Astrobotany

Astrobotany is an applied sub-discipline of botany that is the study of plants in space environments. It is a branch of astrobiology and botany.

Astrobotany concerns both the study of extraterrestrial vegetation discovery, as well as research into the growth of terrestrial vegetation in outer space by humans.

It has been a subject of study that plants may be grown in outer space typically in a weightless but pressurized controlled environment in specific space gardens. In the context of human spaceflight, they can be consumed as food and/or provide a refreshing atmosphere. Plants can metabolize carbon dioxide in the air to produce valuable oxygen, and can help control cabin humidity. Growing plants in space may provide a psychological benefit to human spaceflight crews.

The first challenge in growing plants in space is how to get plants to grow without gravity. This runs into difficulties regarding the effects of gravity on root development, providing appropriate types of lighting, and other challenges. In particular, the nutrient supply to root as well as the nutrient biogeochemical cycles, and the microbiological interactions in soil-based substrates are particularly complex, but have been shown to make possible space farming in hypo- and micro-gravity.

NASA plans to grow plants in space to help feed astronauts, and to provide psychological benefits for long-term space flight.

The vegetation red edge (VRE) is a biosignature of near-infrared wavelengths that is observable through telescopic observation of Earth, and has increased in strength as evolution has made vegetative life more complex. On Earth, this phenomenon has been detected through analysis of planetshine on the Moon, which can show a reflection spectrum that spikes at 700 nm. In an article published in Nature in 1990, Sagan et al. described Galileo's detection of infrared light radiating from Earth as evidence of "widespread biological activity" on earth, with evidence of photosynthesis a particularly strong factor.

The increase-in-strength of Earth's VRE biosignature has been assessed through modelling of early Earth radiation. Mosses and ferns, which were dominant on Earth in the Ordovician and Carboniferous periods, produce weaker detectable infrared radiation spikes at 700 nm than modern Earth vegetation. Astrobotanists focused on extraterrestrial vegetation have thus theorized that by using these same models, it could be possible to measure whether exoplanets in their respective Goldilocks zones currently hold vegetation, and by comparing VRE biosignatures to modelled historic Earth radiation, estimate the complexity of this vegetation.

There are a number of obstacles to the detection of exoplanetary VREs: