Category Archives: Space Science

Juno: From Jupiter’s deep jet-streams to the equatorial twilight zone

A couple of items from the Juno mission at Jupiter:

NASA Juno Findings – Jupiter’s Jet-Streams Are Unearthly

For hundreds of years, this gaseous giant planet appeared shrouded in colorful bands of clouds extending from dusk to dawn, referred to as zones and belts. The bands were thought to be an expression of Jovian weather, related to winds blowing eastward and westward at different speeds. This animation illustrates a recent discovery by Juno that demonstrates these east-west flows, also known as jet-streams penetrate deep into the planet’s atmosphere, to a depth of about 1,900 miles (3,000 kilometers). Due to Jupiter’s rapid rotation (Jupiter’s day is about 10 hours), these flows extend into the interior parallel to Jupiter’s axis of rotation, in the form of nested cylinders. Below this layer the flows decay, possibly slowed by Jupiter’s strong magnetic field. The depth of these flows surprised scientists who estimate the total mass involved in these jet streams to be about 1% of Jupiter’s mass (Jupiter’s mass is over 300 times that of Earth). This discovery was revealed by the unprecedented accuracy of Juno’s measurements of the gravity field. Credits: NASA/JPL-Caltech/SwRI/ASI

Data collected by NASA’s Juno mission to Jupiter indicate that the atmospheric winds of the gas-giant planet run deep into its atmosphere and last longer than similar atmospheric processes found here on Earth. The findings will improve understanding of Jupiter’s interior structure, core mass and, eventually, its origin.

Other Juno science results released today include that the massive cyclones that surround Jupiter’s north and south poles are enduring atmospheric features and unlike anything else encountered in our solar system. The findings are part of a four-article collection on Juno science results being published in the March 8 edition of the journal Nature.

“These astonishing science results are yet another example of Jupiter’s curve balls, and a testimony to the value of exploring the unknown from a new perspective with next-generation instruments.  Juno’s unique orbit and evolutionary high-precision radio science and infrared technologies enabled these paradigm-shifting discoveries,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute, San Antonio. “Juno is only about one third the way through its primary mission, and already we are seeing the beginnings of a new Jupiter.”

The depth to which the roots of Jupiter’s famous zones and belts extend has been a mystery for decades. Gravity measurements collected by Juno during its close flybys of the planet have now provided an answer.

“Juno’s measurement of Jupiter’s gravity field indicates a north-south asymmetry, similar to the asymmetry observed in its zones and belts,” said Luciano Iess, Juno co-investigator from Sapienza University of Rome, and lead author on a Nature paper on Jupiter’s gravity field.

On a gas planet, such an asymmetry can only come from flows deep within the planet; and on Jupiter, the visible eastward and westward jet streams are likewise asymmetric north and south. The deeper the jets, the more mass they contain, leading to a stronger signal expressed in the gravity field. Thus, the magnitude of the asymmetry in gravity determines how deep the jet streams extend.

This computer-generated image is based on an infrared image of Jupiter’s north polar region that was acquired on February 2, 2017, by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard Juno during the spacecraft’s fourth pass over Jupiter. Credits: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM. Full image and caption

“Galileo viewed the stripes on Jupiter more than 400 years ago,” said Yohai Kaspi, Juno co-investigator from the Weizmann Institute of Science, Rehovot, Israel, and lead author of a Nature paper on Jupiter’s deep weather layer. “Until now, we only had a superficial understanding of them and have been able to relate these stripes to cloud features along Jupiter’s jets. Now, following the Juno gravity measurements, we know how deep the jets extend and what their structure is beneath the visible clouds. It’s like going from a 2-D picture to a 3-D version in high definition.”

The result was a surprise for the Juno science team because it indicated that the weather layer of Jupiter was more massive, extending much deeper than previously expected. The Jovian weather layer, from its very top to a depth of 1,900 miles (3,000 kilometers), contains about one percent of Jupiter’s mass (about 3 Earth masses).

“By contrast, Earth’s atmosphere is less than one millionth of the total mass of Earth,” said Kaspi “The fact that Jupiter has such a massive region rotating in separate east-west bands is definitely a surprise.”

The finding is important for understanding the nature and possible mechanisms driving these strong jet streams. In addition, the gravity signature of the jets is entangled with the gravity signal of Jupiter’s core.

Another Juno result released today suggests that beneath the weather layer, the planet rotates nearly as a rigid body.

“This is really an amazing result, and future measurements by Juno will help us understand how the transition works between the weather layer and the rigid body below,” said Tristan Guillot, a Juno co-investigator from the Université Côte d’Azur, Nice, France, and lead author of the paper on Jupiter’s deep interior. “Juno’s discovery has implications for other worlds in our solar system and beyond. Our results imply that the outer differentially-rotating region should be at least three times deeper in Saturn and shallower in massive giant planets and brown dwarf stars.”

