Newsletter Articles 2024

January ~ Are We Alone?

Have you ever looked up into the canopy of stars on a clear night and wondered, are we alone? Surely, among the estimated 400 billion stars in our own galaxy, there must be someone on a planet orbiting a far-flung star looking back and asking the same question. The Star Wars, Star Trek and Avengers Infinity series franchises with their plethora of intelligent aliens and huge box office success, suggests that I’m not alone in my musing.

Assuming at least one planet per star (a VERY conservative estimate) gives us 400 billion planets. If the actual average is two or more worlds per sun, the number of potential planets blossoms into the trillions. Of those trillions, astronomers have confirmed the existence of over 5,500 exoplanets to date.

But so far, we have no substantiated sightings of little green men (or women). No neon billboards orbit Risa advertising vacation condo deals. No Ravagers interdict our missions to the Moon or Mars.

But that’s not to say we aren’t trying. SETI (Search for Extra Terrestrial Intelligence) projects have existed since the mid-1950s. They typically utilize large radio telescopes and telescope arrays, listening in on galactic quadrants for electromagnetic signals attributable to a technologically advanced civilization. Projects range in size from The Ohio State University Radio Telescope (now decommissioned), to the 1000-foot diameter Aricebo Telescope (also decommissioned) to the Allen Telescope Array in northern California.

To date, no signals have been detected that could be attributed to anything other than natural phenomena. However, AI is now being utilized to filter out Earth-borne transmissions that might mask the faint signals originating from light years away.

So, what about that exoplanet survey mentioned earlier? Astronomers are beginning to bring tools to bear that may indicate life (whether intelligent or not) exists on these distant orbs. The most promising is atmospheric gas spectroscopy. Certain gases and combinations can only be attributable to biological activity. Here on Earth, molecular oxygen only exists due to photosynthesis. Scientists hope that assaying the atmospheres of exoplanets will reveal the presence of life.

Closer to home, in April, 2023, the European Space Agency launched the Jupiter Icy Moons Explorer, or JUICE. It will spend at least three years at Jupiter’s satellites Ganymede, Callisto and Europa. These Jovian moons are all believed to harbor vast liquid water oceans beneath their shells of ice. In October 2024, NASA will launch a robotic spacecraft named Europa Clipper to that moon. Currently NASA’s Juno spacecraft is orbiting Jupiter with close flybys of Europa and Ganymede.

The combined geologic, and molecular analyses of these missions hope to reveal indicators of life, if any. But life, if found, is expected to be simple, like single-celled archeae or self-replicating molecules.

The Curiosity rover, exploring Gale Crater, discovered that ancient Mars had the right chemistry to support living microbes. It found sulfur, nitrogen, oxygen, phosphorus and carbon—key ingredients necessary for life—in the powder sample drilled from the Sheepbed mudstone in Yellowknife Bay. Mudstones also allude to the persistent presence of water, another requirement for life.

Elsewhere on the Red Planet, the Perseverance rover is searching Jezero Crater for signs of ancient microbial life. The rover’s drill collected core samples of Martian rock and soil but they must be examined microscopically for evidence of microfossils or biochemistry. Unfortunately, the cost to retrieve these samples by a future mission and ferry them back to Earth for detailed analysis has mushroomed. Cancellation of the Mars Sample Return mission is possible. So far, there is no definitive confirmation of past life, even simple life, on Mars.

What are the odds that one day we’ll find ourselves face-to-face with extraterrestrial intelligent life? As yet, scientists still can’t create life in a test-tube, so it’s not possible to calculate. But the longer that search goes on, the lower the odds get for the spontaneous generation of life. And as we are finding out, the universe is hostile to life. Star flares, radiation, heat and cold, asteroid and comet bombardment—these could snuff out early stages of biological activity even before it has a chance to start.

Yeah, but what about all those Unidentified Anomalous Phenomena (UAPs)? Recall that in 2022 the Department of Defense created the All-domain Anomaly Resolution Office (AARO) to report its findings on such sightings.

For decades, credible people both inside and outside of the US military have reported witnessing UAPs. Historically ignored by the DoD, or perhaps quashed, the lack of transparency fueled all manner of conspiracy theories: the government is suppressing the existence of aliens, it’s hiding its possession of alien tech and materials. The popularity of the X-Files series tapped into that fervor.

