Voyager 1 Has Left the Solar System

Voyager 1 appears to have at long last left our solar system and entered interstellar space, says a University of Maryland-led team of researchers. (Credit: NASA)

Voyager 1 appears to have at long last left our solar system and entered interstellar space, says a University of Maryland-led team of researchers.

Carrying Earthly greetings on a gold plated phonograph record and still-operational scientific instruments -- including the Low Energy Charged Particle detector designed, built and overseen, in part, by UMD's Space Physics Group -- NASA's Voyager 1 has traveled farther from Earth than any other human-made object. And now, these researchers say, it has begun the first exploration of our galaxy beyond the Sun's influence.

"It's a somewhat controversial view, but we think Voyager has finally left the Solar System, and is truly beginning its travels through the Milky Way," says UMD research scientist Marc Swisdak, lead author of a new paper published online this week in The Astrophysical Journal Letters. Swisdak and fellow plasma physicists James F. Drake, also of the University of Maryland, and Merav Opher of Boston University have constructed a model of the outer edge of the Solar System that fits recent observations, both expected and unexpected.

Their model indicates Voyager 1 actually entered interstellar space a little more than a year ago, a finding directly counter to recent papers by NASA and other scientists suggesting the spacecraft was still in a fuzzily-defined transition zone between the Sun's sphere of influence and the rest of the galaxy.

why the controversy?

At issue is what the boundary-crossing should look like to Earth-bound observers 11 billion miles (18 billion kilometers) away. The Sun's envelope, known as the heliosphere, is relatively well-understood as the region of space dominated by the magnetic field and charged particles emanating from our star. The heliopause transition zone is both of unknown structure and location. According to conventional wisdom, we'll know we've passed through this mysterious boundary when we stop seeing solar particles and start seeing galactic particles, and we also detect a change in the prevailing direction of the local magnetic field.

NASA scientists recently reported that last summer, after eight years of travel through the outermost layer of the heliosphere, Voyager 1 recorded "multiple crossings of a boundary unlike anything previously observed." Successive dips in, and subsequent recovery of, solar particle counts caught researchers' attention. The dips in solar particle counts corresponded with abrupt increases in galactic electrons and protons. Within a month, solar particle counts disappeared, and only galactic particle counts remained. Yet Voyager 1 observed no change in the direction of the magnetic field.

To explain this unexpected observation, many scientists theorize that Voyager 1 has entered a "heliosheath depletion region," but that the probe is still within the confines of the heliosphere. Swisdak and colleagues, who are not part of the Voyager 1 mission science teams, say there is another explanation.

In previous work, Swisdak and Drake have focused on magnetic reconnection, or the breaking and reconfiguring of close and oppositely-directed magnetic field lines. It's the phenomenon suspected to lurk at the heart of solar flares, coronal mass ejections and many of the sun's other dramatic, high-energy events. The UMD researchers argue that magnetic reconnection is also key to understanding NASA's surprising data.

Though often depicted as a bubble encasing the heliosphere and its contents, the heliopause is not a surface neatly separating "outside" and "inside." In fact, Swisdak, Drake and Opher assert that the heliopause is both porous to certain particles and layered with complex magnetic structure. Here, magnetic reconnection produces a complex set of nested magnetic "islands," self-contained loops which spontaneously arise in a magnetic field due to a fundamental instability. Interstellar plasma can penetrate into the heliosphere along reconnected field lines, and galactic cosmic rays and solar particles mix vigorously.

Most interestingly, drops in solar particle counts and surges in galactic particle counts can occur across "slopes" in the magnetic field, which emanate from reconnection sites, while the magnetic field direction itself remains unchanged. This model explains observed phenomena from last summer, and Swisdak and his colleagues suggest that Voyager 1 actually crossed the heliopause on July 27, 2012.

