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Curriculum for Astrochemical Engineering

An engineer pondering chemical processes for use in space learned in an advanced postgraduate course in Astrochemical Engineering. Credits: DALL∙E 3

In a paper in the journal Sustainability a global team of researchers has created a two year curriculum to train the next generation of engineers who will design the chemical processes for the new industrial revolution expected to unfold on the high frontier in the next few decades.

Current chemical engineering (ChE) training is not adequate to prepare the next generation of leaders who will guide humanity through the utilization of material resources in space as we expand out into the solar system.

Astrochemical Engineering is a potential new field of study that will adapt ChE to extraterrestrial environments for in situ resource utilization (ISRU) on the Moon, Mars and in the Asteroid Belt, as well as for in-space operations. The body of knowledge suggested in this paper, culminating in Master of Science degree, will provide training to inform the design ISRU equipment, life support systems, the recycling of wastes, and chemical processes adapted for the unique environments of microgravity and space radiation, all under extreme mass and power constraints.

The first year of the program focuses on theory and fundamentals with a core module teaching the physical science of celestial bodies of the solar system, low gravity processes, cryochemistry (extremely low temperature chemistry), and of particular interest, circular systems as applied to environmental control and life support systems (ECLSS) to recycle materials as much as possible. Students have the option to specialize in either process engineering or a more general concentration in space science.

For the process engineering option in year one, students will learn how materials and fluids behave in the extreme cold of space. This will include the types of equipment needed for processes in a vacuum environment including microreactors and heat exchangers, as well as methods for separation and mixing of raw materials.

In the space science specialization, year one will include production of energy and its utilization in space. Applications include solar energy capture and conversion to electricity, nuclear fission/fusion energy, artificial photosynthesis, and the role of energy in life support systems.

In the second year, students learn basic chemical processes for ISRU on other worlds. Processes such as electrolysis for cracking hydrogen and oxygen from water; and the reactions Sabatier, Fischer-Tropsch and Haber-Bosche for production of useful materials.

The second year process engineering specialization focuses on ISRU on the Moon with ice mining, processing regolith and fluid transport under vacuum conditions. Propulsion systems are also covered including methane/oxygen engines, hydrogen logistics, cryogenic propellent handling in space and both nuclear thermal and electric propulsion. Space science specialization in year two covers life support systems and space agriculture.

A design project is required at the end of each year to demonstrate comprehension of the concepts learned in the curriculum, and is split between an individual report and a group project.

Coupled with synthetic geology for unlocking a treasure trove of space materials in the Periodic Table, innovative equipment for ISRU on the drawing board and research on ECLSS, Astrochemical Engineering will be a valuable skill set for the next generation of pioneers at the dawn of the age of space resource utilization.

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Lunar-derived propellant fueling a cislunar economy may be competitive with Earth

AI generated image depicting a propellant factory on the Moon. Credits: DALL-E

The economics of an in-space industry based on lunar-derived rocket propellant was examined by Florida Space Institute planetary physicist Philip Metzger in a prepublication paper submitted to arXiv on March 16 . The study will be published in the June issue of Acta Astronautica. Many skeptics of this approach believe that with launch costs plummeting, driven down primarily due to reusability pioneered by SpaceX, it will be cheaper to power the nascent cislunar economy with propellant launched from Earth rather then fuel derived from lunar ice mining.

In his analysis, Metzger examines a cislunar economy of companies that operate geostationary satellites which need to purchase boost services using orbital transfer vehicles fueled by cryogenic hydrogen and oxygen. The question is, would sourcing H2/O2 from ice mined on the Moon be competitive with launching propellant from Earth. He notes that previous studies that favored Earth to solve this problem were flawed because they compared the different technologies for mining water on the Moon (e.g. strip mining, borehole sublimation, tent sublimation, or excavation with beneficiation) rather than analyzing the economics of the cis-lunar economy as a sector.

With that approach in mind, Metzger develops an economic model with figures of merit to assess how various technologies for ice mining compare to Earth sourced propellant. One such parameter is the “gear ratio” G, which in the parlance of orbital dynamics, is the ratio of the mass of hardware and propellant before versus after moving between two locations in accordance with the rocket equation. The other key metric is the production mass ratio Ø, which is the mass of propellant delivered to a specific location divided by the mass of the capital equipment needed to produce the fuel.

The “tent sublimation technology” mentioned in the paper was invented by George Sowers and is featured in his 2019 NIAC Phase I Final Report on ice mining from cold bodies in the solar system covered by SSP previously.

