We are University of Florida research scientists Rob Ferl and Anna-Lisa Paul working to feed Martians! For more than 20 years, we’ve been studying how to grow plants in space to enable explorations. AMA!

My child's elementary school text book states that roots grow down because of gravity. We were wondering, are the roots pulled down by gravity or are they reaching down in search of water? In the absence of gravity, would the roots seek out water no matter the direction?

Great questions!

Yes, on Earth, plants' roots do grow down because gravity is the most powerful directional cue for them. When there is no gravity, plant roots need another way to know how to navigate. We found in our research that when plants have directional light they can use that as a cue of which way to grow. So, when there is no gravity, roots will grow away from a light source. If there is no light and no gravity, plants still know how to grow away from where they are planted, even without any cues. You can think of it as "instinct" in that there are inherent features of how cells grow that direct roots to spiral away from where they're planted. This way plants will not use up all the resources in one little spot. Yes, water can also be a cue, and it too has a greater effect on root directions when you take gravity out of the equation!

My 6 year old wants to know why you like to do lots of science?

Wow, what a lovely question! I think that we like doing science precisely because were are still 6 years old! Well, at least in our hearts we are. And maybe our heads :) That curiosity of why lighting bugs light up and why the stars are in those patterns - that curiosity of a six year old - still drives us. No question. Doing science helps keeps that curiosity alive and to think that we can get paid to do this? That is just a bonus.

Space biology keeps us young. Science keeps us young. We like doing science for that reason. And primarily, without a doubt, we find it FUN!

Hey Martian Farmers:

If you had the opportunity to be the first research scientists to go to Mars, or the Moon, what types of experiments would you want to take along?

For sure you are thinking exactly the kinds of things that we think about. And to take a small diversion here, we like the movie The Martian precisely because science is portrayed as a major activity on Mars. To be sure, the fact that they had a botanist on the crew is pretty darn cool.

But to answer your question, there are a few key things about Mars that we would want study using plants. First, what kinds of nutrients would plants be able to efficiently pull from the Martian soil. Second, how well would the plants do in whatever habitat is being used to support the plants. Third, we would want to grow multiple generations of plants just to see how genetically stable plants would be in the radiation environment of mars.

So what would we want to take with us to do these experiments? At least several different kinds of seeds, so that we could do several kinds of experiments there. Back to The Martian, its hard to fathom why NASA sent a botanist with no seeds!

Have you been able to mimic the kind of soil plants might find on Mars?

Actually, yes to some degree. Simulants are made available by Johnson's Space Center, the Mars simulant is made based on volcanic material from Hawaii. Now, knowing more about the mineral compositions through Rovers, they can further tweak the simulant to make them even more Mars-like. We have in fact grown plants in our lab with these Mars simulants, and they do quite well.

BUT we don't have real Martian soil.

So, a sample return mission to Mars would tell you a lot, right?

Mars sample return will be one of the grandest multi mission projects ever undertaken! Think about the whole thing - collecting samples on a rover, caching them, taking them to a return vehicle and then catching them back here on Earth. Will be amazing for sure.

And yes, sample return is a big deal and an important deal for every single aspect of dealing with Mars exploration. Having samples to analyze back here will vastly enhance any data taken from rovers. While we woule not get enough sample back to grow plants directly in those samples, data from those samples would result in really high fidelity simulants, and those simulants we could use.

I imagine you get many questions regarding "The Martian" (or similar books/films), and whether it's an accurate portrayal of the work in plant molecular biology, but I'm curious to know if there were any pieces of literature – non-fiction or even sci-fi – that inspired you to pursue your career in science?

Anna-Lisa: I started reading science books as a kid, and the first book that inspired me was a Time-Life book called "The Plants". I was fascinated by how plants worked and that's what started me in on my love of plants, and at the same time, I was reading a book on dinosaurs from the Gobi Desert that instilled in me the desire to be an exploration scientist. So, doing plant space biology combines both those things. (I also like to read science fiction - check out David Brin's Uplift series.)

Rob: Literature? Maybe. Saturday morning cartoons? for sure! Fireball XL5 absolutely showed me that exploration would be fun, that space would be excellent and that people can go to strange and beautiful places to explore, to meet new beings. Start Trek only reinforced that whole notion. But back to the literature question, my parents were avid supporters of reading and i remember vividly science and engineering books about the early space race. So on the literature side, science readers. On the video side? cartoons and Star Trek.

Anna-Lisa: Oh, right! Star Trek's a big one! Definitely Star Trek inspired me as well, and I still believe we should go boldly!

Hi! I'm a PhD student at UF interested in controlled environment/space agriculture!

