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Beans, beans, do they really make you fart? Scientists investigate
Why a new literary prize for climate fiction will make a difference
The man transforming data from two dramatic storms into music
Why it's vital we fight prejudices about the elderly once and for all
Why it's vital we fight prejudices about the elderly once and for all
NASA’s Juno Provides High-Definition Views of Europa’s Icy Shell
Imagery from the solar-powered spacecraft shows some intriguing features on the ice-encased Jovian moon.
Images from the JunoCam visible-light camera aboard NASA’s Juno spacecraft supports the theory that the icy crust at the north and south poles of Jupiter’s moon Europa is not where it used to be. Another high-resolution picture of the icy moon, by the spacecraft’s Stellar Reference Unit (SRU), reveals signs of possible plume activity and an area of ice shell disruption where brine may have recently bubbled to the surface.
The JunoCam results recently appeared in the Planetary Science Journal and the SRU results in the journal JGR Planets.
On Sept. 29, 2022, Juno made its closest flyby of Europa, coming within 220 miles (355 kilometers) of the moon’s frozen surface. The four pictures taken by JunoCam and one by the SRU are the first high-resolution images of Europa since Galileo’s last flyby in 2000.
True Polar WanderJuno’s ground track over Europa allowed imaging near the moon’s equator. When analyzing the data, the JunoCam team found that along with the expected ice blocks, walls, scarps, ridges, and troughs, the camera also captured irregularly distributed steep-walled depressions 12 to 31 miles (20 to 50 kilometers) wide. They resemble large ovoid pits previously found in imagery from other locations of Europa.
This black-and-white image of Europa’s surface was taken by the Stellar Reference Unit (SRU) aboard NASA’s Juno spacecraft during the Sept. 29, 2022, flyby. The chaos feature nicknamed “the Platypus” is seen in the lower right corner.NASA/JPL-Caltech/SwRI This annotated image of Europa’s surface from Juno’s SRU shows the location of a double ridge running east-west (blue box) with possible plume stains and the chaos feature the team calls “the Platypus” (orange box). These features hint at current surface activity and the presence of subsurface liquid water on the icy Jovian moon.A giant ocean is thought to reside below Europa’s icy exterior, and these surface features have been associated with “true polar wander,” a theory that Europa’s outer ice shell is essentially free-floating and moves.
“True polar wander occurs if Europa’s icy shell is decoupled from its rocky interior, resulting in high stress levels on the shell, which lead to predictable fracture patterns,” said Candy Hansen, a Juno co-investigator who leads planning for JunoCam at the Planetary Science Institute in Tucson, Arizona. “This is the first time that these fracture patterns have been mapped in the southern hemisphere, suggesting that true polar wander’s effect on Europa’s surface geology is more extensive than previously identified.”
The high-resolution JunoCam imagery has also been used to reclassify a formerly prominent surface feature from the Europa map.
“Crater Gwern is no more,” said Hansen. “What was once thought to be a 13-mile-wide impact crater — one of Europa’s few documented impact craters — Gwern was revealed in JunoCam data to be a set of intersecting ridges that created an oval shadow.”
The PlatypusAlthough all five Europa images from Juno are high-resolution, the image from the spacecraft’s black-and-white SRU offers the most detail. Designed to detect dim stars for navigation purposes, the SRU is sensitive to low light. To avoid over-illumination in the image, the team used the camera to snap the nightside of Europa while it was lit only by sunlight scattered off Jupiter (a phenomenon called “Jupiter-shine”).
This innovative approach to imaging allowed complex surface features to stand out, revealing intricate networks of cross-cutting ridges and dark stains from potential plumes of water vapor. One intriguing feature, which covers an area 23 miles by 42 miles (37 kilometers by 67 kilometers), was nicknamed by the team “the Platypus” because of its shape.
Characterized by chaotic terrain with hummocks, prominent ridges, and dark reddish-brown material, the Platypus is the youngest feature in its neighborhood. Its northern “torso” and southern “bill” — connected by a fractured “neck” formation — interrupt the surrounding terrain with a lumpy matrix material containing numerous ice blocks that are 0.6 to 4.3 miles (1 to 7 kilometers) wide. Ridge formations collapse into the feature at the edges of the Platypus.
For the Juno team, these formations support the idea that Europa’s ice shell may give way in locations where pockets of briny water from the subsurface ocean are present beneath the surface.
About 31 miles (50 kilometers) north of the Platypus is a set of double ridges flanked by dark stains similar to features found elsewhere on Europa that scientists have hypothesized to be cryovolcanic plume deposits.
“These features hint at present-day surface activity and the presence of subsurface liquid water on Europa,” said Heidi Becker, lead co-investigator for the SRU at NASA’s Jet Propulsion Laboratory in Southern California, which also manages the mission. “The SRU’s image is a high-quality baseline for specific places NASA’s Europa Clipper mission and ESA’s (European Space Agency’s) Juice missions can target to search for signs of change and brine.”
