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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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NASA Astronaut Sunita Williams Refutes Health Concerns Amid ISS Mission

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NASA Astronaut Sunita Williams Refutes Health Concerns Amid ISS Mission

NASA astronaut Sunita Williams has recently addressed speculations surrounding her health condition while on the International Space Station (ISS), discarding recent claims made by media outlets regarding her wellbeing. In response to reports that suggested she appeared “gaunt” due to an extended stay on the ISS, Williams clarified her status during a video interview on November 12, explaining that her weight has remained unchanged since her arrival in orbit.

Routine Exercise and Physical Adaptations

Williams, who commands Expedition 72 aboard the ISS, responded to health concerns publicly, indicating that any changes in her physical appearance are the result of rigorous exercise routines rather than health deterioration. Like all astronauts on extended missions, she has been following an intense workout regimen designed to counteract the muscle and bone density loss commonly associated with prolonged microgravity exposure. Williams stated that her routine includes running on a treadmill, riding an exercise bike and lifting weights. It is a form of exercise that has led to increased muscle mass, particularly in her thighs and glutes, while her overall weight remains consistent.

NASA’s Statement on Crew Health

NASA had previously denied the reports, emphasising that Williams and her fellow crew members, including NASA astronaut Butch Wilmore, are in good health. Williams and Wilmore, who arrived at the ISS on June 6 aboard Boeing’s Starliner capsule, were initially scheduled for a ten-day mission under the Crew Flight Test programme. Technical issues with Starliner’s thrusters led NASA to extend their stay on the ISS until early 2025, when they are expected to return with SpaceX’s Crew-9 mission astronauts.

Current ISS Crew Status

The current ISS team, led by Williams, includes three NASA astronauts and three Russian cosmonauts, all working collaboratively despite recent media scrutiny. Williams assured viewers that her health and morale remain robust as the crew carries out essential research and maintenance tasks on the orbiting laboratory showing NASA’s confidence in their well-being during extended missions.

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Math reveals secrets to gaining height on a half-pipe

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Math reveals secrets to gaining height on a half-pipe

A recent study reveals how skateboarders can use mathematical insights to increase their speed and height on half-pipes. Florian Kogelbauer, a mathematician from ETH Zurich, and his research team have examined how specific movements impact a skateboarder’s performance on U-shaped ramps. By alternating between crouching and standing in certain areas, skaters can generate extra momentum, leading to higher jumps and faster speeds. This research, published in Physical Review Research, could lead to more efficient techniques for skaters aiming to improve their skills.

Modelling Momentum on Half-Pipes

The research was published in American Physical Society Journal. The technique of “pumping,” or alternating between crouching and standing, is essential for building speed on half-pipes. Kogelbauer’s team created a model to show how the body’s centre of mass affects movement on a ramp, much like the mechanics of a swing. In their calculations, they found that crouching while moving downhill and standing while moving uphill helps skaters gain height more effectively. This rhythm, the team suggests, could help skaters reach higher elevations on the ramp in fewer motions.

Testing the Theory with Real Skaters

To test the model’s validity, researchers observed two skateboarders as they navigated a half-pipe. They were asked to reach a specific height as quickly as possible. Video analysis revealed that the more experienced skater naturally followed the model’s suggested pattern, reaching the target height with fewer motions. The less experienced skater, who did not follow the pattern as precisely, required more time to reach the same height. This contrast suggests that experienced skaters intuitively apply these principles for better performance.

Broader Applications Beyond Skateboarding

According to Sorina Lupu, an engineer at the California Institute of Technology, this simplified model may also have applications in robotics. By demonstrating how minimal adjustments in body position can impact speed and height, this study offers insights that could make robotic movement more efficient. For engineers, this research indicates that straightforward models of human movement could be used to enhance robotic performance, providing an alternative to complex machine-learning models often used in robotics.

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Global Fossil CO2 Emissions Hit Record in 2024

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Global Fossil CO2 Emissions Hit Record in 2024

Global carbon emissions from fossil fuel combustion have reached an unprecedented peak in 2024, with the Global Carbon Project reporting a projected 37.4 billion tonnes of fossil CO2 emissions, a 0.8% increase from 2023. The report underscores an urgent call for emissions reduction as the world’s annual output of CO2 from fossil fuels and land-use changes collectively approaches 41.6 billion tonnes. Despite increased efforts to mitigate climate impacts, there are no clear signs of a peak in global fossil CO2 emissions, heightening the risk of surpassing critical climate thresholds.

Sector-Specific Emissions and Regional Insights

As per a report by University of Exeter, emissions from fossil fuels, including coal, oil, and gas, are anticipated to rise in 2024, accounting for 41 percent, 32 percent, and 21 percent of fossil CO2 emissions, respectively. Coal emissions are expected to increase by 0.2 percent, oil by 0.9 percent, and natural gas by 2.4 percent. On a regional level, China, responsible for 32 percent of global emissions, is projected to see a slight increase of 0.2 percent, while emissions in the United States are expected to fall by 0.6 percent.

The European Union’s emissions are forecasted to decrease by 3.8 percent, whereas India, contributing 8 percent of global emissions, is projected to experience a 4.6 percent rise. Emissions from aviation and shipping sectors are also set to increase by 7.8 percent this year, though they remain below pre-pandemic levels.

Carbon Budget and Climate Warnings

According to Professor Pierre Friedlingstein from the University of Exeter, who led the study, the absence of a peak in fossil CO2 emissions further reduces the remaining carbon budget needed to keep warming below the Paris Agreement’s 1.5-degree Celsius target. At the current emission rate, a 50 percent probability exists of surpassing this threshold within the next six years. Meanwhile, Professor Corinne Le Quéré of the University of East Anglia acknowledged ongoing efforts in renewable energy deployment and reduced deforestation but stressed that substantial emissions reductions are still essential.

Urgency for Accelerated Action

The report emphasises that while some nations demonstrate progress in emissions reduction, these efforts have not been sufficient to reverse the overall global trend. Dr Glen Peters from the CICERO Center for International Climate Research noted that global climate action remains “a collective challenge,” with gradual declines in emissions in certain regions counterbalanced by increases elsewhere.

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