Given your research experiences with the ISS, what sorts of additions to the Veggie and Advanced Plant Habitat growth modules would be most helpful for future plant research in space?

Also, are there gravity thresholds at which you've seen genes switch on and off? What phenotype differences do you foresee in microgravity versus low-gravity?

Both plant habitats are pretty sophisticated for having to work in the very limited resources on the ISS. The fantasy habitat would be larger, have wider range of lighting and imaging capabilities and more capacity to grow larger crops through their life cycle.

We haven't done gene expression analyses on gravity gradients but others in the field have done work on small centrifuges on the ISS. However, we do know that plants grown in microgravity mount a huge response on the gene expression level. At the phenotypic level plants seem to have modified cell walls. Although just looking at them, they look pretty normal. Also, root growth patterns are very different in microgravity because they have to use different cues than the gravity that they are used to.

How well do crops stand up to the space radiation environment? Are there any particularly tough ones we might want to grow on Mars?

No biology, and certainly no plants or crops, have been in deep space since the Apollo era. So, we don’t really know how plants will respond to deep space radiation. We can extrapolate from how plants respond to radiation stress on earth, and on the basis of that, we know that leafy crops and first-generation crops are pretty resistant to radiation stress. But for the next generation, meaning the seeds of crops, those are going to be more sensitive to radiation, and we will need to pay attention on how to protect our crops.

Is the movie The Martian pretty realistic? He just scooped up some dirt and planted potatoes!

To be sure, we love the movie! How often do scientists have Matt Damon as our avatar? Just too cool. Anyway, it is realistic with respect to plant growth? Yep, but remember he did not just scoop up martian dirt and grow potatoes. Remember he mixed in human waste! Does this make sense? Of course! the use of human and other animal fertilizer is very realistic and has been practiced here on Earth since the beginning of agriculture. The waste provides carbon and nitrogen, which the martian soil would lack.

And here is a key point, one point that really keeps plant growth a big part of the NASA exploration agenda - the use of biological life support. Just like here on Earth, where plants take up our wastes and produce our food, fiber, oxygen and clean water, so too would they do that on Mars!

NASA recently announced that it was going to open applications for a new astronaut class. What types of professions would you like to see better represented in the astronaut core?

Plant molecular biologists! Or any scientist in general. ;)

I want to tell you that we, the young generation of people who are in this profession of plant science feel very inspired by you. You are one of my greatest role models, all your efforts are greatly appreciated.

Could you please describe how the sensation was when you made the flight in the F-104 with the Starfighters in 2015? Do you have any plans to travel to space? What is your biggest motivation to continue doing what you do?

Juan Jimenez

Thank you for your kind words! It is so nice to hear from you.

The F-104. wow. We had been in zero-g many time. We had flown in many aircraft. And i (rob) am myself a pilot. So the sensation of flying in a supersonic jet? Truly an amazing combination of speed, a real physical sensation of acceleration and high g forces, and then the high altitude view of the earth while in zero g - all made for an amazing combination of senses that relate to operational spaceflight. We did these flights in anticipation of the world of scientists flying with their experiments in suborbital space.

https://www.boulder.swri.edu/NSRC2020/Site5/Home2020.html

The whole question of plans to travel in space? Well, we certainly have the desire, and the first best opportunities will likely be suborbital and actually could occur with this program:

https://www.nasa.gov/directorates/spacetech/flightopportunities/index.html

Biggest motivation? Exploration, plain and simple. Humans are explorers. We go boldly.

What was it like working in a gravity free environment?

We have never been to space, per se, but we have done a lot of work on parabolic flight aircraft, which gives you about 30 seconds of microgravity every two minutes. If you think this sounds hard, you would be right! But you're asking about microgravity...the weirdest thing about working in microgravity is that at first you think it will be like swimming, it's not, not even close. Because you have nothing to push against. If you find yourself out in the middle of the aircraft with nothing to hold on to, you just stay there until gravity comes back or a friend rescues you.

When you're working in microgravity you have to be mindful that there is no "down," so if you're trying to put liquid in one container into another, you cannot pour it. When we were training an astronaut on the KC135 aircraft, a procedure we thought would work to harvest our plants in space turned out to be wrong because in microgravity, the plants did not stick to the material we thought would be best for containing the plants. We would not have known that if we had not tested it first!

Here's ALP actually reminiscing on the "Vomit Comet": https://www.youtube.com/watch?v=purGp-1juCE

How does your work help us understand our earth environment better? Are there impacts that your research makes in the current biological sciences field?

