Un astronaute américain a partagé une photo prise depuis la Station spatiale internationale (ISS), sur laquelle on distingue des traînées lumineuses témoignant de la présence des satellites Starlink. Un cliché impressionnant montrant l'omniprésence de ces engins, alors même que SpaceX souhaite en déployer bien plus.

"Saturn and some of its 274 moons are pretty weird," writes Smithsonian magazine: [Saturn moon] Titan has strangely few impact craters, Hyperion is tiny and misshapen, and Iapetus has a tilted orbit. What's more, planets tend to wobble along their rotational axes as they spin, like an off-kilter spinning top in the moments before it topples over. Formally called precession, scientists have long thought that Saturn's wobble rate should match Neptune's because they're probably gravitationally linked. However, data from NASA's Cassini spacecraft, which studied the ringed planet from 2004 to 2017, revealed that Saturn's precession rate is slightly speedier than Neptune's. In 2022, some researchers suggested that the destruction of a hypothetical moon, called Chrysalis, around 160 million years ago may have knocked Saturn out of sync and formed the pieces that became the planet's rings. But this work implied that Chrysalis probably would've crashed into Titan, posing a major problem, study co-author Matija Äuk, an astronomer at the SETI Institute, tells New Scientist's Leah Crane. In that case, Chrysalis' debris couldn't have become the rings, he says. So, Äuk and his colleagues used computer simulations to investigate what would happen if Chrysalis did smack into Titan. If that happened around 400 million years ago, they found, the crash would've wiped away Titan's craters and made its orbit more elliptical. The altered path may have slowly pushed the trajectories of other moons, which then scraped against one another and left chunks of ice and rock that now make up Saturn's rings. The timing seems to align with the rings' estimated age of roughly 100 million years. Additionally, one piece of kicked-up debris may have formed the weird moon Hyperion, which may have subsequently tilted the orbit of the moon Iapetus, according to the analysis. The scenario could also resolve Saturn's unexpected wobble, which is currently "a little bit too fast," Äuk tells Jacopo Prisco at CNN. The study has been accepted for publication in the Planetary Science Journal, and is already available on the preprint server arXiv.

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Deux éclipses de Lune ont eu lieu en 2025, elles étaient toutes deux totales. La prochaine éclipse lunaire (la première éclipse de Lune de 2026) est imminente. Quand aura-t-elle lieu ? Que pourra-t-on voir ? La France pourra-t-elle en profiter ?

Les trois sujets de l'actualité qui ont le plus attiré l'attention cette semaine sur Numerama. Et aussi, une vidéo sur la stratégie de Samsung avec les Galaxy S27.

Alors que les plans du programme Artémis ont été bouleversés par la Nasa, comment vont s'en sortir les grandes entreprises qui participent au projet ? Avec cette nouvelle version, elles vont devoir faire leurs preuves.

A start-up called Reflect Orbital "proposes to use large, mirrored satellites to redirect sunlight to Earth at night," reports the Washington Post, "with plans to bathe solar farms, industrial sites and even entire cities in light that could, if desired, reach the intensity of daylight...." Slashdot noted their idea in 2022 — but Reflect Orbital now expects to launch its first satellite in April, according to the article. "But its grand vision is largely 'aspirational,' as its young founder, Ben Nowack, told me..." Reflect Orbital's Nowack describes a scene right out of sci-fi: An extremely bright star appears on the northern horizon and makes its way across the sky, illuminating a 5-kilometer circle on Earth, then setting on the southern horizon about five minutes later, just as another such "star" appears in the north. To make the night even brighter, a customer could make 10 "stars" appear at once in the north by ordering them on an app. Two such artificial stars are in development in Reflect Orbital's factory. Nowack showed them to me on a Zoom call. The first to launch is 50 feet across, but he plans later to build them three times that size. If all goes according to plan, he'll have 50,000 of them circling the Earth in 2035 at an altitude of around 400 miles. Nowack plans to start selling the service "in mostly developing nations or places that don't have streetlights yet." Eventually, he thinks, he can illuminate major cities, turn solar fields and farms into round-the-clock operations for any business or municipality that pays for it. He likened his technology to the invention of crop irrigation thousands of years ago. "I see this as much the same thing," he said, arguing that people would no longer have to "wait for the sun to shine." The article adds that Elon Musk's SpaceX "wants to launch as many as a million satellites to serve as orbiting data centers — 70 times the number of satellites now in orbit." (America's satellite-regulation Federal Communications Commission grants a "categorical exclusion" from environmental review to satellites on the grounds that their operations "normally do not have significant effects on the human environment.") The public comment periods for the two proposals close on March 6 and March 9.