Although G is constrained by the laws of physics, reasonable values are possible and a value of Ø ≥ 35 is the threshold above which lunar propellant wins out. The tent sublimation technology is estimated to have Ø over 400, an order of magnitude higher than the minimum to gain an advantage. Metzger’s new approach took into account that launch costs will eventually come down as far as possible but even then, found that lunar propellant can be produced at a competitive advantage. The only caveat is validation of the TRL and reliability of ice mining technologies.

“Lunar-derived rocket propellant can outcompete rocket propellant launched from Earth, no matter how low launch costs go.”

Although not included in Metzger’s study, a method for extraction of water from lunar regolith is heating by low power microwaves. A recent study found that this technology is effective for extracting water from simulated lunar soil laced with ice. It would be interesting to see if Ø for this technique exceeds the advantage threshold.

Developing the business case for lunar water is the first step in rapidly bootstrapping an off-Earth economy.  Metzger has written about this previously where he sees robotics, 3D printing and in situ resource utilization being leveraged to accelerate growth of a solar system civilization.

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Where is the mother lode of space mining? The Moon or near-Earth asteroids?

Conceptual rendering of TransAstra Honey Bee Optical Mining Vehicle designed to harvest water from near-Earth asteroids: Credits: TransAstra Corporation

Advocates for mining the Moon and asteroids for resources to support a space based economy are split on where to get started. Should we mine the Moon’s polar regions or would near-Earth asteroids (NEAs) be easier to access?

Joel Sercel, founder and CEO of TransAstra Corporation, is positioning his company to be the provider of gas stations for the coming cislunar economy. In a presentation on asteroid mining to the 2020 Free Market Forum he makes the case (about 10 minutes into the talk) that from an energy perspective in terms of delta V, NEAs located in roughly the same orbital plane as the Earth’s orbit may be easier to access for mining volatiles and rare Earth elements.

Scott Dorrington of the University of New South Wales discusses an architecture of a near-Earth asteroid mining industry in a paper from the proceedings of the 67th International Astronautical Congress. He models a transportation network of various orbits in cislunar space for an economy based on asteroid water-ice as the primary commodity. The network is composed of mining spacecraft, processing plants, and space tugs moving materials between these orbits to service customers in geostationary orbit.

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Illustration depicting the layout of a transportation network in an asteroid mining industry in cislunar space. Credits: Scott Dorrington

On the other side of the argument, Kevin Cannon of the Colorado School of Mines in a post on his blog Planetary Intelligence lays out the case for the Moon being the best first choice. All of the useful elements available on asteroids are present on the Moon, and in some cases they are easier to access in terms of concentrated ore deposits. Although delta V requirements are higher to lift materials off the Moon, its much closer to where its needed in a cislunar economy. Trips out to a NEA would take a long time with current propulsion systems. In addition, he thinks mining NEAs would be an “operational nightmare” as most of these bodies are loose rubble piles of rocks and pebbles with irregular surfaces and very low gravity. This makes it hard to “land” on the asteroid, or difficult to capture and manipulate them. In an email I asked him if he was aware of SHEPHERD, a concept for gentle asteroid retrieval with a gas-filled enclosure which SSP covered in a previous post, but he had not heard of it. TransAstra’s Queen Bee asteroid mining spacecraft has a well thought out capture mechanism as well, although this concept like SHEPHERD are currently at very low technology readiness levels.

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SHEPHERD-Fuel variant harvesting ice from a NEA and condensing it into liquid water in storage tanks, then subsequent separation into hydrogen and oxygen (top). These tanks become the fuel source for a self-propelling tanker block (bottom) which can be delivered to a refueling rendezvous point in cislunar space. Credits: Concept depicted by: Bruce Damer and Ryan Norkus with key design partnership from Peter Jenniskens and Julian Nott

Cannon also makes the point that there is very little mass in the accessible NEAs when compared to the abundance of elements on the Moon.

“There’s more than enough material for near-term needs on the Moon too, and it’s far closer and easier to operate on.”

Finally, he believes that the Moon would be a better stepping stone to mining the asteroids then NEAs would be. This is because most of the mass in the asteroid belt is located in the largest bodies Ceres and Vesta. Operations for mining on these worlds would be more akin to activities on the Moon then on near-Earth asteroids.

