Solar System 10 Things: Two Years of Juno at Jupiter

Our Juno mission arrived at the King of Planets in July 2016. The intrepid robotic explorer has been revealing Jupiter’s secrets ever since.

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Here are 10 historic Juno mission highlights:

1. Arrival at a Colossus

After an odyssey of almost five years and 1.7 billion miles (2.7 billion kilometers), our Juno spacecraft fired its main engine to enter orbit around Jupiter on July 4, 2016. Juno, with its suite of nine science instruments, was the first spacecraft to orbit the giant planet since the Galileo mission in the 1990s. It would be the first mission to make repeated excursions close to the cloud tops, deep inside the planet’s powerful radiation belts.

2. Science, Meet Art

Juno carries a color camera called JunoCam. In a remarkable first for a deep space mission, the Juno team reached out to the general public not only to help plan which pictures JunoCam would take, but also to process and enhance the resulting visual data. The results include some of the most beautiful images in the history of space exploration.

3. A Whole New Jupiter

It didn’t take long for Juno—and the science teams who hungrily consumed the data it sent home—to turn theories about how Jupiter works inside out. Among the early findings: Jupiter’s poles are covered in Earth-sized swirling storms that are densely clustered and rubbing together. Jupiter’s iconic belts and zones were surprising, with the belt near the equator penetrating far beneath the clouds, and the belts and zones at other latitudes seeming to evolve to other structures below the surface.

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4. The Ultimate Classroom

The Goldstone Apple Valley Radio Telescope (GAVRT) project, a collaboration among NASA, JPL and the Lewis Center for Educational Research, lets students do real science with a large radio telescope. GAVRT data includes Jupiter observations relevant to Juno, and Juno scientists collaborate with the students and their teachers.

5. Spotting the Spot

Measuring in at 10,159 miles (16,350 kilometers) in width (as of April 3, 2017) Jupiter’s Great Red Spot is 1.3 times as wide as Earth. The storm has been monitored since 1830 and has possibly existed for more than 350 years. In modern times, the Great Red Spot has appeared to be shrinking. In July 2017, Juno passed directly over the spot, and JunoCam images revealed a tangle of dark, veinous clouds weaving their way through a massive crimson oval.

“For hundreds of years scientists have been observing, wondering and theorizing about Jupiter’s Great Red Spot,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “Now we have the best pictures ever of this iconic storm. It will take us some time to analyze all the data from not only JunoCam, but Juno’s eight science instruments, to shed some new light on the past, present and future of the Great Red Spot.”

6. Beauty Runs Deep

Data collected by the Juno spacecraft during its first pass over Jupiter’s Great Red Spot in July 2017 indicate that this iconic feature penetrates well below the clouds. The solar system’s most famous storm appears to have roots that penetrate about 200 miles (300 kilometers) into the planet’s atmosphere.

7. Powerful Auroras, Powerful Mysteries

Scientists on the Juno mission observed massive amounts of energy swirling over Jupiter’s polar regions that contribute to the giant planet’s powerful auroras – only not in ways the researchers expected. Examining data collected by the ultraviolet spectrograph and energetic-particle detector instruments aboard Juno, scientists observed signatures of powerful electric potentials, aligned with Jupiter’s magnetic field, that accelerate electrons toward the Jovian atmosphere at energies up to 400,000 electron volts. This is 10 to 30 times higher than the largest such auroral potentials observed at Earth.

Jupiter has the most powerful auroras in the solar system, so the team was not surprised that electric potentials play a role in their generation. What puzzled the researchers is that despite the magnitudes of these potentials at Jupiter, they are observed only sometimes and are not the source of the most intense auroras, as they are at Earth.

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8. Heat from Within

Juno scientists shared a 3D infrared movie depicting densely packed cyclones and anticyclones that permeate the planet’s polar regions, and the first detailed view of a dynamo, or engine, powering the magnetic field for any planet beyond Earth (video above). Juno mission scientists took data collected by the spacecraft’s Jovian InfraRed Auroral Mapper (JIRAM) instrument and generated a 3D fly-around of the Jovian world’s north pole.

Imaging in the infrared part of the spectrum, JIRAM captures light emerging from deep inside Jupiter equally well, night or day. The instrument probes the weather layer down to 30 to 45 miles (50 to 70 kilometers) below Jupiter’s cloud tops.

9. A Highly Charged Atmosphere

Powerful bolts of lightning light up Jupiter’s clouds. In some ways its lightning is just like what we’re used to on Earth. In other ways, it’s very different. For example, most of Earth’s lightning strikes near the equator; on Jupiter, it’s mostly around the poles.