So far, none of the annual reports by the AARO attribute any sightings to extraterrestrial activity. They are typically attributed to natural phenomena, equipment glitches, or observer fatigue, state of mind, etc. However, some analyses are not released, designated as classified.

The public frustration built to the point that congress finally acted. But the UAP Disclosure Act gives departments so much latitude about what they release to the national archives, that little is expected to change. So the madness continues… But applying Occam’s Razor to this situation, it’s more likely the nondisclosures are related to experimental aircraft or could reveal classified activities/capabilities of the US military, or what we know about those of other countries.

When I was younger, I was certain that we would make first contact within my lifetime. But as our search continues to yield null results, I am less sure. It could take centuries to meet our neighbors, if we ever do.

So, given what we know today, are we alone in the universe? I see five possibilities, listed, in my estimation of likelihood.

1) No one is out there. We really are alone. All the evidence in fact supports this conclusion. But I also acknowledge that while the spontaneous origin of life is infinitesimal, it’s not zero. Which leads me to…

2) Intelligent life is out there but it’s less common (more dispersed) than we thought. Put another way, the occurrence of life within the galaxy will be proportional to that miniscule probability. Of those nearly half-trillion star systems, only a handful would support sentient life. Separated by thousands of light years, and the so-far inviolable constraints of the speed of light, it’s unlikely we would ever meet any extraterrestrial civilizations.

3) Intelligent life is out there but they don’t use a radio spectrum to communicate. One of my takeaways from reading Adrian Tchaikovsky’s Children of Time series is that communication can take on many forms, some of which aren’t amenable to radio broadcast. Some transmission tech may be outside the spectra that SETI analyses. Just this year, NASA tested laser communication between Earth and the Moon. Not only is it outside said radio spectrum, it’s also highly targeted. If your receiver lies outside the coherent laser beam, you never detect a transmission.

4) Intelligent life is out there but they are strategically quiet, malicious and predatory ala Independence Day, Predator or Alien. To paraphrase Orson Wells, they view us from afar, intellects vast, cool and unsympathetic, regarding this Earth with envious eyes, slowly and surely drawing their plans against us… There are more examples of this in nature than we can count: Burmese pythons gobble up native Everglades animal species, Scott’s Broom and Himalaya Blackberry choke out prairie habitat in western Washington and Oregon, invasive carp displace native fish across the United States. It’s difficult to believe the rules of natural selection won’t apply to all corners of the galaxy, which leads us to my final and most likely surmise.

5) Intelligent life is out there but they avoid us because WE are the malicious, predatory ones. The history of Homo sapiens is a violent one vis-à-vis our hominid cousins. Wherever our species expanded, prior occupants have disappeared, leaving traces of their genome within us, the spoils of war. Homo neanderthalensis, Homo sapiens ssp Denisova, Homo floresiensis, Homo erectus. They’ve all succumbed to the “superior” species.

With no others to compete with, we turn on ourselves. Warfare and violent conflict seem baked into our very DNA. We fight over scarce resources (the premise of my EPSILON SciFi Thrillers). In this scenario, alien minds are vast, but peaceable. And so they watch, and wait, for that day when Homo sapiens sheds the genes that make it so aggressive, so dangerous.

Sadly, this means I won’t see my cosmic neighbors within my lifetime. But perhaps when we are finally led by our better angels, we’ll truly see for the first time the wonders of the cosmos.

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Want a deeper dive? Check out these sources.
https://en.wikipedia.org/wiki/Milky_Way
https://phys.org/news/2016-10-planets-galaxy.html
https://en.wikipedia.org/wiki/Search_for_extraterrestrial_intelligence
https://www.scientificamerican.com/article/will-an-ai-be-the-first-to-discover-alien-life
https://www.defense.gov/News/Releases/Release/Article/2314065/establishment-of-unidentified-aerial-phenomena-task-force/
https://www.defense.gov/News/Releases/Release/Article/3561843/statement-by-pentagon-press-secretary-brig-gen-pat-ryder-on-the-annual-report-o/

February ~

No article was available for this month.

March ~ Atmospheric Life Support on Mars

Of all the essentials of life, oxygen (O2) is the most important. Korean Haenyeo divers can hold their breath for over three minutes. But for the rest of us, hypoxia, the sudden loss of O2, results in unconsciousness within seconds.

