The discovery comes from a chemical experiment carried out on another planet for the first time. Results show that the Martian surface is capable of preserving molecules that could act as potential signs of ancient life. However, the experiment cannot determine whether these organic compounds came from past life on Mars, natural geological processes, or meteorites that struck the planet.

To confirm any true evidence of past life, scientists would need to bring Martian rock samples back to Earth for detailed study.

New Experiment Reveals Preserved Ancient Chemistry

The research was led by Amy Williams, Ph.D., a geological sciences professor at the University of Florida and a member of both the Curiosity and Perseverance rover science teams. Curiosity arrived on Mars in 2012 to investigate whether the planet once had conditions suitable for microbial life. Perseverance, which landed in 2021, is focused on searching for direct signs of ancient life.

“We think we’re looking at organic matter that’s been preserved on Mars for 3.5 billion years,” said Williams, who helped develop the experiment. “It’s really useful to have evidence that ancient organic matter is preserved, because that is a way to assess the habitability of an environment. And if we want to search for evidence of life in the form of preserved organic carbon, this demonstrates it’s possible.”

Williams and an international team published the findings April 21 in the journal Nature Communications.

DNA-Like Molecule Among Key Discoveries

The experiment identified more than 20 different chemicals. Among them was a nitrogen-containing molecule with a structure similar to compounds involved in building DNA, something never before detected on Mars. The rover also found benzothiophene, a large sulfur-containing molecule with two connected rings, which is commonly delivered to planets by meteorites.

“The same stuff that rained down on Mars from meteorites is what rained down on Earth, and it probably provided the building blocks for life as we know it on our planet,” Williams said.

Gale Crater and Clay Minerals Preserve Organics

Curiosity, operated by NASA’s Jet Propulsion Laboratory, landed in Gale crater in August 2012. This site was once a lake bed. The experiment took place in 2020 in the Glen Torridon region, an area rich in clay minerals that formed in the presence of water. These clays are especially good at trapping and preserving organic material, making them ideal locations for this type of investigation.

SAM Instrument and TMAH Chemical Analysis

The analysis was carried out using the Sample Analysis at Mars instrument suite, known as SAM. Jennifer Eigenbrode, Ph.D., an astrobiologist at NASA’s Goddard Space Flight Center and co-author of the study, helps lead the instrument team. SAM has contributed many of the mission’s key discoveries about Mars’ chemistry, atmosphere, and potential habitability.

In this experiment, scientists used a chemical called TMAH to break down larger organic molecules into smaller fragments. These fragments could then be examined by SAM’s onboard instruments. Because Curiosity only carries about two cups of TMAH, researchers had to carefully plan the experiment and select the best possible sampling site.

Implications for Future Mars and Titan Missions

The success of this method is shaping future exploration plans. Upcoming missions, including the Rosalind Franklin rover on Mars and the Dragonfly mission to Saturn’s moon Titan, are expected to carry similar TMAH-based experiments to search for organic compounds.

“We now know that there are big complex organics preserved in the shallow subsurface of Mars, and that holds a lot of promise for preserving large complex organics that might be diagnostic of life,” Williams said.

This concept became widely known through the double-slit experiment. When electrons were fired through two narrow openings, they produced a pattern of alternating light and dark bands on a detector. This pattern revealed that each electron behaved like a wave, with its quantum wave-function passing through both slits at once and interfering with itself. Scientists later confirmed this effect with neutrons, helium atoms, and even larger molecules, establishing matter-wave diffraction as a key principle of quantum mechanics. However, despite these advances, this phenomenon had not been directly observed in positronium. Positronium is a short-lived, two-body system made up of an electron and a positron bound together and orbiting a shared center of mass. Because both components have equal mass, researchers have long sought to understand how such a system would behave when forming a beam and undergoing diffraction.

First Observation of Positronium Wave Behavior

A research team from Tokyo University of Science, Japan, led by Professor Yasuyuki Nagashima and joined by Associate Professor Yugo Nagata and Dr. Riki Mikami, has now achieved that goal. They successfully demonstrated matter-wave diffraction in a beam of positronium. The beam used in their experiment had the necessary energy range and coherence to produce clear interference effects. Their results, published in Nature Communications, provide strong new evidence of wave-particle duality in an unusual system.