10. Extra Innings

In June, we approved an update to Juno’s science operations until July 2021. This provides for an additional 41 months in orbit around. Juno is in 53-day orbits rather than 14-day orbits as initially planned because of a concern about valves on the spacecraft’s fuel system. This longer orbit means that it will take more time to collect the needed science data, but an independent panel of experts confirmed that Juno is on track to achieve its science objectives and is already returning spectacular results. The spacecraft and all its instruments are healthy and operating nominally. ​

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The Science Behind the Summer Solstice

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Thursday, June 21 – is the summer solstice in the northern hemisphere. But what causes this change in seasons? And what exactly is a solstice? It’s all about Earth’s tilt!

Many people believe that Earth is closer to the Sun in the summer and that is why it is hotter. And, likewise, they think Earth is farthest from the Sun in the winter.

Although this idea makes sense, it is incorrect. There is a different reason for Earth’s seasons.

Earth’s axis is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth’s surface gets some of each.

Earth has seasons because its axis doesn’t stand up straight. Today, the north pole is tipped toward the Sun, and the south pole is tipped away from the Sun. The northern summer solstice is an instant in time when the north pole of the Earth points more directly toward the Sun than at any other time of the year. It marks the beginning of summer in the northern hemisphere and winter in the southern hemisphere.

To mark the beginning of summer, here are four ways to enjoy the many wonders of space throughout the season:

1. Spot the International Space Station

As the third brightest object in the sky, the International Space Station is easy to see if you know when to look up. Sign up to get alerts when the station is overhead: https://spotthestation.nasa.gov/. Visible to the naked eye, it looks like a fast-moving plane only much higher and traveling thousands of miles an hour faster!

2.  Treat your ears to space-related podcasts

From our “Gravity Assist” podcast that takes you on a journey through the solar system (including the Sun!) to our “NASA in Silicon Valley” podcast that provides an in-depth look at people who push the boundaries of innovation, we have podcast offerings that will suit everyone’s taste. For a full list of our podcasts, visit https://www.nasa.gov/podcasts.

3. Explore space by downloading NASA apps

Our apps for smartphones, tablets and digital media players showcase a huge collection of space-related content, including images, videos on-demand, NASA Television, mission information, feature stories, satellite tracking and much more. For a full list of our apps available for download, visit https://www.nasa.gov/connect/apps.html

4. Watch launches to space

This summer, we have multiple opportunities for you to take in the sights of spacecraft launches that will deliver supplies and equipment to astronauts living aboard the International Space Station, explore our solar system and much more. Be sure to mark your calendar for upcoming launches and landings!

 

 

 

 

What are white dwarfs?

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Some curiosities about white dwarfs, a stellar corpse and the future of the sun.

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Where a star ends up at the end of its life depends on the mass it was born with. Stars that have a lot of mass may end their lives as black holes or neutron stars.

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A white dwarf is what stars like the Sun become after they have exhausted their nuclear fuel. Near the end of its nuclear burning stage, this type of star expels most of its outer material, creating a planetary nebula.

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In 5.4 billion years from now, the Sun will enter what is known as the Red Giant phase of its evolution. This will begin once all hydrogen is exhausted in the core and the inert helium ash that has built up there becomes unstable and collapses under its own weight. This will cause the core to heat up and get denser, causing the Sun to grow in size.

It is calculated that the expanding Sun will grow large enough to encompass the orbit’s of Mercury, Venus, and maybe even Earth.

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A typical white dwarf is about as massive as the Sun, yet only slightly bigger than the Earth. This makes white dwarfs one of the densest forms of matter, surpassed only by neutron stars and black holes.

The gravity on the surface of a white dwarf is 350,000 times that of gravity on Earth.

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White dwarfs reach this incredible density because they are so collapsed that their electrons are smashed together, forming what is called “degenerate matter.” This means that a more massive white dwarf has a smaller radius than its less massive counterpart. Burning stars balance the inward push of gravity with the outward push from fusion, but in a white dwarf, electrons must squeeze tightly together to create that outward-pressing force. As such, having shed much of its mass during the red giant phase, no white dwarf can exceed 1.4 times the mass of the sun.

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While many white dwarfs fade away into relative obscurity, eventually radiating away all of their energy and becoming a black dwarf, those that have companions may suffer a different fate.

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If the white dwarf is part of a binary system, it may be able to pull material from its companion onto its surface. Increasing the mass can have some interesting results.

One possibility is that adding more mass to the white dwarf could cause it to collapse into a much denser neutron star.

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A far more explosive result is the Type 1a supernova. As the white dwarf pulls material from a companion star, the temperature increases, eventually triggering a runaway reaction that detonates in a violent supernova that destroys the white dwarf. This process is known as a single-degenerate model of a Type 1a supernova.

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If the companion is another white dwarf instead of an active star, the two stellar corpses merge together to kick off the fireworks. This process is known as a double-degenerate model of a Type 1a supernova.

