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Thomas Appéré

@thomasappere.bsky.social

Enseignant agrégé de Physique-Chimie-NSI | PhD Docteur en Planétologie | NAEC pour @astro4edu.bsky.social | J'assemble les photos venues d'autres mondes 🚀🛰📷 | Collectionneur et concepteur de LEGO spatiaux

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Aurélien Genin@astroaure.eurosky.social · yesterday

☄️ A la veille de l'impact d'un second étage de Falcon 9 sur la Lune, un papier étudie ce débris pour en mesurer sa période de rotation (~7min) et son spectre (très différent de celui d'un astéroïde). Il estime à ~40m de diamètre le cratère qui sera créé par l'impact arxiv.org/pdf/2608.00360

Position prédite de l'impact sur la LuneEvolution de la période de rotation du débris. Celle-ci augmente depuis Mars (ralentissement de la rotation) après une chute inattendue entre janvier et févrierSpectre (visible et infrarouge proche) du débris comparé aux spectres moyens d'astéroïdes S et D
Aurélien Genin@astroaure.eurosky.social · 2w ago

☄️ Le 5 août à 8h34m33s CEST, un second étage de Falcon 9 va percuter la Lune ! L'impact aura lieu vers le cratère Einstein, sur le limbe lunaire mais du côté visible depuis la Terre. Malheureusement, il sera du côté éclairé et il fera jour en Europe... 1/2 arxiv.org/pdf/2607.14625

Localisation prévue de l'impact
Don Davis@ddavisspaceart.bsky.social · 2d ago

51 years ago I painted a trio of Viking related works for NASA HQ including the widely reproduced one of the landing on Mars. I have reimagined the Landing portrayal in updated form using digital methods of visualization and painting. I chose the same angle but with reality replacing anticipation.

This oil painting portrays the Viking 1 landing on Mars, which appeared in countless publications. The story of this work is relayed in an earlier post and is shown here for comparison with the new portrayal of this very view, showing the event as it would have appeared. This 1975 anticipatory painting was done with oils on a gesso smoothed 16 X 20 canvas panel, using traditional art methods including a tracing paper guide featured earlier. This work shows in retrospect my ideal of the 'spirit of space art', showing something of a summary of what is known of the subject while conveying what it is about the subject's known or theorized attributes that I find visually compelling. The new digital painting updates that visual impression with one based on our current knowledge. The new digital work was also done at the same size as this one was for possible printing purposes, 16 by 20 inches at 300 DPI. #Sciart In 1976 the pair of Viking spacecraft orbiter/lander combos were sent to Mars. Before Viking, Mars was still largely a place of our imaginations, an unknown that we wrote stories about then studied from Earth and space. The dominance of cratered terrain on the portions of Mars photographed by Mariners 4, 6 and 7 gave an initially Lunar impression of that world, which changed during the development of the Viking lander after Mariner 9 revealed the planet. The first landing was aimed for a flat flood plain, judged as a decent place to search for life. The landing date was July 4, however the intended site appeared too rough for comfort in the high quality orbiter photos, causing the landing to wisely be delayed. A smoother site further 'down stream' was found using photo and radar data. The landing proceeded quite nominally, a magnificent achievement that apparently accounted for what it had to and made it the first time. The first photo from the surface was a look at a footpad to see how solid the 'footing' appeared. Then a moderate resolution panorama of the surroundings was obtained, first showing the rocks, hills, dunes-and bright sky. The latter was my biggest surprise as a space artist. The adjustments to the color balance of the later photos were gradually narrowed down. The ubiquitous dust is planet wide, suspended in the air and coloring the sky a luminous tan ochre. This digital painting shows the view a meter above the surface seeing the lander briefly kicking up dust less than a second before touchdown with the footpads 1.4 meters high. The landing rockets were designed with many nozzles to disturb the surroundings as little as possible. The nearby disturbed dust resembles in color that of the sky. We are 6 meters away from the center of the lander. field of view is 60 degrees, we are looking Northwest with the Sun and Earth off the frame to the left. This is a digital art update of the pre mission oil painting I did for NASA HQ 1n 1975. #Sciart
Helen Czerski@helenczerski.bsky.social · 3d ago

A lovely little bit of physics that you might have spotted if you ever play with a slinky. We should all play more, because we should all embrace our curiosity. And finding out how the physical world works is fun!

Thomas Appéré@thomasappere.bsky.social · last wk.

Dans moins de 3 mois, j'emmènerai 29 élèves au Japon pour un voyage alliant culture, apprentissage de la langue et découverte du spatial japonais 🇯🇵 L'objectif : assister au décollage de la mission MMX à destination de Mars 🚀 Pour aider les familles à financer ce voyage share.google/UPkCZepvs4XN... 🙏

De Vannes aux portes de Mars : un voyage scolaire exceptionnel au Japon

Financement participatif organisé par OGEC ST PAUL-ST GEORGES 56 - Voyage scolaire de 29 lycéens au Japon en oct. 2026 pour découvrir la culture nippone et assister au décollage d’une mission martienn...

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Rêves d'espace@revesdespace.bsky.social · last wk.

