Five Years of Great Discoveries for NASA's IBEX

During its first five years, IBEX has made some astounding discoveries

Image Credit: NASA's Goddard Space Flight Center

IBEX discovered a giant ribbon at the edge of the solar system, an anomaly that has now been determined to be a reflection where solar wind particles heading out into interstellar space are reflected back into the solar system by a galactic magnetic field. Image Credit: NASA/IBEX. View larger

IBEX found that Energetic Neutral Atoms, or ENAs, are coming from a region just outside Earth's magnetopause where nearly stationary protons from the solar wind interact with the tenuous cloud of hydrogen atoms in Earth's exosphere.Image Credit: NASA's Goddard Space Flight Center. View larger

A recent mapping of the heliotail shows it has two lobes of slower particles on the sides, faster particles above and below, with the entire structure twisted, as it experiences the pushing and pulling of magnetic fields outside the solar system.Image Credit: NASA's Goddard Space Flight Center. View larger

IBEX has found that there's more oxygen in our solar system than there is in the nearby interstellar material. Image Credit: NASA's Goddard Space Flight Center. View larger

Launched on Oct. 19, 2008, the Interstellar Boundary Explorer, or IBEX, spacecraft, is unique to NASA's heliophysics fleet: it images the outer boundary of the heliosphere, a boundary at the furthest edges of the solar system, far past the planets, some 8 million miles away. There, the constant stream of solar particles flowing off the sun, the solar wind, pushes up against the interstellar material flowing in from the local galactic neighborhood.

IBEX is also different because it creates images from particles instead of light. IBEX, scientists create maps from the observed neutral atoms. Some are of non-solar origin, others were created by collisions of solar wind particles with other neutral atoms far from the sun. Observing where these energetic neutral atoms, or ENAs, come from describes what's going on in these distant regions. Over the course of six months and many orbits around Earth, IBEX can paint a picture of the entire sky in ENAs. 

During its first five years, IBEX has made some astounding discoveries.

Mapping the Boundaries

In its first year, IBEX scientists created the first-ever all-sky map of the heliosphere's boundary, where the influence of the solar wind diminishes and interacts with the interstellar medium. The most startling finding is that the map was not uniform or symmetrical, but shows a bright ribbon of energetic neutral atoms snaking through it.

During its second and third years, IBEX showed that the heliosphere's boundaries changed more rapidly than expected, with variations as short as six months. Additional sets of all-sky maps showed the evolution of the interstellar boundary region: the mysterious ribbon feature at the nose, of the heliosphere – in the front as it moves through space – evolved.  Also, a knot-like feature spread and diminished. This variation over time is challenging scientists to try to understand how the heliosphere can change so rapidly.

ENAs Near Earth

Because IBEX is orbiting Earth, it also can look back toward Earth's neutral-atom environment and so has provided the first ENA images of the magnetosphere from the outside.

Nearby, IBEX has scanned the moon, as well. The moon has no atmosphere or magnetosphere, so the solar wind slams unimpeded into its surface. IBEX observations showed that the moon creates a backscattered, neutral solar wind: about 10 percent of the impinging solar-wind protons bounce off the lunar surface, becoming ENAs as they do.

The Heliosphere: Looking Ahead and Looking Behind

Measurements by IBEX announced in 2012 show the influence of the heliosphere on the local interstellar medium is different than expected. Previous models showed a boundary ahead of the heliosphere, outside the influence of the sun: a shock formed by the entire heliosphere pushing through the interstellar material around it. IBEX data suggests that there is no bow shock preceding the heliosphere's movement through space.

IBEX also offered up the first observations of the heliotail. If our eyes could see particles and we looked straight down the tail we would see an unexpected shape a little like a four-leaf clover. The two side leaves are filled with slow moving particles and the upper and lower leaves with fast ones.

Into the Galaxy

Much further away, IBEX also provided information about the local galactic environment. It made the first direct measurements of neutral hydrogen, oxygen, and neon coming into the heliosphere from the interstellar medium. The measurements show that the composition of the current galactic neighborhood is different than that of the sun and the solar system. This puzzle may mean that the sun has moved out of the region where it formed, or that some of the oxygen has been captured by dust in interstellar space.

