Scientists Are Devising Clever Solutions to Feed Astronauts on Mars Space Flights
Astronaut and Expedition 64 Flight Engineer Soichi Noguchi of the Japan Aerospace Exploration Agency displays Extra Dwarf Pak Choi plants growing aboard the International Space Station. The plants were grown for the Veggie study which is exploring space agriculture as a way to sustain astronauts on future missions to the Moon or Mars.
Astronauts at the International Space Station today depend on pre-packaged, freeze-dried food, plus some fresh produce thanks to regular resupply missions. This supply chain, however, will not be available on trips further out, such as the moon or Mars. So what are astronauts on long missions going to eat?
Going by the options available now, says Christel Paille, an engineer at the European Space Agency, a lunar expedition is likely to have only dehydrated foods. “So no more fresh product, and a limited amount of already hydrated product in cans.”
For the Mars mission, the situation is a bit more complex, she says. Prepackaged food could still constitute most of their food, “but combined with [on site] production of certain food products…to get them fresh.” A Mars mission isn’t right around the corner, but scientists are currently working on solutions for how to feed those astronauts. A number of boundary-pushing efforts are now underway.
The logistics of growing plants in space, of course, are very different from Earth. There is no gravity, sunlight, or atmosphere. High levels of ionizing radiation stunt plant growth. Plus, plants take up a lot of space, something that is, ironically, at a premium up there. These and special nutritional requirements of spacefarers have given scientists some specific and challenging problems.
To study fresh food production systems, NASA runs the Vegetable Production System (Veggie) on the ISS. Deployed in 2014, Veggie has been growing salad-type plants on “plant pillows” filled with growth media, including a special clay and controlled-release fertilizer, and a passive wicking watering system. They have had some success growing leafy greens and even flowers.
"Ideally, we would like a system which has zero waste and, therefore, needs zero input, zero additional resources."
A larger farming facility run by NASA on the ISS is the Advanced Plant Habitat to study how plants grow in space. This fully-automated, closed-loop system has an environmentally controlled growth chamber and is equipped with sensors that relay real-time information about temperature, oxygen content, and moisture levels back to the ground team at Kennedy Space Center in Florida. In December 2020, the ISS crew feasted on radishes grown in the APH.
“But salad doesn’t give you any calories,” says Erik Seedhouse, a researcher at the Applied Aviation Sciences Department at Embry-Riddle Aeronautical University in Florida. “It gives you some minerals, but it doesn’t give you a lot of carbohydrates.” Seedhouse also noted in his 2020 book Life Support Systems for Humans in Space: “Integrating the growing of plants into a life support system is a fiendishly difficult enterprise.” As a case point, he referred to the ESA’s Micro-Ecological Life Support System Alternative (MELiSSA) program that has been running since 1989 to integrate growing of plants in a closed life support system such as a spacecraft.
Paille, one of the scientists running MELiSSA, says that the system aims to recycle the metabolic waste produced by crew members back into the metabolic resources required by them: “The aim is…to come [up with] a closed, sustainable system which does not [need] any logistics resupply.” MELiSSA uses microorganisms to process human excretions in order to harvest carbon dioxide and nitrate to grow plants. “Ideally, we would like a system which has zero waste and, therefore, needs zero input, zero additional resources,” Paille adds.
Microorganisms play a big role as “fuel” in food production in extreme places, including in space. Last year, researchers discovered Methylobacterium strains on the ISS, including some never-seen-before species. Kasthuri Venkateswaran of NASA’s Jet Propulsion Laboratory, one of the researchers involved in the study, says, “[The] isolation of novel microbes that help to promote the plant growth under stressful conditions is very essential… Certain bacteria can decompose complex matter into a simple nutrient [that] the plants can absorb.” These microbes, which have already adapted to space conditions—such as the absence of gravity and increased radiation—boost various plant growth processes and help withstand the harsh physical environment.
MELiSSA, says Paille, has demonstrated that it is possible to grow plants in space. “This is important information because…we didn’t know whether the space environment was affecting the biological cycle of the plant…[and of] cyanobacteria.” With the scientific and engineering aspects of a closed, self-sustaining life support system becoming clearer, she says, the next stage is to find out if it works in space. They plan to run tests recycling human urine into useful components, including those that promote plant growth.
The MELiSSA pilot plant uses rats currently, and needs to be translated for human subjects for further studies. “Demonstrating the process and well-being of a rat in terms of providing water, sufficient oxygen, and recycling sufficient carbon dioxide, in a non-stressful manner, is one thing,” Paille says, “but then, having a human in the loop [means] you also need to integrate user interfaces from the operational point of view.”
Growing food in space comes with an additional caveat that underscores its high stakes. Barbara Demmig-Adams from the Department of Ecology and Evolutionary Biology at the University of Colorado Boulder explains, “There are conditions that actually will hurt your health more than just living here on earth. And so the need for nutritious food and micronutrients is even greater for an astronaut than for [you and] me.”