Carbon dioxide (CO2) in elevated concentrations is toxic. Ten percent renders us unconscious. Nitrogen (N2), the majority atmospheric constituent, is critical for long-term sustainment of life. Water, in the form of rain and snow is vital on Earth, but in a confined space containing electronics it can pose serious risks.

The regulation of these gases on board spacecraft and future bases on the Moon and Mars is accomplished by a chain of chemical reactions. For our discussion, let’s begin with the respiration of a glucose molecule by a crew member.

When metabolized, this six-carbon sugar provides the energy that makes life possible. Our crew member exhales the byproducts, CO2 and water. In the closed quarters of the International Space Station (ISS), accumulating CO2 quickly becomes life-threatening. Exhaled water condenses in electronics, increasing the risks of short circuits and/or fire.

Glucose and oxygen metabolism is represented with the following chemical equation:

C6H12O6 + 6O2 → 6CO2 + 6H2O

When it was first deployed, the ISS employed a CO2 scrubber. Lithium hydroxide absorbed the gas and then vented it into space. Water vapor was collected and added to the water recycling system.

The O2 used up in respiration was replenished through water electrolysis. The hydrogen (H2)generated was also vented. Because only half the water required to maintain O2 levels was recycled, regular supplemental shipments were flown to the ISS.

Here is the chemical reaction of electrolysis:

6H2O(recycled) + 6H2O(supplemental) → 6O2 + 12H2

In 2010 this wasteful environmental system was partially addressed with the Advanced Closed Loop System (ACLS). By adding a Sabatier reactor, the ACLS combined the CO2 from respiration with the H2 left over from electrolysis, yielding water and methane (CH4).

Today, the water added by the Sabatier reactor is returned to the electrolysis process. Only the methane is vented into space. However, each molecule vented represents the net loss of two H2 molecules. H2 is routinely shipped to the ISS to make up for what is wasted.

Here is the Sabatier chemical equation:

6CO2 + 12H2(from electrolysis) + 12H2(supplemental) → 12H2O + 6CH4

This system works well for orbital facilities that can be readily resupplied with H2. That might even include future long-term lunar missions, where resupply from Earth is a three-day flight away.

But for flights to Mars, and Red Planet surface bases, NASA is evaluating adding methane pyrolysis to completely close the loop. Heating CH4 to 1200 degrees Celsius in a steel reactor vessel dissociates it into its constituent elements, atomic carbon and H2.

The solid carbon can be removed from the chamber and used to create organic compounds, or for graphene, the precursor of carbon fiber. The H2 can be returned to the Sabatier process, eliminating shipments of supplemental H2. Look for a pyrolytic system to be tested on the Lunar Gateway orbital station, or one or more continuously occupied Moon bases.

Here is the CH4 pyrolysis reaction at 1200 degrees C:

6CH4 → 6C + 12H2

Another atmospheric gas that must be closely regulated and cycled is N2. It is vital for two reasons. First, it dampens the combustion potential of a pure oxygen atmosphere. Second, nitrates are essential fertilizers for agriculture. Without it, colonists will be unable to grow the crops required to be self-sustaining.

Here on Earth, we tend to regard N2 as inert. We don’t metabolize it like we do oxygen. We even eliminate it in limited circumstances. Hospitalized patients in respiratory distress are routinely administered pure O2.

However, pure oxygen in a closed cabin is flammable. The tiniest spark will initiate a conflagration that will burn until all available free O2 is used up.

I recall the Apollo 1 training disaster, when an electrical short circuit aboard the command module started an onboard fire. Technicians stationed outside were unable to open the capsule hatch quickly enough before the exterior paint began to blister from the intense heat generated inside. Astronauts Virgil Grissom, Edward White and Roger Chaffee perished in this tragedy. Ever since, NASA has utilized cabin atmospheres comparable to natural air—79% N2, 21% O2. Without N2, any Mars colony is doomed to suffer the same fate as the Apollo 1 mission.

But N2 is a necessity for another reason. In a process called the nitrogen cycle, N2 is converted to nitrate salts (NO3-), usually by bacterial metabolism. Nitrates are used by plants to generate proteins, nucleic acids, and other nitrogen-containing compounds. In the absence of nitrates, higher forms of life are not possible.

While the percentage of atmospheric N2 is low on the Red Planet, 2.7%, it can be collected by compressing the thin Martian air and screening it out of the predominant CO2. Watch for future NASA unmanned Mars missions to evaluate N2 collection systems. I’ll discuss the nitrogen cycle and applications in more detail in an upcoming edition of JOTH.