IBEX also found that the speed of the galactic wind registered around 52 thousand miles per hour. By comparing this wind to previous results from other missions over the last 40 years, scientists believe that the direction of the wind has changed by about 7 degrees in the last four decades. While the cause of this shift is unknown, it may be telling us something about changing conditions as we move through our region of the Milky Way.

IBEX is a NASA Heliophysics Small Explorer mission. The Southwest Research Institute in San Antonio, Texas, leads IBEX with teams of national and international partners. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the Explorers Program for the agency's Science Mission Directorate in Washington.

Related Links

• NASA's IBEX website

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Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, Md. 

NASA Spacecraft Maps the Solar System's Tail

Other stars show tails that trail behind them like a comet’s tail. Scientists used NASA’s Interstellar Boundary Explorer to confirm that our solar system has one too. From top left and going counter clockwise, the stars shown are: LLOrionis; BZ Cam; and Mira. Image Credit: NASA/HST/R.Casalegno/GALEX 

Like a comet, the solar system has a tail. NASA's Interstellar Boundary Explorer (IBEX) has for the first time mapped out the structure of this tail, which is shaped like a four-leaf clover. 

Scientists describe the tail, called the heliotail, based on the first three years of IBEX imagery in a paper published in the July 10 edition of the Astrophysical Journal.

A new video from NASA explores the solar system's comet-like tail.  

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While telescopes have spotted such tails around other stars, it has been difficult to see whether our star produced one. The particles found in the tail -- and throughout the entire heliosphere, the region of space influenced by our sun -- do not shine, so they cannot be seen with conventional instruments. 

"By examining the neutral atoms, IBEX has made the first observations of the heliotail," said David McComas, IBEX principal investigator at Southwest Research Institute in San Antonio, Texas, and the paper's lead author. "Many models have suggested the heliotail might look like this or like that, but we have had no observations. We always drew pictures where the tail of the solar system just trailed off the page, since we couldn't even speculate about what it really looked like."

IBEX measures the neutral particles created by collisions at the solar system's boundaries. This technique, called energetic neutral atom imaging, relies on the fact that the paths of neutral particles are not affected by the solar magnetic field. Instead, the particles travel in a straight line from collision to IBEX. Consequently, observing where the neutral particles came from describes what is going on in these distant regions. 

"Since first light in 2008, the IBEX mission team has amazed us with its discoveries at the interstellar boundary, including a previously unknown ribbon of energetic neutral particles stretching across it," said Arik Posner, NASA's IBEX program scientist in Washington. "The new IBEX image of the heliotail fills in a previously blank area on the map. We are first-hand witnesses of rapid progress in heliophysics science."

By combining observations from the first three years of IBEX imagery, the team showed a tail with a combination of fast and slow moving particles. There are two lobes of slower particles on the sides and faster particles above and below. This four-leaf clover shape can be attributed to the fact that the sun has been sending out fast solar wind near its poles and slower wind near its equator for the last few years. This is a common pattern in the most recent phase of the sun's 11-year activity cycle. 

The clover shape does not align perfectly with the solar system, however. The entire shape is rotated slightly, indicating that as it moves further away from the sun and its magnetic influence, the charged particles begin to be nudged into a new orientation, aligning with the magnetic fields from the local galaxy.

Scientists do not know how long the tail is, but think that it eventually fades away and becomes indistinguishable from the rest of interstellar space. Scientists are testing their current computer simulations of the solar system against the new observations to improve our understanding of the comet-like tail streaming out behind us.

For more information about the IBEX mission, visit: http://www.nasa.gov/ibex

Credits: Production editor: Dr. Tony Phillips | Credit: Science@NASA

More information:

IBEX is a NASA Heliophysics Small Explorer mission. The Southwest Research Institute leads IBEX with a team of national and international partners. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the Explorers Program for NASA's Science Mission Directorate in Washington. 