Demmig-Adams, who has worked on increasing the nutritional quality of plants for long-duration spaceflight missions, also adds that there is no need to reinvent the wheel. Her work has focused on duckweed, a rather unappealingly named aquatic plant. “It is 100 percent edible, grows very fast, it’s very small, and like some other floating aquatic plants, also produces a lot of protein,” she says. “And here on Earth, studies have shown that the amount of protein you get from the same area of these floating aquatic plants is 20 times higher compared to soybeans.”
Aquatic plants also tend to grow well in microgravity: “Plants that float on water, they don’t respond to gravity, they just hug the water film… They don’t need to know what’s up and what’s down.” On top of that, she adds, “They also produce higher concentrations of really important micronutrients, antioxidants that humans need, especially under space radiation.” In fact, duckweed, when subjected to high amounts of radiation, makes nutrients called carotenoids that are crucial for fighting radiation damage. “We’ve looked at dozens and dozens of plants, and the duckweed makes more of this radiation fighter…than anything I’ve seen before.”
Despite all the scientific advances and promising leads, no one really knows what the conditions so far out in space will be and what new challenges they will bring. As Paille says, “There are known unknowns and unknown unknowns.”
One definite “known” for astronauts is that growing their food is the ideal scenario for space travel in the long term since “[taking] all your food along with you, for best part of two years, that’s a lot of space and a lot of weight,” as Seedhouse says. That said, once they land on Mars, they’d have to think about what to eat all over again. “Then you probably want to start building a greenhouse and growing food there [as well],” he adds.
And that is a whole different challenge altogether.
Did researchers finally find a way to lick COVID?
A professor of medicine at the University of Michigan is researching whether lactoferrin, which is found in dairy products such as ice cream, can help to prevent COVID-19 infections.
Already vaccinated and want more protection from COVID-19? A protein found in ice cream could help, some research suggests, though there are a bunch of caveats.
The protein, called lactoferrin, is found in the milk of mammals and thus in dairy products, including ice cream. It has astounding antiviral properties that have been taken for granted and remain largely unexplored because it is a natural product, meaning that it cannot be patented and exploited by pharmaceutical companies.
Still, a few researchers in Europe and elsewhere have sought to better understand the compound.
Jonathan Sexton runs a drug screening program at the University of Michigan where cells are infected with a pathogen and then exposed to a library of the thousands of small molecule drug compounds – which can enter the body more easily than drugs with heavier molecules – approved by the FDA. In addition, the library includes compounds that passed phase 1 safety studies but later proved ineffective against the targeted disease. Each drug is dissolved in a solvent for exposure to the cells in the laborious testing process made feasible by robotic automation.
When COVID hit, researchers scrambled to identify any approved drug that might help fight the infection. Sexton decided to screen the drug library as well as some dietary supplements against SARS-CoV-2, the virus that causes the disease. Sexton says that the grunt work fell to Jesse Wotring, “a very talented PhD student,” who pulled lactoferrin off the shelf. But the regular solvent used in the testing process would destroy the protein, so he had to take another approach and do all the work by hand.
“We were agnostic,” says Sexton, who didn't have a strong interest in lactoferrin or any of the other compounds in the library, but the data was quite clear; lactoferrin “consistently produced the best efficacy...it was the absolute home run.” The findings were published in separate papers last year and in February.
It turns out that lactoferrin has several different mechanisms of action against SARS-CoV-2, inhibiting the virus from entering cells, moving around within them and replicating. Lactoferrin also modulates the overall immune response, which makes it difficult for the virus to simultaneously mutate resistance to the protein at every step of replication. “It has broad efficacy against every [SARS-CoV-2] variant that we've tested,” he says.
From bench to bedside
Sexton's initial interest was to develop a drug for the acute phase of COVID infection, to treat a hospitalized patient or prevent that hospitalization. But with the quick approval of vaccines and drugs to treat the disease, he increasingly focused on ways to better prevent infection and inhibit spread of the virus.
“If you can get lactoferrin to persist in your upper GI tract, then it may very well prevent the primary infection, and that's what we're really interested in.” He reasoned that a chewing gum formula might release enough lactoferrin into the mucosal tissue of the mouth and upper airways to inhibit replication and give the immune system a chance to knock out the virus before it can establish a foothold. It could also reduce the amount of virus spread through talking.
To get enough lactoferrin to have a possible beneficial effect, one would have to drink gallons of milk a day, “and that would have other undesirable consequences, like getting extremely obese,” says Sexton. Obesity is one of the leading risk factors for severe COVID disease.
Testing that theory has been difficult. The easiest way would be a “challenge trial,” where volunteers take the drug, or in this case gum, are exposed to the pathogen, and protection is measured. Some COVID challenge studies have been conducted in Europe but the FDA remains hesitant to allow such a study in the U.S. A traditional prevention study would be like a vaccine trial, involving thousands, perhaps tens of thousands of volunteers over a period of months or years, and it would be very expensive. No one has stepped forward to foot the bill.
So the next step for Sexton is a clinical trial of newly diagnosed COVID patients who will be given standard of care treatment, and layered on top of that they will receive either lactoferrin, probably in pill form, or a placebo. He has identified initial funding. “We would study their viral load over time as well as their symptoms.”
