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Tag Archives: Jupiter

From JPL press releases, July 4, 2016:

While Americans celebrated the evening of Independence Day, 1.7 billion miles (2.7 billion kilometres) NASA’s Juno spacecraft, launched nearly five years ago, reached its final destination: the most massive planet in our Solar System, Jupiter.

juno_burn

Credit: NASA/JPL-Caltech

Juno now starts its tour of Jupiter in a 53.5-day orbit. The spacecraft saves fuel by executing a burn that places it in a capture orbit with a 53.5-day orbit instead of going directly for the 14-day orbit that will occur during the mission’s primary science collection period. The 14-day science orbit phase will begin after the final burn of the mission for Juno’s main engine on October 19.

Most of Juno’s instruments deal with Jupiter’s particles and magnetic field, which is 20,000 times more powerful than Earth’s. The main instruments are in a vault made of 400 pounds of titanium to protect them from the strong radiation. The Junocam, its imaging camera, is outside that protection, and may not last as long as other instruments; further, it will give images as it rotates that will have to be transformed to the equivalent of steady views.

Links: Full details via the JPL press release; NASA Juno mission page; NY Times: Jupiter and its moons graphic.

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From a JPL press release dated November 21, 2014:

Scientists have produced a new version of what is perhaps NASA’s best view of Jupiter’s ice-covered moon, Europa. The mosaic of color images was obtained in the late 1990s by NASA’s Galileo spacecraft. This is the first time that NASA is publishing a version of the scene produced using modern image processing techniques.

Credit: NASA/JPL-Caltech/SETI Institute

Credit: NASA/JPL-Caltech/SETI Institute

The new image more closely approximates what the human eye would see than the earlier version (released in 2001). The image features many long, curving and linear fractures in the moon’s bright ice shell. Scientists are eager to learn if the reddish-brown fractures, and other markings spattered across the surface, contain clues about the geological history of Europa and the chemistry of the global ocean that is thought to exist beneath the ice.

In addition to the newly processed image, a new video details why this likely ocean world is a high priority for future exploration.

Links: more details about the image above; Europa exploration movie; NASA’s Europa homepage.

Mission Juno website hosts a wealth of Jupiter resources, including news, discussions, images, movies, and explanatory animations about the mission, its science goals and what we know about the Solar System’s largest planet. A special feature is a series of 9 short movies from Bill Nye “the Science Guy”!

Credit: NASA/JPL-Caltech

See the Mission Juno website from the Southwest Research Institute (SwRI).

More than 400 years after its discovery by Italian astronomer Galileo Galilei (see Figure 3-2, p. 38), the largest moon in the Solar System – Jupiter’s moon Ganymede – has finally been fully mapped (see Section 7.1g(iii), pp. 175–176). Since its discovery in January 1610, Ganymede has been the focus of repeated observation, first by Earth-based telescopes, and later by the flyby missions and spacecraft orbiting Jupiter. These studies depict a complex, icy world whose surface is characterized by the striking contrast between its two major terrain types: the dark, very old, highly cratered regions, and the lighter, somewhat younger (but still very old) regions marked with an extensive array of grooves and ridges.

Credit: USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech

Scientists have now produced the first global geologic map of Ganymede, Jupiter’s seventh moon. The map combines the best images obtained during flybys conducted by NASA’s Voyager 1 and 2 spacecraft (1979) and Galileo orbiter (1995–2003) and is now published by the U.S. Geological Survey as a global map. It technically illustrates the incredibly varied geologic character of Ganymede’s surface and helps planetary scientists to make sense of the apparent chaos of its complex surface, in order to decipher the icy world’s evolution. It will also enable researchers to compare the geologic characters of other icy satellite moons in the Solar System.

The European Space Agency’s Jupiter Icy Moons Explorer mission is slated to be orbiting Ganymede around 2032, with instrument contributions from NASA.

Earth-bound astronomers can observe Ganymede (with binoculars) in the evening sky this month, as Jupiter is in opposition and easily visible.

Links: JPL press release; a rotating Ganymede movie; the geologic map.