 

  
Source: NASA's Science News

A Major Step Forward in Explaining the Ribbon in Space Discovered by NASA’s IBEX Mission

 

In 2009, NASA's Interstellar Boundary Explorer (IBEX) mission science team constructed the first-ever all-sky map of the interactions occurring at the edge of the solar system, where the sun's influence diminishes and interacts with the interstellar medium. A 2013 paper provides a new explanation for a giant ribbon of energetic neutral atoms – shown here in light green and blue -- streaming in from that boundary. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio. › View larger

The vast edges of our solar system – the boundary at the edge of our heliosphere where material streaming out from the sun interacts with the galactic material – is essentially invisible. It emits no light and no conventional telescope can see it. However, particles from inside the solar system bounce off this boundary and neutral atoms from that collision stream inward. Those particles can be observed by instruments on NASA’s Interstellar Boundary Explorer (IBEX). Since those atoms act as fingerprints for the boundary from which they came, IBEX can map that boundary in a way never before done. In 2009, IBEX saw something in that map that no one could explain: a vast ribbon dancing across this boundary that produced many more energetic neutral atoms than the surrounding areas.

Scientists did not know what processes at the edge of the solar system could cause this mysterious increase in neutral atoms, or why any part of the boundary should be different from any other. In the years since, scientists have devised models and theories to try to explain the ribbon and now, building on earlier interpretations scientists have added a new hypothesis to help solve this puzzle.

In a paper published in the Astrophysical Journal, researchers propose a “retention theory” that for the first time explains the key observation of the unexplained ribbon’s width. The paper appeared online on Feb. 4, 2013.

Indeed, since the discovery of the ribbon, over a dozen competing theories seeking to explain the phenomenon have been put forth. The new theory builds on one that was first published along with the discovery of the ribbon in 2009 and then quantitatively simulated in 2010. This theory posited that the ribbon exists in a special location where neutral hydrogen atoms from the solar wind cross the local galactic magnetic field. Neutral atoms are not affected by magnetic fields, but when their electrons get stripped away they become charged ions and begin to gyrate rapidly around magnetic field lines. This process frequently aims ions back toward the sun. So those ions that pick up electrons at the right time might explain the extra boost of neutral atoms that create the ribbon. The problems were that physical processes might break down the distribution needed for it to work and that models based on this process showed a ribbon narrower than IBEX observed.

The new theory adds a key process: That rapid rotation creates waves or vibrations in the magnetic field, and the charged ions then become physically trapped in a region by these waves, which in turn would amplify the ion density and produce the broader ribbon seen.

"Think of the ribbon as a harbor and the solar wind particles it contains as boats," says Nathan Schwadron, the first author on the paper and scientist at The University of New Hampshire, Durham. “The boats can be trapped in the harbor if the ocean waves outside it are powerful enough. This is the nature of the new ribbon model. The ribbon is a region where particles, originally from the solar wind, become trapped or retained due to intense waves and vibrations in the magnetic field."

Models done with these waves taken into account agree with the available observations, and the mathematical modeling results look remarkably like what the ribbon actually looks like, says Schwadron.

“This is a perfect example of the scientific process," says David McComas, who is the other author on the paper and the principal investigator for the IBEX mission at the Southwest Research Institute in San Antonio, Texas. "We observe something completely new and unexpected with IBEX, develop various hypotheses to explain the observations, and then develop mathematical models to try to validate the hypotheses.”

Although the retention theory may check all the boxes, the IBEX team is still far from claiming that the ribbon is fully explained. A major test for the retention theory will be watching how the ribbon changes in step with observed changes in the solar wind.

"What we are learning with IBEX is that the interaction between the sun's magnetic fields and the galactic magnetic field is much more complicated than we previously thought," says Eric Christian, the mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. "By modifying an earlier model, this paper provides the best explanation so far for the ribbon IBEX is seeing."

If the theory is correct, points out Schwadron, it will help us understand more about how our heliosphere interacts with the rest of the universe. “The ribbon can be used to tell us how we’re moving through the magnetic fields of the interstellar medium and how those magnetic fields then influence our space environment,” he says.

