Last updated July 17, 2018 at 9:32 am
A team have created a way to create hydrogen and oxygen in space by flinging their apparatus up and down a giant tube.
A capsule is winched into place before firing at the ZARM drop tower. Credit: Stefan Schmidbauer / ZARM
As we begin to move out towards the stars, we’re going to need to be able to make hydrogen to use as energy for transportation, electrical power and oxygen generation.
There are even ideas that we could produce it on the moon as a sort of solar-system-service-station to refuel spacecraft on their way into deep space.
However one complication has been the difficulty in creating a process to produce hydrogen in microgravity.
Researchers from Caltech have seemingly overcome that complication by developing a light-driven cell which efficiently splits water in near-zero gravity to produce hydrogen and oxygen.
Plants the gold standard
Comparison of a thin-film chip (top) and a chip with the nanostructures (bottom). The peaks prevent bubble coalescence and formation of a bubble layer. Credit: Brinkert et al 2018, Nature Communications
Plants are already the gold standard when it comes to converting light and water into fuel and oxygen. For years, scientists have been trying to mimic and improve this natural process using artificial photosynthesis.
In general it’s worked pretty well and has a growing role in Earth-bound applications. But in space, it’s far more complicated.
Gravity allows gas to form into bubbles and release from the surface of a chip, letting them rise to the surface of the liquid and be captured. However, when gravity isn’t involved the bubbles stay attached to the surface of the chip and coalesce into a layer, and reducing the light-driven splitting effect.
The team overcame this by creating nanoscale peaks on the chip to make the bubbles release from the surface, creating, for the first time, an efficiently operating photoelectrochemical cell in near-zero gravity.
Enter the BFT – Big Friendly Tube
The difficulty in developing this technology comes from our very own planet – it’s pretty difficult to simulate zero-gravity on Earth, so the scientists turned to a giant drop tower at ZARM to simulate off-planet conditions.
The giant tower – 146m tall – in Bremen, Germany, is an amazing facility. A catapult system accelerates capsules containing experiments upwards from the base of the tower, accelerating the capsules to 168km/h in less than a quarter of a second.
When the capsule reaches the top of the tower it falls back down into a giant polystyrene-filled deceleration container. All in all, the capsule is in flight for just over 9.3 seconds.
The tower works on the principle that all falling objects are automatically nearly weightless – an experience familiar to someone in a descending elevator. As soon as the capsule has finished acceleration out of the catapult (0.25 seconds), the contents are essentially weightless all the way up, and back down the tower.
To increase that effect even more, they minimise the effects of aerodynamic drag by creating a vacuum in the tower.
Together, the lack of air resistance and weightlessness creates microgravity conditions, where the experiments experience one-millionth of Earth’s gravity for more than 9 seconds at a time.
In the case of the Caltech experiments, a precise automated process of cameras, lights and mechanicals ensured that scientists could control, measure and observe what was happening to the photoelectrochemical cells for the entire time they were in microgravity.
The authors believe that their chip could lead to improvements and extensions of life support systems for long-duration space voyages. They also hope that the research can also improve light-driven water-splitting devices on Earth.
The research has been published in Nature Communications
Video courtesy of Tom Scott