A truly striking result released in the Nature papers is the beautiful new imagery of Jupiter’s poles captured by Juno’s Jovian Infrared Auroral Mapper (JIRAM) instrument. Imaging in the infrared part of the spectrum, JIRAM captures images of light emerging from deep inside Jupiter equally well, night or day. JIRAM probes the weather layer down to 30 to 45 miles (50 to 70 kilometers) below Jupiter’s cloud tops.

“Prior to Juno we did not know what the weather was like near Jupiter’s poles. Now, we have been able to observe the polar weather up-close every two months,” said Alberto Adriani, Juno co-investigator from the Institute for Space Astrophysics and Planetology, Rome, and lead author of the paper. “Each one of the northern cyclones is almost as wide as the distance between Naples, Italy and New York City — and the southern ones are even larger than that. They have very violent winds, reaching, in some cases, speeds as great as 220 mph (350 kph). Finally, and perhaps most remarkably, they are very close together and enduring. There is nothing else like it that we know of in the solar system.”

Jupiter’s poles are a stark contrast to the more familiar orange and white belts and zones encircling the planet at lower latitudes. Its north pole is dominated by a central cyclone surrounded by eight circumpolar cyclones with diameters ranging from 2,500 to 2,900 miles (4,000 to 4,600 kilometers) across. Jupiter’s south pole also contains a central cyclone, but it is surrounded by five cyclones with diameters ranging from 3,500 to 4,300 miles (5,600 to 7,000 kilometers) in diameter. Almost all the polar cyclones, at both poles, are so densely packed that their spiral arms come in contact with adjacent cyclones. However, as tightly spaced as the cyclones are, they have remained distinct, with individual morphologies over the seven months of observations detailed in the paper.

“The question is, why do they not merge?” said Adriani. “We know with Cassini data that Saturn has a single cyclonic vortex at each pole. We are beginning to realize that not all gas giants are created equal.”

Abstracts of the March 8 Juno papers can be found online:

To date, Juno has completed 10 science passes over Jupiter and logged almost 122 million miles (200 million kilometers), since entering Jupiter’s orbit on July 4, 2016. Juno’s 11th science pass will be on April 1.

Juno launched on Aug. 5, 2011, from Cape Canaveral, Florida. During its mission of exploration, Juno soars low over the planet’s cloud tops — as close as about 2,200 miles (3,500 kilometers). During these flybys, Juno is probing beneath the obscuring cloud cover of Jupiter and studying its auroras to learn more about the planet’s origins, structure, weather layer and magnetosphere.

NASA’s Jet Propulsion Laboratory, 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 NASA’s Science Mission Directorate. The Italian Space Agency (ASI), contributed two instruments, a Ka-band frequency translator (KaT) and the Jovian Infrared Auroral Mapper (JIRAM). Lockheed Martin Space, Denver, built the spacecraft.

The public can follow the mission on Facebook and Twitter at:

More information on Jupiter can be found at: https://www.nasa.gov/jupiter

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Another beautiful view of Jupiter created by a citizen scientist:

Jovian ‘Twilight Zone’

This image captures the swirling cloud formations around the south pole of Jupiter, looking up toward the equatorial region.

NASA’s Juno spacecraft took the color-enhanced image during its eleventh close flyby of the gas giant planet on Feb. 7 at 7:11 a.m. PST (10:11 a.m. EST). At the time, the spacecraft was 74,896 miles (120,533 kilometers) from the tops of Jupiter’s clouds at 84.9 degrees south latitude.

Citizen scientist Gerald Eichstädt processed this image using data from the JunoCam imagerThis image was created by reprocessing raw JunoCam data using trajectory and pointing data from the spacecraft. This image is one in a series of images taken in an experiment to capture the best results for illuminated parts of Jupiter’s polar region.

To make features more visible in Jupiter’s terminator — the region where day meets night — the Juno team adjusted JunoCam so that it would perform like a portrait photographer taking multiple photos at different exposures, hoping to capture one image with the intended light balance. For JunoCam to collect enough light to reveal features in Jupiter’s dark twilight zone, the much brighter illuminated day-side of Jupiter becomes overexposed with the higher exposure.

JunoCam’s raw images are available for the public to peruse and process into image products at:

www.missionjuno.swri.edu/junocam

More information about Juno is at:

https://www.nasa.gov/juno and http://missionjuno.swri.edu

Image credits: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt

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Videos: Planetary Post with Robert Picardo + PlanetVac with HoneyBee Robotics and Masten Space

Here is the latest episode of the Planetary Post with Robert Picardo, sponsored by the Planetary SocietyBehind the Scenes with Bill Nye 

And here is a video providing more details about the Society’s PlanetVac Xodiac project mentioned by Picardo. The project is a Society-led collaboration with HoneyBee Robotics and Masten Space Systems.

