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First closeup picture of Europa in 20 years reveals rugged terrain and degraded crater
We're basically space paparazzi.
In 1999, the 311 inhabitants of Moonbase Alpha embarked upon an unintentional trip through the cosmos. See, humanity had been storing its nuclear waste on the far side of the Moon when an unknown source of radiation caused it to explode. The resulting burst of energy knocked the Moon out of orbit and sent it hurtling through space. These are the inciting incidents of Space: 1999 (now streaming on Peacock!), a British science fiction series which aired from 1975 to 1977.
Over the course of two seasons, the residents of Moonbase Alpha exited the solar system, travelled through black holes, and continued their journey to the far reaches of space. In the course of their adventures, many an alien species was treated to a visit from Earth’s only Moon. Surely, that would be a terrifying but scientifically exciting experience, and one which we are unfortunately not privy to. In real life, if want to learn about places beyond our own little planet, we have to go there ourselves. Or, at least, send our machines.
In August of 2011 we set out to do just that with the launch of the Juno spacecraft. After a successful launch, Juno spent the next five years on a carefully curated trip to Jupiter. Space is mind bogglingly big. After traveling 1,740 million miles, it finally arrived and became just one more satellite in the already crowded Jovian orbit. What sets it apart from the other objects orbiting our solar system’s largest planet was that it has instruments.
It set up shop around Jupiter and got to work completing its primary mission, investigating the planet itself and returning mind blowing images of Jupiter in the process. Then, with its primary mission checked off, Juno turned its eye toward the rest of the planetary neighborhood to scope out some of Jupiter’s largest moons. In June of 2021, Juno made close flybys of the biggest moon on the block, Ganymede, and returned stunning photos of its surface. Now, more than a decade after we strapped it to a rocket, Juno has arrived at perhaps the most intriguing celestial body in our solar system.
Europa is the fifth largest moon in the solar system, coming in at about 90% the size of our own Moon, and it’s believed to harbor a vast global saltwater ocean beneath its icy exterior. Water, of course, is likely the most important ingredient for life and when coupled with a source of energy, like the thermal vents which could punctuate Europa’s seafloor, it makes the moon an exciting place to investigate.
Future missions, like NASA’s upcoming Europa Clipper which is set to launch in 2024, could settle the question of whether there is life elsewhere in the universe once and for all. And the data from Juno might help to identify areas of interest and provide more information about the composition of Europa’s surface.
Juno’s first flyby of Europa occurred on September 29 of this year and is only the third close flyby — fewer than 500 kilometers above the surface — in history. The craft whizzed past the icy moon at a height of only 352 kilometers, barely higher than the Galileo visit a couple of decades back.
As it passed overhead, moving at 14.7 miles per second, the craft captured its first image of Annwn Regio, a stunning region near Europa’s equator. The photo reveals a crisscross of long, sprawling scars across the moon’s face, fractures in its floating ice shell. Light from the Sun cascades across it until, at the left edge of the image, the light fades and the moon falls into shadow. At the terminator, the line between light and dark, Europa’s features are revealed in stark relief, including an uneven pit which could be the fading remains of an ancient impact.
That photo was taken with JunoCam, a public outreach camera aboard Juno which is driven and used by citizen scientists. Unlike other space-based instruments which are typically used and controlled by professional scientists and astronomers, JunoCam allows the public to identify areas of interest and process finished images.
Getting it to work took some incredible engineering. Juno rotates twice every minute which would usually produce smeared, stretched, or blurry images, but JunoCam has a trick up its sleeve. The camera images only a couple of lines of pixels at a time and corrects for rotation as it goes. Those pixels are then stitched together into a finished photograph. Moreover, Juno only had a two hour window in which to capture the image before it flew past the moon and continued its orbit around Jupiter.
Despite those challenges, it was able to produce one of the highest resolution photos of Europa ever captured, with each pixel representing only 0.6 miles. The flyby altered Juno’s orbit, reducing the transit time around Jupiter from 43 days to 38, which means it should be back at Europa before too long and we’ll be treated once again to novel views of a world which might be hiding alien life. We hope they wave as we pass.