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At other times, the white dwarf may pull just enough material from its companion to briefly ignite in a nova, a far smaller explosion. Because the white dwarf remains intact, it can repeat the process several times when it reaches the critical point, briefly breathing life back into the dying star over and over again.

 

NASA’s Spitzer Space Telescope

Images captured by NASA’s Spitzer Space Telescope. (Some images include data from other telescopes)

The Spitzer Space Telescope is the final mission in NASA’s Great Observatories Program – a family of four space-based observatories, each observing the Universe in a different kind of light. The other missions in the program include the visible-light Hubble Space Telescope (HST), Compton Gamma-Ray Observatory (CGRO), and the Chandra X-Ray Observatory (CXO).

The Cryogenic Telescope Assembly, which contains the a 85 centimeter telescope and Spitzer’s three scientific instruments

The Spacecraft, which controls the telescope, provides power to the instruments, handles the scientific data and communicates with Earth

It may seem like a contradiction, but NASA’s Spitzer Space Telescope must be simultaneously warm and cold to function properly. Everything in the Cryogenic Telescope Assembly must be cooled to only a few degrees above absolute zero (-459 degrees Fahrenheit, or -273 degrees Celsius). This is achieved with an onboard tank of liquid helium, or cryogen.  Meanwhile, electronic equipment in The Spacecraft portion needs to operate near room temperature.

Spitzer’s highly sensitive instruments allow scientists to peer into cosmic regions that are hidden from optical telescopes, including dusty stellar nurseries, the centers of galaxies, and newly forming planetary systems. Spitzer’s infrared eyes also allows astronomers see cooler objects in space, like failed stars (brown dwarfs), extrasolar planets, giant molecular clouds, and organic molecules that may hold the secret to life on other planets.

Spitzer was originally built to last for a minimum of 2.5 years, but it lasted in the cold phase for over 5.5 years. On May 15, 2009 the coolant was finally depleted and the Spitzer “warm mission” began.  Operating with 2 channels from one of its instruments called IRAC, Spitzer can continue to operate until late in this decade. Check out: Fast Facts and Current Status.

Credit NASA | images: NASA/Spitzer
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Solar System 10 Things to Know: Planetary Atmospheres

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Every time you take a breath of fresh air, it’s easy to forget you can safely do so because of Earth’s atmosphere. Life on Earth could not exist without that protective cover that keeps us warm, allows us to breathe and protects us from harmful radiation—among other things.

What makes Earth’s atmosphere special, and how do other planets’ atmospheres compare? Here are 10 tidbits:

1. On Earth, we live in the troposphere, the closest atmospheric layer to Earth’s surface. “Tropos” means “change,” and the name reflects our constantly changing weather and mixture of gases.

It’s 5 to 9 miles (8 to 14 kilometers) thick, depending on where you are on Earth, and it’s the densest layer of atmosphere. When we breathe, we’re taking in an air mixture of about 78 percent nitrogen, 21 percent oxygen and 1 percent argon, water vapor and carbon dioxide.

2. Mars has a very thin atmosphere, nearly all carbon dioxide. Because of the Red Planet’s low atmospheric pressure, and with little methane or water vapor to reinforce the weak greenhouse effect (warming that results when the atmosphere traps heat radiating from the planet toward space), Mars’ surface remains quite cold, the average surface temperature being about -82 degrees Fahrenheit (minus 63 degrees Celsius).

3. Venus’ atmosphere, like Mars’, is nearly all carbon dioxide. However, Venus has about 154,000 times more carbon dioxide in its atmosphere than Earth (and about 19,000 times more than Mars does), producing a runaway greenhouse effect and a surface temperature hot enough to melt lead. A runaway greenhouse effect is when a planet’s atmosphere and surface temperature keep increasing until the surface gets so hot that its oceans boil away.

4. Jupiter likely has three distinct cloud layers (composed of ammonia, ammonium hydrosulfide and water) in its “skies” that, taken together, span an altitude range of about 44 miles (71 kilometers). The planet’s fast rotation—spinning once every 10 hours—creates strong jet streams, separating its clouds into dark belts and bright zones wrapping around the circumference of the planet.

5. Saturn’s atmosphere—where our Cassini spacecraft ended its 13 extraordinary years of exploration of the planet—has a few unusual features. Its winds are among the fastest in the solar system, reaching speeds of 1,118 miles (1,800 kilometers) per hour. Saturn may be the only planet in our solar system with a warm polar vortex (a mass of swirling atmospheric gas around the pole) at both the North and South poles. Also, the vortices have “eye-wall clouds,” making them hurricane-like systems like those on Earth.

Another uniquely striking feature is a hexagon-shaped jet streamencircling the North Pole. In addition, about every 20 to 30 Earth years, Saturn hosts a megastorm (a great storm that can last many months).