IBEX is the latest in NASA’s series of low-cost, rapidly developed Small Explorer space missions. Southwest Research Institute in San Antonio, TX leads the IBEX mission with teams of national and international partners. NASA’s Goddard Space Flight Center in Greenbelt, Md. manages the Explorers Program for the Heliophysics Division of NASA’s Science Mission Directorate in Washington, D.C.

For more information about the IBEX mission, go to:  › http://www.nasa.gov/ibex

 

Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, MD 

IBEX Reveals a Missing Boundary At the Edge Of the Solar System

IBEX studies the outer reaches of the solar system by observing neutral atoms that cross or bounce off of its boundaries. Credit: NASA/Goddard Space Flight Center. Download video


For the last few decades, space scientists have generally accepted that the bubble of gas and magnetic fields generated by the sun – known as the heliosphere – moves through space, creating three distinct boundary layers that culminate in an outermost bow shock. This shock is similar to the sonic boom created ahead of a supersonic jet. Earth itself certainly has one of these bow shocks on the sunward side of its magnetic environment, as do most other planets and many stars. A collection of new data from NASA's Interstellar Boundary Explorer (IBEX), however, now indicate that the sun does not have a bow shock.

In a paper appearing online in Science Express on May 10, 2012, scientists compile data from IBEX, NASA's twin Voyager spacecraft, and computer models to show that the heliosphere just isn't moving fast enough to create a bow shock in the tenuous and highly magnetized region in our local part of the galaxy.

"IBEX gives a global view. It shows the whole of this region," says Eric Christian who is the mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. and who was formerly the program scientist for Voyager. "At the same time the Voyager spacecraft are actually there, in situ, measuring its environment at two locations. The combination of IBEX and Voyager gives you great science and now the new IBEX results strongly indicate that there is no bow shock."

Since the 1980s, the boundaries of the heliosphere have largely been assumed to be a series of three. The first is a fairly spherical boundary called the termination shock -- the point where the solar wind streaming from the sun slows down below supersonic speeds. From there the wind continues more slowly until it collides with the material in the rest of the galaxy and is pushed back, deflecting around the outskirts of the heliosphere, streaming back toward the tail of the moving bubble. This second boundary is called the heliopause. The third boundary was thought to be the bow shock, formed as the heliosphere plowed its way through the local galactic cloud the same way a supersonic jet pushes aside the air as it moves.

The heliosphere surrounding our solar system is buffeted by strong magnetic fields, shown here as the black, diagonal, upward-pointing arrows. The heliosphere and the interstellar material of the local cloud pass by each other at a speed of 52,000 miles per hour, as shown by the blue arrow. The density of the material and the ramming pressures of the magnetic field coupled with the relatively slow speed of the heliosphere add up to indicate that there is no bow shock at the front of the heliosphere. Credit: SWRI. View larger

The two Voyager spacecraft have confirmed the existence of the first boundary, and have seen evidence for the second as they move toward it. However, each Voyager spacecraft has seen different things on their respective trips – one moving in a more northerly direction, one moving more to the south. They've encountered different regions at different distances from the sun, suggesting the very shape of the heliosphere is squashed and asymmetrical. Scientists believe this asymmetry is caused by the force and direction of magnetic fields ramming into the heliosphere from outside, the same way a hand pushing on a balloon will force it out of shape. This was the first clue that there's a strong magnetic field exerting pressure on the outskirts of the solar system. Independently, IBEX has seen a well-defined band, or ribbon, at the edge of the heliosphere, believed to be defined by this external magnetic field. Other studies from IBEX have helped quantify the magnitude of the magnetic field, showing that it is on the strong end of what was previously thought possible.

Stars travel through the galaxy surrounded by a bubble of charged gas and magnetic fields, rounded at the front and trailing into a long tail behind. The bubble is called an astrosphere, or -- in the case of the one around our sun -- a heliosphere. This image shows a few examples of astrospheres that are very strong and therefore visible. Credit: NASA/Goddard Space Flight Center. View larger

"We've seen one after another signature of a very strong magnetic field in the galactic environment," says Nathan Schwadron, a space scientist at the University of New Hampshire in Durham who is one of the authors on the paper. "That magnetic field influences the structure of the heliosphere and the boundaries themselves. That leads to a whole new paradigm."

