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.
Kids' immune systems come into contact with so many antigens every day that extra cleaning and disinfecting won't harm them, experts say.
Cleaning has taken on a whole new meaning in Frank Mosco's household during the COVID-19 pandemic. There's a protocol for everything he and his two teenage daughters do.
Experts agree that over-disinfecting is better than inadequate disinfecting, especially during a pandemic.
"We wipe down every package that comes into the house and the items inside," says Mosco, a technologist and social justice activist in Hastings-on-Hudson, N.Y. "If it's a fruit or vegetable, I use vinegar and water, or water and soap. Then we throw out the boxes, clean up the table, and wash our hands." Only then do they put items away.
As the novel coronavirus continues to pose an invisible threat, parents of infants to adolescents are pondering how vigorously and frequently to clean and disinfect surfaces at home and apply hand sanitizer in public. They also fret over whether there can be too much of a good thing: Will making everything as seemingly germ-free as possible reduce immunity down the road?
Experts agree that over-disinfecting is better than inadequate disinfecting, especially during a pandemic. Every family should assess their particular risks. Factors to consider include pre-existing medical conditions, the number of people living in the same home, and whether anyone works in a hospital or other virus-prone environment, says Kari Debbink, assistant professor of biology at Bowie State University in Bowie, Maryland.
Constantly cleaning everything in sight isn't necessary, she explains, because coronavirus tends to spread mainly via immediate contact with respiratory droplets—catching it from surfaces is a less-likely scenario. The longer the virus stays on a surface, the less contagious it becomes.
Some parents worry that their children's growing bodies may become accustomed to an environment that is "too clean." Debbink, a virologist, offers a salient reminder: "The immune system comes into contact with many, many different antigens every day, and it is 'trained' from birth onwards to respond to pathogens. Doing a little more cleansing and disinfecting during the pandemic will not weaken the immune system."
Other experts agree. "There should be no negative outcome to properly washing your hands more frequently," says Stacey Schultz-Cherry, an infectious diseases specialist at St. Jude Children's Research Hospital in Memphis, Tennessee. "Even with enhanced disinfection, kids are still getting exposed to immune-boosting microbes from playing outside, having pets, etc."
"There's no reason why hand sanitizer would weaken anyone's immune system of any age."
Applying hand sanitizer consisting of at least 60 percent alcohol helps clean hands while outdoors, says Angela Rasmussen, associate research scientist and a virologist at Columbia University's Mailman School of Public Health in New York. "There's no reason why hand sanitizer would weaken anyone's immune system of any age," she adds, and recommends moisturizer so hands don't dry out from frequent use. Meanwhile, "cleaning and disinfecting at home also don't have an impact on antiviral immunity, in kids or adults."
With the coronavirus foremost in parents' minds, Patricia Garcia, a pediatric hospitalist, has fielded many questions about how thoroughly they should wipe, rub, scrub, or mop. As medical director of Connecticut Children's Healthy Homes Program in Hartford, which takes aim at toxins and other housing hazards, she reassures them with this mantra: "You're never going to get it perfectly sterilized, and that's okay."
To quell some of these concerns, in March the U.S. Environmental Protection Agency (EPA) released a list of products for household use. None of these products have been specifically tested against SARS-CoV-2, the novel coronavirus that causes COVID-19. But the agency expects these products to be effective because they have demonstrated efficacy against a different human coronavirus similar to SARS-CoV-2 or an even harder-to-kill virus.
Many products on the list contain isopropyl alcohol or hydrogen peroxide. "When using an EPA-registered disinfectant," the agency's website instructs, "follow the label directions for safe, effective use. Make sure to follow the contact time, which is the amount of time the surface should be visibly wet."
Bear in mind that not all cleaners actually disinfect, cautions Alan Woolf, a pediatrician at Boston Children's Hospital who directs its environmental health center and is a professor at Harvard Medical School. Some cleaners remove visible dirt, grease, and grime, but they don't kill viruses. Disinfectants by their nature inactivate both bacteria and viruses. "That's an important distinction," Woolf says.
