Voyager 1: Is It In or Is It Out?

Nearly 18.7 billion kilometers from Earth — about 17 light-hours away — NASA’s Voyager 1 spacecraft is just about on the verge of entering interstellar space, a wild and unexplored territory of high-energy cosmic particles into which no human-made object has ever ventured. Launched in September 1977, Voyager 1 will soon become the first spacecraft to officially leave the Solar System.

Or has it already left?

I won’t pretend I haven’t heard it before: Voyager 1 has left the Solar System! Usually followed soon after by: um, no it hasn’t. And while it might all seem like an awful lot of flip-flopping by supposedly-respectable scientists, the reality is there’s not a clear boundary that defines the outer limits of our Solar System. It’s not as simple as Voyager rolling over a certain mileage, cruising past a planetary orbit, or breaking through some kind of discernible forcefield with a satisfying “pop.” (Although that would be cool.)

The outer edge of the heliosphere has been found to contain many different regions, which Voyager 1 has been passing through since 2004. (NASA/JPL-Caltech)
The outer edge of the heliosphere has been found to contain many different regions, which Voyager 1 has been passing through since 2004. (NASA/JPL-Caltech)

Rather, scientists look at Voyager’s data for evidence of a shift in the type of particles detected. Within the transitionary zone that the spacecraft has most recently been traveling through, low-energy particles from the Sun are outnumbered by higher-energy particles zipping through interstellar space, also called the local interstellar medium (LISM). Voyager’s instruments have been detecting dramatic shifts in the concentrations of each for over a year now, unmistakably trending toward the high-energy end — or at least showing a severe drop-off in solar particles — and researchers from the University of Maryland are claiming that this, along with their model of a porous solar magnetic field, indicates Voyager has broken on through to the other side.

Read more: Voyagers Find Giant Jacuzzi-like Bubbles at Edge of Solar System

“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,” said Marc Swisdak, UMD research scientist and lead author of a new paper published this week in The Astrophysical Journal Letters.

According to Swisdak, fellow UMD plasma physicist James F. Drake, and Merav Opher of Boston University, their model of the outer edge of the Solar System  fits recent Voyager 1 observations — both expected and unexpected. In fact, the UMD-led team says that Voyager passed the outer boundary of the Sun’s magnetic influence, aka the heliopause… last year.

Read more: Winds of Change at the Edge of the Solar System

But, like some of last year’s claims, these conclusions aren’t shared by mission scientists at NASA.

“Details of a new model have just been published that lead the scientists who created the model to argue that NASA’s Voyager 1 spacecraft data can be consistent with entering interstellar space in 2012,” said Ed Stone, Voyager project scientist at Caltech, in a press release issued today. “In describing on a fine scale how magnetic field lines from the sun and magnetic field lines from interstellar space can connect to each other, they conclude Voyager 1 has been detecting the interstellar magnetic field since July 27, 2012. Their model would mean that the interstellar magnetic field direction is the same as that which originates from our sun.

The famous "Golden Record" carried aboard both Voyager 1 and 2 contains images, sounds and greetings from Earth. (NASA)
The famous “Golden Record” carried aboard both Voyager 1 and 2 contains images, sounds and greetings from Earth. (NASA)

“Other models envision the interstellar magnetic field draped around our solar bubble and predict that the direction of the interstellar magnetic field is different from the solar magnetic field inside. By that interpretation, Voyager 1 would still be inside our solar bubble.”

Stone says that further discussion and investigation will be needed to “reconcile what may be happening on a fine scale with what happens on a larger scale.”

Whether still within the Solar System — however it’s defined — or outside of it, the bottom line is that the venerable Voyager spacecraft are still conducting groundbreaking research of our cosmic neighborhood, 36 years after their respective launches and long after their last views of the planets. And that’s something nobody can argue about.

“The Voyager 1 spacecraft is exploring a region no spacecraft has ever been to before. We will continue to look for any further developments over the coming months and years as Voyager explores an uncharted frontier.”