“Positronium is the simplest atom composed of equal-mass constituents, and until it self-annihilates, it behaves as a neutral atom in a vacuum. Now, for the first time, we have observed quantum interference of a positronium beam, which can pave the way for new research in fundamental physics using positronium,” says Prof. Nagashima.

Creating a High-Quality Positronium Beam

The breakthrough relied on producing a highly controlled positronium beam. To do this, the researchers first generated negatively charged positronium ions. They then used a precisely timed laser pulse to remove an extra electron, resulting in a fast-moving, neutral, and coherent stream of positronium atoms.

This beam was directed toward a sheet of graphene. The spacing between atoms in the graphene closely matched the de Broglie wavelength of the positronium at the energies used in the experiment. As the positronium atoms passed through the two-to-three-layer graphene sheet, some of them made it through and were detected. The resulting measurements revealed a distinct diffraction pattern, confirming wave-like behavior.

Clear Diffraction Patterns and Quantum Behavior

Compared with earlier techniques, this method produces positronium beams with higher energies, reaching up to 3.3 keV. It also provides a narrower spread of energies and a more tightly directed beam. Conducting the experiment in an ultra-high vacuum kept the graphene surface clean, allowing the diffraction pattern to be observed more clearly.

The results showed that even though positronium consists of two particles, it behaves as a single quantum object. The electron and positron do not diffract separately but instead act together as one wave.

“This groundbreaking experimental milestone marks a major advance in fundamental physics. It not only demonstrates positronium’s wave nature as a bound lepton-antilepton system (a system that behaves like a tiny atom) but also opens pathways for precision measurements involving positronium,” says Dr. Nagata.

The team also investigated whether positronium would produce interference in the same way as a single particle like an electron. Their findings confirmed that it does, reinforcing the idea that it functions as a unified quantum entity.

Future Applications in Materials Science and Antimatter Research

In addition to confirming its quantum properties, positronium diffraction could lead to practical applications. Because positronium carries no electric charge, it may be useful for analyzing material surfaces without causing damage. This makes it especially valuable for studying insulators or magnetic materials that can interfere with charged particle beams.

Looking ahead, experiments involving positronium interference could also make it possible to test how antimatter responds to gravity. This remains an open question, as direct measurements have not yet been achieved, even for electrons.

About Professor Yasuyuki Nagashima from Tokyo University of Science

Dr. Yasuyuki Nagashima is a Professor in the Department of Physics at Tokyo University of Science, Japan, specializing in positron and positronium physics. His research focuses on the properties of negative ions of positronium and the positronium beam. He also studies positron annihilation-induced ion desorption from solid surfaces. In 2020, he received the Hiroshi Takuma Memorial Prize from the Matsuo Foundation. His laboratory conducts fundamental research on exotic particle-matter interactions while developing new positron-based experimental techniques for applied physics.

About Associate Professor Yugo Nagata from Tokyo University of Science

Dr. Yugo Nagata is an Associate Professor in the Department of Physics at Tokyo University of Science, Japan, specializing in positronium and atomic physics. In 2023, he received the Young Scientist Award of the Japanese Positron Science Society.

This work was supported by JSPS KAKENHI (Grants Nos. JP25H00620, JP21H04457, and JP17H01074).

With this self-formed beam, the team produced 3D images of the human blood-brain barrier at speeds about 25 times faster than the current gold-standard approach, while preserving similar image quality. The method also makes it possible to watch individual cells absorb drugs in real time. This could help scientists evaluate whether treatments for conditions such as Alzheimer’s or ALS are actually reaching their intended targets in the brain.

“The common belief in the field is that if you crank up the power in this type of laser, the light will inevitably become chaotic. But we proved that this is not the case. We followed the evidence, embraced the uncertainty, and found a way to let the light organize itself into a novel solution for bioimaging,” says Sixian You, assistant professor in the MIT Department of Electrical Engineering and Computer Science (EECS), a member of the Research Laboratory for Electronics, and senior author of a paper on this imaging technique.