Read the full NASA Voyager statement here:  NASA Voyager Statement about Competing Models to Explain Recent Spacecraft Data

Voyager Interstellar Mission :

In the 36th year after their 1977 launches, the twin Voyager 1 and 2 spacecraft continue exploring where nothing from Earth has flown before. Their primary mission was the exploration of Jupiter and Saturn. After making a string of discoveries there -- such as active volcanoes on Jupiter's moon Io and intricacies of Saturn's rings -- the mission was extended. Voyager 2 went on to explore Uranus and Neptune, and is still the only spacecraft to have visited those outer planets. The current mission for both spacecraft, the Voyager Interstellar Mission, is to explore the outermost edge of the Sun's domain and beyond. Both Voyagers are capable of returning scientific data from a full range of instruments, with adequate electrical power and attitude control propellant to keep operating until 2020. Voyager 2 is expected to enter interstellar space a few years after its twin. The Voyager spacecraft were built and continue to be operated by NASA's Jet Propulsion Laboratory, in Pasadena, Calif.

University of Maryland scientists lead the Deep Impact spacecraft science team and are part of the science teams of many of the other spacecraft exploring our Solar System, including both Voyagers and Cassini.

Source : University of Maryland.

By Science and Universe

: University of Maryland.By Science and Universe

A cometary graveyard

<<Image : These illustration show the asteroid belt in the present day and in the early Solar System, located between the Sun (at centre) and four terrestrial planets (near the Sun) and Jupiter (at bottom left). The top image shows the conventional model for the asteroid belt; largely composed of rocky material. The middle image shows the proposed model, with a small number of active comets and a dormant cometary population. The lower diagram shows how the asteroid belt might have looked in the early Solar System, with vigorous cometary activity. Credit: Ignacio Ferrin / University of Antioquia

A team of astronomers from the University of Anitoquia, Medellin, Colombia, have discovered a graveyard of comets. The researchers, led by Antioquia astronomer Prof. Ignacio Ferrin, describe how some of these objects, inactive for millions of years, have returned to life leading them to name the group the 'Lazarus comets'. The team publish their results in the Oxford University Press journal Monthly Notices of the Royal Astronomical Society.

Comets are amongst the smallest objects in the Solar System, typically a few km across and composed of a mixture of rock and ices. If they come close to the Sun, then some of the ices turn to gas, before being swept back by the light of the Sun and the solar wind to form a characteristic tail of gas and dust.

Most observed comets have highly elliptical orbits, meaning that they only rarely approach the Sun. Some of these so-called long period comets take thousands of years to complete each orbit around our nearest star. There is also a population of about 500 short period comets, created when long period comets pass near Jupiter and are deflected in orbits that last anything between 3 and 200 years. Although uncommon events, comets also collide with the Earth from time to time and may have helped bring water to our planet.

The new work looked at a third and distinct region of the Solar System, the main belt of asteroids between the orbits of Mars and Jupiter. This volume of space contains more than 1 million objects ranging in size from 1 m to 800 km. The traditional explanation for asteroids is that they are the building blocks of a planet that never formed, as the movement of the pieces was disrupted by the strong gravitational field of Jupiter.

In the last decade 12 active comets have been discovered in the asteroid main belt region. This was something of a surprise and the Medellin team set out to investigate their origin. The team, made up of Prof. Ferrin and his colleagues Profs. Jorge Zuluaga and Pablo Cuartas, now think they have an explanation.

"We found a graveyard of comets", exclaims Professor Ferrín. He adds: "Imagine all these asteroids going around the Sun for aeons, with no hint of activity. We have found that some of these are not dead rocks after all, but are dormant comets that may yet come back to life if the energy that they receive from the Sun increases by a few per cent."

Surprisingly, this can happy fairly easily, as the orbits of many objects in the asteroid belt are nudged by the gravity of Jupiter. The shape of their orbits can then change, leading to a decrease in the minimum distance between the object and the Sun (perihelion) and a slight increase in average temperature.

According to this interpretation, millions of years ago the main belt was populated by thousands of active comets. This population aged and the activity subsided. What we see today is the residual activity of that glorious past. Twelve of those rocks are true comets that were rejuvenated after their minimum distance from the Sun was reduced a little. The little extra energy they received from the Sun was then sufficient to revive them from the graveyard.

Prof. Ferrin describes the 12 active comets. "These objects are the 'Lazarus comets', returning to life after being dormant for thousands or even millions of years. Potentially any one of the many thousands of their quiet neighbours could do the same thing."

Article Source : Royal Astronomical Society (RAS).