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A start-up called Reflect Orbital "proposes to use large, mirrored satellites to redirect sunlight to Earth at night," reports the Washington Post, "with plans to bathe solar farms, industrial sites and even entire cities in light that could, if desired, reach the intensity of daylight...." Slashdot noted their idea in 2022 — but Reflect Orbital now expects to launch its first satellite in April, according to the article. "But its grand vision is largely 'aspirational,' as its young founder, Ben Nowack, told me..." Reflect Orbital's Nowack describes a scene right out of sci-fi: An extremely bright star appears on the northern horizon and makes its way across the sky, illuminating a 5-kilometer circle on Earth, then setting on the southern horizon about five minutes later, just as another such "star" appears in the north. To make the night even brighter, a customer could make 10 "stars" appear at once in the north by ordering them on an app. Two such artificial stars are in development in Reflect Orbital's factory. Nowack showed them to me on a Zoom call. The first to launch is 50 feet across, but he plans later to build them three times that size. If all goes according to plan, he'll have 50,000 of them circling the Earth in 2035 at an altitude of around 400 miles. Nowack plans to start selling the service "in mostly developing nations or places that don't have streetlights yet." Eventually, he thinks, he can illuminate major cities, turn solar fields and farms into round-the-clock operations for any business or municipality that pays for it. He likened his technology to the invention of crop irrigation thousands of years ago. "I see this as much the same thing," he said, arguing that people would no longer have to "wait for the sun to shine." The article adds that Elon Musk's SpaceX "wants to launch as many as a million satellites to serve as orbiting data centers — 70 times the number of satellites now in orbit." (America's satellite-regulation Federal Communications Commission grants a "categorical exclusion" from environmental review to satellites on the grounds that their operations "normally do not have significant effects on the human environment.") The public comment periods for the two proposals close on March 6 and March 9.

Read more of this story at Slashdot.

Le septième vol de la fusée Alpha, opérée par l'entreprise américaine Firefly Aerospace, doit décoller le dimanche 1er mars depuis la Californie. Après la perte d'un étage lors d'un test au sol l'an dernier, le lanceur est de retour sur le pas de tir. Le décollage est à suivre en direct.

On February 24th, the Vera C. Rubin Observatory activated its automated alert system, sending out roughly 800,000 real-time notifications flagging asteroids, supernovae, flaring black holes and "other transient celestial events," reports Scientific American. And this is only the beginning -- that number is projected to climb into the millions as it continues scanning the ever-changing sky. From the report: The astronomical observatory equipped with world's largest camera hit a key milestone on February 24, when a complex data-processing system pushed hundreds of thousands of alerts out to scientists eager to pore over its most exciting sightings. The Vera C. Rubin Observatory began operations last year, capturing stunning, panoramic time-lapse views of the cosmos with ease. Rubin's first images, based on just 10 hours of observations, let space fans zoom seemingly forever into an overwhelmingly starry sky. But watchful astronomers were always awaiting the next step: the system that would automatically alert them to the most promising activity in the overhead sky amid the 1,000 or so enormous images that Rubin's telescope captures every night. "We can detect everything that changes, moves and appears," said Yusra AlSayyad, an astronomer at Princeton University and Rubin's deputy associate director for data management, to Scientific American last summer. "It's way too much for one person to manually sift through and filter and monitor themselves." So even as they were designing and building the Rubin Observatory itself, scientists were also designing an alert system to help astronomers navigate the flood of data. As soon as the telescope began observations, the team started constructing a static reference image of the entire sky in impeccable detail. Now the data processing systems that support the observatory are starting to automatically compare every new Rubin image to the corresponding section of that background template. The systems identify all of the differences, each of which is individually flagged. The algorithms can also distinguish between a potential supernova and a possible newfound asteroid, for example. Alerting the scientific community is the final, crucial step. Astronomers -- as well as members of the public -- can sign up for notifications based on the type of sighting they're interested in and the brightness of the observation in question. And now that the alerts system has gone live, users receive a tiny, fuzzy image with some astronomical metadata of each observation that fits their criteria -- all just a couple of minutes after Rubin captures the original image.