The goal is to design, build, and demonstrate a low cost system for gathering a sample of material from the surface of a planet or moon. They plan to attach a prototype version to a Masten vertical-takeoff and landing rocket vehicle and do a demo mission in California.

… Enter PlanetVac—short for Planetary Vacuum—a project by Honeybee Robotics sponsored by The Planetary Society. In 2013, we helped fund a successful test of this next-generation system in the lab, and in May, we’re taking it out for a test flight on a rocket called Xodiac. Xodiac, built by Masten Space Systems, takes off and lands vertically in California’s Mojave Desert. This allows space hardware developers to test new equipment and make sure prototypes can survive the stresses of a rocket launch and landing—all without actually flying to space. Our May Xodiac test will give PlanetVac a bigger challenge than the lab and represent the next step in qualifying it for full-fledged space missions.

PLANETVAC SAMPLE COLLECTION: Attached to a lander leg, PlanetVac collects a surface sample by using an inert gas to move regolith into the sample container.

The Society is seeking donations for crowd-funding the project: PlanetVac at the Planetary Society.

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Videos: Latest NASA Mars Report + Using the Insight lander to study Mars interior

A short report from NASA JPL with the latest news from Mars:

And this longer video shows a talk by Troy Hudson of JPL about NASA’s Mars InSight Mission, which is scheduled to launch in May of this year and land on Mars in November. Hudson focused on using Insight’s sensors to investigate the interior of Mars:

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Videos: TMRO Orbit 11.08 – Exploring Pluto with New Horizons

The latest program from TMRO.tv includes Alan Stern of the New Horizons mission to Pluto and beyond: Exploring Pluto with New Horizons – Orbit 11.08 – TMRO

We have special guest Dr. Alan Stern joining us this week to talk about the New Horizons spacecraft, Pluto and exploration. 

News topics and recent launches:

Launches:
SpaceX Launches Paz and First Starlink Satellites

News:
Exoplanet Hunter TESS arrives in Florida
National Space Council meets for 2nd time
Mars 2020 Will Take A Visitor Home

TMRO is viewer supported:

TMRO shows are crowd funded. If you like this episode consider contributing to help us to continue to improve. Head over to http://www.patreon.com/tmro for per-episode contribution or http://www.minds.com/tmro for monthly contributions and reward information.

A couple of TMRO Spacepod short reports:

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The Opportunity rover continues going strong after 5000 Martian days

The Mars rover Opportunity landed on the Red Planet on Jan. 25, 2004. Nearly 5000 Martian days later, the robust little robot continues to explore and make discoveries. Here are two items from NASA JPL about Opportunity:

** 5,000 Days on Mars; Solar-Powered Rover Approaching 5,000th Martian Dawn

NASA’s Mars Exploration Rover Opportunity recorded the dawn of the rover’s 4,999th Martian day, or sol, with its Panoramic Camera (Pancam) on Feb. 15, 2018, yielding this processed, approximately true-color scene. The view looks across Endeavour Crater, which is about 14 miles (22 kilometers) in diameter, from the inner slope of the crater’s western rim. Opportunity has driven a little over 28.02 miles (45.1 kilometers) since it landed in the Meridiani Planum region of Mars in January, 2004, for what was planned as a 90-sol mission. A sol lasts about 40 minutes longer than an Earth day.

The Sun will rise on NASA’s solar-powered Mars rover Opportunity for the 5,000th time on Saturday, sending rays of energy to a golf-cart-size robotic field geologist that continues to provide revelations about the Red Planet.

“Five thousand sols after the start of our 90-sol mission, this amazing rover is still showing us surprises on Mars,” said Opportunity Project Manager John Callas, of NASA’s Jet Propulsion Laboratory, Pasadena, California.

A Martian “sol” lasts about 40 minutes longer than an Earth day, and a Martian year lasts nearly two Earth years. Opportunity’s Sol 1 was landing day, Jan. 25, 2004 (that’s in Universal Time; it was Jan. 24 in California). The prime mission was planned to last 90 sols. NASA did not expect the rover to survive through a Martian winter. Sol 5,000 will begin early Friday, Universal Time, with the 4,999th dawn a few hours later. Opportunity has worked actively right through the lowest-energy months of its eighth Martian winter.

The channel descending a Martian slope in this perspective view is “Perseverance Valley,” the study area of NASA’s Mars rover Opportunity as the rover passes its 5,000th Martian day. The view overlays a HiRISE image onto a topographic model with five-fold vertical exaggeration, to show shapes. Credits: NASA/JPL-Caltech/Univ. of Arizona/WUSTL. Full image and caption

From the rover’s perspective on the inside slope of the western rim of Endeavour Crater, the milestone sunrise will appear over the basin’s eastern rim, about 14 miles (22 kilometers) away. Opportunity has driven over 28 miles (45 kilometers) from its landing site to its current location about one-third of the way down “Perseverance Valley,” a shallow channel incised from the rim’s crest of the crater’s floor. The rover has returned about 225,000 images, all promptly made public online.