Frequently touched surfaces—for instance, doorknobs, light switches, toilet-flushing levers, and countertops—should not only be cleaned, but also disinfected at least daily during a pandemic if someone in the household is sick. The objects one touches upon coming home are the ones most likely to become contaminated with viruses, experts say.
Before bringing items inside, "it might be good to clear off a counter space where they will be placed," says Debbink, the biology professor and virologist. "This way, they come into contact with as few items and surfaces as possible."
If space permits, another option would be to set aside nonperishable items. "I've heard of some families putting things in a 'mud room' and closing the door for 48 hours, some leaving things in their garage or car trunk," says Stephanie Holm, co-director of the Western States Pediatric Environmental Health Specialty Unit at the University of California, San Francisco. "Letting new purchases sit for 48 hours undisturbed would greatly reduce the number of viable viruses present."
Cleaning surfaces is recommended before disinfecting them. Holm suggests using unscented soap and microfiber cloths instead of paper towels, which can transmit bacteria and viruses from one area to another.
Soap has the power to eradicate viruses with at least 20 seconds of contact time. It attacks the coronavirus's protective coat, explains infectious diseases specialist Schultz-Cherry. "If you destroy the coat, the virus is no longer infectious. Influenza virus is also very sensitive to soap."
"The most important thing that parents should do for children's immune systems is make sure they are up to date on all their vaccines."
For cribs, toys, and other mouth-contact surfaces, sanitizing with soap and water, not disinfectants, is advisable, says pediatrician Woolf. Fresh fruits and vegetables also can be cleaned with soap, removing dirt and pesticide residue, he adds.
"Some parents are nervous about using disinfectant on toys, which is understandable, considering many toys end up in children's mouths, so soap and water can be an alternative," says pediatrician Garcia, who recommends using hot water.
While some toys can go in the washing machine and dryer or dishwasher, others need to be cleaned by hand, with dish soap or a delicate detergent, as indicated on their labels. But toys with electrical components cannot be submerged in water, in which case consulting the EPA's list of disinfectants may be a parent's best option, she says.
Labels on the back of cleaning and disinfecting products also contain specific instructions. Not allowing a liquid to sit on a surface for the recommended time results in exposure to chemicals without even accomplishing the intended purpose of disinfection. For most household bleach-containing agents, the advisable "dwell time" is 10 minutes. "Many people don't realize this," says Holm, the environmental health specialist who also trained as a physician.
Beware of combining any type of cleaners or disinfectants that aren't already premixed. Doing so can release harmful gases into the air, she cautions.
During the pandemic, Mosco and his daughters have been very conscientious about decontaminating whatever comes through their doors. Mosco says he doesn't believe the family is overusing cleaning and disinfecting products. Although he's fastidious, he says, "a completely sterile environment is not the goal."
His mother, who was a nurse, instilled in him that exposure to some bacteria is a good thing. In turn, he "always encouraged his kids to play with animals, and to have fun in sand and dirt, with plenty of sunlight to keep their immune systems strong."
Even though a vaccine for coronavirus currently doesn't exist, parents can take some comfort in the best weapon available today to protect kids from deadly pathogens: "The most important thing that parents should do for children's immune systems," says virologist Rasmussen, "is make sure they are up to date on all their vaccines."
A researcher works in the lab at Alnylam Pharmaceuticals, which has pioneered the development of RNAi therapies.
In October 2006, Craig Mello received a strange phone call from Sweden at 4:30 a.m. The voice at the other end of the line told him to get dressed and that his life was about to change.
"We think this could be effective in [the early] phase, helping the body clear the virus and preventing progression to that severe hyperimmune response which occurs in some patients."
Shortly afterwards, he was informed that along with his colleague Andrew Fire, he had won the Nobel Prize in Physiology or Medicine.
