We're fortunate to call Earth home, with its protective atmosphere, moderate temperatures, and what we consider a "relatively normal" level of gravity. Life might not be as rosy if we found ourselves in a place with different conditions.
Take space, for instance. In space, there's virtually no gravity, making human bones fragile, and hunger might go unnoticed since our bodies can't sense changes without gravity. Zero gravity isn't exactly friendly to human beings. However, it doesn't mean everything goes haywire in a weightless state. In fact, some things gain superpowers in the absence of gravity.
Protein crystals form in microgravity within the Kibo module of the space station. Image source: Japan Aerospace Exploration Agency (JAXA).
Companies are competing to develop an exotic glass fiber from space: ZBLAN. Image source: Official website of the National Laboratory of the International Space Station.
Low-defect Fiber Optic Materials
"ZBLAN," or "super pure fluoride," is a special fiber optic material primarily used in medical products, fiber lasers, and near-infrared applications. It has long been considered a standout product of space manufacturing.
According to research by NASA, ZBLAN manufactured in microgravity environments is smoother and clearer compared to those produced under Earth's gravity, potentially preventing defects.
As of the latest news from SpaceNews on February 23, the Silicon Valley startup "Defect Photonics" produced over 5 kilometers of ZBLAN within two weeks aboard the International Space Station (ISS). Their aim is to use ZBLAN to manufacture underwater cables. ZBLAN, compared to silica (the glass fiber in underwater communication cables), is much more transparent, resulting in less signal attenuation. The company plans to continue manufacturing more preforms in microgravity in space in the future.
Sturdier Microgravity Cement
Cement is a fundamental material for building houses. According to a paper published in The Astronomical Journal in 2019, astronauts aboard the ISS successfully mixed cement in a microgravity environment for the first time. The results were surprising: the microstructure of the cement samples processed on the space station showed significant changes compared to those processed on Earth.
Researchers sent the basic components of cement to the ISS and mixed water and the main mineral component, tricalcium silicate, in a bag, allowing it to harden for 42 days through hydration. The results showed that cement mixed in microgravity indeed solidified similarly to those on Earth.
Cement on Earth tends to have a layered structure due to gravity, whereas in the ISS's absence of gravity, the density of mixed cement is more uniform, making space cement sturdier. Additionally, space cement has more voids, and the porosity significantly affects the material's performance. This result marks an important step towards the goal of "building houses on the moon."
Regenerated "Alien" Flatworms
The first batch of animals sent into space wasn't the famous stray dog named "Laika" but a group of fruit flies. On February 20, 1947, fruit flies were launched into subcritical space aboard a V-2 rocket and returned alive. Scientists aimed to explore the effects of space radiation on organisms, thus selecting fruit flies genetically similar to humans. Today, simple invertebrates are still sent via rockets just to see what happens.
According to the official website of the ISS National Laboratory, on January 10, 2015, 15 flatworms were launched into space through the SpaceX-5 commercial resupply mission. These flatworms had their heads and tails cut off, placed in a tube half-filled with air and half with water, and stayed aboard the ISS for 5 weeks. Flatworms are known for their strong regenerative abilities; when cut in half, each half can develop into a complete organism. However, upon returning to Earth, they underwent a miraculous change, growing two heads directly from one trunk.
Perplexed scientists cut off both heads of the flatworms, only to find two heads growing back again. Space permanently altered these flatworms. Scientists hope to understand the effects of the space environment on the human body by studying the changes in flatworms before and after their space journey.
Stronger "Space Proteins"
When manufacturing drugs in space, their performance becomes stronger.
Protein crystal growth experiments are crucial projects in space flight activities. On Earth, it's difficult to produce single, pure protein crystals due to gravity's influence, but the unique microgravity environment in space allows proteins to unfold and bind more fully, better filtering impurities, ultimately forming nanoscale, highly pure, and uniform protein crystals.
NASA has been dedicated to protein crystal growth experiments on the ISS. As of 2021, pharmaceutical companies and academic researchers have conducted over 500 protein crystal growth experiments on the ISS, making it the largest single category experiment conducted on the space station to date. They modified protein crystals, leading to the discovery of a new drug for treating tuberculosis and finding new mechanisms for delivering anticancer drugs.
The Japan Aerospace Exploration Agency (JAXA) is also actively engaged in microgravity protein crystal growth research. One study examined the crystal structure of proteins associated with Duchenne muscular dystrophy. Microgravity crystallization research has produced several promising compounds, including one molecule called TAS-205.
Moreover, large pharmaceutical companies are increasingly recognizing the benefits of crystal growth under microgravity for drug development. For example, Merck's PD-1 drug originated from protein purification and crystallization experiments on the ISS. As early as 2019, Merck published a research report stating that protein crystallization under microgravity conditions enhanced the efficacy of its cancer drug Keytruda. According to the latest news in February this year, the drug's sales in 2023 surpassed Humira, making it the new global "drug king."
