Astronauts to Grow Lettuce In Space

A prototype version of Veggie with red romaine lettuce plants growing inside of it.
Image Credit:  NASA/Gioia Massa

SpaceX's Dragon module is scheduled to launch today at 20:58 UTC and among the more interesting things in the cargo manifest is a new grow chamber nicknamed "Veggie".

This is not NASA's first time attempt at hydroponics by any means, but this proof-of concept has something I haven't seen before - planting pillows.  The pillows contain one of two different sized arcillite (calcined clay media) to test which of the sizes provides better water and root distribution for the lettuce.

As with all NASA experiments, there are a multitude of research goals for Veggie, but three that caught my eye.

First is the tech behind the growth chamber and the data loggers used.

Second is the concern with food safety and microbial growth, highlighting the classic differences between hydroponics and aquaponics regarding the sanitizing of equipment.  It also explains why the plant pillows are one-time use.

Finally, there is the psychological aspect for the crew, from the inclusion of some fresh produce in their diet to the daily care of living plants.  I'd designate Veggie the ISS water cooler and wonder if any astronauts would fall over (space physics anyone?) just to smell the fresh air.

You can read more info about the Veg-01 experiment here.

Tracker Update

The first two public modules for Tracker, water quality and grow beds, are online and you can sign up for free here.

Water quality allows you to upload results from the API Freshwater Master Test Kit, and track that over time.  You can see the screenshot below.  Adding a note and image to a water quality reading is a feature that will be turned on this week.




Grow beds are easily the feature we are the most excited about with regards to integrating environmental and water quality monitoring to analyze the health of a plant.  Speaking of plants, each plant has an associated seed packet, which you can grab from the shared community list, or upload and share your own.  Similar to water quality readings, you will be able to add notes to your seed packets to record things like germination rates, which you can refer back to anytime.



Beta testers, the ADACS modules are being kept separate for the time being while each of these new modules are put online and tested, after which we will integrate the controllers one at a time.  You can find more information in your message box.

Staggered Growth


A square foot garden can produce a surprising amount in a small space and those growing the ingredients for the secret family spaghetti sauce will naturally plant the box so they can harvest everything at once.   This a great practice when canning or preserving, but it does not translate so well to aquaponics.   After all, aquaponic plants aren't just a delight on the senses (I'm eyeing you dill), but also contribute to solid filtration and, of course, nitrate absorption;   in other words, they serve a critical role in the balance of the ecosystem.

Seeking to maximize the growing season, gardener's will already have seedlings ready to transplant in empty garden cells.   While you may view this as a bit zealous, this practive of staggered growth, alternating the timing of your transplants, is almost a necessity to maintaining balance in your aquaponics system.   As your fish age, ammonia production steadily increases, requiring an equally increasing ability to remove nitrate.   Look at the example below, where there is a small grow bed with three large plants and one small spinach, all of which are assumed to be fully mature.   Please note that these scenarios and their corresponding data are entirely fictitious and were chosen for conceptual purposes.














The nitrate data shows that over the course of 10 days, the four plants are keeping the nitrates relatively in check.




Shift the slider above to the right to simulate the removal of a spinach plant.   You will see that in the days after the removal of the spinach, you get get a small, yet perceptible, bump in the nitrate levels.   This is as you would expect from a small plant, despite the spinach being a nitrogen hog.   What is important to note is that the remaining plants are still holding the nitrate levels reasonably steady.

If you replay the scenario, but instead harvest the tomato, squash and cucumber, you are left with a lowly spinach to handle the volume of nitrate produced.   Again, slide the toggle below the red chart to the right.




As expected, the change in the nitrate readings is more dramatic.   Not only is the spinach unable to make up for the loss of its companions, but the difference begins to compound on itself.   The excess nitrates from yesterday are added to the new batch produced today and so on.

Staggered planting and maintaining a good ratio of small to large plants is key to avoiding this situation and is easily done by tracking plant ages.   The grow bed below is much like the situation above, where the tomato, squash and cucumber are all nearing their harvest date together, eventually leaving a small spinach to pick up the nitrate absorption slack.   In this case, I paid attention to staggering when I planted my grow bed, but I did not account for the growing cycle of each plant, hence all of my large plants are done around the same time.


Managing staggered growth is critical to maintaining a system balance and is easy to do when you account for harvest periods and plant sizes.


Interactive Lessons


It seems every introduction to aquaponics begins the same way:   stating the environment of an aquaponics system is a compromise between the ideal preferences of the plants, fish and nitrifying bacteria.   While the statement is factually correct, it is nearly useless for people new to this unique growing method.   Inevitably, to backup our statement, we pour on the detail.   For example (using wide ranges here for emphasis), fish prefer a pH of 6.5-7.5, plants a range of 5.5-6.5 and bacteria from 6.5-8.0.   That's when the glassy-eyed look of someone suffering from information overload sets in.  Can't you picture them trying to mentally map the overlaps?

Outside of the startup price, this phenomenon of information overload is the primary barrier to entry in aquaponics.   The irony is that the information is all readily available, but all too often in a format difficult to process.   Professional Commercial courses attempt to solve this barrier in three ways:

  • Whiteboards / shiny slideshows with a ton of dry statistics and cute pictures.
  • People to read the slideshow to you in the voice of Professor Binns (that's right, I made a Harry Potter reference)
  • Hands-on training

Lets face it, the hands-on training is by far the most valuable, giving you a visual and tactile connection to the data, i.e., providing context.

With today's modern technology, it's time for a modern approach, so we've been putting together a series of lessons where you get the horribly dry statistics (sans Professor Binns) paired with interactive widgets  that you can revisit over and over without the $1,000+ price tag.

To give you a sense of what these lessons are like, take the case of pH, which is a great starting point when teaching the concept of the system as a compromise.   In our example, we'll assign an ideal range to each component of the system, and to the system overall.

  • Overall system:  6.7 - 7.1
  • Plants:  5.5 - 7.0
  • Fish:  6.5 - 8.0
  • Bacteria:  6.7 - 8.0

Start with a neutral pH and slide the toggle button up to simulate an alkaline system.   Notice how quickly the plants are outside of their range.   Slide the toggle the other way and the system shifts towards an acidic enviornment, which is great for the plants but not the fish or bacteria.   You can see from the System gauge the narrow window you have to work in, while at the same time you can get a sense how the pH shifts affect the individual system components.




This is a simplistic example; it gets more complicated when you factor in each type of plant and fish with their own preferences.   When they are posted, you will be able to find these lessons in Learn, but hopefully this gives you a sense of where we are going with these and the scope they entail:

  • Water quality
  • Environment
  • System design
  • Fish and plant disease occurrence and progression

This concept of giving data immediate context is the principle behind Tracker.

Water Quality DAQ is Going Up

**Update**
The Water Quality DAQ is online.

The Water Quality DAQ chapter is going up over the weekend.  It tracks

  • Water Temperature
  • pH
  • Dissolved Oxygen

Water Quality DAQ.

Some new features, which will be added in an update to the Environment DAQ, are an easy method of grabbing past data and displaying the last time the Arduino synced along with the last time the screen refreshed.


New ability to see past data.

Similar to past projects,
  • You can set email and SMS alerts when data moves outside of your defined ranges.  
  • The gauges are used for real-time graphing