Eight years earlier, biologists Fire and Mello had made a landmark discovery in the history of genetics. In a series of experiments conducted in worms, they had revealed an ancient evolutionary mechanism present in all animals that allows RNA – the structures within our cells that take genetic information from DNA and use it to make proteins – to selectively switch off genes.
At the time, scientists heralded the dawn of a new field of medical research utilizing this mechanism, known as RNA interference or RNAi, to tackle rare genetic diseases and deactivate viruses. Now, 14 years later, the pharmaceutical company Alnylam — which has pioneered the development of RNAi-based treatments over the past decade — is looking to use it to develop a groundbreaking drug for the virus that causes COVID-19.
"We can design small interfering RNAs to target regions of the viral genome and bind to them," said Akin Akinc, who manages several of Alnylam's drug development programs. "What we're learning about COVID-19 is that there's an early phase where there's lots of viral replication and a high viral load. We think this could be effective in that phase, helping the body clear the virus and preventing progression to that severe hyperimmune response which occurs in some patients."
Called ALN-COV, Alnylam's treatment hypothetically works by switching off a key gene in the virus, inhibiting its ability to replicate itself. In order to deliver it to the epithelial cells deep in the lung tissue, where the virus resides, patients will inhale a fine mist containing the RNAi molecules mixed in a saline solution, using a nebulizer.
But before human trials of the drug can begin, the company needs to convince regulators that it is both safe and effective in a series of preclinical trials. While early results appear promising - when mixed with the virus in a test tube, the drug displayed a 95 percent inhibition rate – experts are reserving judgment until it performs in clinical trials.
"If successful this could be a very important milestone in the development of RNAi therapies, but virus infections are very complicated and it can be hard to predict whether a given level of inhibition in cell culture will be sufficient to have a significant impact on the course of the infection," said Si-Ping Han, who researches RNAi therapeutics at California Institute of Technology and is not involved in the development of this drug.
So far, Alnylam has had success in using RNAi to treat rare genetic diseases. It currently has treatments licensed for Hereditary ATTR Amyloidosis and Acute Hepatic Porphyria. Another treatment, for Primary Hyperoxaluria Type 1, is currently under regulatory review. But its only previous attempt to use RNAi to tackle a respiratory infection was a failed effort to develop a drug for respiratory syncytial virus (RSV) almost a decade ago.
However, the technology has advanced considerably since then. "Back then, RNAi drugs had no chemical modifications whatsoever, so they were readily degraded by the body, and they could also result in unintended immune stimulation," said Akinc. "Since then, we've learned how to chemically modify our RNAi's to make them immunosilent and give them improved potency, stability, and duration of action."
"It would be a very important milestone in the development of RNAi therapies."
But one key challenge the company will face is the sheer speed at which viruses evolve, meaning they can become drug-resistant very quickly. Scientists predict that Alnylam will ultimately have to develop a series of RNAi drugs for the coronavirus that work together.
"There's been considerable interest in using RNAi to treat viral infections, as RNA therapies can be developed more rapidly than protein therapies like monoclonal antibodies, since one only needs to know the viral genome sequence to begin to design them," said David Schaffer, professor of bioengineering at University of California, Berkeley. "But viruses can evolve their sequences rapidly around single drugs so it is likely that a combinatorial RNAi therapy may be needed."
In the meantime, Alnylam is conducting further preclinical trials over the summer and fall, with the aim of launching testing in human volunteers by the end of this year -- an ambitious aim that would represent a breakneck pace for a drug development program.
If the approach does ultimately succeed, it would represent a major breakthrough for the field as a whole, potentially opening the door to a whole new wave of RNAi treatments for different lung infections and diseases.
"It would be a very important milestone in the development of RNAi therapies," said Han, the Caltech researcher. "It would be both the first time that an RNAi drug has been successfully used to treat a respiratory infection and as far as I know, the first time that one has been successful in treating any disease in the lungs. RNAi is a platform that can be reconfigured to hit different targets, and so once the first drug has been developed, we can expect a rapid flow of variants targeting other respiratory infections or other lung diseases."