I describe the closed system in my first book, Crimson Lucre. In situ water is hydrolyzed for the Prospector Base air supply. The same process is performed externally to generate O2 and H2 for rocket propellant for the workhorse Ascent/Descent Vehicles.

In Crimson Lucre, the pyrolytic reaction chamber is hacked by shadowy Earthbound elements intending to destroy the facility. Only the quick thinking of commander Dallas Gordon prevents an explosion that would burst the base’s inflated domes.

In my second book, Red Dragon, mission geologist Dave Caraway figures out how to combine the leftover graphene with perchlorate from water purification to create explosives for the mining operation. Those compounds are repurposed as defensive weapons against Pang Xianjing, who establishes a secret garrison to finish the job of eradicating Prospector Base.

Dave re-employs his explosive recipe in book four, Red Planet Lancers, to defend the permanent base, Ep City, against Emperor Zhang Aiguo’s invading forces.

Who knew chemistry could be so entertaining? But here in the real world, watch for the basic environmental systems I described, or some variant thereof, to be tested on the Moon and deployed on Mars.

Want a deeper dive? Check out these sources.
https://en.wikipedia.org/wiki/ISS_ECLSS#:~:text=It%20uses%20electrolysis%20to%20produce,hydrogen%20is%20vented%20into%20space.
https://en.wikipedia.org/wiki/Sabatier_reaction
https://www.space.com/16903-mars-atmosphere-climate-weather.html#:~:text=According%20to%20ESA%2C%20Mars’%20atmosphere,therefore%20cannot%20breathe%20Martian%20air.
https://www.nasa.gov/mission/apollo-1/#:~:text=Apollo%201%20Tragedy&text=AS%2D204).-,The%20mission%20was%20to%20be%20the%20first%20crewed%20flight%20of,the%20command%20module%2C%20or%20CM.

April ~ Water Recycling on Mars

Water is essential for life. A typical adult drinks a liter per day to maintain their health—two or more liters in hot desert conditions. Americans consume almost 400 liters per person per day for drinking, cooking, washing clothes and bathing.

Water use aboard the International Space Station is more constrained. Astronauts get by with about four liters per day for drinking, cooking, tooth brushing, and general hygiene. Personal water use in a Mars base will be similarly restricted, with the caveat that any long-term occupancy will require this life-giving fluid to grow crops—lots of it.

Early missions—two month’s duration on-planet—will bring their own water. Alternately, water, food and medical supplies will be prepositioned, shipped with the habitat modules. But as missions extend and bases are permanently occupied, an alternate supply will be needed.

We think of the Red Planet as an arid world, but that only holds true for the liquid phase. The North Polar ice cap contains as much as 300,000 cubic miles of water ice. Hellas Planitia, the setting for the EPSILON series, may at one time have contained an ocean. Today, vast glaciers are believed buried under up to a kilometer of dust and regolith. Even in equatorial regions, water ice lurks underground or in always shaded areas. It makes more sense to mine ice and melt it than it does to transport what’s needed for along-term presence from Earth.

But all that Martian water comes with impurities. Soils, dust, and ice are all contaminated with perchlorates. These toxic powerful oxidizers are chemically comparable to chlorine bleach. In addition to perchlorates, all that dust blowing around contains plenty of heavy metals. The Red Planet’s water, before it can be used, must be purified. And once it’s been consumed, it will have to be purified again to filter out urine salts.

The ISS utilizes a two-tier reclamation system unimaginatively called the Water Recovery System. The first subsystem collects vapor from breath and sweat in a dehumidifier. From there it’s condensed and directed to the Water Processing Unit which produces potable water.

A second component, the Urine Processor Assembly, uses vacuum distillation to extract water vapor. The concentrated brine is then osmotically filtered. The purified liquid that collects on the membrane surface is heated, vaporized and added to the WPU, leaving the salts behind. After adding iodine, the reclaimed water is returned to use by the crew.

It should be noted that even though the ISS recycles 98% of its water, all solid waste (poop) is either burned or flown to Earth for study. No closed loop there—yet.

So, what treatment method is most likely to be employed on Mars? Hauling mass to the Fourth Rock from the Sun will be an expensive proposition. That includes water. As a result, the amount will be highly constrained. Recycling systems on the ISS and refined on the Moon during the Artemis Program will recycle this precious commodity.

