At 11 pm on Friday (BST, 18:01 EDT), SpaceX launched an uncrewed Dragon cargo spacecraft on its way to the International Space Station (ISS). This Dragon capsule has been to the ISS twice before, making it the first to fly in space for a third time. This is the 18th SpaceX Commercial Resupply Services (CRS) contract mission for NASA: CRS-18.

A SpaceX Falcon 9 rocket lifting off from Cape Canaveral, carrying the Dragon spacecraft on the company’s 18th Commercial Resupply Services (CRS-18) mission to the ISS.
[Image credit: NASA/Kim Shiflett]

This afternoon, Expedition 60 Flight Engineers Nick Hague and Christina Koch of NASA used the station’s robotic arm, Canadarm2, to capture Dragon. It’s carrying 5000 or so pounds (about 2200 kg) of science experiments and essential supplies into space, some of which involve plants (and a couple of which are just a little odd).

Sphingomonas desiccabilis, one of three microbes chosen for the BioRock experiment, growing on basalt.
[Image credits UK Centre for Astrobiology/University of Edinburgh]

One of the experiments that the astronauts will then have to unpack is a UK-led international project to build space rock mining devices. On Earth, microbes are used in commercial mining, to break down rocks and liberate the minerals we want. The idea behind the Biorock project is to investigate how that process might work in microgravity, and on Mars, but microbes could also be used to turn lunar/Martian rocks into soil for agriculture, or to liberate nutrients for use in a life-support system.

And then there’s Space Moss, an experiment to compare mosses (bryophytes) grown on the space station with those grown on Earth to determine how microgravity affects growth, development, gene expression, photosynthesis, and other features. Mosses are tiny plants without roots, which makes them idea for ISS experiments, and they show changes in biomass and photosynthesis rate in response to changes in gravity. Mosses may be good sources of food (yum!) and oxygen for long-term space missions or off-world bases, but a better understanding of the mechanisms of moss response to microgravity could also help engineer plants to grow better on Earth.

Also on this flight are some palm seeds, which have been sent into space by the United Arab Emirates (UAE). The date palm (which has the most wonderful scientific name – Phoenix dactylifera) was chosen because palm seeds “are usually planted in circumstances similar to the Martian environment”. Palm trees are deeply rooted in the UAE ’s heritage and are the oldest trees in the region, and the country would like to plant the first palm tree on Mars. In the meantime, these seeds will fly on the ISS and be returned to Earth to grow. The project is being flown by Nanoracks, a commercial space company.

Nitrogen nodules on broad bean roots
Nodules on plant roots – a sign the plant has formed a symbiotic relationship with nitrogen-fixing bacteria

Nanoracks is also flying student experiments, as part of the Student Spaceflight Experiments Program (SSEP) [and oh, how do I wish such a thing had existed when I was at school!]. The students are investigating all kinds of cool things, including whether blue oyster mushrooms can decompose wastes in space, which could provide raw materials for life support. There are also experiments germinating watercress, radish, alfalfa, beetroot, mint, tomatoes & culinary lavender, plus investigations of quinoa, mung beans and spinach. And some that involve brine shrimp, which could potentially be used to feed space fish. Student experiments don’t normally get written up and published though, so we may never know how these turned out. (An exception to that rule is the Rocket Science experiment that flew to the ISS as part of Tim Peake’s Principia mission. The seeds were sown back on Earth by school children, and the results have been published.)

Space Tango, another commercial company, is also flying some interesting experiments on CRS-18. There’s one from Japan on the The Effects of Microgravity on Microbial Nitrogen Fixation. On Earth, plants partner up (form symbiotic relationships) with nitrogen-fixing bacteria in order to get their hands on nitrogen, a key nutrient that they can only absorb in certain forms. This experiment will investigate how two different strains of bacteria (Azotobacter vinelandii and Rhizobium leguminosarum) respond to the stress of spaceflight and demonstrate whether or not bacterial nitrogen fixation will be able to support sustainable agriculture in space.

Also on CRS-18 are a pouch full of Nickelodeon’s green slime, which is part of a new publicity campaign by the children’s television network to encourage young students to pursue science, tech and engineering fields. The astronauts will video how the slime moves in microgravity, and the video will be used to develop a curriculum for young students.

Oh, and there’s also an Adidas soccer ball. Because, apparently, “observing and measuring the motion of soccer balls in microgravity improves understanding of the general behaviour of free-flying objects. This could contribute to better design and use of free-flying objects such as small robots in spacecraft.” You have to wonder how much Adidas payed for that, or whether it will all end in tears, with an astronaut with a football-face injury.

In other news, NASA has announced that the first fruit grown in space* will be an Española chilli pepper. This variety of Capsicum annuum was chosen because it grows at high altitudes, has a short growing period, won’t grow too tall and is easy to pollinate. They’re due to launch between November 2019 and January 2020, and the plants will grow in the Advanced Plant Habitat (APH).

[*As is often the case with ‘first’ announcements, this one isn’t quite accurate – the Russians have been growing peas in their half of the ISS for a while now, and pea pods are, technically, a fruit.]


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