This DVD with 616,400 digitized signatures is now part of Saturn.

Starting in November 1995, postcards with signatures from people from 81 nations were received, scanned, stored on a DVD, and attached to the Cassini spacecraft before its 1997 launch. After Cassini completed its groundbreaking mission at Saturn, the spacecraft (including the DVD) was intentionally deorbited into Saturn's atmosphere, and it vaporized to become part of the planet.

Want to make your mark on space history? Time is running out to send your name around the Moon on Artemis II! go.nasa.gov/49vl6z2

Spaceflight doesn't just change your perspective — it shifts the actual position of your brain inside your skull, a new study reports.

Many of us know about the famed "overview effect," which describes how a trip to the final frontier changes how astronauts view the world and their place in it. But the new study focused on the physiological rather than the philosophical.

Rachel Seidler and a team at the Massachusetts Institute of Technology (MIT) took MRI scans of the brains of 26 astronauts and 24 non-astronaut participants to determine what, if any, impacts prolonged spaceflight has on one of our body's most important organs.

Their study, published on Jan. 12, showed a consistent pattern of the brain shifting backward and upward, and rotating upward, after time in microgravity, with some positional changes still detectable months after astronauts return to Earth.

Scientists have long tracked how spaceflight affects the human body, but exactly what microgravity does to the brain's anatomy remains an ongoing question. This study analyzed data from 15 astronauts who provided MRI scans before and after their missions to space, and combined that with MRI data from another 11 astronauts and two dozen participants of a long-duration, head-down tilt bed rest "microgravity analog" experiment.

The first-place-winning video in Nikon’s Small World in Motion Competition 2025 documents the self-pollination of a thymeleaf speedwell flower. Filming at 5X magnification, winner Jay McClellan used a custom-built motion-control system to capture the flower. on.natgeo.com/4jMSUwn

Octopus and cuttlefish are masters of disguise. Many species can quickly shift both the color and surface texture of their skin, and scientists have long tried to reproduce that trick using manmade materials. In a paper published in Nature, Stanford researchers report a major advance: a flexible material that swells into new textures and colors within seconds, forming patterns with details finer than a human hair.

“Textures are crucial to the way we experience objects, both in how they look and how they feel,” said Siddharth Doshi, a doctoral student in materials science and engineering at Stanford and first author on the paper. “These animals can physically change their bodies at close to the micron scale, and now we can dynamically control the topography of a material – and the visual properties linked to it – at this same scale.”

The team says the approach could improve dynamic camouflage for people and robots, and it may enable flexible, color-changing displays for wearable technologies. The findings also broaden the possibilities in nanophotonics, a field that precisely shapes how light behaves to support advances in electronics, encryption, biology, and more.

“There’s just no other system that can be this soft and swellable, and that you can pattern at the nanoscale,” said Nicholas Melosh, a professor of materials science and engineering and a senior author on the paper. “You can imagine all kinds of different applications.”

A team of New York University scientists has created a gear mechanism that relies on fluids to generate rotation. The invention holds potential for a new generation of mechanical devices that offer greater flexibility and durability than do existing gears—whose origins date back to ancient China.

"We invented new types of gears that engage by spinning up fluid rather than interlocking teeth—and we discovered new capabilities for controlling the rotation speed and even direction," says Jun Zhang, a professor of mathematics and physics at NYU and NYU Shanghai and the senior author of the paper.

Gears are among the oldest machine parts, dating back to 3,000 BCE in China, where they were used in two-wheeled chariots to cross the Gobi Desert. Over time, they've been deployed in the famous Antikythera mechanism, which predicted astronomical positions in ancient Greece, as well as in windmills, clocks, and, now, robotics.

However, gears' teeth, whether wood, metal, or plastic, are inflexible, so they are vulnerable to breaking—and they must interlock perfectly to work.

Some fish can walk - and choose to! 🦵🏽

Find out how they do this, why, and see it in action in this week’s Surprising Science! 🐟

Made it.

At 6:42pm ET on Jan. 17, the stacked Artemis II rocket and spacecraft reached Launch Pad 39B after a nearly 12-hour journey from the Vehicle Assembly Building at NASAKennedy in Florida.