A pretreatment step to remove perchlorates and heavy metals will be needed if the base uses Martian ice for its water supply. I expect NASA will test to determine if perchlorates can be removed using the Urine Processor Assembly.

Unlike on the ISS, concentrated pee will become a resource on Mars. After garden modules are established to support long-term missions, it will serve as fertilizer. Care will have to be taken to exclude from waste water the heavy metals and perchlorates introduced into the habitats through EVAs. Those contaminants would render urine salts unusable.

I use humans to monitor these systems in the EPSILON SciFi Thriller Series. In reality, they’ll be monitored and regulated with AI as the size and duration of human presence on the Red Planet expands.

The next time you pour yourself a glass of tap water, consider what it would take to reuse it if that was all you got for months on end.

Next month’s topic: Thermal Management on Mars. ‘til then,

Want a deeper dive? Check out these sources.
https://www.nasa.gov/missions/station/iss-research/nasa-achieves-water-recovery-milestone-on-international-space-station/#:~:text=Each%20crew%20member%20needs%20about,hygiene%20such%20as%20brushing%20teeth.
https://en.wikipedia.org/wiki/Urine

May ~ Thermal Management on Mars

In the interest of full disclosure, I’m not an HVAC specialist. Nor was thermodynamics one of my stronger college courses. The calculations used here are top-of-napkin at best, using formulas found on the internet or that aforementioned thermo textbook. (Yup, It’s still on my shelf.) So if you happen to find a glaring error in my math or assumptions, please reply to this email and let me know about it. I’ll happily publish a correction in a subsequent edition.

Mars is cold. Really cold.

Hellas Planitia is the largest known impact crater on the Red Planet and in the solar system. At 9 kilometers deep, it’s also the lowest point. In the winter, when the air is coldest and most dense, atmospheric pressure is around 12 Pascals. While this is 12/1000ths Earth’s sea level barometric pressure, it’s still the greatest surface pressure on Mars.

The basin’s floor’s relatively mild climate still drops to -96degrees C ( -140 degrees F!) during a winter night. Keeping a habitat temperate enough for astronaut comfort will be critical to survival and mission success.

How much energy will it take to keep the first astronauts warm on such a night on that first expedition to Mars? We’ll dig into a bit of surprisingly simple math to find out.

But first, let’s review a few assumptions about our equipment. For our first mission, we’ll provide our intrepid explorers a 10-meter diameter dome structure for two months. Both weight and volume will be considerations for the Mars transit, so our habitat should be inflatable. An inflatable structure is lightweight and compressible. A continuous fabric dome will also have fewer seams to generate pressure leaks than a rigid geodesic structure with dozens of triangular panels.

Okay, our dome is standing. How much energy will it take to keep the interior at 20 degrees C (68 degrees F) when it’s – 96 degrees C outside? Here on Earth, the building construction industry relies on a term called the R-value to determine heating system capacity. A few simple formulas using R will provide our answer.

R-value: R = (K)(m2)/W (A value derived experimentally for a given material)

Heat Flow Rate: Φ = 1/R = W/(K)(m2) (The amount of heat energy lost per degree temperature difference per square meter)

Total Heat Flux: F = (Φ)(ΔT)(A) (The amount of heat energy lost through a structure for a given temperature differential)

Where:
ΔT = 96 + 20 = 116K (The temperature spread between our interior and exterior temperatures)

A = (4πr2/2) + (πr2) = (4(3.14159)(5)2/2) + (3.14159)(5)2 = 157.2m2 + 15.7m2 = 172.8m2 (The surface area of a 10m half sphere, our dome, plus the floor area)

All that remains now is to determine what material to look at for our dome. Here on Earth, outdoor adventurers and explorers routinely use an inflatable product that allows them to sleep comfortably on snow, no matter how cold the weather. The Thermarest company manufacturers several inflatable sleeping pads. One model, the NeoAir® XthermTM is a 3-inch thick matt with “Triangular Core MatrixTM construction and ThermaCapture Technology.” In layman’s terms, they’ve engineered the heck out of this product. We’ll pattern our walls after it.

Granted, I doubt it’s reasonable to use a woven nylon fabric for a Mars habitat. But a similar technology might be durable enough if the inside and outside surfaces were carbon fiber. The XthermTM has an R-value of 7.5. To make things simple, I’m neglecting the heat loss through the airlock.

