ESA Document - Emits - ESA

s
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 160 of 422
A greenhouse has not been introduced at this stage of the study. The study team is aware of the
positive impact of the greenhouse on the different functions of a LSS, the nutrition of the crew
and on the crew psychology. On the basis of preliminary knowledge, a greenhouse would
provide::
• A high degree of closure of carbon dioxide to oxygen conversion
• A high degree of water loop closure
• A high percentage of fresh food to the crew
However, it would cause an increase in structural mass and power requirements that perhaps
offset the gain of mass on the LSS. Therefore, at this stage of the study and the incomplete tradeoff
between LSS with greenhouse and LSS without greenhouse, the greenhouse was not
considered.
3.3.2.3 Waste management strategy
The long duration of this mission inherently involves the production of substantial amounts of
both organic and inorganic solid waste. This amount adds up to several tonness and has to be
taken into account and dealt with in an efficient way. Several options were considered for waste
management. It was decided to jettison the generated solid waste using existing airlocks to
minimise the mass penalties of the mission. However, some treatment and storage is still
necessary before jettisoning. This treatment depends on the nature of the waste and can be
described as follows.
Waste treatment strategy
The handling of the inorganic waste (i.e. cleaning supplies, hygiene supplies, waste collection
supplies, etc) is somewhat easier than for organic waste as it does not require because much
treatment. Care must be taken in correctly classifying the nature of the waste. Supplies classified
as inorganic upon launch become organic waste upon use by the crew.
The first step in the management of the inorganic waste would be to compact it to reduce its
volume. Mass reduction is possible by reducing the waste reusable solid, gaseous and liquid
compounds. After compaction, decontamination and bioresistant storage would be sufficient to
have the inorganic waste safely stored before jettisoning.
The management of the organic waste (i.e. used tissues, faecal material, hair and skin material,
nail clippings, food leftovers, etc) is more complicated and it requires waste stabilization. Three
main technologies could be used for this purpose: chemical stabilization, sterilization or
lyophilization (commonly referred to as freeze drying). Mass and power considerations, and
assessing their technology readiness level, lyophilization looks most promising for the reduction
of the organic waste.
Lyophilization is the process of removing water from a product by sublimation and desorption. It
is performed in lyophilization equipment which consists of a drying chamber with temperature
controlled shelves, a condenser to trap water removed from the product, a cooling system to
supply refrigerant to the shelves and condenser, and a vacuum system to reduce the pressure in
the chamber and condenser to facilitate the drying process. Lyophilizers come in a wide variety
of sizes and configurations and can be equipped with options that allow system controls to range
from fully manual to completely automated. Lyophilization cycles consist of three phases: