Could we grow plants on asteroids?

Header image: Mars’ asteroid-sized satellites Deimos and Phobos. Image credit: ESA

Today is Asteroid Day, designed to promote global awareness of the risk of us Earth being hit by an asteroid, and all the ensuing chaos and mayhem. But that’s gloomy, so instead I thought I’d take a look at some of the research that has been done on growing plants on asteroids!

Most asteroids orbit between Jupiter and Mars, with a few in the outer solar system between Saturn and Uranus and several groups with orbits that swing into the inner system. Astronomers used to call them the ”vermin of the skies’, because these these minor planets would unexpectedly appear on photographic plates, ruining deep sky studies.

ESA explains that there seem to be three distinct ‘flavours’ of asteroid. Most are as dark as charcoal and carbon-rich. These carbonaceous (C-type) asteroids are probably leftovers from the formation of the solar system. The brighter stony (S-type) asteroids are composed of nickel-iron and magnesium silicates. And M-type asteroids, the rarest but brightest type, are made of almost pure nickel-iron.

In 2010, Japan’s Hayabusa mission brought samples of asteroid Itokawa. Hayabusa2 dropped its payload of samples from asteroid Ryugu in December 2020. And NASA’s OSIRIS-REx is currently on its way home with samples of asteroid Bennu, delivering its return capsule to Utah in 2023.

So we’re learning a lot about the composition of asteroids, and people are using that data to try growing plants in asteroid regolith!

Last year, Sherry Fieber-Beyer and Steven Russell at the University of North Dakota were studying whether lettuce, radishes and peppers can grow in simulated asteroid regolith, an exact mineral copy of samples taken from