A photograph of Jupiter's Moon Europa. Image Credit: NASA/JPL/DLR.

NASA’s Juno Spacecraft to Make Close Approach to Jupiter’s Icy Moon Europa

As Juno approaches Jupiter's ice-covered moon, Europa, the spacecraft will come within 222 miles (358 kilometers) of its surface at 2:36 am PDT (5:36 am EDT) on September 20.

Scientists are increasingly curious whether life developed elsewhere in the solar system. There are a couple of interesting places where we can look at. Mars, for example, is a promising planet where life likely existed in the very distant past. Dozens of robotic missions are exploring the red planet in hopes of finding out whether this was the case. But in addition to Mars, there are other places where we can look for life. One of those places is a Jovian moon called Europa.

On September 29, NASA’s Juno spacecraft will fly by Europa to gather information for its future Europa Clipper mission. This distant moon is believed to have an ocean underneath its icy surface, and some scientists think it is even hospitable. For the first time, Juno will pass within 358 kilometers of the surface of Europa at 10:36 UTC, a milestone in its exploration of Jupiter and its moons. It will also collect valuable data on the interior, the composition of the Moon’s surface, and the ionosphere of Europa. The spacecraft will take some of the highest resolution images ever taken of parts of Europa’s surface.

NASA reports that such information may prove useful to future missions, which include its Europa Clipper, scheduled to launch in 2024 and study Europa’s icy surface. Europa is about 90% the size of Earth’s Moon. Below Europa’s miles-thick ice shell may lie a salty ocean, raising questions about whether life could exist there. In addition to modifying Juno’s trajectory, the flyby will shorten the time it takes for Juno to orbit Jupiter from 43 to 38 days after the close flyby.

This will be the closest approach by a NASA spacecraft to Europa since Galileo approached on Jan. 3, 2000, at 218 miles (351 kilometers). Juno’s extended mission will mark the second encounter with a Galilean moon. In June 2021, the mission explored Ganymede, while in 2023 and 2024, it plans to make close approaches to Io. The collection of data will begin an hour before the closest approach when the spacecraft is 51,820 miles away from Europa.

John Bordi, Juno’s deputy mission manager at JPL, said that Juno would pass the moon at a velocity of 14.7 miles per second (23.6 kilometers per second). During the planned flyby, all the steps must be executed perfectly to ensure our data collection is successful since the spacecraft must be reoriented shortly afterward for our upcoming close encounter with Jupiter, which happens only seven-and-a-half hours later, Bordi explained.

Europa encounter will activate the entire suite of instruments and sensors onboard the spacecraft. The Jupiter Energetic-Particle Detector Instrument (JEDI) on Juno will collect data on Europa’s ionosphere using its medium-gain (X-band) radio antenna. As Juno explores Europa’s interaction with Jupiter’s magnetosphere, it will use the Waves, Jovian Auroral Distributions Experiment (JADE), and Magnetometer (MAG) experiments.

Additionally, Waves and MAG will scan for plumes of water above Europa’s surface. Despite having the right equipment, Bolton said, capturing a plume would take 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.” Europa’s water-ice crust will be studied by Juno’s Microwave Radiometer (MWR), which will provide information about its composition and temperature. Until now, there has never been such a collection of data on the moon’s icy shell.

Furthermore, as part of the flyby, JunoCam (a public-engagement camera) will take four visible-light images of the moon. In order to determine what changes have occurred to Europa’s surface features over the past two decades, Juno’s science team will compare the images with those from previous missions. Image resolution is expected to be better than 0.6 miles (1 kilometer) per pixel for these visible-light images.

Despite being in Europa’s shadow, Juno’s visible-light imagers will be able to collect data because Jupiter’s atmosphere reflects enough sunlight. The Stellar Reference Unit on Juno is designed to photograph star fields and locate bright stars to help the spacecraft get its bearings on Europa. It will take a high-resolution black-and-white image of the surface of Europa. NASA has also revealed that JIRAM (Jovian Infrared Auroral Mapper) will collect infrared images of its surface in the meantime.

In 2030, the Europa Clipper mission will perform nearly 50 flybys of Europa using Juno’s close-up views and data from the MWR instrument. By gathering data on Europa’s atmosphere, surface, and interior, Europa Clipper will assist scientists in understanding Europa’s global subsurface ocean, the thickness of its ice crust, and the possible formation of subsurface plumes.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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