Along with increased evidence for a strong external magnetic field, IBEX has also provided a new measurement for the speed of the heliosphere itself with respect to the local cloud.

"We recently analyzed two years worth of IBEX data, and they showed that the speed of the heliosphere – with respect to the local cloud of material – is only 52,000 miles per hour, instead of the previously believed 59,000," says David McComas at the Southwest Research Institute in San Antonio, Texas, who is first author on this paper and also the principal investigator for IBEX. "That might not seem like a huge difference, but it translates to a quarter less pressure exerted on the boundaries of the heliosphere. This means there's a very different interaction, a much weaker interaction, than previously thought."

In essence, it means that, like an airplane going too slowly to produce a sonic boom, the heliosphere isn't moving fast enough to create a bow shock, given the density and pressures of the material its moving through.

The heliosphere's boundaries lie roughly 10 billion miles away from Earth, but are nonetheless crucial for understanding our place in the universe. Indeed, the heliopause provides some protection for our solar system from the harsh, radiation environment surrounding it. By knowing the nature of these boundaries, scientists can start to better understand the propagation of particles that do have enough energy and speed to make it into our environment.

As scientists incorporate this substantive new understanding into their physical models, they will also be waiting for more evidence from both IBEX and the Voyagers, which they hope will continue to send back observations for many years to come.

"Imagine the point at which Voyager crosses the threshold of the heliopause and either does or does not see what IBEX is predicting," says Schwadron. "There will be enormous opportunities for scientific advancement."

For more information about the IBEX mission, go to:
http://www.nasa.gov/ibex


Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, MD

IBEX: Glimpses of the Interstellar Material Beyond our Solar System

IBEX has directly sampled multiple heavy elements from the Local Interstellar Cloud for the first time. Credit: NASA/Goddard Scientific Visualization Studio. Download video

A great magnetic bubble surrounds the solar system as it cruises through the galaxy. The sun pumps the inside of the bubble full of solar particles that stream out to the edge until they collide with the material that fills the rest of the galaxy, at a complex boundary called the heliosheath. On the other side of the boundary, electrically charged particles from the galactic wind blow by, but rebound off the heliosheath, never to enter the solar system. Neutral particles, on the other hand, are a different story. They saunter across the boundary as if it weren't there, continuing on another 7.5 billion miles for 30 years until they get caught by the sun's gravity, and sling shot around the star.

There, NASA's Interstellar Boundary Explorer lies in wait for them. Known as IBEX for short, this spacecraft methodically measures these samples of the mysterious neighborhood beyond our home. IBEX scans the entire sky once a year, and every February, its instruments point in the correct direction to intercept incoming neutral atoms. IBEX counted those atoms in 2009 and 2010 and has now captured the best and most complete glimpse of the material that lies so far outside our own system.

The results? It's an alien environment out there: the material in that galactic wind doesn't look like the same stuff our solar system is made of.

Neutral atoms from the galactic wind sweep past the solar system's magnetic boundary, the heliosheath, and travel some 30 years into our solar system toward the sun. NASA's Interstellar Boundary Explorer (IBEX) can observe those atoms and provide information about the mysterious neighborhood outside our home. Credit: NASA/Goddard Conceptual Image Lab. Download video

"We've directly measured four separate types of atoms from interstellar space and the composition just doesn't match up with what we see in the solar system," says Eric Christian, mission scientist for IBEX at NASA's Goddard Space Flight Center in Greenbelt, Md. "IBEX's observations shed a whole new light on the mysterious zone where the solar system ends and interstellar space begins."

More than just helping to determine the distribution of elements in the galactic wind, these new measurements give clues about how and where our solar system formed, the forces that physically shape our solar system, and even the history of other stars in the Milky Way.

