Alors que le vaisseau spatial Juno s’approche de près de la lune Europa, il devrait fournir une science précieuse – et des images remarquables – pour
” data-gt-translate-attributes=”[{” attribute=””>NASA’s upcoming Europa Clipper mission.
In less than three days, on Thursday, September 29, at 2:36 a.m. PDT (5:36 a.m. EDT), NASA’s Juno spacecraft will come within 222 miles (358 kilometers) of the surface of <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”[{” attribute=””>Jupiter’s ice-covered moon, Europa. During the close flyby, the solar-powered spacecraft is expected to obtain some of the highest-resolution images ever taken of portions of Europa’s surface. It will also collect valuable data on the moon’s interior, surface composition, and ionosphere, along with its interaction with Jupiter’s magnetosphere.
Future missions could benefit greatly from this detailed information. One such mission is Europa Clipper, which is set to launch in 2024 to study the icy moon. “Europa is such an intriguing Jovian moon, it is the focus of its own future NASA mission,” said Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio. “We’re happy to provide data that may help the Europa Clipper team with mission planning, as well as provide new scientific insights into this icy world.”
This image of Jupiter’s moon Europa was taken by the JunoCam imager aboard NASA’s Juno spacecraft on Oct. 16, 2021, from a distance of about 51,000 miles (82,000 kilometers). Credit: Image data: NASA/JPL-Caltech/SwRI/MSSS, Image processing: Andrea Luck CC BY
Europa is about 90% the size of Earth’s Moon, with an equatorial diameter of 1,940 miles (3,100 kilometers). Researchers believe a salty ocean lies below a miles-thick ice shell, sparking questions about potential conditions capable of supporting life underneath Europa’s surface.
Gravitational forces from the close flyby will modify Juno’s trajectory, reducing the time it takes to orbit Jupiter from 43 to 38 days. It will be the closest a NASA spacecraft has approached Europa in over 22 years, since Galileo came within 218 miles (351 kilometers) on January 3, 2000. Additionally, this flyby marks the second encounter with a Galilean moon during Juno’s extended mission. In June 2021, the mission explored Ganymede and plans include making close approaches of Io in 2023 and 2024.
Data collection on the spacecraft will begin an hour prior to closest approach, when the Juno is 51,820 miles (83,397 kilometers) from Europa.
“The relative velocity between spacecraft and moon will be 14.7 miles per second (23.6 kilometers per second), so we are screaming by pretty fast,” said John Bordi, Juno deputy mission manager at <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”[{” attribute=””>JPL. “All steps have to go like clockwork to successfully acquire our planned data, because soon after the flyby is complete, the spacecraft needs to be reoriented for our upcoming close approach of Jupiter, which happens only 7 ½ hours later.”
Juno’s extended mission includes flybys of the moons Ganymede, Europa, and Io. This graphic depicts the spacecraft’s orbits of Jupiter – labeled “PJ” for perijove, or point of closest approach to the planet – from its prime mission in gray to the 42 orbits of its extended mission in shades of blue and purple. Credit: NASA/JPL-Caltech/SwRI
Juno’s full suite of instruments and sensors will be activated for the Europa encounter. The spacecraft’s Jupiter Energetic-Particle Detector Instrument (JEDI) and its medium-gain (X-band) radio antenna will collect data on Europa’s ionosphere. Its Waves, Jovian Auroral Distributions Experiment (JADE), and Magnetometer (MAG) experiments will measure <span class="glossaryLink" aria-describedby="tt" data-cmtooltip="
” data-gt-translate-attributes=”[{” attribute=””>plasma in the moon’s wake as Juno explores Europa’s interaction with Jupiter’s magnetosphere.
MAG and Waves will also search for possible water plumes above Europa’s surface. “We have the right equipment to do the job, but to capture a plume will require a lot of luck,” said Bolton. “We have to be at the right place at just the right time, but if we are so fortunate, it’s a home run for sure.”
Inside and Out
Juno’s Microwave Radiometer (MWR) will gaze into Europa’s water-ice crust to obtain data on its composition and temperature. This is the first time that data like this will be gathered to study the moon’s icy shell.
Additionally, during the flyby the mission expects to take four visible-light images of the moon with JunoCam (a public-engagement camera). The Juno science team will compare them to images from previous missions, so they can find any changes in Europa’s surface features that might have occurred over the past two decades. These visible-light images will have an expected resolution of better than 0.6 miles (1 kilometer) per pixel.
Ce film a été généré à partir d’images collectées le 29 octobre 2018, lors du 16e périjove de Junon (le point auquel une orbite se rapproche le plus du centre de Jupiter). Les scientifiques citoyens Gerald Eichstädt ont créé ce film en utilisant les données de l’imageur JunoCam du vaisseau spatial. Crédit : image améliorée par Gerald Eichstädt basée sur des images fournies avec l’aimable autorisation de NASA/JPL-Caltech/SwRI/MSSS
Juno sera dans l’ombre d’Europe au plus près de la lune. Cependant, l’atmosphère de Jupiter reflétera suffisamment de lumière solaire pour que les imageurs à lumière visible de Juno collectent des données. La caméra vedette de la mission (appelée la Unité de référence stellaire) prendra une image haute résolution en noir et blanc de la surface d’Europe. Il a été conçu pour prendre des images de champs d’étoiles et rechercher des étoiles brillantes avec des positions connues pour aider Juno à se repérer. Pendant ce temps, le Jovian Infrared Auroral Mapper (JIRAM) tentera de capturer des images infrarouges de sa surface.
Les vues rapprochées de Juno et les données de son instrument MWR informeront la mission Europa Clipper, qui effectuera près de 50 survols de la lune glacée après son arrivée à Europa en 2030. Europa Clipper recueillera des données sur l’atmosphère, la surface et l’intérieur de la lune. Grâce à ces informations, les scientifiques espèrent mieux comprendre l’océan souterrain mondial d’Europe, l’épaisseur de sa croûte de glace et les éventuels panaches qui pourraient évacuer l’eau souterraine dans l’espace.
En savoir plus sur la mission
Le Jet Propulsion Laboratory (JPL) de la NASA, une division de Caltech à Pasadena, en Californie, gère la mission Juno pour le chercheur principal, Scott J. Bolton, du Southwest Research Institute de San Antonio. Juno fait partie du programme New Frontiers de la NASA, qui est géré au Marshall Space Flight Center de la NASA à Huntsville, en Alabama, pour la direction des missions scientifiques de l’agence à Washington. Lockheed Martin Space à Denver a construit et exploite le vaisseau spatial.
