Daniel Schubert

Review and analysis of over 40 years of space plant growth systems

The cultivation of higher plants occupies an essential role within bio-regenerative life support systems. It contributes to all major functional aspects by closing the different loops in a habitat like food production, CO2 reduction, O2 production, waste recycling and water management. Fresh crops are also expected to have a positive impact on crew psychological health. Plant material was first launched into orbit on unmanned vehicles as early as the 1960s. Since then, more than a dozen different plant cultivation experiments have been flown on crewed vehicles beginning with the launch of Oasis 1, in 1971. Continuous subsystem improvements and increasing knowledge of plant response to the spaceflight environment has led to the design of Veggie and the Advanced Plant Habitat, the latest in the series of plant growth systems. The paper reviews the different designs and technological solutions implemented in higher plant flight experiments. Using these analyses a comprehensive comparison is compiled to illustrate the development trends of controlled environment agriculture technologies in bio-regenerative life support systems, enabling future human long-duration missions into the solar system.

Greenhouse Module for Space System: A Lunar Greenhouse Design

Abstract In the next 10 to 20 years humankind will return to the Moon and/or travel to Mars. It is likely that astronauts will eventually build permanent settlements there, as a base for long-term crew tended research tasks. It is obvious that the crew of such settlements will need food to survive. With current mission architectures the provision of food for longduration missions away from Earth requires a significant number of resupply flights. Furthermore, it would be infeasible to provide the crew with continuous access to fresh produce, specifically crops with high water content such as tomatoes and peppers, on account of their limited shelf life. A greenhouse as an integrated part of a planetary surface base would be one solution to solve this challenge for long-duration missions. Astronauts could grow their own fresh fruit and vegetables in-situ to be more independent from supply from Earth. This paper presents the results of the design project for such a greenhouse, which was carried out by DLR and its partners within the framework of the Micro-Ecological Life Support System Alternative (MELiSSA) program. The consortium performed an extensive system analysis followed by a definition of system and subsystem requirements for greenhouse modules. Over 270 requirements were defined in this process. Afterwards the consortium performed an in-depth analysis of illumination strategies, potential growth accommodations and shapes for the external structure. Five different options for the outer shape were investigated, each of them with a set of possible internal configurations. Using the Analytical Hierarchy Process, the different concept options were evaluated and ranked against each other. The design option with the highest ranking was an inflatable outer structure with a rigid inner core, in which the subsystems are mounted. The inflatable shell is wrapped around the core during launch and transit to the lunar surface. The paper provides an overview of the final design, which was further detailed in a concurrent engineering design study. During the study, the subsystem parameters (e.g. mass, power, performance) were calculated and evaluated. The results of the study were further elaborated, leading to a lunar greenhouse concept that fulfils all initial requirements. The greenhouse module has a total cultivation area of more than 650 m² and provides more than 4100 kg of edible dry mass over the duration of the mission. Based on the study, the consortium also identified technology and knowledge gaps (not part of this paper), which have to be addressed in future projects to make the actual development of such a lunar greenhouse, and permanent settlements for long-term human-tended research tasks on other terrestrial bodies, feasible in the first place.

Greenhouse Modules and Regenerative Life-Support Systems for Space

Long exploration missions to the Moon and Mars will require the growth of food on site to sustain the crew because current launchers are unable to send the required mass of consumables into orbit at an affordable cost. Growing fresh food will also be of prime importance for the crew dietary and psychological requirements. ESA expertise on advanced life support systems within the MELiSSA (Micro-Ecological Life Support System Alternative) project, coupled to the EDEN (Evolution and Design of Environmentally-closed Nutrition Sources) project in DLR join forces to study a greenhouse within the MELiSSA loop for a manned base on the Moon surface. Both projects are aimed at studying and developing regenerative life support systems for long duration space missions: MELiSSA is a closed artificial ecosystem program based on microbiological and physicochemical waste degradation and higher plants; EDEN combines different CEA Technologies (Controlled Environmental Agriculture) within an automatic planetary Greenhouse-Module (GHM). Previous studies on Greenhouse Modules have addressed mass, volume, and energy consumption needs but the technologies and data on which these calculations were based are now outdated or were limited at that time. They thus need to be reassessed to have better estimates of these variables and evaluate what it takes to grow plants on the Moon. A study of the lunar environment based on various elements such as illumination, radiation levels, accessibility, and temperature gradients, enables to make a comparative analysis for the best location to setup a greenhouse module on the Moon surface. Trade-offs between electrical and natural lighting, and various grow accommodation options, based on the ALISSE criteria are also conducted. Finally, this leads to the identification of critical points and recommendation on future work for preliminary greenhouse concepts.