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C'est un séisme pour le programme spatial habité américain. Prévu avec la mission Artémis III, attendu pour 2028, le retour des USA sur la Lune n'aura pas lieu dans ces conditions. La mission Artémis III est remaniée et servira à autre chose.

Développé par l’entreprise américaine Rocket Lab, le projet HASTE doit décoller dans la soirée du 27 février 2026 pour un test hypersonique. Il est question ici de placer un véhicule expérimental sur une trajectoire suborbitale et une vitesse vertigineuse. Le décollage est à suivre en direct.

Alors que la mission Artémis II espère décoller pour la Lune d'ici quelques semaines, l'ambiance n'est pas au beau fixe pour la suite du programme. Artémis III, dont l'objectif est de déposer des astronautes sur le satellite, est dans le viseur du comité de sécurité de la NASA, qui craint des failles majeures pour la mission.

Les tests du vaisseau Starship sont sur le point de démarrer, en vue d'un vol d'essai de la fusée courant mars 2026. Elon Musk considère que le nouveau design de l'étage supérieur va permettre au lanceur d'être entièrement réutilisable.

Une première mondiale. L'ESA a franchi une étape majeure dans la connectivité mondiale sécurisée : la première liaison laser au monde à un gigabit par seconde entre un avion et un satellite géostationnaire.

On en sait un peu plus sur les soucis qui ont causé une évacuation d'urgence à bord de la Station spatiale internationale. Mike Fincke avait besoin de matériel d'imagerie qu'on ne trouve que sur Terre, et les expériences en cours de Sophie Adenot portent justement sur ces technologies.

Le projet HASTE doit décoller dans la soirée du 25 février 2026 pour un test hypersonique. Développée par l’entreprise américaine Rocket Lab, cette fusée sert à placer des véhicules expérimentaux sur des trajectoires suborbitales à des vitesses vertigineuses. Le décollage est à suivre en direct.

Admirer une éclipse solaire, cela s'anticipe. Quand est prévue la prochaine éclipse de Soleil ? Il faut patienter : une éclipse totale est annoncée en août 2026. Voici où il faut se trouver à la surface de la Terre pour la contempler.

Le projet HASTE doit décoller dans la soirée du 25 février 2026 pour un test hypersonique. Développée par l’entreprise américaine Rocket Lab, cette fusée sert à placer des véhicules expérimentaux sur des trajectoires suborbitales à des vitesses vertigineuses. Le décollage est à suivre en direct.

L’Agence spatiale européenne (ESA) et ArianeGroup viennent de boucler avec succès la première campagne d’essais de Greta, un moteur-fusée d'un tout nouveau genre. Imprimé en 3D, il utilise d'autres composés pour sa propulsion.

Le projet HASTE doit décoller dans la soirée du 25 février 2026 pour un test hypersonique. Développée par l'entreprise américaine Rocket Lab, cette fusée réutilisable doit servir à placer des satellites sur des trajectoires suborbitales, à un rythme soutenu.