Figure 1.
Scissors (top), Pepper Grinder (middle), and Guillotine (blade removed) (bottom) planting boxes with young Daikon radish microgreens.
Figure 2.
Parabolic flight phases. Hypergravity was experienced during ascent, microgravity at the inflection point, and hypergravity upon descent. Airplane image courtesy of Zero Gravity Corporation.
Figure 3.
Experimental setup within the ZeroG aircraft. Left: overview of the glovebox in its flight configuration within the aircraft. Right: a view inside the glovebox showing one of the two cameras filming the inside.
Figure 4.
Photograph showing (left) Guillotine, (center) Scissors, and (right) Pepper Grinder microgreen planting boxes.
Figure 5.
Pepper Grinder hardware. (A) Top view of the assembled hardware. (B) Top view of the different pieces of the hardware.
Figure 6.
Guillotine hardware. (A) Top view of the assembled hardware, (B) Top view of the different pieces of the hardware, (C) CAD drawing of the different hardware elements.
Figure 7.
Scissor and growth hardware. (A) Top view of the scissors and growth lid. (B) Top view of the different pieces of the growth hardware and scissors.
Figure 8.
Bagging methods. Left: attached bag. Right: zip-top bag.
Figure 9.
Attached bag on Pepper Grinder hardware. (A) Loose string, position while cutting the microgreens. (B) Tied string, position after harvesting complete.
Table 1.
Quantitative and qualitative data collected in-flight and post-flight.
| Quantitative Data | Qualitative Data | |
|---|---|---|
| In-Flight |
|
|
| Post-Flight |
|
|
Table 2.
Criteria and associated weights used for the trade analysis, along with justification for each criterion.
| Criteria | Evaluation Data | Data Collection | Justification | Weight |
|---|---|---|---|---|
| Time of Execution | Average total harvest time across all operators | Flight video analysis | Crew time needs to be minimized | 1 |
| Microgreen Debris | Average debris counts across all operators | Flight video analysis | Loss of food and environmental safety hazard—needs to be minimized | 2 |
| Yield (edible biomass) | Fresh mass adjusted by planting density | Post-flight weighing | Biomass production needs to be maximized | 2 |
| Root debris | Average root debris counts across all operators | Post-flight count | Food safety hazard needs to be minimized | 2 |
| Percentage of microgreens left on the hardware | Ratio between microgreen plants remaining on hardware and total plants | Post-flight count | Loss of food—needs to be minimized | 1.5 |
| Number of seedlings growing under the lids | Average number across all units of a given hardware | Post-flight photo analysis count | Loss of food—needs to be minimized | 1.5 |
| Percentage of no failures of the hardware | Ratio between number of hardware failure and total runs | Flight video analysis | Severe loss of food, potential food safety hazard—needs to be minimized | 2 |
| Perceived ease of use | Average score across all operators | In-flight surveys | Mental health of crew—needs to be maximized | 1 |
Table 3.
Average and standard deviation for eight different criteria and the six combinations.
| Cutting & Bagging Method | Number of Cases | Mean Time of Execution (s) +/*− Standard Deviation | Microgreen Debris (number) | Yield (g of edible biomass) | Root Debris (number) | Microgreens left on Hardware (%) | Seedlings Growing under Lid (number)** | No Hardware Failure (%) | Perceived Ease of Use*** |
|---|---|---|---|---|---|---|---|---|---|
| Guillotine Attached | 9 | ab 18.00 +/− 4.4 | ab 7.78 +/− 7.0 | ab 19.39 +/− 5.7 | a 1.89 +/− 2.4 | a 12.56 +/− 8.0 | ab 13.14 +/− 10.7 | a 100 +/− 0 | 4.03 |
| Guillotine Manual | 11 | ab 19.27 +/− 3.7 | a 8.82 +/− 4.3 | a 23.42 +/− 7.0 | a 2.55 +/− 2.7 | a 4.91 +/− 3.4 | ab 13.14 +/− 10.7 | a 100 +/− 0 | 4.03 |
| Pepper Grinder Attached | 10* | a 13.20 +/− 4.7 | b 2.60 +/− 1.8 | ab 15.24 +/− 2.6 | a 0.90 +/− 1.4 | a 0.40 +/− 0.5 | a 16.00 +/− 5.3 | ab 80 +/− 40 | 1.87 |
| Pepper Grinder Manual | 9* | ab 16.89 +/− 5.0 | a 11.00 +/− 5.9 | b 12.36 +/− 3.0 | a 0.89 +/− 1.6 | a 0.67 +/− 0.67 | a 16.00 +/− 5.3 | a 100 +/− 0 | 1.87 |
| Scissors Attached | 10* | b 20.89 +/− 5.7 | b 2.00 +/− 1.7 | a 22.68 +/− 7.7 | a 0.90 +/−1.4 | b 30.20 +/− 16.7 | b 6.54 +/− 3.7 | b 60 +/− 49 | 4.77 |
| Scissors Manual | 9 | ab 19.56 +/− 3.9 | a 12.11 +/− 4.3 | ab 21.42 +/− 9.1 | a 1.67 +/− 1.9 | a 11.2 +/− 7.6 | b 6.54 +/− 3.7 | a 100 +/− 0 | 4.77 |
The letters indicate the different significance between means of the different groups following a one-way ANOVA test on the given criterion, for the factor Cutting & Bagging method.
* N=9 for the yield computation of Pepper Grinder with attached bagging. N=8 for the yield computation of Pepper Grinder with manual bagging. N=9 for the time of execution computation of Scissors with attached bagging.
Table 4.
Normalized and weighted data for each criterion of the six combinations of Cutting & Bagging method.
| Cutting & Bagging Method | Time of Execution (s) | Microgreen Debris (number) | Yield (g of edible biomass) | Root debris (number) | Microgreens left on Hardware (%) | Seedlings Growing under the Lid (number)* | No Hardware Failure (%) | Perceived Ease of Use** | Total | Rank |
|---|---|---|---|---|---|---|---|---|---|---|
| Guillotine Attached | 0.77 | 1.05 | 1.66 | 1.21 | 0.90 | 0.88 | 2.00 | 0.55 | 9.01 | 5 |
| Guillotine Manual | 0.71 | 0.87 | 2.00 | 0.70 | 1.28 | 0.88 | 2.00 | 0.55 | 8.98 | 6 |
| Pepper Grinder Attached | 1.00 | 1.90 | 1.30 | 1.99 | 1.50 | 0.61 | 1.60 | 1.00 | 10.91 | 1 |
| Pepper Grinder Manual | 0.82 | 0.51 | 1.06 | 2.00 | 1.49 | 0.61 | 2.00 | 1.00 | 9.49 | 3 |
| Scissors Attached | 0.63 | 2.00 | 1.94 | 1.99 | 0.02 | 1.50 | 1.20 | 0.39 | 9.67 | 2 |
| Scissors Manual | 0.70 | 0.33 | 1.83 | 1.39 | 0.96 | 1.50 | 2.00 | 0.39 | 9.10 | 4 |
Figure 10.
Graphical representation of the trade analysis results, giving the scores of each Cutting & Bagging combination. The evaluation criteria are indicated, their color indicate their weight: red = 2, yellow = 1.5, green = 1.
Figure 11.
Photos of the three types of growth hardware after harvesting. (A) Guillotine. (B) Pepper Grinder. (C) Scissors.