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Radiation as a service: How the private sector can protect America’s space infrastructure

Photograph of the Starfish Prime high-altitude nuclear test explosion on July 9, 1962. Credit: U.S. Defense Threat Reduction Agency

This time last year, United States government officials released details indicating Russia may be developing a space-based nuclear weapon system to target Western satellites. While a flagrant violation of international norms, ambitions […]

The post Radiation as a service: How the private sector can protect America’s space infrastructure appeared first on SpaceNews.

Firefly Aerospace’s Blue Ghost mission achieves perfect lunar landing

The US firm Firefly Aerospace has claimed to be the first commercial company to achieve “a fully successful soft landing on the Moon”. Yesterday, the company’s Blue Ghost lunar lander touched down on the Moon’s surface in an “upright, stable configuration”. It will now operate for 14 days where it will drill into the lunar soil and image a total eclipse from the Moon where the Earth blocks the Sun.

Blue Ghost was launched on 15 January from NASA’s Kennedy Space Center in Florida via a SpaceX Falcon 9 rocket. Following a 45-day trip, the craft landed in Mare Crisium, touching down within its 100 m landing target next to a volcanic feature called Mons Latreille.

The mission is carrying 10 NASA instruments, which includes a lunar subsurface drill, sample collector, X-ray imager, and dust mitigation experiments. “With the hardest part behind us, Firefly looks forward to completing more than 14 days of surface operations, again raising the bar for commercial cislunar capabilities,” notes Shea Ferring, chief technology officer at Firefly Aerospace.

In February 2024, the Houston-based company Intuitive Machines became the first private firm to soft land on the Moon with its Odysseus mission. Yet it suffered a few hiccups prior to touch down and rather than landing vertically, did so at a 30 degree angle, which affected radio-transmission rates.

The Firefly mission is part of NASA’s Commercial Lunar Payload Services initiative, which contracts the private sector to develop missions with the aim of reducing costs.

Firefly’s Blue Ghost Mission 2 is expected to launch next year, where it will aim to land on the far side of the Moon. “With annual lunar missions, Firefly is paving the way for a lasting lunar presence that will help unlock access to the rest of the solar system for our nation, our partners, and the world,” notes Jason Kim, chief executive officer of Firefly Aerospace.

The post Firefly Aerospace’s Blue Ghost mission achieves perfect lunar landing appeared first on Physics World.

Ask me anything: Artur Ekert – ‘Nature doesn’t know that we divided all phenomena into physics, chemistry and biology’

What skills do you use every day in your job?

Apart from the usual set of mathematical skills ranging from probability theory and linear algebra to aspects of cryptography, the most valuable skill is the ability to think in a critical and dissecting way. Also, one mustn’t be afraid to go in different directions and connect dots. In my particular case, I was lucky enough that I knew the foundations of quantum physics and the problems that cryptographers were facing and I was able to connect the two. So I would say it’s important to have a good understanding of topics outside your narrow field of interest. Nature doesn’t know that we divided all phenomena into physics, chemistry and biology, but we still put ourselves in those silos and don’t communicate with each other.

Artur Ekert flying a small plane
Flying high and low “Physics – not just quantum mechanics, but all its aspects – deeply shapes my passion for aviation and scuba diving,” says Artur Ekert. “Experiencing and understanding the world above and below brings me great joy and often clarifies the fine line between adventure and recklessness.” (Courtesy: Artur Ekert)

What do you like best and least about your job?

Least is easy, all admin aspects of it. Best is meeting wonderful people. That means not only my senior colleagues – I was blessed with wonderful supervisors and mentors – but also the junior colleagues, students and postdocs that I work with. This job is a great excuse to meet interesting people.

What do you know today that you wish you’d known at the start of your career?

That it’s absolutely fine to follow your instincts and your interests without paying too much attention to practicalities. But of course that is a post-factum statement. Maybe you need to pay attention to certain practicalities to get to the comfortable position where you can make the statement I just expressed.

The post Ask me anything: Artur Ekert – ‘Nature doesn’t know that we divided all phenomena into physics, chemistry and biology’ appeared first on Physics World.

Harvard’s springtail-like jumping robot leaps into action

Globular springtails (Dicyrtomina minuta) are small bugs about five millimetres long that can be seen crawling through leaf litter and garden soil. While they do not have wings and cannot fly, they more than make up for it with their ability to hop relatively large heights and distances.

This jumping feat is thanks to a tail-like appendage on their abdomen called a furcula, which is folded in beneath their body, held under tension.

When released, it snaps against the ground in as little as 20 milliseconds, flipping the springtail up to 6 cm into the air and 10 cm horizontally.

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have now created a robot that mimics this jumping ability.

