The candidate crops for planetary food systems include: wheat, white and sweet potatoes, soybean, peanut, strawberry, dry bean including le ntil and pinto, radish, rice, lettuce, carrot, green onion, tomato, p eppers, spinach, and cabbage. Crops such as wheat, potatoes, soybean,  peanut, dry bean, and rice can only be utilized after processing, while others are classified as ready-to-eat. To process foods in space,  the food processing subsystem must be capable of producing a variety  of nutritious, acceptable, and safe edible ingredients and food produ cts from pre-packaged and resupply foods as well as salad crops grown  on the transit vehicle or other crops grown on planetary surfaces. D esigning, building, developing, and maintaining such a subsystem is b ound to many constraints and restrictions. The limited power supply, storage locations, variety of crops, crew time, need to minimize waste , and other equivalent system mass (ESM) parameters must be considere d in the selection of processing equipment and techniques

Campanella, O.

Chen, G.

Corvalan, C.

Fortune, S.

Gandolph, J.

Mauer, L. J.

Okos, M.

Perchonok, D. M.

Weiss, I.

Wijeratne, W.

NASA Technical Reports Server

 1 
Foods for a Mission to Mars: Equivalent System Mass and Development of a 
Multipurpose Small-Scale Seed Processor 
 
J. Gandolph1, G. Chen2, I. Weiss1, D. M. Perchonok3, W. Wijeratne4, S. Fortune4, C. 
Corvalan1, O. Campanella2, M. Okos2, and L.J. Mauer1* 
 
1Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West 
Lafayette, IN 47907 
2Agricultural and Biological Engineering, Purdue University, 745 Agricultural Mall 
Drive, West Lafayette, IN 47907 
3NASA Johnson Space Center, Mail Code SF3, 2101 NASA Road 1, Houston, Texas 
77058 
4Insta-Pro International, 10104 Douglas Avenue, Des Moines, Iowa 50322 
 
*Corresponding Author L.J. Mauer: phone 765-494-9111, e-mail 
mauer@purdue.edu 
 
Description of the problem 
 
The candidate crops for planetary food systems include: wheat, white and sweet 
potatoes, soybean, peanut, strawberry, dry bean including lentil and pinto, radish, rice, 
lettuce, carrot, green onion, tomato, peppers, spinach, and cabbage. Crops such as wheat, 
potatoes, soybean, peanut, dry bean, and rice can only be utilized after processing, while 
others are classified as ready-to-eat (Levri et al. 2003). To process foods in space, the 
food processing subsystem must be capable of producing a variety of nutritious, 
acceptable, and safe edible ingredients and food products from pre-packaged and re-
supply foods as well as salad crops grown on the transit vehicle or other crops grown on 
planetary surfaces. Designing, building, developing, and maintaining such a subsystem is 
bound to many constraints and restrictions.  The limited power supply, storage locations, 
variety of crops, crew time, need to minimize waste, and other equivalent system mass 
(ESM) parameters must be considered in the selection of processing equipment and 
techniques. Equivalent System Mass (ESM) is a metric developed by NASA to describe 
https://ntrs.nasa.gov/search.jsp?R=20070031842 2019-08-30T01:38:02+00:00Z
 2 
system and sub-system influences on closed loop networks in terms of a single parameter, 
mass (Levri et al. 2003). The food system of a Mars mission may use a large percentage 
of total mission ESM, potentially up to 50% (Hanford, and Ewert 2002), and any 
decrease in this ESM would be extremely beneficial to the success of a mission. The non-
crew time ESM, or so called crew-independent ESM, is calculated as shown in Equation 
1: 
 
 
iCiPiViiNCT CPVMESM ⋅+⋅+⋅+= γγγ,  
Equation (1) 
  Where: 
 
ESM is the Equivalent System Mass value of  the technology / equipment i  in kg 
 
Mi  is the mass of the technology / equipment  i in kg 
 
Vi is the volume of the technology / equipment i in m3  
 
Pi  is the power drawn by the technology / equipment i in kW 
 
Ci is the cooling requirement of the technology / equipment  i in kW (assumed to be 
equal to power) 
 