She is joined on the paper by lead author Honghao Cao, an EECS graduate student; EECS graduate students Li-Yu Yu and Kunzan Liu; postdocs Sarah Spitz, Francesca Michela Pramotton, and Federico Presutti; Zhengyu Zhang PhD ’24; Subhash Kulkarni, an assistant professor at Harvard University and the Beth Israel Deaconess Medical Center; and Roger Kamm, the Cecil and Ida Green Distinguished Professor of Biological and Mechanical Engineering at MIT. The paper appears today in Nature Methods.

A Surprising Laser Behavior Emerges

The finding began with an observation that did not fit expectations.

The researchers had previously built a precise fiber shaper, a device that allows careful control of laser light traveling through a multimode optical fiber, which is capable of carrying high levels of power.

Cao gradually increased the laser power to test the limits of the fiber.

Normally, increasing power causes the light to scatter more due to imperfections inside the fiber. Instead, as the power approached the threshold where the fiber might be damaged, the light suddenly concentrated into a single, extremely sharp beam.

“Disorder is intrinsic to these fibers. The light engineering you typically need to do to overcome that disorder, especially at high power, is a longstanding hassle. But with this self-organization, you can get a stable, ultrafast pencil beam without the need for custom beam-shaping components,” You says.

Conditions That Enable Self-Organizing Light

To reproduce this effect, the team identified two key requirements.

First, the laser must enter the fiber at a perfectly aligned, zero-degree angle, which is stricter than standard practice. Second, the power must be increased until the light begins interacting directly with the glass material of the fiber.

“At this critical power, the nonlinearity can counter the intrinsic disorder, creating a balance that transforms the input beam into a self-organized pencil beam,” Cao explains.

Such conditions are rarely explored because researchers typically avoid high power levels to prevent damaging the fiber. Precise alignment is also not usually necessary since multimode fibers can already carry large amounts of energy.

When combined, however, these factors allow the system to produce a stable beam without complex optical engineering.

“That is the charm of this method — you could do this with a normal, optical setup and without much domain expertise,” You says.

Sharper Imaging With Fewer Artifacts

Tests showed that this pencil beam is both stable and highly detailed compared to similar beams. Many conventional beams produce “sidelobes” — blurred halos that reduce image clarity.

In contrast, this beam remains clean and tightly focused.

The researchers then applied the technique to image the human blood-brain barrier, a dense layer of cells that shields the brain from harmful substances but also blocks many drugs.

Faster 3D Imaging of the Blood-Brain Barrier

Scientists often need to observe how drugs move through the blood vessels in this barrier and whether they successfully reach brain tissue. Traditional optical methods typically capture one 2D slice at a time, requiring repeated scans to build a complete 3D image.

Using the new pencil beam approach, the team generated rapid, high-precision images while also tracking how cells absorb proteins in real time.

“The pharmaceutical industry is especially interested in using human-based models to screen for drugs that effectively cross the barrier, as animal models often fail to predict what happens in humans. That this new method doesn’t require the cells to have a fluorescent tag is a game-changer. For the first time, we can now visualize the time-dependent entry of drugs into the brain and even identify the rate at which specific cell types internalize the drug,” says Kamm.

“Importantly, however, this approach is not limited to the blood-brain barrier but enables time-resolved tracking of diverse compounds and molecular targets across engineered tissue models, providing a powerful tool for biological engineering,” Spitz adds.

The system produced cellular-level 3D images with improved quality and did so roughly 25 times faster than existing methods.

“Usually, you have a tradeoff between image resolution and depth of focus — you can only probe so far at a time. But with our method, we can overcome this tradeoff by creating a pencil-beam with both high resolution and a large depth of focus,” You says.

Future Applications and Next Steps

Looking ahead, the researchers aim to better understand the physics behind this self-organizing beam and the mechanisms that allow it to form. They also plan to extend the method to other applications, including imaging neurons, and to explore ways to bring the technology into practical use.

This work was funded, in part, by MIT startup funds, the National Science Foundation (NSF), the Silicon Valley Community Foundation, Diacomp Foundation, the Harvard Digestive Disease Core, a MathWorks Fellowship, and the Claude E. Shannon Award.