Biomass Production System (BPS) Photosynthesis Experiment and System Testing and Operations (PESTO) Results

Results

Expedition
4 Flight Engineer Dan Bursch saved the day on April 19, 2002, when he
performed a quick corrective action after the humidity control system
experienced difficulties due to exposure to the dry Station environment
during harvest procedures. Bursch replaced the air-water mixture in the
reservoir (which formed bubbles that clogged the tubes) with water, keeping
the subsystem activated and saving a substantial amount of science return.
Without his immediate assistance, the environmental control subsystems
would have remained disabled for 1 to 2 days, and the science team estimate
that 85 percent of the plants being grown this cycle in chambers 1 and
3 would have been lost. As a preventive measure, the team have reordered
the steps in the harvest procedure to minimize the humidity control system’s
exposure to cabin air. The problem happened again during the week of April
29, when BPS lost prime in chamber 2. Bursch and ground operations scrambled
to remove bubbles from the water reservoir and to bring chamber back up
to normal, but the problem continues. By May 10, the science team decided
to turn off the humidity control system in chamber 2, allowing humidity
to build up inside the chamber without the help of the water reservoir.
Bursch then swapped the the wheat plants growing in chamber 2 with Brassica
rapa plants growing in chamber 4. Brassica rapa better tolerates
the high humidity now present in chamber 2.

In
addition to
the unexpected activities involving chamber 2, Bursch continues to perform
normal BPS/PESTO operations, such as taking water, plant, and gas samples
from the chambers and cross-pollinating the flower heads. The science
team have declared the experiment "very successful," with a
majority of the PESTO on-orbit science objectives being met by the end
of May. Bursch has also recorded more than 1700 images of the experiment.
The Payload Operations Center at Marshall Space Flight Center have dubbed
Bursch an "argonaut," in honor of his invaluable services to
the experiment.

Numerous
ground-based experiments were conducted to define experimental protocols
for PESTO. Research teams at NASA using BPS growth chambers tested a variety
of solid substrates, growth media, as well as different atmospheric pressures,
relative humidity, and nutrient and gas levels, to come up with the protocol
that would produce an optimum balance of root development, foliage growth,
and seed production. The teams also examined basic horticultural issues,
such as plant density and seed orientation, that would affect the overall
health of the plants. A drip-irrigated peat vermiculite system produced
the best biomass, seed yield, and harvest index during ground-based testing
conducted by Kennedy Space Center.

Applications

As
the human population becomes larger, less fertile land will be available
to grow food. Alternative agricultural systems that can efficiently produce
greater quantities of high-quality crops in a small area will be increasingly
important. Data from both the operation of BPS and PESTO research will
advance greenhouse and controlled-environment agricultural systems and
will help farmers produce better, healthier crops in a small space using
the optimum amount of nutrients. The BPS system can also be used to grow
nonedible, ornamental plants in homes and public buildings. The automated
systems could cater to each planting’s specific needs, ensuring healthy
plantscapes under the most challenging growing conditions with minimal
human tending.

This
same knowledge that improves ground-based agriculture is critical to future
beyond-low Earth orbit missions. The amount of dehydrated, packaged, and
frozen food necessary to sustain a crew during a Mars mission, for example,
would prohibitively increase the mass of spacecraft and the overall cost
of the mission. Some of the crew’s food would need to come from a selection
of renewable crops grown in biomass production systems—advanced versions
of the BPS hardware. The biomass production systems may also be used as
a filtration system for water and atmospheric gases. Plant growth chambers
would also offer a comforting, green reminder of Earth to a crew a long
way from home. Direct
measurements of photosynthesis in microgravity, along with other research,
must be conducted before NASA can design a workable Bioregenerative Life
Support System.

Elements
of BPS hardware can also be adapted to other commercial uses. Its automated
humidity and atmospheric gas controls can be used to improve environmental
quality in private and public buildings. Planet
Products Corporation, a sister c¦ÿÿny of Orbital Technologies Corp.,
will develop valuable, proven technologies from flight hardware like BPS
for commercial markets.

In
the process of creating useful technology and science, BPS-PESTO allows
grade-school students to be "co-investigators" on real space
research. Supported by hands-on activities, Farming in Space examines
basic principles and concepts related to plant biology, agricultural production,
ecology, and the space environment. The activities encourage curiosity
in the sciences, while also teaching good scientific methodology.

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