The γ’s are defined as conversion factors or cost equivalencies used to convert the 
non-mass parameters into mass measurements. These constants are calculated based on 
the mission, design of the vessel, power supply, and cooling system (Levri et al. 2000). 
Hanford and Ewert (2002) computed equivalencies for advanced missions. Several 
researchers have calculated ESM of select types of food processing equipment to 
compare ESM for individual food types; however, a survey of ESM parameters for a 
wide variety of currently available food processing unit operations and packaging 
materials has not been completed. 
 3 
Conversion of highly processed crops into palatable food products will require a 
variety of processing operations that include mixing, cooking, and solid-liquid separation. 
Due to the ESM restraints, multi-purpose equipment specifically designed for minimum 
ESM, minimum crew-time involvement, and maximum versatility for food production is 
needed. A survey of available equipment and current ESM parameters is a starting point, 
but ideally targeted equipment would be designed for NASA missions. The proposed 
seed processor offers all of these processing operations in a single compact and 
lightweight equipment, able to produces multiple foods and food ingredients and work in 
a low gravity environment with minimal crew time and energy for operation and 
cleaning. The multi-purpose nature of the seed processor could reduce the equivalent 
system mass (ESM) of equipment necessary to perform a variety of essential food 
processing operations by reducing the amount of equipment that must be sent and 
reducing crew time necessary to process and prepare foods. 
In addition, there is a non-NASA demand for very low capacity extruders to 
process high value seed materials available only in small quantities.  The smallest Insta-
Pro extruder is 300 kg/hr in capacity.  For small agribusiness in developing countries, a 
lower capacity extruder is desirable.  Research and development organizations involved 
in biotechnological innovations concerning new cultivars also demand very low capacity 
extruders compatible with the limited supply of the experimental seed materials.  The 
proposed small-scale multipurpose seed processor is directly relevant to meet these 
demands. 
 
Objectives: 
1. To collect the parameters needed for calculating the ESM of processing and 
packaging scenarios for a mission to Mars and prepare spreadsheets of ESM 
information for different scenarios.  
 
2. To design and manufacture a small scale multipurpose seed processor that is able 
to provide the crew of future long duration space flights with a variety of 
nutritious, safe, and palatable foods similar to those produced by industrial 
extruders. 
 4 
 
 
Findings to date 
 
Equivalent system mass of food processing equipment 
Gandolph et al. (2004) compiled ESM-parameter information (mass, volume, and 
power) for currently available, small-scale food processing equipment and to provide 
average, high, and low ESM values for each class of equipment (hand-held and bench-top 
mixers, etc.) that performs the following unit operations: mixing, size reduction, heat 
transfer (heating and cooling), and extraction (water, oil, and juice).  In this study, each 
piece of equipment was assumed to perform a single task, the power required for cooling 
was set equivalent to the power needed to operate the equipment, and the crew-time was 
not considered in the preliminary ESM estimates.  These values could serve as a 
reference for comparing ESM parameters of other equipment not considered in this 
document, for evaluating effects of multi-purpose use (multiple functions or food 
products), and for evaluating effects of different crew-time requirements on ESM related 
to food processing scenarios.  
 
Equivalent system mass of bread production 
Weiss et al. (2003, 2004) investigated the impact of grain mill type on the ESM of 
producing yeast and flat breads and collected ESM data for producing yeast and flat 
breads from commercial mixes or raw ingredients (flour, etc.). Wheat is a candidate crop 
for the Advanced Life Support system, and cereal grains and their products will be 
included on long-term space missions beyond low earth orbit. While the exact supply 
scenario has yet to be determined; some type of post-processing of these grains must 
occur if they are shipped as ingredients or grown on site for use in foods, and equipment 
capable of processing grains must be evaluated. There were significant differences in 
ESM values for making breads, and production methods, milling methods, and baking 
methods all contributed to these differences. The need to develop multi-use equipment 
simultaneously with product formulations and menu rotations is necessary due to the high 
 5 
cost of launching materials into space and the need to minimize the food system 
contribution to total mission ESM. 
 