These are excellent questions and they deserve good answers! We would posit first and foremost that our main goals are to understand the movement of terrestrial life off this planet, to better understand the limits of our life in the solar system and to better understand the extent of life in the universe.

That all said, yep there are earth benefits and contributions to current biological sciences. You might want to visit the information on the ISS National Laboratory - one the ISSNLs big goals is benefit life on earth, and they do a really good job of outreach.

https://www.issnationallab.org/

And the entire ISS science program really does an outstanding job of relating space science to earth benefits.

https://www.nasa.gov/mission_pages/station/main/index.html

One of the big goals in our lab is to understand the limits of plant adaptation by using the novel environment of space to query those limits. A lot of our work has informed the value of specific genes involved in stress responses, even here on Earth.

But one of the coolest things the community has done, all of us in plant space biology, is show that complex life can undergo growth and development - making complicated developmental decisions, in the absence of gravity, one of the most dominant physical forces on the Earth. Having shown that roots and leaves and flowers all can grow from the embryo of a seed so as to look like a normal plant is, well, huge! Yet many, many of the things that we think MUST be associated with gravity signals, like roots growing "down" and shoots growing "up" actually have little or nothing to do with gravity. All of this, every bit, informs biology thought and removes the bias of assigning growth behavior to gravity.

Hello Space Gardeners,

What hinders growing space carrots and other vegetables the most? Is it the soil, lack of moisture, atmosphere?

These are really good questions, so let us get a couple of ideas out there. First, its not any one thing that limits plant growth in space. Probably the biggest thing is that none of these crops, in fact no terrestrial biology, had evolved to live in space, especially in the microgravity environment of space. So, we don't really know how plants respond to being in space, but we are learning a lot on the ISS. One thing is that the engineering to support plant growth, to deal with your questions of moisture and atmospheric managment, are truly big issues in space. Solving them is a big engineering project that has been going on for decades and is not yet fully solved.

Water does not behave the same in space as on the earth so its actually easy to either drown or dry out plants in space. The air does not mix by convection like it does on the Earth. And on the ISS there is a lot of CO2, more so than here on Earth. So all your points are good ones and still active questions that need exploration class solutions. This is also true when you consider living on the moon or Mars, where even more variables have to be considered.

You've gone to the Arctic, Antarctic, and flown on a bunch of weird aircraft -- What is you best memory or favorite event that you've experienced? Least?

Follow up: ever vomited on the the vomit comet?

Anna-Lisa: I'd say Antarctica is probably my favorite, though the arctic is a close second. Least favorite? I don't have one - i even liked throwing up on the vomit comet, well, it was worth it. And i don't get sick much anymore.

Rob: Flying in aircraft like the F104 are truly favorites. I have to say that both the arctic and Antarctica remain truly emotional experiences. Least favorite? I dont throw up often, but early in my vomit comet experiences i did, and it was a whole body, fully involved, horrible event. I had been trying cinnamon candies to settle my stomach, so my puke was bright red. really

What are your plans to handle the much higher level of radiation due to no native atmosphere or magnetosphere?

I mean? Not even taking lethal solar flares into consideration...

We are assuming you mean either on the surface of Mars or in transit. To be honest, the handling of radiation is a big issue. Estimates range from radiation not being any problem to radiation being prohibitively dangerous. That all said, how do we "handle" it? There are two things at play here. First, is there a shielding scheme that can work? The physics of this is beyond our knowledge, but one key item here is that water is a pretty good shield. And the vegetative parts of plants are reasonably resistant to radiation. So one habitat shielding idea is to grow plants on the exterior walls of the habitat, helping keep water near the walls, therefore protecting the humans inside. Of course this does not help the plants themselves handle the radiation. Second is that we are just now entering an era when biology will go beyond the van Allen belts - so we hope to be able to handle radiation by learning a LOT more about what it does to biology, and what biology can do to deal with the effects of radiation.

So as scientists, we would mostly answer your question by saying that we need to do more science to find out the best answers to your questions!

Thank you.

Excellent answer.

Do you guys think there is enough water on Mars to handle both radiation shielding and water needs of plants?

Great question! We would not be the best experts to talk about how much water there is on Mars, but here are a couple of points for consideration:

- there certainly is a good amount of water on Mars, relative to the needs of plants and people, especially early on.

- it is likely that we will be taking a good bit of water with us, at least enough to keep the transit habs habitable. The cool thing about water in these habs is that it shoudl be essentially completely recyclable. Plants take in our dirty water and transpire clean water. So once we get started, we dont need a lot of inputs over time from the Martian surface.

What plant was able to stay alive the longest before it died? We're you able to get a mature plant to grow?