By Science & Universe

Violent Sun

Human spaceflight and operations image of the week

Image << SWAP sees the Sun

The SWAP instrument on board ESA's Proba-2 sees the Sun, 30 July 2013, at 9:28:57.258 CEST. SWAP (Sun Watcher using Active Pixel System detector and Image Processing) is a small telescope that captures the solar corona at wavelengths corresponding to temperatures of about a million degrees (around 17.1 nanometers).

Credits: ESA/SWAP PROBA2 science centre

ESA’s Sun-watching Proba-2 satellite has been in orbit since November 2009, demonstrating a range of technologies and serving as a platform for scientific observations.

The 130-kg satellite carries two solar monitors. One is SWAP (Sun Watcher using Active Pixel System detector and Image Processing), a small telescope that captures the solar corona at wavelengths corresponding to temperatures of about a million degrees. The image above shows the latest SWAP image, from 30 July.

SWAP images are used to study the origin of solar phenomena, including solar flares and coronal mass ejections – massive eruptions of material into interplanetary space. Both are important sources of space weather, which profoundly affects the environmental conditions in Earth’s magnetosphere, ionosphere and thermosphere.

Space weather is not only of academic interest. In Europe’s economy today, numerous sectors are potentially affected by space weather, ranging from space-based telecommunications, broadcasting, weather services and navigation through to power distribution and terrestrial communications, especially at northern latitudes.

The satellite has been managed since 1 July by ESA’s Space Situational Awareness (SSA) programme, complementing support provided by ESA’s Science directorate for the Proba-2 Science Centre at the Royal Observatory Belgium.

Proba-2 data are used directly by the SSA Space Weather Coordination Centre at SpacePole, Brussels, to generate space weather products and services for a growing number of customers such as satellite operators, telecom and navigation users, and government agencies and research institutes.

Credits: ESA/SWAP PROBA2 science centre

NASA's IRIS Telescope Offers First Glimpse of Sun's Mysterious Atmosphere

These two images show a section of the sun as seen by NASA's Interface Region Imaging Spectrograph, or IRIS, on the right and NASA's SDO on the left. The IRIS image provides scientists with unprecedented detail of the lowest parts of the sun's atmosphere, known as the interface region.

Image Credit: 

NASA/SDO/IRIS

The moment when a telescope first opens its doors represents the culmination of years of work and planning -- while simultaneously laying the groundwork for a wealth of research and answers yet to come. It is a moment of excitement and perhaps even a little uncertainty. On July 17, 2013, the international team of scientists and engineers who supported and built NASA's Interface Region Imaging Spectrograph, or IRIS, all lived through that moment. As the spacecraft orbited around Earth, the door of the telescope opened to view the mysterious lowest layers of the sun's atmosphere and the results thus far are nothing short of amazing. The data is crisp and clear, showing unprecedented detail of this little-observed region.

"These beautiful images from IRIS are going to help us understand how the sun's lower atmosphere might power a host of events around the sun," said Adrian Daw, the mission scientist for IRIS at NASA's Goddard Space Flight Center in Greenbelt, Md. "Anytime you look at something in more detail than has ever been seen before, it opens up new doors to understanding. There's always that potential element of surprise."

As the telescope door opened on July 17, 2013, IRIS’s single instrument began to observe the sun in exceptional detail. IRIS’s first images showed a multitude of thin, fibril-like structures that have never been seen before, revealing enormous contrasts in density and temperature occur throughout this region even between neighboring loops that are only a few hundred miles apart. The images also show spots that rapidly brighten and dim, which provide clues to how energy is transported and absorbed throughout the region.

The IRIS images of fine structure in the interface region will help scientists track how magnetic energy contributes to heating in the sun’s atmosphere. Scientists need to observe the region in exquisite detail, because the energy flowing through it powers the upper layer of the sun’s atmosphere, the corona, to temperatures greater than 1 million kelvins (about 1.8 million F), almost a thousand times hotter than the sun's surface itself.

IRIS is a NASA Small Explorer mission that launched from Vandenberg Air Force Base, Calif., on June 27, 2013. IRIS's capabilities are uniquely tailored to unravel the interface region. Understanding the interface region is important because it forms the ultraviolet emission that impacts near-Earth space and Earth’s climate. Energy traveling through the region also helps drive the solar wind, which during extreme space weather events near Earth can affect satellites, power grids, and global positioning systems, or GPS.