NASA's Interstellar Boundary Explorer (IBEX) has found that there's more oxygen in our solar system than there is in the nearby interstellar material. That suggests that either the sun formed in a different part of the galaxy or that outside our solar system life-giving oxygen lies trapped in dust or ice grains unable to move freely in space. Credit: NASA/Goddard. View larger

In a series of science papers appearing in the Astrophysics Journal on January 31, 2012, scientists report that for every 20 neon atoms in the galactic wind, there are 74 oxygen atoms. In our own solar system, however, for every 20 neon atoms there are 111 oxygen atoms. That translates to more oxygen in any given slice of the solar system than in the local interstellar space.

"Our solar system is different than the space right outside it and that suggests two possibilities," says David McComas the principal investigator for IBEX at the Southwest Research Institute in San Antonio, Texas. "Either the solar system evolved in a separate, more oxygen-rich part of the galaxy than where we currently reside or a great deal of critical, life-giving oxygen lies trapped in interstellar dust grains or ices, unable to move freely throughout space." Either way, this affects scientific models of how our solar system – and life – formed.

Studying the galactic wind also provides scientists with information about how our solar system interacts with the rest of space, which is congruent with an important IBEX goal. Classified as a NASA Explorer Mission -- a class of smaller, less expensive spacecraft with highly focused research objectives -- IBEX's main job is to study the heliosheath, that outer boundary of the solar system's magnetic bubble -- or heliosphere -- where particles from the solar wind meet the galactic wind.

Previous spacecraft have already provided some information about the way the galactic wind interacts with the heliosheath. Ulysses, for one, observed incoming helium as it traveled past Jupiter and measured it traveling at 59,000 miles per hour. IBEX's new information, however, shows the galactic wind traveling not only at a slower speed -- around 52,000 miles per hour -- but from a different direction, most likely offset by some four degrees from previous measurements. Such a difference may not initially seem significant, but it amounts to a full 20% difference in how much pressure the galactic wind exerts on the heliosphere.

The galactic wind streams toward the sun from the direction of Scorpio and IBEX has found that it travels at 52,000 miles an hour. The speed of the galactic wind and its subsequent pressure on the outside of the solar system's boundary affects the shape of the heliosphere as it travels through space. Credit: NASA/Goddard Scientific Visualization Studio. View larger

"Measuring the pressure on our heliosphere from the material in the galaxy and from the magnetic fields out there," says Christian, "will help determine the size and shape of our solar system as it travels through the galaxy."

These IBEX measurements also provide information about the cloud of material in which the solar system currently resides. This cloud is called the local interstellar cloud, to differentiate it from the myriad of particle clouds throughout the Milky Way, each traveling at different speeds. The solar system and its heliosphere moved into our local cloud at some point during the last 45,000 years.

Since the older Ulysses observations of the galactic wind speed was in between the speeds expected for the local cloud and the adjacent cloud, researchers thought perhaps the solar system didn't lie smack in the middle of this cloud, but might be at the boundary, transitioning into a new region of space. IBEX's results, however, show that we remain fully in the local cloud, at least for the moment.

"Sometime in the next hundred to few thousand years, the blink of an eye on the timescales of the galaxy, our heliosphere should leave the local interstellar cloud and encounter a much different galactic environment," McComas says.

In addition to providing insight into the interaction between the solar system and its environment, these new results also hold clues about the history of material in the universe. While the big bang initially created hydrogen and helium, only the supernovae explosions at the end of a giant star's life can spread the heavier elements of oxygen and neon through the galaxy. Knowing the amounts of such elements in space can help map how the galaxy has evolved and changed over time.

NASA's Interstellar Boundary Explorer (IBEX) studies the outer boundaries of the solar system where particles from the solar wind collide with particles from the galactic wind. Credit: NASA. View larger

"This set of papers provide many of the first direct measurements of the interstellar medium around us," says McComas. "We've been trying to understand our galaxy for a long time, and with all of these observations together, we are taking a major step forward in knowing what the local part of the galaxy is like."