Our research is focused on the model plant arabidopsis - kind of the white mouse of the plant world. We don't have a lot of experience ourselves with other kinds of plants, but for the most part, if you give plants the right environment in which to grow even on the Space Station, they do pretty well. Part of the reason that they do well is because they are masters of their metabolic universe and they adjust their metabolism to grow in new and novel environments. What we study is what is behind these adjustments and how we can help plants do that even more easily.

You really have to rely on astronauts on the space station to conduct your experiments. How does that work? Do you interact with them while they perform your experiments?

First of all, you are absolutely right, yes we do! We do work with the astronauts in the development phase of our experiments. We go out to Houston and train them on how to conduct our experiments. Astronauts are pretty excited about working science and working with the scientists to get the most out of the experiments that are going to orbit. Sometimes, we interact with the astronauts while they are on the Space Station. We can't talk to them directly because it has to go through the Marshall Space Center who essentially calls the Space Station. This way we can answer questions the astronauts might have and guide them with aspects of the experiment. And that's a pretty fun thing because there's a video going where you can see what the astronauts are doing while talking to them.

You have been to both the North Pole and the South Pole. What is it about these environments that helps you understand plants in space?

Excellent question, but one with a complicated answer.

Primarily the high arctic desert of Devon Island is one very special kind of lunar and Martian analog. Devon island has a large impact crater that has not been deeply weathered or changed by biology. So going there gives all of science a view and perspective of what living and working in and near a crater is like. The Arthur Clarke Greenhouse was perched at the edge of the crater as part of the Haughton Mars Project. It let us explore how to grow plants in the soils around a crater, something that we could not do anywhere else. We did that work with colleagues from the Canadian Space Agency and NASA. Check this out https://www.nasa.gov/analogs/hmp

Antarctica is also very special but in a different sort of way. For that project we work with the German space agency and instead of looking at growing plants near a crater, in Antarctica we work with specialists who are thinking about how to feed an expedition crew that is extremely isolated. We worked at the Neumayer III ice station and the German space agency built a containerized plant production unit that functions year round on the ice. In this case, part of the outcome is to, yes, actually provide food to the 9 or so people that live there, isolated, over the winter. If you would like to see this place and the plant growth unit in Antarctica, check this out https://eden-iss.net/

So these extreme places each teach us something different about what feeing Martian explorers might look like.

Greetings! Thank you for answering our questions! What’s an average day like for each of you and how do you stay organized juggling so many important roles and different research projects?

Wow, your question makes us feel special! Juggling so many roles and projects sounds pretty darn cool - yet the real life situation is that work is often, well, work. Going to launches and talking to astronauts and flying in zero g and going to Antarctica are, unfortunately, not every day experiences.

So, average day? Hmmm.

A lot of time is spent in organization and planning, especially with expedition type experiments. Its not like you can spin those up in a few minutes. Each launch, each flight and each expedition takes weeks to months to years of planning. A typical day, therefore, is often taken up in part with planning. And just as an aside, the ratio of such lab and office work to actually being in a plane or in Antarctica is pretty big.

A fair bit of time it taken up with writing. Writing proposals to do all these experiments takes a really large amount of time. Each experiment and each expedition starts with a proposal. Each of these experiments and expeditions also finishes with a publication, so with proposals and papers all needing writing, we spend a fair bit of time on a keyboard.

The funnest part of a typical day is interacting with students and all the cool people that it takes to do this kind of science. We might be talking to NASA HQ or Kennedy Space Center to work on a project idea. We might be talking with students interested in our science. We might be giving seminars on our work to colleagues.

Or maybe lunch is the best part of the day :)

What are the current most pressing concerns for feeding Martians?

I guess developing the habitats, meaning greenhouses that can grow and support plants and protect them from the outside environment on Mars. Things like the atmosphere, the substrate meaning whether we want to use soil-like materials we get from the surrounding area or we use hydroponics or aeroponics, none of this has been worked out.

But, lots of scientists are working on these problems. We (the scientific community) practice in extreme locations like Antarctica and model systems in our laboratories.

Do you find that the best arrangement for growing plants in microgravity is to arrange them around the inside of a cylinder towards a central linear light, or is it more space efficient to grow them in racks with a field of LEDs above each shelf, or what works best?

Okay, that's a pretty specific question!

Bottom line is that folks are still working on what is the best configuration to grow plants in microgravity. To my knowledge, no one has tried the cylindrical approach but that might be problematic because of the lack of convection in microgravity, so airflow is a problem. Right now it looks like the LEDs above the shelf concept is the most efficient, but we're really glad to see folks are thinking about these things even outside the halls of NASA.