UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

We've learned that Interstellar Objects (ISOs) are not strangers to our Solar System. Many have visited, and many more will in the future. The Vera Rubin Observatory is expected to find hundreds each year. Scientists are keen to learn more about them, and a swarm of spacecraft on standby might be the way to do it.

On a basic level, an ISO is simply an object unbound to any star. The two we know of are 'Oumuamua which was detected in 2017, and Comet Borisov, detected in 2019. ISOs typically have very high velocities, follow hyperbolic trajectories that show they don't orbit the Sun, and have unique compositions that set them apart from Solar System bodies. 'Oumuamua, for example, could be a hydrogen iceberg, though this is just one possibility.

Scientists are eager to examine these objects closer and understand their compositions and origins. Unfortunately, their high velocities make them elusive, and we can only glimpse them with ground-based telescopes. What's needed is a way to visit one. The best way to do that is to have a spacecraft waiting to catch up with one as it passes through the inner Solar System.

Or even better, a whole swarm of spacecraft that don't require explicit instructions to rendezvous with an ISO.

Hiroyasu Tsukamoto is with the Department of Aerospace Engineering in the Grainger College of Engineering at the University of Illinois Urbana-Champaign. He and his colleagues developed Neural Rendezvous, a deep learning-driven guidance and control framework that can autonomously guide spacecraft to ISOs. Their work is in a paper titled "Neural-Rendezvous: Provably Robust Guidance and Control to Encounter Interstellar Objects" and published in Aerospace Research Central.

Artist's illustration. ISOs like Oumuamua only come through once, making them difficult targets for rendezvous.

Image Credit: NASA

"A human brain has many capabilities: talking, writing, etcetera," Tsukamoto said in a press release. "Deep learning creates a brain specialized for one of these capabilities with a domain-specific knowledge. In this case, Neural-Rendezvous learns all the information it needs to encounter an ISO, while also considering the safety-critical, high-cost nature of space exploration."

"Our key contribution is not just in designing the specialized brain, but in proving mathematically that it works," Tsukamoto added. "For example, with a human brain we learn from experience how to navigate safely while driving. But what are the mathematics behind it? How do we know and how can we make sure we won't hit anyone?"

The system is based on the "contraction theory for data-driven nonlinear control systems." Contraction theory is a rigorous mathematical framework which can place limits on the effects of disturbances and uncertainties in complex linear systems. Basically, it can provide stability in a complex situation that changes nonlinearly over time.

The Neural-Rendezvous system uses available data to predict a spacecraft's best actions to intercept an ISO. This complexity is necessary because ISOs are unbound and high-speed targets with poorly restrained trajectories.

"We’re trying to encounter an astronomical object that streaks through our solar system just once and we don’t want to miss the opportunity," Tsukamoto said. "Even though we can approximate the dynamics of ISOs ahead of time, they still come with large state uncertainty because we cannot predict the timing of their visit. That's a challenge."

The Hubble space telescope captured this image of Comet 2l/Borisov at perihelion in December 2019.

Image Credit: NASA, ESA, and D. Jewitt (UCLA)

ISOs only pass through the Solar System once. The usual method of observing an object like an asteroid or comet and determining its orbit doesn't work. According to the researchers, it's critical that ISO interceptors can "think" on their own.

"Unlike traditional approaches in which you design almost everything before you launch a spacecraft, to encounter an ISO, a spacecraft has to have something like a human brain, specifically designed for this mission, to fully respond to data onboard in real-time," Tsukamoto said.

There's no way to orbit an ISO. Oumuamua and Borisov were travelling at ~88 and 45 km/s relative to the Sun, so an intercepting spacecraft would need to travel at similar speeds. With our current technological level, a spacecraft would have to carry a prohibitively large volume of propellant to enter into orbit around one of these objects. Fast flybys are likely the only realistic mission architecture.

However, relying on a single spacecraft is like putting all your eggs in one basket. What if the spacecraft is unable to get a clear view of the ISO? Without a good look at the object, scientists won't be able to learn much about its surface and composition. This has led some researchers to consider multiple spacecraft.

