Scientists Are Devising Clever Solutions to Feed Astronauts on Mars Space Flights
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.
What makes people turn against science? After two years of a global pandemic, the world has never felt more divided on questions of science. But this is not a new phenomenon. People have resisted scientific and technological advances throughout history.
This video by Leaps.org, with support from the Gordon and Betty Moore Foundation, captures noteworthy examples from history when people rejected science. What do these cases have in common? Scientific breakthroughs can be revolutionary, but revolutions can be disorienting and anxiety-producing. They transform our livelihoods, culture and even our understanding of what it means to be human. But there's reason for optimism. Many of history’s controversies were overcome. Science has a way of enduring, because it changes things for the better.
Scientists search for a universal coronavirus vaccine
The Covid-19 pandemic had barely begun when VBI Vaccines, a biopharmaceutical company based in Cambridge, Massachusetts, initiated their search for a universal coronavirus vaccine.
It was March 2020, and while most pharmaceutical companies were scrambling to initiate vaccine programs which specifically targeted the SARS-CoV-2 virus, VBI’s executives were already keen to look at the broader picture.
Having observed the SARS and MERS coronavirus outbreaks over the last two decades, Jeff Baxter, CEO of VBI Vaccines, was aware that SARS-CoV-2 is unlikely to be the last coronavirus to move from an animal host into humans. “It's absolutely apparent that the future is to create a vaccine which gives more broad protection against not only pre-existing coronaviruses, but those that will potentially make the leap into humans in future,” says Baxter.
It was a prescient decision. Over the last two years, more biotechs and pharma companies have joined the search to find a vaccine which might be able to protect against all coronaviruses, along with dozens of academic research groups. Last September, the US National Institutes of Health dedicated $36 million specifically to pan-coronavirus vaccine research, while the global Coalition for Epidemic Preparedness Innovations (CEPI) has earmarked $200 million towards the effort.
Until October 2021, the very concept of whether it might be
theoretically possible to vaccinate against multiple coronaviruses remained an open question. But then a groundbreaking study renewed optimism.
The emergence of new variants of Covid-19 over the past year, particularly the highly mutated Omicron variant, has added greater impetus to find broader spectrum vaccines. But until October 2021, the very concept of whether it might be theoretically possible to vaccinate against multiple coronaviruses remained an open question. After all, scientists have spent decades trying to develop a similar vaccine for influenza with little success.
But then a groundbreaking study from renowned virologist Linfa Wang, who runs the emerging infectious diseases program at Duke-National University of Singapore Medical School, provided renewed optimism.
Wang found that eight SARS survivors who had been injected with the Pfizer/BioNTech Covid-19 vaccine had neutralising antibodies in their blood against SARS, the Alpha, Beta and Delta variants of SARS-CoV-2, and five other coronaviruses which reside in bats and pangolins. He concluded that the combination of past coronavirus infection, and immunization with a messenger RNA vaccine, had resulted in a wider spectrum of protection than might have been expected.
“This is a significant study because it showed that pre-existing immunity to one coronavirus could help with the elicitation of cross-reactive antibodies when immunizing with a second coronavirus,” says Kevin Saunders, Director of Research at the Duke Human Vaccine Institute in North Carolina, which is developing a universal coronavirus vaccine. “It provides a strategy to perhaps broaden the immune response against coronaviruses.”
In the next few months, some of the first data is set to emerge looking at whether this kind of antibody response could be elicited by a single universal coronavirus vaccine. In April 2021, scientists at the Walter Reed Army Institute of Research in Silver Spring, Maryland, launched a Phase I clinical trial of their vaccine, with a spokesman saying that it was successful, and the full results will be announced soon.
The Walter Reed researchers have already released preclinical data, testing the vaccine in non-human primates where it was found to have immunising capabilities against a range of Covid-19 variants as well as the original SARS virus. If the Phase I trial displays similar efficacy, a larger Phase II trial will begin later this year.
Two different approaches
Broadly speaking, scientists are taking two contrasting approaches to the task of finding a universal coronavirus vaccine. The Walter Reed Army Institute of Research, VBI Vaccines – who plan to launch their own clinical trial in the summer – and the Duke Human Vaccine Institute – who are launching a Phase I trial in early 2023 – are using a soccer-ball shaped ferritin nanoparticle studded with different coronavirus protein fragments.
VBI Vaccines is looking to elicit broader immune responses by combining SARS, SARS-CoV-2 and MERS spike proteins on the same nanoparticle. Dave Anderson, chief scientific officer at VBI Vaccines, explains that the idea is that by showing the immune system these three spike proteins at the same time, it can help train it to identify and respond to subtle differences between coronavirus strains.
