Asteroids that could potentially impact Earth vary greatly in size, from the catastrophic 10-kilometer-wide asteroid that caused the extinction of the dinosaurs to much smaller ones that strike far more frequently. Now, an international team of researchers, led by physicists at MIT, has discovered a new way to spot the smallest asteroids in our solar system’s main asteroid belt, which could provide critical insights into the origins of meteorites and planetary defense.

The team’s breakthrough approach allows astronomers to detect decameter asteroids—those just 10 meters across—much smaller than those previously detectable, which were about one kilometer in diameter. This marks the first time such small asteroids in the asteroid belt have been spotted, potentially leading to better tracking of near-Earth objects that could pose a threat.

“We have been able to detect near-Earth objects down to 10 meters in size when they are really close to Earth,” said lead author Artem Burdanov, a research scientist at MIT’s Department of Earth, Atmospheric and Planetary Sciences. “We now have a way of spotting these small asteroids when they are much farther away, so we can do more precise orbital tracking, which is key for planetary defense.”

The team used their innovative method to detect over 100 new decameter asteroids, ranging from the size of a bus to several stadiums wide. These are the smallest asteroids ever found in the main asteroid belt, located between Mars and Jupiter, where millions of asteroids orbit.

The findings, published today in Nature, have the potential to improve asteroid tracking efforts, which are critical for understanding the risk of future impacts. Scientists hope that the method could be applied to identify asteroids that may one day approach Earth.

The research team, which includes MIT planetary science professors Julien de Wit and Richard Binzel, as well as collaborators from the University of Liege, Charles University, and the European Space Agency, among others, utilized the James Webb Space Telescope (JWST) for their discovery. JWST’s sensitivity to infrared light made it an ideal tool for detecting the faint infrared emissions of asteroids, which are far brighter at these wavelengths than in visible light.

The team’s approach also relied on an imaging technique called “shift and stack,” which involves aligning multiple images of the same field of view to highlight faint objects like asteroids. This technique was originally developed for exoplanet research but was adapted for asteroid detection.

The researchers believe that these new findings will help improve our understanding of asteroid population

By processing over 10,000 images of the TRAPPIST-1 system—collected to study the planets in that distant star system—the researchers identified eight known asteroids and an additional 138 new ones. These newly discovered asteroids are the smallest main belt asteroids ever detected, with diameters as small as 10 meters.

“This is a totally new, unexplored space we are entering, thanks to modern technologies,” Burdanov said. “It’s a good example of what we can do as a field when we look at the data differently. Sometimes there’s a big payoff, and this is one of them.”

The researchers believe that these new findings will help improve our understanding of asteroid populations, including the many small objects that result from collisions among larger asteroids. Miroslav Broz, a co-author from Charles University in Prague, emphasized the importance of studying these decameter asteroids to model the creation of asteroid families formed from larger, kilometer-sized collisions.

De Wit, a co-author, highlighted the significance of the discovery: “We thought we would just detect a few new objects, but we detected so many more than expected, especially small ones. It is a sign that we are probing a new population regime, where many more small objects are formed through cascades of collisions.”

(With inputs from MIT)

US space agency NASA’s Imaging X-ray Polarimetry Explorer (IXPE) has provided new insights into the structures around a stellar-mass black hole, enhancing our understanding of the swirling disk of material and the shifting plasma region known as the corona. The black hole is part of the binary system Swift J1727.8-1613, and was discovered during an extraordinary brightening event in the summer of 2023. This outburst briefly made the black hole outshine nearly all other X-ray sources, according to NASA.

Swift J1727 is the first such black hole to be observed by IXPE as it went through the stages of an X-ray outburst, from its onset to its peak and eventual return to inactivity. Scientists say the data collected during this outburst offers first-time insight into the behaviour and evolution of black hole X-ray binary systems.

Astrophysicist Alexandra Veledina, from the University of Turku in Finland, described the event as “incredibly quick.” From the initial detection of the outburst, Swift J1727 took only days to reach its peak. By that time, IXPE and other telescopes were already gathering crucial data to track the outburst’s progression. “It was exhilarating to observe the outburst all the way through its return to inactivity,” Veledina added.

The outburst, which briefly surpassed the brightness of the Crab Nebula (the standard X-ray reference), lasted until late 2023. Notably, this event occurred just 8,800 light-years away from Earth, making it an exceptional discovery in terms of both brightness and proximity. The system was named after the Swift Gamma-ray Burst Mission, which initially detected the event on August 24, 2023, using its Burst Alert Telescope.