Combination of Physico-Chemical Life Support Systems with Space Greenhouse Modules: A System Analysis

The cultivation of higher plants occupies an essential role within bio-regenerative life support systems. It con-tributes to all major functional aspects by closing the different loops in a habitat like food production, CO2 reduction, O2 production, waste recycling and water management. Fresh crops are also expected to have a positive impact towards the crew’s psychological health. Nevertheless, plant cultivation in closed environ-ments is challenging and further research on system, subsystem and crop level is required. The controlling and maintaining of closed environment agriculture systems such as space greenhouse modules is difficult due to lack of buffer capacity, low flexibility concerning varying crew size and eclipse periods, and the absence of backup systems in case of plant and system failures. The addition of physico-chemical (P/C) life support sys-tems (LSS) as an intermediate system between the greenhouse module and the habitat/spacecraft has the po-tential to reduce or even eliminate the mentioned difficulties of greenhouse modules. This paper will investi-gate the potential of combining components of physico-chemical systems with greenhouse modules to increase the readiness of the latter. This would allow the creation of a more efficient life support systems by taking advantage of the experience gained in physico-chemical technologies and the related reliability and heritage of these technologies.

Concurrent engineering Knowledge Management architecture

The present paper documents the development and application of a Knowledge Management (KM) architecture and tool, customized to the specific needs within the Concurrent Engineering (CE) scenario. The paper gives an overview and update on the recent development work, executed for ESAs Concurrent Design Facility (CDF). Here, a tailored KM system for the specific needs of the CE design process has been created. An in-depth investigation of the KM awareness within the CE-environment and its participants marked the beginning of the research. The developed KM architecture is divided into four major sections: Capture, Organization, Distribution and Development of knowledge. Every section has several interface modules that are interacting with each other. In addition to these, the concept of a Knowledge Unit (KU) is introduced, where its different contents (e.g. documents, trade-off tables, mass summaries) are stored and linked with so-called metadata, which gives additional information. During a CE-session, engineers do not have the possibility to review extensive report-libraries regarding their relevant subsystem. Therefore, accessing knowledge needs to be straightforward. The challenging task to transfer tacit knowledge elements of CE studies, which are usually created during Round-Tables or Splinter-Meetings, requires new approaches in soft- and hardware support. The developed prototype software platform SPOCK (Software Platform for Organizing & Capturing Knowledge) helps to facilitate all aspects of capturing and distributing knowledge within the Concurrent Engineering environment.

Initial survey on fresh fruit and vegetable preferences of Neumayer Station crew members: Input to crop selection and psychological benefits of space-based plant production systems

Abstract The inclusion of higher plants in bio-regenerative life support systems has been suggested to contribute to a nutritious menu, increase food acceptability and provide psychological benefits to the crew. In 2017, the EDEN ISS project will deploy a greenhouse module to the Neumayer Station III in Antarctica. This system will be used to advance bio-regenerative life support system technologies and operations. An initial survey was conducted to improve crop selection for the EDEN ISS greenhouse module by further investigating the aspects of food acceptability and psychological benefits of crop cultivation. Former members of the overwintering crews of the three Neumayer stations were asked about their fresh food and vegetable preferences and about further aspects concerning Antarctic plant production. Results confirm the benefits of growing higher plants in isolated and confined environments and offer insight on the importance of crop selection aspects like taste, texture, pungency and colour.

EDEN ISS – growing food for space exploration

A new project is underway under the European Union‘s Research and Innovation Action program Horizon 2020, within the topic of ‘Space exploration / Life support.’ Thirteen international organizations, including universities, corporations and small businesses, in the cross-disciplinary fields of food growth, life support, engineering and design come together in taking one step further towards the independent exploration in worlds unknown such as the Moon or Mars. During the four year project, they will collaboratively develop innovations in cultivating food in closed-loop systems.