Food Packaging Waste Scenarios 
 Because handling unusable package waste in an enclosed, bioregenerative life 
support environment will be difficult, it is imperative to investigate alternate packaging 
scenarios that will both minimize waste and maximize product quality (barrier properties 
are essential). Using the Baseline Values and Assumptions Document (BVAD) waste 
assumptions (Hanford and Ewert 2002), package waste mass for the 1080 day mission to 
Mars would be between 1555 kg and 1750 kg. All comparisons of other packaging 
options obtained from a survey of literature/commercial products were made to reference 
values from Levri (2001), adapted and shown in Table 1.  
 
Table 1. Packaging waste estimates for a mission to Mars. 
Packaging Type Mass per 
clean 
package (g) 
Number of 
packages consumed 
per person per day 
Waste (package mass, g) 
per day for 6 crew 
members 
Package waste (kg) for 
1080 day mission with 
6 crew members 
Rehydratable 16.61 6.29 627 677 
Thermostabilized(1-
serving) 
8.61 3.71 192 207 
Beverages  
(+ straw) 
14.56 3.43 300 324 
Irradiated 8.00 0.43 21 23 
Natural form/IMF 6.93 3.57 149 161 
Fresh foods (tortillas) 10.50 1.57 99 107 
   Total package waste (kg) 
=   
1499  
(some estimates up to 
1750 kg) 
 
Based on these estimates, spreadsheets were developed to predict packaging waste 
generated for a variety of food storage and consumption scenarios (Snuffin et al. 2005). 
To summarize conclusions, removing the rehydratable foods following the 240 day 
outbound flight has the greatest single impact on package waste, reducing the waste by 
 6 
~17% if irradiated, IMF, and/or thermostabilized foods are substituted. Removing 90% of 
single-serve beverages during the 600 day surface stay reduced package waste by ~11% 
Biodegradable packaging may not be a viable option for space foods due to barrier 
property limitations and strict control of food quality and safety. Impact of biodegradable 
packages on solid waste handling systems is unknown. Depending on amount of mass 
reduction over current package formats, lighter-weight high-barrier package materials 
that meet NASA constraints could reduce package waste (with an average 1 gram per 
package reduction, the total package waste would be reduced by ~8%). More work is 
needed in the design of high-barrier package formats for a mission to Mars, considering 
ESM, multi-use formats, and integration with waste-processing and other subsystems in 
the enclosed habitat. 
 
The small scale multi-purpose seed processor (MSP) 
 The developmental stages for modeling, designing, and constructing a small scale 
multi-purpose seed processor are described in the following five sections: 1) design and 
fabrication of a prototype extruder; 2) testing the prototype; 3) designing an oil press; 4) 
designing a (on line?) slit die viscometer; and 5) downscaling and design of the small 
scale multi-purpose seed processor (MSP). 
 
1) Design and fabrication of a 30kg/hr prototype dry extruder 
            A 30 kg/hr extruder has been designed and fabricated.  The design was the result 
of a 10-fold scale-down of the smallest commercial extruder manufactured by Insta-Pro 
International (Des Moines, Iowa).  This was the first step in a proposed gradual scale-down 
of the commercial extruder to a size suitable for the NASA application.  The design and 
construction of the 30 kg/hr prototype extruder (shown in Figure 1) was intended to 
validate the mathematical model used for the scale-down process (Chen et al. 2005) and 
to demonstrate that the machine is functional at this level of downscaling.  
 
Deleted: extruder 
 7 
 
 
Figure 1. The 30kg/hr Prototype Dry Extruder 
 
2) Testing the 30kg/hr extruder  
            The functionality of this prototype was tested with raw materials selected from the 
NASA candidate crop list. The machine was tested for its functionality in processing full 
fat soybeans. The commercial process of full fat soy is designed to deactivate the 
endogenous protease inhibitors and release the oil for its subsequent extraction in an oil 
press.  The adequacy of the thermal deactivation process was determined by measuring 
the urease activity of soybean at the beginning and end of the process. The target was to 
deactivate urease activity by 90% of initial value.   
             The machine was able to successfully process full fat soybeans, and no major 
troubleshooting was necessary. Trials showed that it was possible to attain similar 
temperature profiles in the prototype to those observed during the commercial process.  
The process temperature at the discharge end of the extruder was approximately 300° F.  
The throughput rate of the extruder was 31 kg/hr.  These results were useful for 
validating the mathematical models used for the extruder scale-down.  The urease 
activities in the raw bean and the processed full fat soybean were 2.13 pH units and 0.02 
pH units, respectively.  This represents a 99% deactivation of urease activity.   
        When rice was introduced with soy, the temperature profile was in excess of the 
desired target, which indicated that the screw configuration must be changed for 
Deleted: processing 
Deleted: successfully 
 8 
processing different cereal-based products.  Further development will focus on the design 
of a universal screw for processing a variety of cereals. 
 