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Image of Vesta taken from the NASA Dawn spacecraft. Credit: NASA/JPL

What about moving a NEA to cislunar space as proposed by NASA under the Obama Administration with the Asteroid Redirect Mission? Paul Sutter, an astrophysicist at SUNY Stony Brook and the Flatiron Institute, investigates this scenario and suggests that at least the argument for these asteroids being too far away might be mitigated by this approach, although it would take a long time to retrieve them using solar electric propulsion, as recommended in the article. The trip time might be reduced with advanced propulsion such as nuclear thermal rockets currently under investigation by NASA.

It should be noted that TransAstra has both bases covered. They are working on innovations such as their Sun Flower™ power tower for harvesting water at the lunar poles as well as the company’s Apis™ family of spacecraft for asteroid capture and mining of NEAs.

Conceptual illustration of TransAstra’s Sun Flower™ power towers collecting solar energy above a permanently shadowed region on the Moon to provide power for ice mining operations. Credits: TransAstra Corp.

Update 28 August 2021: Take a deep dive into TransAstra’s future plans with Joel Sercel interviewed by Peter Garretson, Senior Fellow in Defense Studies at the American Foreign Policy Council podcast Space Strategy.

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Power towers at the Peaks of Eternal Light

Peaks of Eternal Light at the lunar south pole annotated with crater labels. Mosaic of 40 images taken by the ESA SMART-1 spacecraft 2005/2006. Area covers 500 x 150 km. Credits: ESA/SMART-1/AMIE camera team; M. Ellouzi/B. Foing, CC BY-SA 3.0 IGO

As most space settlement enthusiasts know, the Peaks of Eternal Light on the rims of craters in the lunar polar regions hold much promise as the ideal location to place collectors for solar energy to power ice mining operations. At the south pole in particular, these peaks lie within just a few kilometers of large frozen water deposits in the permanently dark shallows. But how much solar power is available? Companies such as Trans Astronautica Corporation will want to know so they can inform plans for their Sun Flower™ collector invention as part of a Lunar Polar Mining Outpost.

In a paper posted this month on the pre-print server arXiv.org, a team of researchers at Harvard University and Technische Universität Berlin present the results of a study to answer this question. Using data from high resolution maps of solar illumination on the ridges of Shackleton crater and others, they determined the total available power from collector towers of various heights if they were placed at these locations.

The study found that the power available depends heavily on the height of the panels above the local surface but could be substantial, from a few megawatts for towers of heights less than 100m up to the gigawatt range for towers of 500m or more. This is sufficient power for mining several thousand tons of water per year from Shackleton crater.

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Where should we get oxygen on the Moon?

Artist impression of activities at a Moon Base which could include oxygen production. Credits: ESA – P. Carril

Kevin Cannon of the Cannon Group at the Colorado School of Mines can help find the answer. In a recent post on his Planetary Intelligence blog, the Assistant Professor of Geology and Geological Engineering describes a trade study comparing extraction of oxygen from regolith such as Metalysis’ ESA funded study to getting O2 from ice mining at the lunar poles as favored by NASA. Nothing stands out from a cursory look at the pros and cons of each approach.

In a more data driven analysis to compare apples to apples, Cannon examines energy costs of mining oxygen and plots it against the amount of bulk material that has to be processed to produce an equal amount of O2 from different sources ranging from plain silicate regolith to various grades of water ice endmembers. The analysis even includes processing material from various types of asteroid resources. The types of ice/regolith mixtures can vary widely as described in one of Cannon’s tweets.

Artist’s impression of different types of water ice / regolith endmembers. Credits: Lena Jakaite / strike-dip.com / Colorado School of Mines

Cannon’s analysis reaches the conclusion that “At 1.5-2% water by weight, icy regolith is essentially on par with O2-from-regolith on a joule for joule basis. In other words, if you had a pile of icy regolith already sitting on the surface, it makes sense to throw it out if the grade is less than about 1.5% and extract oxygen directly from the silicate regolith instead.”

More brilliance from the mind of Kevin Cannon can be found in these posts: Want to eat like a Martian in an environmentally friendly manner?, The logistics of dining off Earth, SpaceX will need suppliers for Mars settlement, The accessibility of lunar ice. And of course, don’t forget to visit kevincannon.rocks.

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NASA’s measurement plan for a lunar water reserve

Diagram depicting NASA’s Lunar Water ISRU Measurement Study (LWIMS). Credits: NASA

NASA just published a Technical Memorandum on its Lunar Water ISRU Measurement Study (LWIMS). The TM describes the establishment of a measurement plan for identification and characterization of a water reserve on the Moon. This program would support the Artemis program to achieve a sustainable lunar presence by 2028.

