Plants Would Still Grow Well Under Alien Skies

This is an artist's illustration of the rocky super Earth HD 219134. It orbits a K-type star, a long-lived stable type of main sequence star. The light from K-type stars is different than the Sun's. Can Earth plants photosynthesize effectively near these stars? Image Credit: By NASA/JPL-Caltech - http://photojournal.jpl.nasa.gov/jpeg/PIA19833.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=41995148

Photosynthesis changed Earth in powerful ways. When photosynthetic organisms appeared, it led to the Great Oxygenation Event. That allowed multicellular life to evolve and resulted in the ozone layer. Life could venture onto land, protected from the Sun’s intense ultraviolet radiation.

But Earth’s photosynthetic organisms evolved under the Sun’s specific illumination. How would plants do under other stars?

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Chickpeas Grown in Lunar Regolith Are Stressed but Reach Maturity

Image of the chickpea plants after five weeks displaying a diversity of chlorophyll. (Texas A&M AgriLife photo by Jessica Atkins)

A recent preprint investigates how chickpeas have been successfully grown in lunar regolith simulants (LRS), marking the first time such a guideline has been established not only for chickpeas, but also for growing food for long-term human space missions. This study was conducted by researchers from Texas A&M University and Brown University and holds the potential to develop more efficient methods in growing foods using extraterrestrial resources, specifically with NASA’s Artemis program slated to return humans to the lunar surface in the next few years.

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What’s the Best Way to Water Plants in Space?

Humans have maintained a continuous presence in space on the International Space Station (ISS) for more than 20 years now. It is our longest-running and most comprehensive experiment in long-duration spaceflight. But the ISS is continually supplied with consumables – food, water, and oxygen – so astronauts are largely reliant on Earth. If Humanity is ever going to live and work in space long term, we’re going to have to learn to be more self-reliant – and that means growing food in space.

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Future Astronauts Could Enjoy Fresh Vegetables From an Autonomous Orbital Greenhouse

Growing trays inside EDEN ISS. Credit: DLR

If humanity is going to become a spare-faring and interplanetary species, one of the most important things will be the ability of astronauts to see to their needs independently. Relying on regular shipments of supplies from Earth is not only inelegant; it’s also impractical and very expensive. For this reason, scientists are working to create technologies that would allow astronauts to provide for their own food, water, and breathable air.

To this end, a team of researchers from Tomsk Polytechnic University in central Russia – along with scientists from other universities and research institutes in the region – recently developed a prototype for an orbital greenhouse. Known as the Orbital Biological Automatic Module, this device allows plants to be grown and cultivated in space and could be heading to the International Space Station (ISS) in the coming years.

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Red Suns and Black Trees: Shedding a New Light on Alien Plants

 

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The grass may definitely not be greener on some alien worlds, suggests a new study from the UK. For example, planets in double-star systems could have grey or black vegetation.

Researcher Jack O’Malley-James of the University of St Andrews in Scotland worked out how photosynthesis in plants is affected by the color of the light they receive. On Earth, most plants have evolved to be green in order to take advantage of the yellowish color of the sunlight that’s received on the surface of our planet. (Our Sun, classified as a “Population I yellow dwarf star”, would look bright white from space but our atmosphere makes it appear yellow.) There are lots of other stars like our Sun in the Universe, and many of them are in multiple systems sharing orbits with other types of stars…red dwarfs, blue stars, red giants, white dwarfs…stars come in many different colors depending on their composition, age, size and temperature. We may be used to yellow but nature really has no preference! (Although red dwarfs happen to be the garden variety star in our own galaxy.)

Terrestrial examples of dark-colored plants

Planets that orbit within these multiple systems and exist within the habitable “Goldilocks” zone (and we are finding more and more candidates every day!) could evolve plants that depend on suns with different colors than ours. Green does a good job powering photosynthesis here, but on a planet orbiting a red dwarf and Sun-like star plants could very well be grey or black to absorb more light energy, according to O’Malley-James.

“Our simulations suggest that planets in multi-star systems may host exotic forms of the more familiar plants we see on Earth. Plants with dim red dwarf suns for example, may appear black to our eyes, absorbing across the entire visible wavelength range in order to use as much of the available light as possible.”

– Jack O’Malley-James, School of Physics and Astronomy, University of St Andrews

The study takes into consideration many different combinations of star varieties and how any potential life-sustaining planets could orbit them.

In some instances different portions of a planet may be illuminated by a differently-colored star in a pair…what sorts of variations in plant (and subsequently, animal) evolution could arise then?

And it’s not just the colors of plants that could evolve differently. “For planets orbiting two stars like our own, harmful radiation from intense stellar  flares could lead to plants that develop their own UV-blocking sunscreens, or photosynthesizing microorganisms that can move in response to a sudden flare,” said O’Malley-James.

Kermit may have been right all along…being green might really not be easy!

Read more on the Royal Astronomical Society’s news release or on the University of St Andrews website.

Top image credit: Jason Major