Mississauga
Astronomical Society
Eighteenth Meeting
Speakers’ Night
Day:
. Friday,
March 19,
2004
Speaker:
Dr. Mike Dixon
Life support for the Mission
to Mars
Dr.
Mike Dixon, Director of the Controlled Environmental Systems Research
Facility
(CESRF) at Guelph University spoke about his work of growing
plants in very harsh environments and investigating their role in
sustainable
life support in space. Because 75 square meters of plant growing space
is
necessary for each person, it is unlikely that low earth orbit stations
will
have a biologic system – it is easier to ship in supplies. The same
goes for
the Moon. However, within 50 years or less, humans will likely walk on
Mars and
will need a sustainable life support system.
Plants
have the roles of food and oxygen production, carbon dioxide uptake and
fresh
water recycling. Only highly edible plants should be considered because
food is
the main limiting factor for sustained life support. Non-edible parts
are
recycled. Lighting is the limiting factor for high density growth. This
is
being addressed by fibreoptic tube lighting in the lower parts of the
canopy. Research
is focused now on decreasing the 75 sq. m. requirement down to 25. Dr.
Dixon
described the microecologic lifesupport system MELISSA with its
microbial
anaerobes, photoheterotrophes, nitrifying bacteria and higher plants. Areas of research, among others, include
atmospheric management, biodegradable plant growth media, attributes of
candidate crops, recycling nutrients, hyperbaric growth chambers. Funding can be obtained because many of these
issues are relevant to Earth problems such as indoor air pollution and
greenhouses.
Mars
is very inhospitable to plants with its low pressure of less than 1% of
the
Earth, and severe UV radiation. An
enclosed
structure containing 1 atmosphere of pressure would be very massive and so Dr. Dixon had
experimented with plant growth at 1/10 atm using hyperbaric chambers. He showed a video of peppers as the pressure
was gradually decreased to 1/10 atm. Wilting occurred due to low vapour
pressure,
but when moisture could be adequately supplied, the peppers did well.
Candidate
plants for such life support need to be genetically modified to cope
with
shade, low temperatures, pressure, humidity, carbon dioxide, variable
atmosphere composition, disease resistance. In addition such plants
need to
have a high harvest index (how much of the plant can be eaten) and
should have
a good psychologic appeal to people living with them. Dr. Dixon
demonstrated an
experimental greenhouse on Devon Island (landscape of Haughton
Crater on Devon is similar to Gusev crater on Mars) and
noted that technology from
this could be applied to space, and further modifications brought back
for use
on the Earth. Remote robotic systems should be available by year 2011. He then discussed the Canada Life building in
Toronto with its biologic room that filters air
through walls
filled with plants and microorganisms. Volatiles such as xylene are
decomposed
by such a system. Portable biofilters are being developed as an
offshoot.
The
Tomato Sphere Project http://www.tomatosphere.org/
gives students from Grade 3 to 10 the opportunity to grow tomatoes from
seeds
which have been exposed to a Mars – like environment. The first project
involved 100,000 seeds carried onto the space shuttle by Marc Garneau,
and then
distributed to schools across Canada. Seeds in the second
project were exposed to UV, temperature and pressure as would be found
on Mars
and were distributed to 5,000 schools. Round 3 is now underway.
Future
studies need to confirm plant physiology, investigate
pressure-sensitive genes,
develop algorithms for atmospheric composition, and integrate biotic
systems.
Research collaborators are industry, government agencies, universities
and 5
space agencies. Special interest in this research has been shown by the
Chinese
who are developing an active space program.
Dr.
Dixon noted that a student now in Grade 3 might be the first Canadian
to go to
Mars.
His
very interesting talk was received with much enthusiasm and questions.
Submitted by Chris Malicki,
Secretary
Chris
Malicki, Secretary
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Mississauga
Astronomical Society