3) Development of the oil press  
             The design of the oil press, which has been based on principles similar to those 
used in the design of the prototype extruder, has been completed. Engineering drawings 
for the fabrication of the press have also been finished, and the press fabrication is on-
going.   
 
4) Design of the (on line?) slit die viscometer  
             One of the important tasks in development of the multipurpose extruder is the 
study of rheological behavior of various raw materials of NASA interest (e.g. candidate 
crops or bulk ingredients) during the extrusion process.  These studies are necessary to 
optimize the extrusion process and ensure that the products will have acceptable physical 
and sensory characteristics. For this purpose it was proposed to design an on-line slit die 
viscometer to characterize the rheology of extrudate melts which have been previously 
subjected to extrusion. The design and engineering drawings of this viscometer have been 
completed, and the fabrication of the viscometer is on-going.    
 
5) Downscaling and design of the small scale multi-purpose seed processor (MSP) 
In summary, a mathematical model used for the scale-down of food extruders has 
been validated by successful design of the 30 kg/hr prototype extruder. It has been 
demonstrated that the machine is functional at this level of downscaling. In the next step, 
the same downscaling method will be applied to the design of the small scale multi-
purpose seed processor (MSP) which will minimize the mass, volume, power 
consumption and other ESM metrics while satisfying a set of constraints. These 
constraints, such as residence time distribution and specific mechanical energy, will be 
imposed to guarantee a final product quality comparable to products produced in 
industrial size extruders.  
 The primary NASA application of the designed MSP will be for performing a 
Deleted: design 
Deleted: be able to 
Deleted: the 
Deleted: operating conditions
 9 
variety of processing operations including size reduction, cooking, liquid extraction, 
dehydration, stabilization, and texturization for long duration ALS system. These 
operations will convert seeds grown on planetary surfaces or shipped as bulk ingredients 
into a variety of nutritious and safe food products, such as pasta, vegetable oil, dense and 
expanded snacks, breakfast cereals, and texturized meat-like vegetable proteins without 
requiring external heat supply. Because different food products require different 
operating conditions (such as temperature, pressure and shear rate), the MSP is designed 
to allow the (inter?)changing of some parts, e.g. screws, and the motor rotation speed to 
meet processing requirements of different products. Additional applications of the MSP 
include using the seed processor as a press for phase separation of solid and liquids, in 
particular oil - and water in a low gravity environment. Another potential use of the MSP 
include dehydration and volume reduction for wet solid wastes, as well as microbial and 
enzyme inactivation to reduce biological hazards. 
 
Research needs. 
There is a dual need to both characterize the ESM of currently available food 
processing equipment and to develop new multi-purpose equipment to fit within NASA 
mission constraints. ESM considerations must also include crew-time, equipment 
capacity or throughputs, actual power draw, equipment wear and tear, behavior of foods 
and processes in reduced gravity, and differences in crew-time needed to operate, for 
example, one type of food processor versus another. Also important to note is that, for 
foods, ESM does not take into account product quality as defined by nutritional value, 
sensory characteristics, diet cycle, and chemical or physical food stability. 
Interdisciplinary research efforts are needed to develop an integrated food subsystem for 
NASA missions beyond low Earth orbit. 
 
 
Acknowledgements 
This research was supported in part by NASA grant NAG5-12686 and NASA-
SBIR grant NNJ06JA26C.  
 
Deleted: or 
 10 
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Foods for a Mission to Mars: Equivalent System Mass and Development of a Multipurpose Small-Scale Seed Processor

Foods for a Mission to Mars: Equivalent System Mass and Development of a Multipurpose Small-Scale Seed Processor

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