A Habitat for Pioneers
The video is quite amazing is it not? It shows plants growing 408 km up, beyond the sky, in Low Earth Orbit. It is travelling at 27,600 km/hr. This is the APH or the Advanced Plant Habitat on board the International Space Station. The Advanced Plant Growth Habitat is the largest growth chambers present aboard the ISS. Build by NASA and ORBITEC, it is a research module involving study of parameters conducible to growth of Plants in space, along with their optimization.
The module has been designed for a decadal mission, and is destined to collect physiological data from the plant habitat. In doing so, it would provide essential breadcrumbs to the proper understanding of terrestrial biology in space under the conditions of microgravity.
The APH was launched to the ISS in two separate commercial resupply missions: the OA-7 in April of 2017 and SpaceX-11 in June 2017. This was followed by assembly and installation in the Japanese Experiment Module Kibo in the November of 2018. This was done (just as the VEGGIE system) on the EXpedite the PRocessing of Experiments to Space Station (EXPRESS) rack
WHAT’S ALL THIS TALK ABOUT?
The importance of the APH system is its capability to perform seed to seed agricultural cycles. It essentially encompasses the capability of continuance of life through formation of viable filial generations. This purpose has great prospects in the future of interstellar travel, where we might be faced with the prospects of having to cope with long durations of travel in confined and isolated transport systems. Essentially, as explained by a NASA scientist, it encompasses the formation of a ‘little Mother Earth’.
It would be unfair to comment on the APH without realizing its diverse roles in furthering the habitability and sustainability of plant life on Earth. The stress conditions endured aboard the ISS are specific to those observed under conditions of drought or regions faced with blight. Hence, they serve as perfect model plants to answer questions raised and provide solutions to problems faced on Earth itself. Additionally, the formulation of an automated system capable of growing plants raises the opportunity of implementing this technology in regions with no knowledge of farming and provide fresh and nutritious food in urban capitals without increasing stress on farming communities. It is an especially important step to a sustainable future
Watch the Time Lapse Video of Dwarf Wheat growing in APH.
One of the most striking difference between plant growth on Earth and aboard the ISS is the absence of gravity. Gravity plays a silent but definite role in the proper growth of plants. These factors greatly influence plant development especially through the phenomenon of gravitropism. Aboard the ISS, the value of gravity is 0.1g, under this stressor, the plant must generate morphological alterations in order to carry out its normal functions.
Technicalities of the Matter
The APH can be referred to as a closed loop system in possession of an environmentally controlled growth chamber. The interface and the mechanics of the research unit is fully autonomous. It does require the help of astronauts, who ensure proper water supply to the said unit, changes the environmental filters such as the Ethylene scrubber, harvests the plants under study, collects biological samples and performs periodic maintenance. However, one of the primary focus while designing this module was to ensure plant bioscience research with minimal maintenance activities. It is primarily controlled from the ground through the uniquely named PHARMER system or Plant Habitat Avionics Real-Time Manager in EXPRESS Rack. This unit is capable of delivering real time data telemetry along with remote commanding opportunities and a photo downlink to the team based at Kennedy.
A remarkable faucet of this system is the presence of LED system which has the capability to alter between red, blue and green regions. It has the capability to range from 0 to 1000 μmol m–2 s–1 of light unit, which is the highest light level in any spaceflight chamber. Essentially, this parameter adds another dimension to the capabilities of this chamber. The growth chamber can control temperature in the range of 18° to 30° Celsius, relative humidity in the range of 50%-90%, CO2 concentration in the range of 400 to 5000 μmol mol–1. It can also simulate wind speeds of 0.3 to 1.5 m/s. The system itself boasts of over 180 sensors which detect real time information and beam back to the Ground Team.
The plants themselves germinate in the APH Science Carrier which is a four-quadrant rooting module making use of fertilized substrate-based media. The watering system is derived essentially from the condensed humidity, and can also be drawn from the potable water source aboard the ISS.
The device is structured so that any critical subsystem can be easily removed and replace aboard the space station (open architecture). The engineering of the chamber supports continuous operation for over a year without the requirement for maintenance services. Essentially, it can support bioscience research on the space station for up to 135 days of scientific investigation.
The first set of experiments to be conducted aboard the APH (Christened Plant Habitat 1 or PH-01) comprised Arabidopsis seeds, small flowering plant (cabbage and mustard). However, even before the first experiment is initiated, there was a test run held using Dwarf Wheat and Arabidopsis.
An essential accolade to the contribution of the APH to Space Biology is the capability to grown and harvest radishes for the first time aboard the ISS. This is a remarkable step forward in the future of sustainable space exploration.
It is quite amazing how far we have come, and yet how far we have to go. The immense tenacity of the human brain has overcome barriers which no one knew existed, to grow organisms in environments where Nature does not dare tread. The APH in conjugation with the VEGGIE system is at the forefront of Plant Technology, yielding results which will bear fruits in all the years to come.
Yet, we must keep in mind the ideas presented in Michael Crichton’s “The Andromeda Strain”.
Stay tuned for more updates to this series!