The findings, published in The Astrophysical Journal and Astronomy & Astrophysics, gives a deeper understanding of the dynamics of black hole systems and the role of X-ray binaries in the broader cosmic landscape.

In an intriguing development, scientists at the Raman Research Institute (RRI) in Bangalore, India, have developed a novel antenna design that could revolutionise our ability to detect the faint signals of Cosmological Recombination Radiation (CRR).

These signals, which are crucial for understanding the thermal and ionization history of the Universe, have so far remained undetected due to their elusive nature. The newly designed antenna is capable of measuring signals in the 2.5 to 4 Gigahertz (GHz) frequency range, which is optimal for detecting CRR, a signal that is approximately one billion times fainter than the Cosmic Microwave Background (CMB).

As per available sources, the universe is approximately 13.8 billion years old, and in its earliest stages, it was extremely hot and dense. During this time, the Universe was composed of a plasma of free electrons, protons, and light nuclei such as helium and lithium. The radiation coexisting with this matter has been detected today as the CMB, which holds vital information about the early cosmological and astrophysical processes.

One such process, known as the Epoch of Recombination, marks the transition from a fully ionized primordial plasma to mostly neutral hydrogen and helium atoms. This transition emitted photons, creating the Cosmological Recombination Radiation (CRR), which distorts the underlying CMB spectrum. Detecting these faint CRR signals would provide a wealth of information about the Universe’s early ionization and thermal history and could even offer the first experimental measurements of helium abundance before it was synthesized in the cores of stars.

However, detecting CRR is a significant challenge because these signals are extremely weak—about nine orders of magnitude fainter than the CMB. To address this, scientists need highly sensitive instruments that can isolate these signals from the vast cosmic noise surrounding them.

To this end, researchers from RRI, including Mayuri Rao and Keerthipriya Sathish, along with Debdeep Sarkar from the Indian Institute of Science (IISc), have developed an innovative ground-based broadband antenna designed to detect signals as faint as one part in 10,000. Their design is capable of making sky measurements in the 2.5 to 4 GHz range, the frequency band most suitable for CRR detection.

According to Keerthipriya Sathish, the lead author of the study, “For the sky measurements we plan to perform, this broadband antenna offers the highest sensitivity compared to other antennas designed for the same bandwidth. The antenna’s frequency-independent performance across a wide range and its smooth frequency response are features that set it apart from conventional designs.”

The antenna is compact and lightweight, weighing just 150 grams, with a square shape measuring 14 cm by 14 cm.

The proposed antenna is a dual-polarized dipole antenna with a unique four-arm structure shaped like a fantail. This design ensures that the antenna maintains the same radiation pattern across its entire operational bandwidth, with a mere 1% variation in its characteristics. This is crucial for distinguishing spectral distortions from galactic foregrounds. The antenna’s custom design allows it to “stare” at the same patch of sky throughout its full operational range of 1.5 GHz (from 2.5 to 4 GHz), which is key to separating the CRR signals from other cosmic noise.

The antenna is compact and lightweight, weighing just 150 grams, with a square shape measuring 14 cm by 14 cm. It is made using a low-loss dielectric flat substrate on which the antenna is etched in copper, while the bottom features an aluminum ground plate. Between these plates lies a radio-transparent foam layer that houses the antenna’s connectors and receiver base.

With a sensitivity of around 30 millikelvin (mK) across the 2.5-4 GHz frequency range, the antenna is capable of detecting tiny temperature variations in the sky. Even before being scaled to a full array, this antenna design is expected to provide valuable first scientific results when integrated with a custom receiver. One of the anticipated experiments is to study an excess radiation reported at 3.3 GHz, which has been speculated to result from exotic phenomena, including dark matter annihilation. These early tests will help refine the antenna’s performance and guide future design improvements aimed at achieving the sensitivity required for CRR detection.

The researchers plan to deploy an array of these antennas in radio-quiet areas, where radio frequency interference is minimal or absent. The antenna’s design is straightforward and can be easily fabricated using methods similar to those employed in Printed Circuit Board (PCB) manufacturing, ensuring high machining accuracy and consistency for scaling up to multiple-element arrays. The antenna is portable, making it easy to deploy in remote locations for scientific observations.

The team is already looking ahead, planning further improvements to achieve even greater sensitivity, with a long-term goal of detecting CRR signals at sensitivities as low as one part per billion. With this innovative antenna design, the team hopes to make significant strides toward uncovering the secrets of the early Universe and its formation.