The Duke Human Vaccine Institute is utilising the same method, but rather than including the entire spike proteins from different coronaviruses, they are only including the receptor binding domain (RBD) fragment from each spike protein. “We designed our vaccine to focus the immune system on a site of vulnerability for the virus, which is the receptor binding domain,” says Saunders. “Since the RBD is small, arraying multiple RBDs on a nanoparticle is a straight-forward approach. The goal is to generate immunity to many different subgenuses of viruses so that there will be cross-reactivity with new or unknown coronaviruses.”
But the other strategy is to create a vaccine which contains regions of the viral protein structure which are conserved between all coronavirus strains. This is something which scientists have tried to do for a universal influenza vaccine, but it is thought to be more feasible for coronaviruses because they mutate at a slower rate and are more constrained in the ways that they can evolve.
DIOSynVax, a biotech based in Cambridge, United Kingdom, announced in a press release earlier this month that they are partnering with CEPI to use their computational predictive modelling techniques to identify common structures between all of the SARS coronaviruses which do not mutate, and thus present good vaccine targets.
Stephen Zeichner, an infectious disease specialist at the University of Virginia Medical Center, has created an early stage vaccine using the fusion peptide region – another part of the coronavirus spike protein that aids the virus’s entry into host cells – which so far appears to be highly conserved between all coronaviruses.
So far Zeichner has trialled this version of the vaccine in pigs, where it provided protection against a different coronavirus called porcine epidemic diarrhea virus, which he described as very promising as this virus is from a different family called alphacoronaviruses, while SARS-CoV-2 is a betacoronavirus.
“If a betacoronavirus fusion peptide vaccine designed from SARS-CoV-2 can protect pigs against clinical disease from an alphacoronavirus, then that suggests that an analogous vaccine would enable broad protection against many, many different coronaviruses,” he says.
The road ahead
But while some of the early stage results are promising, researchers are fully aware of the scale of the challenge ahead of them. Although CEPI have declared an aim of having a licensed universal coronavirus vaccine available by 2024-2025, Zeichner says that such timelines are ambitious in the extreme.
“I was incredibly impressed at the speed at which the mRNA coronavirus vaccines were developed for SARS-CoV-2,” he says. “That was faster than just about anybody anticipated. On the other hand, I think a universal coronavirus vaccine is more equivalent to the challenge of developing an HIV vaccine and we're 35 years into that effort without success. We know a lot more now than before, and maybe it will be easier than we think. But I think the route to a universal vaccine is harder than an individual vaccine, so I wouldn’t want to put money on a timeline prediction.”
The major challenge for scientists is essentially designing a vaccine for a future threat which is not even here yet. As such, there are no guidelines on what safety data would be required to license such a vaccine, and how researchers can demonstrate that it truly provides efficacy against all coronaviruses, even those which have not yet jumped to humans.
The teams working on this problem have already devised some ingenious ways of approaching the challenge. VBI Vaccines have taken the genetic sequences of different coronaviruses found in bats and pangolins, from publicly available databases, and inserted them into what virologists call a pseudotype virus – one which has been engineered so it does not have enough genetic material to replicate.
This has allowed them to test the neutralising antibodies that their vaccine produces against these coronaviruses in test tubes, under safe lab conditions. “We have literally just been ordering the sequences, and making synthetic viruses that we can use to test the antibody responses,” says Anderson.
However, some scientists feel that going straight to a universal coronavirus vaccine is likely to be too complex. Instead they say that we should aim for vaccines which are a little more specific. Pamela Bjorkman, a structural biologist at the California Institute of Technology, suggests that pan-coronavirus vaccines which protect against SARS-like betacoronaviruses such as SARS or SARS-CoV-2, or MERS-like betacoronaviruses, may be more realistic.
“I think a vaccine to protect against all coronaviruses is likely impossible since there are so many varieties,” she says. “Perhaps trying to narrow down the scope is advisable.”
But if the mission to develop a universal coronavirus vaccine does succeed, it will be one of the most remarkable feats in the annals of medical science. In January, US chief medical advisor Anthony Fauci urged for greater efforts to be devoted towards this goal, one which scientists feel would be the biological equivalent of the race to develop the first atomic bomb
“The development of an effective universal coronavirus vaccine would be equally groundbreaking, as it would have global applicability and utility,” says Saunders. “Coronaviruses have caused multiple deadly outbreaks, and it is likely that another outbreak will occur. Having a vaccine that prevents death from a future outbreak would be a tremendous achievement in global health.”
He agrees that it will require creativity on a remarkable scale: “The universal coronavirus vaccine will also require ingenuity and perseverance comparable to that needed for the Manhattan project.”