One issue the FDA is grappling with in considering the proposed trial is that it typically decides whether to approve drugs from a factory by applying a rigorous standard, called good manufacturing practices, while food products, which are the source of lactoferrin, are produced under somewhat different standards. The agency still has not finalized rules on how to deal with natural products used as drugs, such as fecal transplants, convalescent plasma, or medical marijuana.
Sexton is frustrated by the delay because lactoferrin derived from bovine milk whey has been used for many decades as a protein supplement by athletes, it is a large component of most infant formula, and the largest number of clinical studies of lactoferrin involve premature infants. There is no question of its safety, he says.
Do it yourself
So what can you do while waiting for regulatory wheels to spin and clinical trial data to be generated?
Could a dose of Ben & Jerry's provide some protection against SARS-CoV-2?
Sexton chuckles at the suggestion. He supposes it couldn't hurt. But to get enough lactoferrin to have a possible beneficial effect, one would have to drink gallons of milk a day, “and that would have other undesirable consequences, like getting extremely obese.” Obesity is one of the leading risk factors for severe COVID disease.
Pseudo-milk products made from soy, almonds, oats, or other plant products do not contain lactoferrin; it has to come from a teat. So that rules them out.
Whey-based protein shakes might be a useful way to add lactoferrin to the diet.
Probably the best option is to take conventional gelatin capsules of lactoferrin that are widely available wherever supplements are sold. Sexton calculates that about a gram a day, four 250 milligram capsules, should do it. He advises two in the morning and two a night. “You really want to take them on an empty stomach...your stomach treats [the lactoferrin protein] like it would a steak” and chops it for absorption in the intestine, which you do not want. About 70 percent of lactoferrin can get through an empty stomach, but eating food cranks up digestive gastric acids and the amount of intact lactoferrin that gets through to the gut plummets.
Sexton cautions, “We have not determined clinical efficacy yet,” and he is not offering advice as a physician, but in the spirit of harm reduction, he realizes that some people are going to try things that might help them. Lactoferrin “is remarkably safe. And so people have to make their own decisions about what they are willing to take and what they are not,” he says.
In today's episode, Leaps.org interviews Camila dos Santos, a molecular biologist at Cold Spring Harbor Lab, about her research on breasts and what makes them unique compared to any other part of the body.
My guest today for the Making Sense of Science podcast is Camila dos Santos, associate professor at Cold Spring Harbor Lab, who is a leading researcher of the inner lives of human mammary glands, more commonly known as breasts. These organs are unlike any other because throughout life they undergo numerous changes, first in puberty, then during pregnancies and lactation periods, and finally at the end of the cycle, when babies are weaned. A complex interplay of hormones governs these processes, in some cases increasing the risk of breast cancer and sometimes lowering it. Witnessing the molecular mechanics behind these processes in humans is not possible, so instead Dos Santos studies organoids—the clumps of breast cells donated by patients who undergo breast reduction surgeries or biopsies.
Show notes:
2:52 In response to hormones that arise during puberty, the breast cells grow and become more specialized, preparing the tissue for making milk.
7:53 How do breast cells know when to produce milk? It’s all governed by chemical messaging in the body. When the baby is born, the brain will release the hormone called oxytocin, which will make the breast cells contract and release the milk.
12:40 Breast resident immune cells are including T-cells and B-cells, but because they live inside the breast tissue their functions differ from the immune cells in other parts of the body,
17:00 With organoids—dimensional clumps of cells that are cultured in a dish—it is possible to visualize and study how these cells produce milk.
21:50 Women who are pregnant later in life are more likely to require medical intervention to breastfeed. Scientists are trying to understand the fundamental reasons why it happens.
26:10 Breast cancer has many risks factors. Generic mutations play a big role. All of us have the BRCA genes, but it is the alternation in the DNA sequence of the BRCA gene that can increase the predisposition to breast cancer. Aging and menopause are the risk factors for breast cancer, and so are pregnancies.
29:22 Women that are pregnant before the age of 20 to 25, have a decreased risk of breast cancer. And the hypothesis here is that during pregnancy breast cells more specialized, as specialized cells, they have a limited lifespan. It's more likely that they die before they turn into cancer.
33:08 Organoids are giving scientists an opportunity to practice personalized medicine. Scientists can test drugs on organoids taken from a patient to identify the most efficient treatment protocol.
Links:
Camila dos Santos’s Lab Page.
Editor's note: In addition to being a regular writer for Leaps.org, Lina Zeldovich is the guest host for today's episode of the Making Sense of Science podcast.
Lina Zeldovich has written about science, medicine and technology for Popular Science, Smithsonian, National Geographic, Scientific American, Reader’s Digest, the New York Times and other major national and international publications. A Columbia J-School alumna, she has won several awards for her stories, including the ASJA Crisis Coverage Award for Covid reporting, and has been a contributing editor at Nautilus Magazine. In 2021, Zeldovich released her first book, The Other Dark Matter, published by the University of Chicago Press, about the science and business of turning waste into wealth and health. You can find her on http://linazeldovich.com/ and @linazeldovich.