has the ability to solve human sustainability challenges and even can teach us how to better govern ourselves.

Mancuso is an associate professor at the University of Florance and directs the Laboratorio Internazionale di Neurobiologia Vegetale (International Laboratory of Plant Neurobiology, or LINV).

Mancuso’s chief hypothesis can be summed up as follows. Animals can move so they escape from problems. They can run away from predators. They can migrate away from adverse environmental change. In contrast, plants are sessile (fixed in one place). Therefore, plants have no choice but to actually solve problems, and hence engage in forms of intelligence to devise and implement solutions that are sometimes obvious, yet other times subtle or downright devious.

Mancuso asserts that plants by necessity have developed intelligence that differs greatly from animal intelligence. Animals have a central brain, which is a suitable strategy for animals who can get out of the way of destruction. Plants cannot directly escape trouble. They have to survive partial destruction of a magnitude that would kill most animals. For example, plants and their intelligence mechanisms often get partially eaten. Plants have overcome this existential challenge to their intelligence by utilizing extensive redundancy and decentralized intelligence.

For example, acacia trees has developed a solution to discourage predators involving excreting nectar along their branches. That nectar attracts ants who discourage harmful insects from attaching the tree. The subtle element is that the nectar also contains chemicals that make the nectar highly addictive, hence enslaving the ants to the tree. The devious element is that the nectar also contains drugs that make the ants so frenzied and aggressive that they will attach much larger animals who approach the tree. Mancuso takes passionate joy from pointing out that plants are not the mere servants and victims of animals, but often the actual master of animals. Although this could be dismissed as mere professional bravado to position oneself as the alpha biologist at conferences, Mancuso makes a compelling case.

Another example, relevant to space travel, concerns humans being one of the best spreaders (“carriers”) of plant species. Humans have spread local plant species such as potatoes, tomatoes, cocoa and coffee plants across the globe. One poignant example is that of chili peppers, which originated in a region in Mexico. Chilis are painful to eat, but that pain releases highly addictive endorphins in humans. Chili plants have in essence manipulated humans to cultivate chili peppers across the world, to such a degree that chilis, in a just few hundreds of years, have become such highly traditional foods in many cultures that is is difficult to image such cuisines without chili peppers. Now that humans are already transporting plants into space, it is to be wondered at what transformations plants will invoke upon future spacefarers.

A stump above electro-mechanical roots.

Plantoid capable of sol exploration. Credit: plantoid project.

Mancuso also feels that plants hold lessons for future space exploration, since they have redundant, fault-tolerant systems and structures and use only low amounts of energy. He has worked with the European Space Agency to study how decentralized root growth intelligence and mechanisms can be used to create a network of soil explorers comprising “plantoids” (robotics inspired by plants) across the Martian surface. So someday there could be robotic plants in space, perhaps carried by robotic humans!

Further Information:

Capillary structures could provide lower risk water recycling

Rows of small structures

Capillary Evaporator prototype with transparent capillary structures filled with test fluids. Credits: IRPI LLC

Human use a lot of water for drinking and hygiene. Recycling is a key strategy to make the water that is launched into space last longer. Existing water recycling methods in space use harmful chemicals or considerable energy, and do not recycle 100% of the water. Reliability is crucial as well. So the search continues for new approaches to improve the water recycling process.

NASA is considering capillary structures for water recycling. Capillary action involves electrostatic forces literally pulling water through small tubes, similar to how drops of water will hang on objects despite the force of gravity pulling them away. NASA’s capillary structures investigation studies “a new method of water recycling and carbon dioxide removal using structures designed in specific shapes to manage fluid and gas mixtures in microgravity.” The capillary structures equipment is made up of small, 3-D printed geometric shapes and sizes sizes (see above image).

This investigation also involved evaporation. “If you could do controllable evaporation in space, you could do all kinds of things” said Mark Weislogel, one of the project’s principal investigators.  “You could evaporate urine and recover all of the water. All of it. If you had a way of holding the liquid in a passive, no-moving-parts way like a puddle does on earth, but in space, then you could do a lot of unique processing, safely and with no maintenance.”

Just as with the capillary investigations, the evaporation “structures are set up to have different geometries, different angles, different heights, all these different parameters that we are varying across these structures to get quantitative data of evaporation in low gravity,” according to Kyle Viestenz, co-investigator for the project.

“If you could do controllable evaporation in space, you could do all kinds of things” said Mark Weislogel, one of the project’s principal investigators.  “You could evaporate urine and recover all of the water. All of it. If you had a way of holding the liquid in a passive, no-moving-parts way like a puddle does on earth, but in space, then you could do a lot of unique processing, safely and with no maintenance.”

Contractor held in hand.