A quantum state of matter has appeared in a material where physicists thought it would be impossible, forcing a rethink on the conditions that govern the behaviors of electrons in certain materials.

The discovery, made by an international team of researchers, could inform advances in quantum computing, improve electronic efficiencies, and enhanced sensing and imaging.

The state, described as a topological semimetal phase, was theoretically predicted to appear at low temperatures in a material composed of cerium, ruthenium, and tin (CeRu4Sn6), before experiments verified its existence.

At extremely low temperatures, CeRu4Sn6 reaches quantum criticality, a point where a material teeters between changes in its phase, where conditions are so cold that quantum fluctuations dominate, effectively turning the material into a puddle of waves rather than a fog of particles.

The plot twist in this study is that quantum criticality can give rise to states thought to be defined by interactions between particles, such as the behavior of electrons as discrete charge carriers.

"This is a fundamental step forward," says physicist Qimiao Si, from Rice University in the US.

"Our work shows that powerful quantum effects can combine to create something entirely new, which may help shape the future of quantum science."

In physics, topology refers to the geometry of material structures. Particular topological states can protect properties of particles, unlike the way neighboring particles might jostle and disrupt each other's behavior.

It’s true that there are a lot of different theoretical proposals that serve as alternatives or extensions to mainstream physics: string theory, supersymmetry, Gauss-Bonnet gravity, GUTs, and much more. 

Many point to the success of our standard picture of reality, based on Einstein’s general relativity and the quantum field theory of the Standard Model, and (prematurely) dismiss all such alternative explorations. 

However, a tremendous amount of progress has been made simply by constraining and ruling out many such alternatives and extensions through data-driven experiments and observations. That progress is underappreciated, representing a huge achievement whenever it occurs.

Ever since their discovery more than 165 years ago, massive fossilized structures left by an organism known as Prototaxites have proven impossible to categorize.

Researchers in the UK have suggested in a recently published study that there's a very good reason these oddities don't fit neatly on the tree of life – they belong to a branch all of their own, with no modern equivalent.

Some 400 million years ago, the swamps of the late Silurian period would have sprouted a mix of horsetails, ferns, and other prototype plants that look positively alien today.

Among them stretched 8-meter (26-foot) tall towers that defy easy identification. Wide and branchless, these organisms may have been a form of algae or ancient conifer, researchers suspect, based on what little evidence remains.

Loud and clear: Curiosity and Perseverance are both back in touch with Earth following solar conjunction. They’re beginning to downlink data collected while the Sun was blocking the signal path between us and the Red Planet.

Keep up with the latest at science.nasa.gov/mars/

The phrase “House of Cards” is often associated today with a Netflix political drama, but its original meaning refers to a structure that is inherently unstable. That idea is exactly how Sarah Thiele, who began this work as a PhD student at the University of British Columbia and is now at Princeton, and her co-authors describe today’s satellite mega constellation system in a new study released as a preprint on arXiv.

Their choice of words is supported by the numbers. Across all Low-Earth Orbit mega constellations, calculations show that a “close approach”, defined as two satellites passing within less than 1 kilometer of each other, happens about once every 22 seconds. For Starlink alone, such encounters occur roughly every 11 minutes. In addition, each of Starlink’s thousands of satellites must carry out an average of 41 maneuvers each year to avoid collisions with other objects in orbit.

At first glance, this may look like a carefully managed system functioning as intended. But engineers know that “edge cases”, events that fall outside normal operating conditions, are often what trigger major failures. According to the paper, solar storms represent one such edge case for satellite mega constellations. Under typical conditions, solar storms disrupt satellite operations in two main ways.

Days away from irreversible collisions
According to their calculations, as of June 2025, if satellite operators were to lose their ability to send commands for avoidance maneuvers, there would be a catastrophic collision in around 2.8 days. Compare that to the 121 days that they calculated would have been the case in 2018, before the megaconstellation era, and you can see why they are concerned. Perhaps even more disturbingly, if operators lose control for even just 24 hours, there’s a 30% chance of a catastrophic collision that could act as the seed case for the decades-long process of Kessler syndrome.