On a recent public radio broadcast, Philip Marcus, professor of fluid dynamics at the University of California Berkeley, explains the persistence of Jupiter’s Great Red Spot (see Section 7.1b, p. 170).

450x426_q75

Credit: NASA

The Great Red Spot is huge – 36 times larger than the United States, and its winds, which clock in at 250 miles per hour, surpass those of the most violent hurricane. But, its most baffling property is its multi-century lifetime.

Scientists believe that the Red Spot should have lasted just a few years. It avoids being torn apart because it is sandwiched between layers of cold and hot air. But, those layers should have warmed and cooled their ways to oblivion in only 5 years or so and taken the Red Spot along with them.

So why is the Red Spot still here? One explanation is that the Great Red Spot merges with, and absorbs, smaller “spots”. It was thought that by cannibalizing smaller spots, the Red Spot could stay alive indefinitely, but now we know.  That diet is too meager.

Dr. Marcus’s group recently found a new explanation for the Red Spot’s longevity – it has weak, vertical winds. Like storms on Earth, the vertical winds of the Great Red Spot appear to be negligible; they are hundreds of times smaller than the horizontal winds. Therefore, previous studies ignored them.  To their surprise, when they accurately calculated the vertical winds using computer models, the Red Spot’s lifetime increased from 5 years to 800 years. The vertical winds escaped the Great Red Spot and then threaded through the atmosphere, where they harvested energy from the surrounding air. When the winds returned to the Red Spot, they brought their bounty, and that excess energy has sustained the Great Red Spot for centuries.

Links and source: WAMC’s Academic Minute.

Our Solar System seems like a neat and orderly place, with small, rocky worlds near the Sun and big, gaseous worlds farther out, all eight planets following orbital paths unchanged since they formed. However, the true history of the Solar System is far more riotous. Giant planets migrated in and out, tossing interplanetary flotsam and jetsam far and wide.

New clues to this tumultuous past come from the asteroid belt. Millions of asteroids circle the Sun between the orbits of Mars and Jupiter, in a region known as the main asteroid belt. Traditionally, they were viewed as the pieces of a failed planet that was prevented from forming by the influence of Jupiter’s powerful gravity. Their compositions seemed to vary methodically from drier to wetter, due to the drop in temperature as you move away from the Sun.

base

Credit: David A. Aguilar (CfA)

This traditional view has changed, as astronomers have recognized that the current residents of the main asteroid belt weren’t all there from the start. In the early history of the Solar System the giant planets ran amok, migrating inward and outward substantially. Jupiter may have moved as close to the Sun as Mars is now. In the process, it swept the asteroid belt nearly clean, leaving only a tenth of one percent of its original population. As the planets migrated, they stirred the contents of the Solar System. Objects from as close to the Sun as Mercury, and as far out as Neptune, all collected in the main asteroid belt.

Using data from the Sloan Digital Sky Survey, astronomers have examined the compositions of thousands of asteroids within the main belt. They found that the asteroid belt is more diverse than previously realized, especially when you look at the smaller asteroids. This finding has interesting implications for the history of Earth. Astronomers have theorized that long-ago asteroid impacts delivered much of the water now filling Earth’s oceans. If true, the stirring provided by migrating planets may have been essential to bringing those asteroids.

This raises the question of whether an Earth-like exoplanet would also require a rain of asteroids to bring water and make it habitable. If so, then Earth-like worlds might be rarer than we thought.  The paper describing these findings appears in the January 30, 2014 issue of Nature.

Links: Harvard-Smithsonian Center for Astrophysics press release; Nature article.

A new analysis in 2013 of old Hubble Space Telescope images from 2004 has revealed a 12-mile-diameter moon of Neptune, temporarily known as S/2004 N1 (where the S/ means “satellite”).  Its orbital period is 23 hours.

Mark Showalter of the SETI Institute in Mountain View, Calif., discovered the moon on July 1, while studying the faint ring-arcs of Neptune. It is so small and dim that it is roughly one hundred million times fainter than the faintest star that can be seen with the naked eye.

hs-2013-30-a-web_print

Credit: NASA, ESA, and M. Showalter (SETI Institute)

Read the full story at the HubbleSite, Scientific American, or Space.com.