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NASA’s Double Asteroid Redirection Test (DART) spacecraft is designed to be a one hit wonder. It will end its days by crashing into an asteroid at 24,000 kilometres per hour on September 26. Launched from Earth in November 2021, DART is about the size of a bus and was created to test and prove our ability to defend Earth from a dangerous asteroid.

Landing a direct hit on a target from 11 million kilometres away isn’t easy. But while this sounds far, the asteroid was actually selected by NASA because it is relatively close to Earth. This will give engineers the opportunity to test the spacecraft’s ability to operate itself in the final stages before the impact, as it crashes autonomously.

The target asteroid is called Dimorphos, a body 163 metres in diameter that’s orbiting a 780 metre-wide asteroid called Didymos. This “binary asteroid system” was chosen because Dimorphos is in orbit around Didymos, which makes it easier to measure the result of the impact due to the resulting change in its orbit. However, the Dimorphos system does not currently pose any risk to the Earth.

Regardless, NASA is attempting nothing less than a full scale planetary defence experiment to change an asteroid’s path. The technique being used is called “kinetic impact”, which alters the orbit of the asteroid by crashing into it. That’s essentially what is known as a safety shot in snooker, but played on a planetary level between the spacecraft (as the cue ball) and the asteroid.

A tiny deflection could be sufficient to prove that this technique can actually change the path of an asteroid on a collision path with the Earth.

But the DART spacecraft is going to be completely blown apart by the collision because it will have an impact equivalent to about three tonnes of TNT. In comparison, the atomic bomb dropped on Hiroshima was equal to 15,000 tonnes of TNT.

So, with this level destruction and the distance involved, how will we be able to see the crash? Luckily, the DART spacecraft is not travelling alone on its quest, it is carrying LICIACube, a shoebox-size mini spacecraft, known as a cubesat, developed by the Italian Space Agency and aerospace engineering company Argotec. This little companion has recently separated from the DART spacecraft and is now travelling on its own to witness the impact at a safe distance of 55km.

Never before has a cubesat operated around asteroids so this provides new potential ways of exploring space in the future. The impact will also be observed from Earth using telescopes. Combined, these methods will enable scientists to confirm whether the operation has been successful.

It might, however, take weeks for LICIACube to send all images back to Earth. This period will be utterly nerve wracking – waiting for good news from a spacecraft is always an emotional time for an engineer.

What happens next? An investigation team will look at the aftermath of the crash. These scientists will aim to measure the changes in Dimorphos’ motion around Didymos by observing its orbital period. This is the time during which Dimorphos passes in front and behind Didymos, which will happen every 12 hours.

Ground telescopes will aim to capture images of the Dimorphos’ eclipse as this happens. To cause a significant enough deflection, DART must create at least a 73-second orbital period change after impact – visible as changes in the frequencies of the eclipses.

These measurements will ultimately determine how effective “kinetic impact” technology is in deflecting a potentially hazardous asteroid – we simply don’t know yet.

This is because we actually know very little of the asteroids’ composition. The great uncertainty around how strong Dimorphosis is has made designing a bullet spacecraft a truly enormous engineering challenge. Based on ground observation, the Didymos system is suspected to be a rubble-pile made up of lots of different rocks, but its internal structure is unknown.

There are also great uncertainties about the outcome of the impact. Material ejected afterwards will contribute to the effects of the crash, providing an additional force. We don’t know whether a crater will be formed by the impact or if the asteroid itself will suffer major deformation, meaning we can’t be sure how much force the collision will unleash.

Future missions Our exploration of the asteroid system does not end with DART. The European Space Agency is set to launch the Hera mission in 2024, arriving at Didymos in early 2027 to take a close look at the remaining impact effects.

By observing the deformations caused by the DART impact on Dimorphos, the Hera spacecraft will gain a better understanding of its composition and formation. Knowledge of the internal properties of objects such as Didymos and Dimorphos will also help us better understand the danger they might pose to Earth in the event of an impact.

Ultimately, the lessons from this mission will help verify the mechanics of a high-velocity impact. While laboratory experiments and computer models can already help validate scientists’ impact predictions, full-scale experiments in space such as DART are the closest we will get to the whole picture. Finding out as much as we can about asteroids will help us understand what force we need to hit them with to deflect them.

The DART mission has led to worldwide cooperation among scientists hoping to address the global issue of planetary defence and, together with my colleagues on the DART investigation team, we aim to analyse the impact effects. My own focus will be on studying the motion of the material that is ejected from the impact.

The spacecraft impact is scheduled for September 26 at 19:14 Eastern Daylight Time (00:14 British Summer Time on September 27). You can follow the impact on NASA TV.


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Voyager 2’s Flyby Sheds Light on Uranus’s Magnetic Mystery

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Voyager 2's Flyby Sheds Light on Uranus's Magnetic Mystery

A recent analysis of 38-year-old data from NASA’s Voyager 2 spacecraft has provided fresh insights into the unique magnetosphere of Uranus, according to a study published on November 11 in Nature Astronomy. During Voyager 2’s 1986 flyby, Uranus’ magnetosphere was found to be unexpectedly distorted by a blast of solar wind. The findings suggest that the planet’s magnetic field behaves unlike any other in the solar system.