They modified a cockroach-inspired robot to include a latch-mediated spring actuator, in which potential energy is stored in an elastic element – essentially a robotic fork-like furcula.

Via computer simulations and experiments to control the length of the linkages in the furcula as well as the energy stored in them, the team found that the robot could jump some 1.4 m horizontally, or 23 times its body length – the longest of any existing robot relative to body length.

The work could help design robots that can traverse places that are hazardous to humans.

“Walking provides a precise and efficient locomotion mode but is limited in terms of obstacle traversal,” notes Harvard’s Robert Wood. “Jumping can get over obstacles but is less controlled. The combination of the two modes can be effective for navigating natural and unstructured environments.”

The post Harvard’s springtail-like jumping robot leaps into action appeared first on Physics World.

Optical sensors could improve the comfort of indoor temperatures

The internal temperature of a building is important – particularly in offices and work environments –for maximizing comfort and productivity. Managing the temperature is also essential for reducing the energy consumption of a building. In the US, buildings account for around 29% of total end-use energy consumption, with more than 40% of this energy dedicated to managing the internal temperature of a building via heating and cooling.

The human body is sensitive to both radiative and convective heat. The convective part revolves around humidity and air temperature, whereas radiative heat depends upon the surrounding surface temperatures inside the building. Understanding both thermal aspects is key for balancing energy consumption with occupant comfort. However, there are not many practical methods available for measuring the impact of radiative heat inside buildings. Researchers from the University of Minnesota Twin Cities have developed an optical sensor that could help solve this problem.

Limitation of thermostats for radiative heat

Room thermostats are used in almost every building today to regulate the internal temperature and improve the comfort levels for the occupants. However, modern thermostats only measure the local air temperature and don’t account for the effects of radiant heat exchange between surfaces and occupants, resulting in suboptimal comfort levels and inefficient energy use.

Finding a way to measure the mean radiant temperature in real time inside buildings could provide a more efficient way of heating the building – leading to more advanced and efficient thermostat controls. Currently, radiant temperature can be measured using either radiometers or black globe sensors. But radiometers are too expensive for commercial use and black globe sensors are slow, bulky and error strewn for many internal environments.

In search of a new approach, first author Fatih Evren (now at Pacific Northwest National Laboratory) and colleagues used low-resolution, low-cost infrared sensors to measure the longwave mean radiant temperature inside buildings. These sensors eliminate the pan/tilt mechanism (where sensors rotate periodically to measure the temperature at different points and an algorithm determines the surface temperature distribution) required by many other sensors used to measure radiative heat. The new optical sensor also requires 4.5 times less computation power than pan/tilt approaches with the same resolution.

Integrating optical sensors to improve room comfort

The researchers tested infrared thermal array sensors with 32 x 32 pixels in four real-world environments (three living spaces and an office) with different room sizes and layouts. They examined three sensor configurations: one sensor on each of the room’s four walls; two sensors; and a single-sensor setup. The sensors measured the mean radiant temperature for 290 h at internal temperatures of between 18 and 26.8 °C.

The optical sensors capture raw 2D thermal data containing temperature information for adjacent walls, floor and ceiling. To determine surface temperature distributions from these raw data, the researchers used projective homographic transformations – a transformation between two different geometric planes. The surfaces of the room were segmented into a homography matrix by marking the corners of the room. Applying the transformations to this matrix provides the surface distribution temperature on each of the surfaces. The surface temperatures can then be used to calculate the mean radiant temperature.

The team compared the temperatures measured by their sensors against ground truth measurements obtained via the net-radiometer method. The optical sensor was found to be repeatable and reliable for different room sizes, layouts and temperature sensing scenarios, with most approaches agreeing within ±0.5 °C of the ground truth measurement, and a maximum error (arising from a single-sensor configuration) of only ±0.96 °C. The optical sensors were also more accurate than the black globe sensor method, which tends to have higher errors due to under/overestimating solar effects.

The researchers conclude that the sensors are repeatable, scalable and predictable, and that they could be integrated into room thermostats to improve human comfort and energy efficiency – especially for controlling the radiant heating and cooling systems now commonly used in high-performance buildings. They also note that a future direction could be to integrate machine learning and other advanced algorithms to improve the calibration of the sensors.

This research was published in Nature Communications.

The post Optical sensors could improve the comfort of indoor temperatures appeared first on Physics World.

Black hole’s shadow changes from one year to the next

New statistical analyses of the supermassive black hole M87* may explain changes observed since it was first imaged. The findings, from the same Event Horizon Telescope (EHT) that produced the iconic first image of a black hole’s shadow, confirm that M87*’s rotational axis points away from Earth. The analyses also indicate that turbulence within the rotating envelope of gas that surrounds the black hole – the accretion disc – plays a role in changing its appearance.