📡 L'incendie près de l'antenne de communication du Deep Space Network de la NASA près de Madrid a entraîné des dégâts limités (routes et végétation) et aucune structure critique n'est touchée. Les communications spatiales sont maintenues via Goldstone et Canberra, selon la NASA

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Rêves d'espace@revesdespace.bsky.social · 2w ago

🛰️ Bonne soirée à tous avec ces photos sur fond de Terre du bon déploiement de la grande antenne du satellite géostationnaire #Viasat-3 F3 qui avait décollé le 29 avril dernier sur Falcon Heavy. L'antenne fait 22 m de diamètre avec un bras de déploiement d’environ 25 m de long.

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Emily J@emexastris.bsky.social · 2w ago

It also will cripple all of our robotic missions beyond Earth’s orbit. The DSN was already oversubscribed - time and bandwidth books out months in advance - and there simply is no substitute for it. The Spain station is 1/3 of the DSN.

UIS Observatory@uisobservatory.bsky.social · 2w ago

I’d like to make it clear for all the people following me what the sheer gravity of the news is. Without this facility we can’t ensure constant communication with spacecraft beyond Earth orbit. If this facility is off-line, the Artemis program cannot send a crew to the Moon.

Rêves d'espace@revesdespace.bsky.social · 2w ago

🌍🌑 La Terre (à gauche) et la Lune (à droite) par l'une des 2 sondes ESCAPADE de la NASA, en lumière visible et en infrarouge, alors qu'elle se situait à 584 600 km de la Terre, en route pour Mars. 📷 NASA/UCB-SSL/NAU-Radiant/Lucint

L'image montre la lumière visible réfléchie par le Soleil sur la Terre et la LuneImage infrarouge montrant l'énergie émise par la Terre et la Lune. Des anneaux blancs ont été ajoutés sur l'image thermique pour indiquer la taille réelle des 2 corps célestes
Don Davis@ddavisspaceart.bsky.social · 2w ago

A few more Viking 1 Mars surface images. Vikings 1 & 2 yielded a variety and duration of observations that gave the first 'Ground Truth' about this intriguing neighbor world's surface and atmosphere. It's early digital camera design worked well with the brightness range of the surface details.

Late in the afternoon of Martian day 651, on May 20, 1978, the lengthening shadows of the larger rocks were photographed by Viking 1. A few tries were done at obtaining color photos with the higher resolution settings of the camera. A raised rim of a 500 meter wide impact crater about 2.5 km away can be seen at the horizon, looking much like Arizona's Meteor Crater as one approaches it. The image processing attempts to show something of the actual brightness and colors of the scene and sky. The Martian surface is darker than the impression one would have from most of the photos, which are understandably optimized in exposure to bring out surface details. Three tries at using the color and grayscale chart to recover the colors of the scenery. The grayscale ended up being pivotal in obtaining some sense of color balance. I tried incorporating the IR data by using it to modify the blue to try to cancel out the leak of Infra Red through the blue filter, but I was unable to obtain coherent results. So I gave up on making the blue chip blue, which notoriously photographed as purple with that camera anyway, and relied on the gray scale to establish some color anchor point. I am not an engineer trying to account for all the camera quirks, I approach this like I would when photographing my artwork. I have a gray scale and color chart in the frame for reference and adjustments. Basically, using the 'curves' tool in Photoshop to establish a gray point is the key. The initial result is usually ludicrously garish so I then reduce the saturation to best show the red and green chips as as well as the overall scenery, in this case seen 'over the shoulder' of the lander. Of course there is judgement involved in seeking to show what I think the camera is seeing. An early space image processing I did over 20 years ago, of the celebrated Viking 1 Sunset picture. I took the grayscale files and hand blended the rather coarse steps in the brightness contours recorded by that limited grayscale camera system in the twilight. This, along with retouching of brightness variations in the dark foreground spacecraft parts etc. as they were scanned, was done to show this amazing image to its best advantage. I remember being captivated when I first saw a contrasty initial version of this image in a Viking newsletter. Although Viking is a rewarding data set to explore, the monumental and sterling work of Olivier Goursac makes me think twice before thinking I have any new contribution to what has been done. I wish to acknowledge the useful and enduring Viking image browser set up by Holger Isenberg, with all the lander images available to download and play with.
Don Davis@ddavisspaceart.bsky.social · 2w ago

After the 1st context panoramas, the next anticipated image was the first color photo. This arrived and was printed initially too blue, then the next adjusted image came out too reddish. Later work quantified the surface and sky colors in results consistent with the observations of later missions.

