Manned missions beyond Earth orbit face the rather important problem of how to feed the crew and maintain the capsule environment for years on end without any resupply from home. The product of a NASA challenge, AstroGro is a space garden pod aimed at addressing this problem. It relies on 3D printing to produce a system that can be replicated and modified while in the depths of space.
One way to avoid carrying hundreds of tons of groceries and other consumables into space is to use plants as supplemental food as well as a way of recycling air and human waste and removing toxins, such as outgassing from equipment, aboard ship. In addition, fresh food and the sight of growing plants would be a major boost to crew morale.
The idea of an onboard space garden is an old one and basically sound, but it's also a tricky one to implement. It not only has to grow enough food for the table, but it needs to be flexible enough to adapt to the crew's changing needs, scaling up and down as demand requires. It also has to be easily modifiable as technology back home finds improvements.
Part of NASA's 2015 Print Your Own Food challenge aimed at creating new technologies to feed astronauts on deep space missions, AstroGro took the printing angle in a different direction. While other entries concentrated on printing food, AstroGro designed a 3D-printed device for growing food.
AstroGro consists of plastic pods equipped with LED lights, a watering system, and an electronic monitoring system that uses artificial intelligence to provide optimum growing conditions. It is controlled by a smartphone app that can adjust temperature, lighting, and hydration for optimum growth. The modular, scalable organic gardening pods are able to monitor the plants, adapt to changing conditions, and handle multiple pods under a single computer control system that is supposedly simple enough to be operated by a child. The pods not only recycle organic wastes, but the plastic that they are made from can also be melted down and reused.
For monitoring plant growth and health, AstroGro uses a radio frequency (RF) absorption measurement system. The developers say that camera monitoring requires too much investment in equipment and computer algorithms, so AstroGro has a pair of transceiver antenna that run at 2.45 GHz, which is the absorption frequency of the water molecule. A directional transmitter antenna pulses the radio waves through the plant to the receiver antenna and the system measures how much of the energy is absorbed. The greater the absorption, the larger and healthier the plant. The radio waves can even be used to heat the plant to efficiently bring it to the optimum growing temperature.
The AstroGro system has light sensors with spectral filters to judge the quality and intensity of the available light. If it proves inadequate, the LED lights provide supplemental light at the desired frequency. In addition, the pod monitors soil moisture, calculates the hydration cycle, and provides water on schedule at the best pH level.
The pods can also compensate for zero gravity. By setting them in a hexagonal wheel frame, they can be made to rotate fast enough to make up for the lack of gravity and ensure proper growth.
But the key feature of the AstroGro pods is that they can be printed in greater numbers to meet demand, produce different pods for new crops, or be melted down and recycled. Updates sent from Earth can be used to upgrade the pods or replace them with better designs, which is beneficial even on a space station because it removes shipping costs. In addition, the development team sees AstroGro as having applications on Earth as a way of growing food in the home or nearer to market.
The video below introduces AstroGro.