Three primary data inputs feed information into the system. First, predictive modeling provides a ‘water favorability’ index to map out locations on the Moon with water ice potential. This algorithm is fed data by orbital measurements providing information on a regional scale. It is critical that this orbital data is interpreted properly for water-favorable sites on the Moon. To ensure accuracy, lunar landers will take surface measurements in a series of three phases: mobile reconnaissance for validation of the predictive model, focused exploratory missions to verify water’s presence and final reserve mapping to inform an ISRU ice mining plant by 2028.

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Eta Space snags $27 million Tipping Point award to study space based cryogenic propellant depot technologies

Artist rendering of LOXSAT 1, a demonstrator satellite for a cryogenic oxygen fluid management system. Credits: Eta Space

A small Florida Space Coast start up founded by NASA employees called Eta Space was just awarded a 2020 NASA Space Technology Mission Directorate “Tipping Point” contract to develop the first low Earth orbit cryogenic propellant depot. Management of cryogenic fuels is a key technology for storing propellent in space, which will be a component of a transportation infrastructure supported by in situ resource utilization such as ice mining on the moon for processing into rocket fuel. A key focus of the work by Eta Space will be standardization of equipment interfaces allowing multiple customers to tap into storage capability on orbit.

Eta Space’s LOXSAT 1 mission concept will test a range of cryogenic fuel management processes in space over 9 months specific to liquid oxygen management. LOX is a common oxidizer used across multiple propellant systems by several launch providers and is the heaviest cryogenic fluid needed by most customers.

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Intuitive Machine’s PRIME-1 ice mining drill to be delivered to the Moon by 2022

Illustration of Intuitive Machines’ Lunar Lander. Credits: Intuitive Machines

As part of the Commercial Lunar Payload Services (CLPS) initiative, NASA has selected Intuitive Machines to deliver ice harvesting equipment called Polar Resources Ice Mining Experiment (PRIME-1) to the Moon’s south pole. In a press release from yesterday, Intuitive stated that the instrument package includes a drill to excavate ice ladened regolith and a mass spectrometer to characterize the volatiles, the data from which will be used by the VIPER mission to follow shortly thereafter. Knowing how much water is available and how accessible it is will inform subsequent in situ resource utilization efforts needed for sustainable human outposts planned for later this decade.

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Student concept for a crewed lunar rover in support of Artemis

Image depicting EMPRESS. Credits: SEDS-UPRM

When the first woman and next man return to the Moon under the Artemis Program, they will need a mobile scientific platform to assist with exploration of the lunar south pole. Under the Revolutionary Aerospace System Concepts – Academic Linkage (RASC-AL) competition, a team of Students for the Exploration and Development of Space (SEDS) at the University of Puerto Rico, Mayaguez (UPRM) won 1st Place in the contest with their Exploration Multi-Purpose Rover for Expanding Surface Science (EMPRESS). The rover would land at Shackleton crater at the lunar south pole in 2023 taking samples and exploring the region in preparation for the first crewed Artemis mission in 2024.

The rover is envisioned to include two robotic arms and a suite of seven scientific instruments to characterize the lunar surface composition as well as other high priority astrophysical investigations. One the proposed instruments is a neutron spectrometer that could sense the amount of hydrogen in the regolith using data from maps compiled by the Volatiles Investigating Polar Exploration Rover (VIPER) which will survey the lunar south pole for the presence of volatiles and water ahead of the Artemis Missions. This could pave the way for ice mining operations and eventual space settlements in a cislunar water economy.

University of Puerto Rico at Mayagüez winning SEDS team of the 2020 RASC-AL Virtual Forum. Credits: RASC-AL

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Human missions to Mercury and Saturn augmented by in situ resource utilization

A nuclear thermal rocket concept. Credits: NASA/Wired

In a paper presented at the 8th Symposium on Space Resource Utilization (2016), Bryan Palaszewski analyzes multiple mission architectures for human voyages to the inner and outer solar system. The planet Mercury has permanently shadowed craters at its poles which likely contain frozen water enabling ice mining for rocket propellant and oxygen for breathable air to sustain settlements. The outer planets and their moons are reservoirs of significant amounts of useful gases such as hydrogen, helium 3, methane, ethane, and ammonia which can be utilized as in-situ resources. Through nuclear propulsion and living off the land with ISRU, travel times can be reduced and payloads increased for both robotic and human missions. With a positive vision for eventual space settlement, Palaszewski concludes the paper with “These technological innovations will enable Krafft Ehricke’s vision of a polyglobal civilization“.