Designed to research the interface region in more detail than has ever been done before, IRIS's instrument is a combination of an ultraviolet telescope and what's called a spectrograph. Light from the telescope is split into two components. The first provides high-resolution images, capturing data on about one percent of the sun at a time. While these are relatively small snapshots, the images can resolve very fine features, as small as 150 miles across.

While the images are of one wavelength of light at a time, the second component is the spectrograph that provides information about many wavelengths of light at once. The instrument splits the sun's light into its various wavelengths and measures how much of any given wavelength is present. This information is then portrayed on a graph showing spectral "lines." Taller lines correspond to wavelengths in which the sun emits relatively more light. Analysis of the spectral lines can also provide velocity, temperature and density, key information when trying to track how energy and heat moves through the region.

"The quality of images and spectra we are receiving from IRIS is amazing. This is just what we were hoping for," said Alan Title, IRIS principal investigator at the Lockheed Martin Advanced Technology Center Solar and Astrophysics Laboratory in Palo Alto, Calif. "There is much work ahead to understand what we're seeing, but the quality of the data will enable us to do that."

Not only does IRIS provide state-of-the-art observations to look at the interface region, it makes uses of advanced computing to help interpret what it sees. Indeed, interpreting the light flowing out of the interface region could not be done well prior to the advent of today's supercomputers because, in this area of the sun, the transfer and conversion of energy from one form to another is not understood.

The IRIS mission has long-term implications for understanding the genesis of space weather near Earth. Understanding how energy and solar material move through the interface region could help scientists improve forecasts for the kinds of events that can disrupt Earth technologies.

The IRIS Observatory was designed and the mission managed by Lockheed Martin. The Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., built the telescope. Montana State University in Bozeman, Mont. designed the spectrograph. NASA's Ames Research Center in Moffett Field, Calif., provides mission operations and ground data systems. Goddard manages the Small Explorer Program for NASA's Science Mission Directorate in Washington, D.C. The Norwegian Space Centre is providing regular downlinks of science data. Other contributors include the University of Oslo in Norway and Stanford University in Stanford, Calif.

For more information about the IRIS mission, visit: www.nasa.gov/iris

Source : NASA.GOV
By Science and Universe

Side-by-side solar eruptions

Two CMEs (coronal mass ejections) expanded side-by-side into space in less than a day (July 1-2, 2013). The first and smaller of the two slowly emerged directly above the Sun. The second and much larger, faster event, which was apparently triggered by a filament eruption, blossomed out to the left. Neither one was expected to have any impact on Earth. In these coronagraphs, a disk covers the Sun, which is represented by the white circle.

Two solar eruptions expand side-by-side into space in this movie, playing out in front of the ESA/NASA Solar and Heliospheric Observatory, SOHO, on 1–2 July 2013.

The eruptions were coronal mass ejections, or CMEs, huge clouds of magnetised plasma ejected from the Sun’s atmosphere – the corona – and launched into interplanetary space.

CMEs comprise millions of tonnes of gas and race away from the Sun at several million kilometres per hour.

In the event shown in this movie, one small CME slowly emerges directly above the Sun as seen by SOHO. Shortly after, a much larger, faster event bursts from the left, and together the CMEs expand into space.

The larger event was likely triggered as a solar filament became unstable and lifted away from the Sun. Filaments form in magnetic loops and suspend cool, dense gas above the solar surface.From above, filaments appear as dark lineaments against the hotter surface below, but in profile they form giant glowing loops called prominences. When their magnetic fields become unstable, they can trigger flares or CMEs.

Neither of these two CMEs interacted with Earth but when other events like these do, even a glancing blow to the planet’s magnetic field can ignite spectacular natural light displays – aurora – over the poles.

But in the most extreme events CMEs can cause much trouble, initiating geomagnetic storms that can result in regional power outages and communications blackouts.

The shaded disc at the centre of the image is a mask in SOHO’s LASCO instrument that blots out direct sunlight to allow study of the faint details in the Sun's corona. The white circle added within the disc shows the size and position of the visible Sun.
Video : 

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Side-by-side solar eruptions
This movie was first highlighted as the SOHO “Pick of the Week” on 5 July 2013.

Source : ESA
By Science and universe