“We’ve reached lots of milestones, and this is one more,” Callas said, “but more important than the numbers are the exploration and the scientific discoveries.”

The mission made headlines during its first months with the evidence about groundwater and surface water environments on ancient Mars. Opportunity trekked to increasingly larger craters to look deeper into Mars and father back into Martian history, reaching Endeavour Crater in 2011. Researchers are now using the rover to investigate the processes that shaped Perseverance Valley.

For more about Opportunity’s adventures and discoveries, see:

** Long-Lived Mars Rover Opportunity Keeps Finding Surprises

NASA’s Mars Exploration Rover Opportunity keeps providing surprises about the Red Planet, most recently with observations of possible “rock stripes.”

Textured rows on the ground in this portion of “Perseverance Valley” are under investigation by NASA’s Mars Exploration Rover Opportunity, which used its Navigation Camera to take the component images of this downhill-looking scene. The rover reaches its 5,000th Martian day, or sol, on Feb. 16, 2018. Image Credit: NASA/JPL-Caltech. Full Image and Caption

The ground texture seen in recent images from the rover resembles a smudged version of very distinctive stone stripes on some mountain slopes on Earth that result from repeated cycles of freezing and thawing of wet soil. But it might also be due to wind, downhill transport, other processes or a combination.

Opportunity landed on Mars in January 2004. As it reaches the 5,000th Martian day, or sol, of what was planned as a 90-sol mission, it is investigating a channel called “Perseverance Valley,” which descends the inboard slope of the western rim of Endeavour Crater.

“Perseverance Valley is a special place, like having a new mission again after all these years,” said Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis. “We already knew it was unlike any place any Mars rover has seen before, even if we don’t yet know how it formed, and now we’re seeing surfaces that look like stone stripes. It’s mysterious. It’s exciting. I think the set of observations we’ll get will enable us to understand it.”

On some slopes within the valley, the soil and gravel particles appear to have become organized into narrow rows or corrugations, parallel to the slope, alternating between rows with more gravel and rows with less.

This late-afternoon view from the front Hazard Avoidance Camera on NASA’s Mars Exploration Rover Opportunity shows a pattern of rock stripes on the ground, a surprise to scientists on the rover team. It was taken in January 2018, as the rover neared Sol 5000 of what was planned as a 90-sol mission. Image Credit: NASA/JPL-Caltech. Full Image and Caption.

The origin of the whole valley is uncertain. Rover-team scientists are analyzing various clues that suggest actions of water, wind or ice. They are also considering a range of possible explanations for the stripes, and remain uncertain about whether this texture results from processes of relatively modern Mars or a much older Mars.

Other lines of evidence have convinced Mars experts that, on a scale of hundreds of thousands of years, Mars goes through cycles when the tilt or obliquity of its axis increases so much that some of the water now frozen at the poles vaporizes into the atmosphere and then becomes snow or frost accumulating nearer the equator.

“One possible explanation of these stripes is that they are relics from a time of greater obliquity when snow packs on the rim seasonally melted enough to moisten the soil, and then freeze-thaw cycles organized the small rocks into stripes,” Arvidson said. “Gravitational downhill movement may be diffusing them so they don’t look as crisp as when they were fresh.”

Bernard Hallet of the University of Washington, Seattle, agrees the alignments seen in images of Perseverance Valley are not as distinctive as the stone stripes he has studied on Earth. Field measurements on Earth, near the summit of Hawaii’s Mauna Kea where the soil freezes every night but is often dry, have documented how those form when temperature and ground conditions are right: Soils with a mix of silt, sand and gravel expand more where the finer-grain material is most prevalent and retains more water. Freezing expands the soil, pushing larger particles up. If they move to the side, as well as down the general slope, due to gravity or wind, they tend to move away from the finer-grain concentrations and stretch out downslope. Where larger particles become more concentrated, the ground expands less. The process repeats hundreds or thousands of times, and the pattern self-organizes into alternating stripes.

Perseverance Valley holds rocks carved by sand blowing uphill from the crater floor, and wind might also be the key in sorting larger particles into rows parallel to the slope.

“Debris from relatively fresh impact craters is scattered over the surface of the area, complicating assessment of effects of wind,” said Opportunity science-team member Robert Sullivan of Cornell University, Ithaca, New York. “I don’t know what these stripes are, and I don’t think anyone else knows for sure what they are, so we’re entertaining multiple hypotheses and gathering more data to figure it out.”

Every sol Opportunity keeps working may add information to help solve some puzzles and find new ones.

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