Voyager 1 could cross out of our solar system within the next few years. By combining the data from several sets of NASA instruments – Ulysses, Voyager, IBEX and others – we are on the precipice of stepping outside and understanding the complex environment beyond our own frontier for the first time.

The Southwest Research Institute developed and leads the IBEX mission with a team of national and international partners. The spacecraft is one of NASA's series of low-cost, rapidly developed missions in the Small Explorers Program. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the program for the agency's Science Mission Directorate.

For more information about the IBEX mission, go to:

http://www.nasa.gov/ibex - Additional downloadable media

Karen C. Fox
NASA's Goddard Space Flight Center, Greenbelt, MD

IBEX Explores Galactic Frontier, Releases First-Ever All-Sky Map

This animation portrays how the entire sky is flattened to the two-dimensional maps that IBEX presents. Credit: NASA/Goddard Space Flight Center

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This animation zooms in from a view of the Milky Way Galaxy to our heliosphere. It sets the scale for our home in the galaxy. Credit: NASA/Goddard Space Flight Center

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NASA's Interstellar Boundary Explorer, or IBEX, spacecraft has made it possible for scientists to construct the first comprehensive sky map of our solar system and its location in the Milky Way galaxy. The new view will change the way researchers view and study the interaction between our galaxy and sun.

The sky map was produced with data that two detectors on the spacecraft collected during six months of observations. The detectors measured and counted particles scientists refer to as energetic neutral atoms.

The energetic neutral atoms are created in an area of our solar system known as the interstellar boundary region. This region is where charged particles from the sun, called the solar wind, flow outward far beyond the orbits of the planets and collide with material between stars. The energetic neutral atoms travel inward toward the sun from interstellar space at velocities ranging from 100,000 mph to more than 2.4 million mph. This interstellar boundary emits no light that can be collected by conventional telescopes.

The new map reveals the region that separates the nearest reaches of our galaxy, called the local interstellar medium, from our heliosphere -- a protective bubble that shields and protects our solar system from most of the dangerous cosmic radiation traveling through space.

"For the first time, we're sticking our heads out of the sun's atmosphere and beginning to really understand our place in the galaxy," said David J. McComas, IBEX principal investigator and assistant vice president of the Space Science and Engineering Division at Southwest Research Institute in San Antonio. "The IBEX results are truly remarkable, with a narrow ribbon of bright details or emissions not resembling any of the current theoretical models of this region."

NASA released the sky map image Oct. 15 in conjunction with publication of the findings in the journal Science. The IBEX data were complemented and extended by information collected using an imaging instrument sensor on NASA's Cassini spacecraft. Cassini has been observing Saturn, its moons and rings since the spacecraft entered the planet's orbit in 2004.

The IBEX sky maps also put observations from NASA's Voyager spacecraft into context. The twin Voyager spacecraft, launched in 1977, traveled to the outer solar system to explore Jupiter, Saturn, Uranus and Neptune. In 2007, Voyager 2 followed Voyager 1 into the interstellar boundary. Both spacecraft are now in the midst of this region where the energetic neutral atoms originate. However, the IBEX results show a ribbon of bright emissions undetected by the two Voyagers.

"The Voyagers are providing ground truth, but they're missing the most exciting region," said Eric Christian, the IBEX deputy mission scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "It's like having two weather stations that miss the big storm that runs between them."

The IBEX spacecraft was launched in October 2008. Its science objective was to discover the nature of the interactions between the solar wind and the interstellar medium at the edge of our solar system. The Southwest Research Institute developed and leads the mission with a team of national and international partners. The spacecraft is the latest in NASA's series of low-cost, rapidly developed Small Explorers Program. NASA's Goddard Space Flight Center manages the program for the agency's Science Mission Directorate at NASA Headquarters in Washington.

The Cassini-Huygens mission is a cooperative project of NASA and the European and Italian Space Agencies. NASA's Jet Propulsion Laboratory in Pasadena, Calif., provides overall management for Cassini and the Voyagers for the Science Mission Directorate.

Related Links:

Press Release
IBEX Briefing Visuals