Europa Clipper’s focus is on Europa — including investigating whether the icy moon could have conditions suitable for life. It is scheduled to launch on the fall of 2024 and arrive at Jupiter in 2030. Juice (Jupiter Icy Moons Explorer) launched on April 14, 2023. The ESA mission will reach Jupiter in July 2031 to study many targets (Jupiter’s three large icy moons, as well as fiery Io and smaller moons, along with the planet’s atmosphere, magnetosphere, and rings) with a special focus on Ganymede.
Juno executed its 61st close flyby of Jupiter on May 12. Its 62nd flyby of the gas giant, scheduled for June 13, includes an Io flyby at an altitude of about 18,200 miles (29,300 kilometers).
More About the MissionJPL, a division of Caltech in Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. The Italian Space Agency (ASI) funded the Jovian InfraRed Auroral Mapper. Lockheed Martin Space in Denver built and operates the spacecraft.
More information about Juno is available at:
News Media ContactsDC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov
Karen Fox / Charles Blue
NASA Headquarters, Washington
301-286-6284 / 202-802-5345
karen.c.fox@nasa.gov / charles.e.blue@nasa.gov
Deb Schmid
Southwest Research Institute, San Antonio
210-522-2254
dschmid@swri.org
2024-066
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Discovery Alert: An Earth-sized World and Its Ultra-cool Star
4 min read
Discovery Alert: An Earth-sized World and Its Ultra-cool Star An artist’s concept of the exoplanet SPECULOOS-3 b orbiting its red dwarf star. The planet is as big around as Earth, while its star is slightly bigger than Jupiter – but much more massive.Credit: NASA/JPL-Caltech
Our galaxy is a jewel box of red stars. More than 70% of the stars in the Milky Way are M dwarfs, also known as red dwarfs. These stars are cool and dim compared with our Sun, but they often blast orbiting exoplanets with high-energy radiation, especially early in their lives. And those ‘‘lives’’ last a long time. Stars like our Sun burn for about 10 billion years before turning into hungry red giants devouring any planets too nearby. M dwarfs keep burning for 100 billion years or more, perhaps offering a foothold for life, and an even longer window for life to develop.
An international team using robotic telescopes around the world recently spotted an Earth-sized planet orbiting an ultra-cool red dwarf, the dimmest and longest-lived of stars. When the universe grows cold and dark, these will be the last stars burning.
The DiscoveryThe exoplanet SPECULOOS-3 b is about 55 light-years from Earth (really close when you consider the cosmic scale!) and nearly the same size. A year there, one orbit around the star, takes about 17 hours. The days and nights, though, may never end: The planet is thought to be tidally locked, so the same side, known as the dayside, always faces the star, like the Moon to Earth. The nightside would be locked in never-ending darkness.
The DetailsIn our corner of the galaxy, ultra-cool dwarf stars are ubiquitous. They are so faint that their planetary population is largely unexplored. The SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) project, led by Michael Gillon at the University of Liège, Belgium, was designed to change that. Ultra-cool dwarf stars are scattered across the sky, so you need to observe them one by one, for weeks, to get a good chance to detect transiting planets. For that, you need a dedicated network of professional telescopes. This is the concept of SPECULOOS.
‘‘We designed SPECULOOS specifically to explore nearby ultra-cool dwarf stars in search of rocky planets,’’ Gillon said. ‘‘With the SPECULOOS prototype and the crucial help of the NASA Spitzer Space Telescope, we discovered the famous TRAPPIST-1 system. That was an excellent start!’’
Gillon is the lead author of the paper announcing the planet’s discovery, published May 15, 2024, in Nature Astronomy. The project is a true international endeavor, with partnership with the Universities of Cambridge, Birmingham, Bern, Massachusetts Institute of Technology, and ETH Zürich.
The SPECULOOS-3 star is thousands of degrees cooler than our Sun with an average temperature of about 4,760 F (2,627 C), but it pummels its planet with radiation, meaning there’s likely no atmosphere.
Seeing the star, let alone the planet, is a feat in itself. “Though this particular red dwarf is more than a thousand times dimmer than the Sun, its planet orbits much, much closer than the Earth, heating up the planetary surface,” said co-author Catherine Clark, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory in Southern California.
Fun facts- While the planet is as big around as Earth, its star is just a tad bigger than Jupiter – but much more massive.
- The planet receives almost 16 times more energy per second than Earth receives from the Sun.
- Did you catch the cookie connection? The planet-finding program SPECULOOS shares its name with the spiced shortbread. Both hail from Belgium. Sweet!
SPECULOOS-3 b is an excellent candidate for followup observations by the James Webb Space Telescope. Not only might we learn about the potential for an atmosphere and about the surface mineralogy, but it might also help us understand the stellar neighborhood and our place in it.
‘‘We’re making great strides in our study of planets orbiting other stars. We have now reached the stage where we can detect and study Earth-sized exoplanets in detail. The next step will be to determine whether any of them are habitable, or even inhabited,’’ said Steve B. Howell, one of the planet’s discoverers at NASA Ames Research Center in Silicon Valley.
This story was written by the late Kristen Walbolt, who managed both exoplanets.nasa.gov and @NASAExoplanets social accounts, growing the latter from a following of 126,000 to over 1.9 million in just five years. This Discovery Alert and the associated illustration are among the final pieces of Kristen’s work for NASA Exoplanets.
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