Capillary Sorbent contactor with channels to expose liquid to ambient air. Credits: IRPI LLC

Another part of the investigation demonstrates the use of fluids in a carbon dioxide removal system, called the Carbon Dioxide Liquid Sorbent System. This system uses a network of “water falls” to bring a material used to absorb gases, into contact with air, allowing the carbon dioxide to be carried away by the liquid. In a microgravity environment, the liquid does not “fall,” but is driven by surface tension forces generated passively by the unique surface geometry of the capillary structures.

It is unknown if or when this technology would be deployed.

Further Information:

tanks and components mounted on three racks

NASA ISS water recovery equipment at Marshall Space Flight Center. Credit: SustainSpace.

Airbus ESA Advanced Closed Loop System (ACLS)

Two technicians point to large instrument box.

ACLS technology demonstrator generates oxygen and water in a closed system

The Advanced Closed Loop System (ACLS) is an advanced life support system that has been developed by Airbus for the European Space Agency (ESA) to be used as a technology demonstrator on the ISS, in the Destiny module, from summer 2018. The ACLS will be installed in the HTV-7 space transporter at the Tanegashima Space Center in Japan and is due to be transported to the ISS in August 2018. It is set to be operated for a period of one year.

The ACLS will purify air and produce oxygen for the International Space Station (ISS). Specifically, the ACLS extracts a portion of the carbon dioxide in the cabin atmosphere. Then, using hydrogen obtained from splitting water molecules, it will convert the carbon dioxide into methane and water in what is known as the Sabatier process. Oxygen is then produced from this water using electrolysis. Airbus asserts that this will increase overall system efficiency and hence reduce the need for supplies from Earth.

The main advantage claimed for the ACLS is the use of the adsorbent Astrine, a solid amine resin, which has a high adsorption capacity even at the carbon dioxide levels in the cabin air. The ACLS will be contained in an International Standard Payload Rack (ISPR).

A future use for the ACLS may be for the Deep Space Gateway / Lunar Outpost. NASA is reported to be looking to the ESA for part of the habitat.


Orbital Genomics concept

In addition to blogging, SustainSpace engages in concept and product development. SustainSpace authors Afshin Khan and Mark Ciotola have developed the Oribital Genomics venture converted with astro culture. Recently, the Orbital Genomics concept won ESA Space Explorations Masters prize. 


Plants provide food, breathable air and psychological benefits. With plans materializing for a Deep Space Gateway, Lunar Village and the Mars community, there may be a lot more people living in the lower Earth orbit and microgravity environments, besides on the International Space Station. However, food production in space is still in its nascent stage. Existing prepackaged astronaut food is not a healthy option for long haul space missions. There is no way to regularly transport fresh fruit and vegetables. It is becoming increasingly evident that we must be able to successfully grow food in space.

Plant experiments done on ISS have presented various challenges, such as, years of preparation, little iteration and fewer conclusive results. Furthermore, ISS is limited in its genetic analysis capabilities and there are limited astronaut hours for dedicated biological analysis. Hence, for at least the next decade or more, most analysis of plants and seeds grown in space must be accomplished on Earth, which is not feasible.


Agile approaches by Orbital Genomics aims to adapt, develop and finally grow crops in space to solve the food production challenge in lower Earth orbit and planetary bodies of interest. Additionally benefit agriculture on Earth.

Loop where seeds are launched into space, plants returned to Earth, and successive generations launched.

Concept for rapid evolution of plants for adaptability in space environments.

Market Strategy

We also aim to enter the market as an “astroculture uber-service” for citizen scientists, farmers and agricultural companies, who would be provided with a platform for developing space adapted crops and gaining from space treated crops, to adapt in various challenging conditions on Earth, due to climate change and drought.

Rows representing experiments

Sample dashboard for astroculture-as-a-service concept

Circles containing crops are superimposed on squares containing dry, unplanted or fallow land.

SustainSat brings satellite approaches to Earth

SustainSat is a platform that can be used as either a prototype for CubeSats or as an Earth-based sensor and data-logging platform. It is intended as a low-cost, barebones way to learn about the general categories of technologies used in cubesats as well as to use those technologies for sustainability purposes on Earth.

SustainSat is built around the Arduino prototyping platform. It is different from ArduSat in that it is not specifically set up for use in space. SustainSat technology can be adapted for space, such as through ArduSat. However, SustainSat provides devices ready for use on Earth or on balloons and kites. It is perhaps the lowest-cost, simplest way to explore satellite technology in a sophisticated way, while empowering users to create and adapt real devices.

The simplest form of SustainSat is a simple light monitor, such as for sunlight, combined with an inertial unit. Such a device is similar to a real device that monitors solar luminosity, or a 1 pixel space telescope. It provides guidance data for potential reaction wheels or thrusters.

More sophisticated forms of SustainSat include wireless transmitting and data logging capabilities, as well as other sensors. A version of SustainSat that can capture hyperspectral information is under development.