Tsukamoto worked with two other researchers on "a novel multi-spacecraft framework for locally maximizing information to be gained through ISO encounters." Their work is presented in a separate paper titled "Information-Optimal Multi-Spacecraft Positioning for Interstellar Object Exploration." Along with Tsukamoto, the other authors are Arna Bhardwaj and Shishir Bhatta. The authors presented it at the 2024 IEEE Aerospace Conference.

"Because of the speed and uncertainty, it's challenging to obtain a clear view of an ISO during a flyby with 100 percent accuracy, even with Neural-Rendezvous," Tsukamoto said. "Arna and Shishir wanted to show that Neural-Rendezvous could benefit from a multi-spacecraft concept."

"Interstellar objects (ISOs), astronomical objects not gravitationally bound to the Sun, could present valuable opportunities to advance our understanding of the universe's formation and composition," the authors write in their paper. "In response to the unpredictable nature of their discoveries that inherently come with large and rapidly changing uncertainty in their state, this paper proposes a novel multi-spacecraft framework for locally maximizing information to be gained through ISO encounters with formal probabilistic guarantees."

Their framework involves a swarm of spacecraft, called deputy spacecraft, and one designated as chief. The swarm would be located around an ellipsoid representing the space through which an ISO will travel. The ellipsoid consists of multiple points of interest (POIs) that would be covered collectively by the deputies and the chief employing the Neural-Rendezvous system. This method can maximize the information gained from the encounter. In simple terms, it guarantees multiple views of the ISO.

"Now we have an additional layer of decision-making during the ISO encounter," Tsukamoto said. "How do you optimally position multiple spacecraft to maximize the information you can get out of it? Their solution was to distribute the spacecraft to visually cover the highly probable region of the ISO's position, which is driven by Neural-Rendezvous."

The surfaces of the Moon, Mercury, and Mars are easily visible and are littered with impact craters. Earth has been subjected to the same bombardment, but geological activity and weathering have eliminated most of the craters. The ones that remain are mostly only faint outlines or remnants. However, researchers in Australia have succeeded in finding what they think is the oldest impact crater on Earth.

Their research, "A Paleoarchaean impact crater in the Pilbara Craton, Western Australia," is published in Nature Communications. The lead authors are Christopher Kirkland and Professor Tim Johnson, both from Curtin University in Australia. The Pilbara Craton is one of only two pristine Archaean sections of crust and is the subject of much geological research.

Impactors were more common in the distant past, especially large ones. In the Paleoarchaean era, which spans from about 3.6 to 3.2 billion years ago, the Solar System was much more chaotic than it is now. There were more asteroids and debris in orbit around the Sun, and more of them crashed into the planets and the Moon. Earth didn't escape this fate, and ancient impacts affected how the continents formed, shaped the environment, helped make Earth habitable, and affected the overall conditions of the planet.

"Before our discovery, the oldest impact crater was 2.2 billion years old, so this is by far the oldest known crater ever found on Earth," Professor Johnson said.

"We know large impacts were common in the early solar system from looking at the Moon. Until now, the absence of any truly ancient craters means they are largely ignored by geologists," said Johnson. "This study provides a crucial piece of the puzzle of Earth's impact history and suggests there may be many other ancient craters that could be discovered over time."

The crater was excavated by a meteorite striking Earth at more than 36,000 km/h. The crater is more than 100 km wide, and the powerful impact would've affected the entire globe with flying debris. At the time, the only life was microbial and constrained to water.

The impact could have had a long-lasting effect on the Earth, helping shape the planet into what it is today. There's an ongoing scientific discussion about ancient impacts and their effect on the planet's crust. Some think these giant impacts could have initiated deep mantle plumes and subduction zones.

There's some evidence that giant impacts could've created mantle plumes and subduction zones.

Image Credit: Koppers et al. 2025. Mantle plumes and their role in Earth processes. Nat Rev Earth Environ. https://doi.org/10.1038/s43017-021-00168-6

Some scientists go even further and wonder if these large impacts could be responsible for Earth's continents.