6. Uranus gets its signature blue-green color from the cold methane gas in its atmosphere and a lack of high clouds. The planet’s minimum troposphere temperature is 49 Kelvin (minus 224.2 degrees Celsius), making it even colder than Neptune in some places. Its winds move backward at the equator, blowing against the planet’s rotation. Closer to the poles, winds shift forward and flow with the planet’s rotation.

7. Neptune is the windiest planet in our solar system. Despite its great distance and low energy input from the Sun, wind speeds at Neptune surpass 1,200 miles per hour (2,000 kilometers per hour), making them three times stronger than Jupiter’s and nine times stronger than Earth’s. Even Earth’s most powerful winds hit only about 250 miles per hour (400 kilometers per hour). Also, Neptune’s atmosphere is blue for the very same reasons as Uranus’ atmosphere.

8. WASP-39b, a hot, bloated, Saturn-like exoplanet (planet outside of our solar system) some 700 light-years away, apparently has a lot of water in its atmosphere. In fact, scientists estimate that it has about three times as much water as Saturn does.

9. A weather forecast on “hot Jupiters”—blistering, Jupiter-like exoplanets that orbit very close to their stars—might mention cloudy nights and sunny days, with highs of 2,400 degrees Fahrenheit (about 1,300 degrees Celsius, or 1,600 Kelvin). Their cloud composition depends on their temperature, and studies suggest that the clouds are unevenly distributed.

10. 55 Cancri e, a “super Earth” exoplanet (a planet outside of our solar system with a diameter between Earth’s and Neptune’s) that may be covered in lava, likely has an atmosphere containing nitrogen, water and even oxygen–molecules found in our atmosphere–but with much higher temperatures throughout. Orbiting so close to its host star, the planet could not maintain liquid water and likely would not be able to support life.

 

New Magnetic Process in Space

Just as gravity is one key to how things move on Earth, a process called magnetic reconnection is key to how electrically-charged particles speed through space. Now, our Magnetospheric Multiscale mission, or MMS, has discovered magnetic reconnection – a process by which magnetic field lines explosively reconfigure – occurring in a new and surprising way near Earth.
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Invisible to the eye, a vast network of magnetic energy and particles surround our planet — a dynamic system that influences our satellites and technology. The more we understand the way those particles move, the more we can protect our spacecraft and astronauts both near Earth and as we explore deeper into the solar system.

Earth’s magnetic field creates a protective bubble that shields us from highly energetic particles that stream in both from the Sun and interstellar space. As this solar wind bathes our planet, Earth’s magnetic field lines get stretched. Like elastic bands, they eventually release energy by snapping and flinging particles in their path to supersonic speeds.

That burst of energy is generated by magnetic reconnection. It’s pervasive throughout the universe — it happens on the Sun, in the space near Earth and even near black holes.

Scientists have observed this phenomenon many times in Earth’s vast magnetic environment, the magnetosphere. Now, a new study of data from our MMS mission caught the process occurring in a new and unexpected region of near-Earth space. For the first time, magnetic reconnection was seen in the magnetosheath — the boundary between our magnetosphere and the solar wind that flows throughout the solar system and one of the most turbulent regions in near-Earth space.

The four identical MMS spacecraft — flying through this region in a tight pyramid formation — saw the event in 3D. The arrows in the data visualization below show the hundreds of observations MMS took to measure the changes in particle motion and the magnetic field.

The data show that this event is unlike the magnetic reconnection we’ve observed before. If we think of these magnetic field lines as elastic bands, the ones in this region are much smaller and stretchier than elsewhere in near-Earth space — meaning that this process accelerates particles 40 times faster than typical magnetic reconnection near Earth. In short, MMS spotted a completely new magnetic process that is much faster than what we’ve seen before.

What’s more, this observation holds clues to what’s happening at smaller spatial scales, where turbulence takes over the process of mixing and accelerating particles. Turbulence in space moves in random ways and creates vortices, much like when you mix milk into coffee. The process by which turbulence energizes particles in space is still a big area of research, and linking this new discovery to turbulence research may give insights into how magnetic energy powers particle jets in space.

Keep up with the latest discoveries from the MMS mission: @NASASun on Twitter and Facebook.com/NASASunScience.

 

 

Cráteres de la Luna

 

1° From crater Theophilus (100km diameter) below to crater Langrenus above.

2° From bottom to top, dark titanium rich lava in the Sea of Fertility then the diamond shaped patch is the Marsh of Sleep. Small bright crater Proclus is thought to be a recent impact crater and has thrown out bright ejecta that is much lighter than the surrounding ancient weathered rock. Above is the rather hexagonal Mare Crisium.

3° From the Sinus Iridium top left through the Mare Imbrium with the Alpine Valley in the centre. (This original image is horizontal)

4° At the middle and bottom of this image, sunlight is shining on a mountain peak in the Alexander crater which lies beyond the day/night terminator.

Image credit: John Purvis