Findings Highlight Unusual Magnetic Structures

Jamie Jasinski, a planetary scientist at NASA’s Jet Propulsion Laboratory and California Institute of Technology, and lead author of the study, noted that Voyager 2’s timing happened to coincide with an intense solar wind event, a rare occurrence near Uranus. This compression of Uranus’s magnetosphere, seen only around 4% of the time, is thought to be responsible for the unique measurements Voyager captured. Had the spacecraft arrived even a week earlier, Jasinski observed, these conditions would likely have been different, possibly leading to alternative conclusions about Uranus’s magnetic characteristics.

Unlike Earth, Uranus exhibits a complex “open-closed” magnetic process, influenced by its extreme axial tilt. This tilt subjects Uranus to highly variable solar wind effects, resulting in a magnetosphere that opens and closes cyclically.

Implications for Future Uranus Exploration

The study’s conclusions go beyond Uranus itself, offering insights into the magnetic behaviours of its outermost moons, including Titania and Oberon. These moons, it turns out, lie within Uranus’s magnetosphere rather than outside it, making them candidates for investigations into subsurface oceans through magnetic field detection. As Jasinski highlighted, these conditions would simplify detecting any magnetic signatures that suggest liquid beneath the moons’ icy surfaces.

While Voyager 2 remains the only mission to visit Uranus, the study’s findings underscore a growing interest in exploring the ice giant in greater detail.

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Tajikistan rock shelter reveals ancient human migration routes

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Tajikistan rock shelter reveals ancient human migration routes

Archaeologists have uncovered a rock shelter in Tajikistan’s Zeravshan Valley that was occupied by multiple human species, including Neanderthals, Denisovans, and Homo sapiens, for over 130,000 years. Discovered along the Zeravshan River in the Inner Asian Mountain Corridor (IAMC), this site, known as Soii Havzak, provides new insight into the migration patterns of ancient humans. Researchers believe the IAMC may have facilitated interactions between these groups, offering clues about how they lived and possibly coexisted in Central Asia.

Discovery Along the Zeravshan River

A team led by Dr Yossi Zaidner, senior lecturer at the Institute of Archaeology at the Hebrew University of Jerusalem, recently excavated the site. Evidence of various human occupations was found, including stone tools and animal bones dating from 150,000 to 20,000 years ago. Zaidner noted that Central Asia’s IAMC could have served as a natural migration route, allowing distinct human populations to cross paths. “This discovery is crucial for understanding ancient human presence in Central Asia and how different human species may have interacted here,” he stated in a press release.

Significance for Human Migration and Interaction

Artifacts from Soii Havzak, including stone blades, rock flakes, crafted flints, and signs of fire use, suggest repeated use of the shelter by different human groups. The find highlights Central Asia’s significance in ancient migration routes, with the Zeravshan River likely serving as a pathway for early humans as they dispersed across continents.

A Pathway for Ancient Civilisations

Beyond its prehistoric importance, the Zeravshan Valley later became a key route on the Silk Road, linking distant civilisations such as China and Rome. Researchers expect further studies at Soii Havzak to shed light on the broader implications of this region in ancient human migration and cross-cultural interactions, aiming to deepen understanding of human history and evolution during the Middle Paleolithic era.

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NASA’s Juno shows Jupiter’s storms and moon Amalthea up close

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NASA’s Juno shows Jupiter’s storms and moon Amalthea up close

NASA’s Juno spacecraft has delivered breathtaking images of Jupiter, highlighting the planet’s swirling, multicoloured storms and unique moons. During Juno’s 66th close flyby on October 23, the spacecraft approached the planet’s polar regions and captured close-up views of its fifth-largest moon, Amalthea. The raw images collected by JunoCam have since been processed by citizen scientists, who enhanced colours and contrasts to reveal Jupiter’s atmospheric details in a new light.

Spectacular Details of Jupiter’s Storms Revealed

Citizen scientist Jackie Branc processed one of Juno’s most striking images, showcasing a region on Jupiter called a Folded Filamentary Region (FFR), located near the planet’s subpolar areas. FFRs are known for their complex cloud patterns, which include white billows and fine, thread-like filaments. This recent image captures Jupiter’s stormy atmosphere with an emphasis on these fine details, giving scientists and the public alike a vivid view of the planet’s dynamic weather systems.

Juno’s data, available to the public online, allows enthusiasts and researchers to adjust image features such as contrast and colour balance. This collaborative effort has enabled a range of perspectives on Jupiter’s atmospheric bands, turbulent clouds, and powerful vortices.

Amalthea: A Close-Up of Jupiter’s Unique Moon

Juno also captured images of Amalthea, a small, potato-shaped moon only 84 kilometres in radius. In images processed by Gerald Eichstädt, the white balance was adjusted to distinguish Amalthea from the blackness of space, presenting the moon in stark relief. This view of Amalthea, with its rugged, irregular shape, adds to our understanding of Jupiter’s complex satellite system.

Launched in 2016, the Juno mission was originally planned to conclude in 2021, but its mission has been extended, with plans to end in September 2025. When its mission concludes, Juno will plunge into Jupiter’s atmosphere, marking the end of its successful exploration journey.

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