"The role of meteorite impacts in the origin, modification, and destruction of crust during the first two billion years of Earth history (4.5–2.5 billion years ago; Ga) is disputed," the authors write. "Whereas some argue for a relatively minor contribution overall, others have proposed that individual giant impactors (>10–50 km diameter) can initiate subduction zones and deep mantle plumes, arguably triggering a chain of events that formed cratons, the ancient nuclei of the continents."

Cratons are the large, stable parts of Earth's crust and upper mantle, known as the lithosphere. As the continents moved around, sometimes merging and sometimes rifting, cratons survived. Scientists call them the 'seeds' of continents.

Many scientists think that Earth's ancient rocks formed above mantle plumes. Others think that the oldest rocks formed because of plate tectonics. In both cases, the formation is driven by heat from the planet's interior. However, Johnson and his colleagues are pursuing a different idea.

In a 2022 paper, Johnson and fellow researchers proposed that the heat necessary to form cratons and continents came from an otherworldly source: impacts. Impactors many kilometres in diameter could've delivered the heat. "Giant impacts provide a mechanism for fracturing the crust and establishing prolonged hydrothermal alteration by interaction with the globally extensive ocean," they wrote. Massive mantle melting from the impact would've created a thick nucleus that eventually formed a continent, they explained.

They were talking specifically about Australia's Pilbara Craton, the "best-preserved Archaean (4.0–2.5 billion years ago (Ga)) continental remnant."

Based on that, Kirkland, Johnson, and their fellow researchers knew where to look for evidence. While much of the evidence they had was microscopic, like zircon crystals and spherules, they wanted something more visible to convince other geologists. They knew what the evidence would look like: shatter cones. Shatter cones are rare and form in only two situations: in bedrock under impact craters or nuclear explosions. In both cases, there's an extremely powerful shock.

As Johnson explains in The Conversation, they went to the Pilbara for two weeks of fieldwork in 2021. Remarkably, they found shatter cones on the first day.

This image shows some of the shatter cones the researchers found in the study region.

Credit: Tim Johnson, Curtin University

"Our observations showed that above the layer with the shatter cones was a thick layer of basalt with no evidence of impact shock. This meant the impact had to be the same age as the Antarctic Member rocks, which we know are 3.5 billion years old," Johnson and his colleagues wrote in The Conversation.

This schematic shows the geological layers in the study area, the Antarctic Creek Member. "We speculate that the carbonate breccias represent the lithified and hydrothermally-altered products of impact-related deposits," the authors explain.

Image Credit: Kirkland et al. 2025

The Antarctic Member is a complex, mostly metasedimentary layer located in the central East Pilbara Terrane in Western Australia. This type of rock is first formed from solidified sediments. Then, it is buried under subsequent rock layers and subjected to heat and intense pressure, turning it into a metamorphic rock. Since the layers above it are unshocked, the researchers can date the impact.

This map from the published research shows the region's geology in detail. The study area is marked with a red star. The dashed lines are where spherules have been found in the region.

Image Credit: Kirkland et al. 2025

These findings are clear evidence of ancient impacts, which scientists were almost certain must have occurred just as they did on other Solar System bodies. They also offer evidence that ancient impacts formed cratons and, hence, led to the formation of continents. However, it's too soon to conclude that this is how things happened. It needs more research. This discovery will also likely drive further investigation into other ancient terranes on Earth for evidence of shatter cones.

Ancient impacts could have shaped our planet beyond geology. Some research shows that these ancient impacts could have given life an initial nudge. Their impacts provided long-lasting heat in the form of systems of hydrothermal vents. This allowed hot water to interact with rock, which could've created environments rich in chemistry and minerals. Scientists think these elements are critical for the emergence of life.

“Uncovering this impact and finding more from the same time period could explain a lot about how life may have got started, as impact craters created environments friendly to microbial life such as hot water pools," Professor Kirkland said.

"It also radically refines our understanding of crust formation: the tremendous amount of energy from this impact could have played a role in shaping early Earth's crust by pushing one part of the Earth's crust under another or by forcing magma to rise from deep within the Earth's mantle toward the surface," Kirkland added.

"It may have even contributed to the formation of cratons, which are large, stable landmasses that became the foundation of continents," he concluded.