The first color photograph from the surface of Mars arrived about 24 hours after the landing as grayscale 'scans' of the landscape with the red, green and blue filters. The 3 component images came in with the red brightest and the blue the dimmest, which when initially combined appeared so red that they were skeptical of the colors. The initial hurried release of that image occurred 8 hours after the data was received. The intent was to make the sky a neutral gray, but during the photograph's mass printing from a master negative the color balance of that first batch somehow drifted toward the blue, giving an initial 'Earth like' impression to the scene and sky. This initial release (upper left) appeared on TV news and the covers and color spreads of many magazines. Later (lower left) A slightly 'over corrected' version emphasizing the reddish ambience was released. Later work with the digital files shows an approximation of the scene as if lit by noon sunlight with minimal ambient contribution (upper right) and an approximation of the scene with the ambient lighting from the bright butterscotch colored sky factored in (lower right). This is the closest to what eventual human explorers could see and photograph there with their own cameras. The initial prints were distributed, I was fortunate to get one which I still have, and a large color print was shown on an easel, which people were gathered at transfixed, staring at this first 'window' into Mars. High end color CRT monitors with that image were scattered across the press area. They were adjusted better than the prints, using separate RGB adjustments in the back. I got close to one monitor and someone warned me not to touch it, that someone had just gotten yelled at by Jim Martin for playing with the colors! I later learned more about this story, which contributed to a conspiracy narrative which the early internet conveyed that NASA was trying to hide the true Earthlike appearance of Mars.
Don Davis@ddavisspaceart.bsky.social · 2w ago

Mars as imagined just before the landing. This painting, one of a trio done for NASA HQ, ended up being used for the JPL landing press badge. What a thing that was to see when I arrived and signed in!

This painting was, as is much of Astronomical/Space art, a summary of what was known of the subject as well as what about it I found visually appealing. Low gravel bar ridges and dunes dominate the scene, based on the original landing site chosen in Chryse Planita. A suggestion of sedimentary layering is shown in the lower right foreground knoll. The sky was portrayed as blue, making the assumption that it would be like a Stratospheric altitude Earthly sky. Earth is the daylight star just to the left of the lander. The aeroshell on it's parachute from which the lander was dropped drifts downwind in the distance to the left. The reference materials I had available then were a step or two short of how the lander actually appeared, with the biggest difference being the lack of the rubbery fabric covers over the propellent tanks. #SciartThe press badge issued to media at the JPL press area. The last appearance of the Mars of old based on imagination and educated guesswork. This badge is now among my treasured trophies.
Rêves d'espace@revesdespace.bsky.social · 2w ago

🔴 Il y a 50 ans, l'atterrisseur Viking 1 posait ses pieds sur le sol de #Mars à Chryse Planitia le 20 juillet 1976. Les premiers échantillons de sol martien étaient prélevés pour tenter de répondre à la question : Mars fut-elle habitable ?

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Rêves d'espace@revesdespace.bsky.social · 4w ago

👨🏻‍🚀🪂 L'ISRO a réalisé hier un 5e test de déploiement des parachutes pour la capsule habitable #Gaganyaan. Un simulateur de masse équipé du système de décélération, qui comprend 10 parachutes de 4 types, a été largué depuis un avion IAF IL-76 à une altitude de 2,5 km.

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Rêves d'espace@revesdespace.bsky.social · 4w ago

🛰️ La sonde New Horizons de la NASA, qui a survolé Pluton en 2015 et explore actuellement la ceinture de Kuiper, s'est réveillée après une hibernation de 321 jours. Elle se trouve désormais à 9,5 milliards de km de la Terre. Le signal vers la sonde met 8 heures et 52 minutes

Le centre de contrôle de la sonde New Horizons (crédit NASA/Johns Hopkins APL/SwRI/Justin Gladden)
Astropierre@astropierre.com · 4w ago

Le télescope spatial James Webb, à l'occasion de son quatrième anniversaire scientifique, a sorti de nouvelles images à haute résolution de la célèbre galaxie Centaurus A, dévoilant une mosaïque dense d'étoiles et une galaxie active en perpétuelle évolution. 🔭 esawebb.org/news/weic2615/

Comparaison en trois volets de différentes vues de la galaxie Centaurus A. Le panneau supérieur gauche montre une image en lumière visible de la galaxie dans son ensemble, sur fond de ciel noir parsemé d'étoiles blanches, bleues et jaunes. Centaurus A présente une bande de poussière sombre traversant un centre brillant. Un encadré blanc délimite la région observée par Webb. Le panneau supérieur droit offre un gros plan sur cette zone, combinant des observations de Webb dans le proche et le moyen infrarouge. La galaxie est orientée en diagonale ; elle possède un noyau blanc éclatant entouré d'une lueur orangée. Une large bande de poussière aux teintes orangé doré forme un parallélogramme au centre, tandis qu'une multitude de minuscules étoiles confèrent à l'image une texture finement tachetée. Un contour en pointillés indique la zone plus restreinte présentée en bas, correspondant à la vue de Webb dans l'infrarouge moyen. La galaxie s'étend horizontalement sur un fond noir parsemé d'étoiles violettes et blanches, et le parallélogramme brille d'un éclat blanc. Des nuages ​​vaporeux et des structures roses en forme de boucles entourent le centre.
E. Bottlaender@bottlaeric.bsky.social · last mo.

Voici Kamo'oalewa, minuscule petit astéroïde et quasi-satellite terrestre (il partage notre orbite mais ne fait pas le tour de la Terre), photographié par la mission chinoise Tianwen-2. C'est l'un, sinon le plus petit corps célèste jamais approché dans le Système solaire : 18m de diamètre !

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