The first image of M87*’s shadow was based on observations made in 2017, though the image itself was not released until 2019. It resembles a fiery doughnut, with the shadow appearing as a dark region around three times the diameter of the black hole’s event horizon (the point beyond which even light cannot escape its gravitational pull) and the accretion disc forming a bright ring around it.

Because the shadow is caused by the gravitational bending and capture of light at the event horizon, its size and shape can be used to infer the black hole’s mass. The larger the shadow, the higher the mass. In 2019, the EHT team calculated that M87* has a mass of about 6.5 billion times that of our Sun, in line with previous theoretical predictions. Team members also determined that the radius of the event horizon is 3.8 micro-arcseconds; that the black hole is rotating in a clockwise direction; and that its spin points away from us.

Hot and violent region

The latest analysis focuses less on the shadow and more on the bright ring outside it. As matter accelerates, it produces huge amounts of light. In the vicinity of the black hole, this acceleration occurs as matter is sucked into the black hole, but it also arises when matter is blasted out in jets. The way these jets form is still not fully understood, but some astrophysicists think magnetic fields could be responsible. Indeed, in 2021, when researchers working on the EHT analysed the polarization of light emitted from the bright region, they concluded that only the presence of a strongly magnetized gas could explain their observations.

The team has now combined an analysis of ETH observations made in 2018 with a re-analysis of the 2017 results using a Bayesian approach. This statistical technique, applied for the first time in this context, treats the two sets of observations as independent experiments. This is possible because the event horizon of M87* is about a light-day across, so the accretion disc should present a new version of itself every few days, explains team member Avery Broderick from the Perimeter Institute and the University of Waterloo, both in Canada. In more technical language, the gap between observations exceeds the correlation timescale of the turbulent environment surrounding the black hole.

New result reinforces previous interpretations

The part of the ring that appears brightest to us stems from the relativistic movement of material in a clockwise direction as seen from Earth. In the original 2017 observations, this bright region was further “south” on the image than the EHT team expected. However, when members of the team compared these observations with those from 2018, they found that the region reverted to its mean position. This result corroborated computer simulations of the general relativistic magnetohydrodynamics of the turbulent environment surrounding the black hole.

Even in the 2018 observations, though, the ring remains brightest at the bottom of the image. According to team member Bidisha Bandyopadhyay, a postdoctoral researcher at the Universidad de Concepción in Chile, this finding provides substantial information about the black hole’s spin and reinforces the EHT team’s previous interpretation of its orientation: the black hole’s rotational axis is pointing away from Earth. The analyses also reveal that the turbulence within the accretion disc can help explain the differences observed in the bright region from one year to the next.

Very long baseline interferometry

To observe M87* in detail, the EHT team needed an instrument with an angular resolution comparable to the black hole’s event horizon, which is around tens of micro-arcseconds across. Achieving this resolution with an ordinary telescope would require a dish the size of the Earth, which is clearly not possible. Instead, the EHT uses very long baseline interferometry, which involves detecting radio signals from an astronomical source using a network of individual radio telescopes and telescopic arrays spread across the globe.

The facilities contributing to this work were the Atacama Large Millimeter Array (ALMA) and the Atacama Pathfinder Experiment, both in Chile; the South Pole Telescope (SPT) in Antarctica; the IRAM 30-metre telescope and NOEMA Observatory in Spain; the James Clerk Maxwell Telescope (JCMT) and the Submillimeter Array (SMA) on Mauna Kea, Hawai’I, US; the Large Millimeter Telescope (LMT) in Mexico; the Kitt Peak Telescope in Arizona, US; and the Greenland Telescope (GLT). The distance between these telescopes – the baseline – ranges from 160 m to 10 700 km. Data were correlated at the Max-Planck-Institut für Radioastronomie (MPIfR) in Germany and the MIT Haystack Observatory in the US.

“This work demonstrates the power of multi-epoch analysis at horizon scale, providing a new statistical approach to studying the dynamical behaviour of black hole systems,” says EHT team member Hung-Yi Pu from National Taiwan Normal University. “The methodology we employed opens the door to deeper investigations of black hole accretion and variability, offering a more systematic way to characterize their physical properties over time.”

Looking ahead, the ETH astronomers plan to continue analysing observations made in 2021 and 2022. With these results, they aim to place even tighter constraints on models of black hole accretion environments. “Extending multi-epoch analysis to the polarization properties of M87* will also provide deeper insights into the astrophysics of strong gravity and magnetized plasma near the event horizon,” EHT Management team member Rocco Lico, tells Physics World.

The analyses are detailed in Astronomy and Astrophysics.

The post Black hole’s shadow changes from one year to the next appeared first on Physics World.

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