I concede that the floor won’t be inflatable. Rather, it will need to be an airtight fabric with rigid lightweight panels set on top. For consistency let’s assign an R-value of 7.5 to minimize heat loss through the floor, a reasonable assumption for a rigid foam product. Given the floor is only 15.7 square meters, less than 10 percent of the overall structure, it shouldn’t take up much volume to ship. On to our calculations:

R = 7.5m2K/W
Φ = 1/R = 0.133W/(K)(m2)
F = (0.133 W/Km2)(116K)(172.8m2) = 2,666W

2,666 Watts. That’s a lot of energy. But thanks to our dome’s small size, it’s less than used by an electric water heater in an average American home.

What should we power our habitat heater with? The ISS relies on 2500 square meters of solar panels, over half the area of a football field, to generate the 75 kilowatts (75,000W) specified for its operations.

I’ve had difficulty nailing down energy allocation for the ISS, but a 1988 paper on space station power requirements recommended allocating 45 kilowatts for experiments, leaving the remaining 30kW for oxygen generation, water reclamation, air circulation, thermal regulation, etc. But the size and mass of the required panels, plus the batteries to store power for use at night, precludes solar power on Mars.

NASA has developed a compact 10kW nuclear reactor called a Kilopower Unit. They were designed with the Artemis and Mars programs in mind. While these devices are relatively heavy, they don’t take up much space. A typical unit is a six-foot tall cylinder, with a foldable ten-foot diameter umbrella-shaped heat dissipator. Four or five devices would suffice for a small first mission. More units could be flown in with subsequent missions to grow the base’s power generation capacity over time.

Their drawback is the Uranium-235 core. Fortunately, underground storage of spent cores on Mars is more straightforward than on Earth. The Red Planet lacks the liquid groundwater to dissolve and transport radionuclides like we experience here. Consider the massive on-going effort to clean up the contaminated groundwater at the Hanford Nuclear Reservation in Washington state. On Mars we can dump them in a hole and forget about them.

What about fusion? It’s certainly cleaner. Unfortunately, I firmly believe we’ll reach the Red Planet long prior to developing commercially viable fusion power generation here. Once we finally do, it will be another ten or twenty years before the components are miniaturized enough to ship a plant to Mars. I’m also doubtful about the availability of deuterium and tritium fuel. If that’s the case, fusion may not be viable there until the next century.

In the EPSILON SciFi Thriller Series, I assumed 40kW for Prospector Base, plus an additional 10 kW factor of safety. It seems reasonable, with an eye toward maximizing environmental equipment power efficiency, for our little dome to get by on 40kW.

The wild card could be the power source needed for any rover prepositioned for early missions. If it comes with its own radionuclide battery, it won’t be a drain on the base’s energy source. If it runs on hydrogen, utilizing either internal combustion or a fuel cell, the electrolysis of water for fuel will be a tremendous drain and may require additional Kilopower units.

In the meantime, the next time you grouse about throwing an extra blanket on your bed on a cold night, just imagine how much colder it would feel if it were minus 140 degrees F outside!

Happy Reading,

Want a deeper dive? Check out these sources.
https://www.energy.gov/energysaver/insulation#:~:text=R%2DValues,its%20thickness%2C%20and%20its%20density.
https://www.forbes.com/home-improvement/home/what-is-insulation-r-value/
https://en.wikipedia.org/wiki/R-value_(insulation)
https://www.nasa.gov/directorates/stmd/tech-demo-missions-program/kilopower-hmqzw/
https://www.rei.com/product/217085/therm-a-rest-neoair-xtherm-nxt-max-sleeping-pad
https://ntrs.nasa.gov/api/citations/19880011861/downloads/19880011861.pdf
https://en.wikipedia.org/wiki/Kilopower#:~:text=The%20prototype%20Kilopower%20uses%20a,to%20electricity%20by%20Stirling%20engines.

June ~ Food on Mars: Part 1

Earth and Mars are in opposition every two years. It’s only practical from a shipping perspective to fly supplies at that same frequency. That includes food. Let’s examine what it would take to feed a crew of astronauts for two years.

NASA cites a daily caloric need of 2500 to 3500 calories, depending on activity level and body size. Assume 3000 calories per day per astronaut. Assuming a long-term staff of ten, and a duration of two years, that’s a total of 21,900,000 calories between shipments for our intrepid explorers.

As far as preservation and storage goes, the space agency can and does use freeze-drying, vacuum sealing, gamma irradiation (to sterilize meat and dairy), refrigeration and freezing.

Diets must contain all the usual vitamins, minerals, protein, carbohydrates and fats. ISS astronauts take a daily multivitamin, too. In zero-g space, humans experience muscle and bone loss. NASA compensates with diets rich in protein and calcium. The same will be true on Mars, where gravity is 1/3rd that of Earth.

Given these nutritional requirements and storage methods, crewmembers aboard the ISS enjoy an astounding variety of foods. But that food comes at a cost: namely about 3.8 pounds per astronaut per day. Our supply ship must provide almost fourteen tons of food for our ten explorers.

The agency is experimenting with a yeast-based nutritional paste to use on long-term missions. An advantage is that it could be dried and shipped as a powder, eliminating the water weight. But living on such a diet would likely increase the psychological strain already experienced by the double whammy of tedium and close quarters. In my opinion, this might work as an emergency backup, but won’t be practical for the long-term. Missions will only be deemed successful if the astronauts return sane.

A lot can happen in two years. An engineer may underestimate the caloric needs of the community. The supply ship could encounter a technical failure. Heck, an unidentified asteroid could strike the vessel.

But there are other options for a long-term Mars mission to obtain nutrition. Red Planet explorers can grow their own crops.

Furthermore, as we’ll see below, agriculture on the Red Planet can, and should, sit at the crux of three critical environmental systems: the carbon, oxygen and water cycles. Plants can be just as critical to existence on Mars as they are on Earth.

How should astronauts farm their own food? I advocate using the Three Sisters method. This ancient practice of planting corn, beans and squash together was first utilized by pre-Columbian Native Americans. It yields an astounding 1774 calories per square foot. Assuming five harvests per year (the grow lights will be on 24/7), that’s 5,870 calories per square foot per year.

At 3,000 calories per day a human requires 1,095,000 calories per year. Doing the math, it will take 187 square feet of garden area per astronaut to provide enough nutrition. If they harvest four times per year, the required “acreage” is 233 square feet. Our crew of ten will need an indoor grow area of between 1,870 and 2,330 square feet. That could be accomplished with one 54-foot diameter dome (not advisable to put all one’s eggs in one basket),or three or four 30-foot diameter domes.

Similar to what I described for the habitat in the April ’24 edition of JOTH, a closed loop water recycling system will need to be set up for each agri-dome. Otherwise, irrigation will become contaminated with nitrate salts.

While water from transpiration and evaporation will likely condense on the dome wall and be collected at the base, a system similar to the Urine Processor Assembly on the ISS will capture and purify water that percolates through the soil and is collected by a grid of perforated pipes.

The first stage will employ vacuum distillation to extract water vapor. The concentrated brine is then osmotically filtered. The purified liquid that collects on the membrane surface is heated, vaporized and returned to the storage tanks, leaving the salts behind.

This same system will be used to remove perchlorates from the regolith prior to planting. Otherwise, the greenhouse environment would be dangerous to both plants and astronauts alike.

As for the carbon cycle, human waste and food scraps will all go into a composting toilet. A shuttle must be set up to deliver the produce to the kitchen and return the waste back to the garden dome. Composting gives off CO2, which will be absorbed by the crops. The compost will amend the regolith into soil.

Functions within the garden such as pest management, soil chemistry, moisture content monitoring, harvesting and composting will need to be automated. See my earlier discussion on autonomous farming in the December ’23 issue of JOTH. This will free up astronauts for other scientific and commercial tasks.

But indoor farming in Martian regolith isn’t the only option. Hydroponics has proven to be a reliable growing method for certain crops. Next month I’ll discuss this third option for food production. And I’ll share my preferred solution to the astronaut calorie conundrum.

In the meantime, imagine how difficult it is just to keep our refrigerators and shelves stocked here on Earth. My wife and I end up shopping for groceries twice a week (keeps fresh fruits and veggies in the household).Consider the care and planning needed knowing the consumables will only be delivered every other year! Or if you had to grow everything you ate yourself! Until then,

Happy Reading,

Want a deeper dive? Check out these sources.
https://www.nasa.gov/wp-content/uploads/2018/05/stemonstrations_nutrition.pdf?emrc=5d7a54
https://science.howstuffworks.com/space-food3.htm#:~:text=The%20space%20shuttle%20carries%20about,meals%20a%20day%2C%20plus%20snacks