– Ed Stone, Voyager project scientist

Built by JPL and launched in 1977, both Voyagers are still capable of returning scientific data from a full range of instruments, with adequate power and propellant to remain operating until 2020.

Read the full UMD news release here, and find out more about the Voyager mission on the NASA/JPL website here.

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Note: The definition of “Solar System” used in this article is in reference to the Sun’s magnetic influence, the heliosphere, and all that falls within its outermost boundary, the heliopause (wherever that is.) Objects farther out are still gravitationally held by the Sun, such as distant KBOs and Oort Cloud comets, but orbit within the interstellar medium. 

NASA Probes Play the Music of Earth’s Magnetosphere

Launched on August 30, 2012, NASA’s twin Radiation Belt Storm Probe (RBSP) satellites have captured recordings of audible-range radio waves emitted by Earth’s magnetosphere. The stream of chirps and whistles heard in the video above consist of 5 separate occurrences captured on September 5 by RBSP’s Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument.

The events are presented as a single continuous recording, assembled by the (EMFISIS) team at the University of Iowa and NASA’s Goddard Space Flight Center.

Called a “chorus”, this phenomenon has been known for quite some time.

“People have known about chorus for decades,” says EMFISIS principal investigator Craig Kletzing of the University of Iowa. “Radio receivers are used to pick it up, and it sounds a lot like birds chirping. It was often more easily picked up in the mornings, which along with the chirping sound is why it’s sometimes referred to as ‘dawn chorus.’”

The radio waves, which are at frequencies that are audible to the human ear, are emitted by energetic particles within Earth’s magnetosphere, which in turn affects (and is affected by) the radiation belts.

The RBSP mission placed a pair of identical satellites into eccentric orbits that will take them from as low as 375 miles (603 km) to as far out as 20,000 miles (32,186 km). During their orbits the satellites will pass through both the stable inner and more variable outer Van Allen belts, one trailing the other. Along the way they’ll investigate the many particles that make up the belts and identify what sort of activity occurs in isolated locations — as well as across larger areas.

Read: New Satellites Will Tighten Knowledge of Earth’s Radiation Belts

Audio Credit: University of Iowa. Visualisation Credit: NASA/Goddard Space Flight Center. (H/T to Peter Sinclair at climatecrocks.com.)

New Satellites Will Tighten Knowledge of Earth’s Radiation Belts


Surrounding our planet like vast invisible donuts (the ones with the hole, not the jelly-filled kind) are the Van Allen radiation belts, regions where various charged subatomic particles get trapped by Earth’s magnetic fields, forming rings of plasma. We know that the particles that make up this plasma can have nasty effects on spacecraft electronics as well as human physiology, but there’s a lot that isn’t known about the belts. Two new satellites scheduled to launch on August 23 August 24 will help change that.

“Particles from the radiation belts can penetrate into spacecraft and disrupt electronics, short circuits or upset memory on computers. The particles are also dangerous to astronauts traveling through the region. We need models to help predict hazardous events in the belts and right now we are aren’t very good at that. RBSP will help solve that problem.”
– David Sibeck, RBSP project scientist, Goddard Space Flight Center

NASA’s Radiation Belt Storm Probes (RBSP) mission will put a pair of identical satellites into eccentric orbits that take them from as low as 375 miles (603 km) to as far out as 20,000 miles (32,186 km). During their orbits the satellites will pass through both the stable inner and more variable outer Van Allen belts, one trailing the other. Along the way they’ll investigate the many particles that make up the belts and identify what sort of activity occurs in isolated locations and across larger areas.

“Definitely the biggest challenge that we face is the radiation environment that the probes are going to be flying through,” said Mission Systems Engineer Jim Stratton at APL. “Most spacecraft try to avoid the radiation belts — and we’re going to be flying right through the heart of them.”

Read: The Van Allen Belts and the Great Electron Escape

Each 8-sided RBSP satellite is approximately 6 feet (1.8 meters) across and weighs 1,475 pounds (669 kg).

The goal is to find out where the particles in the belts originate from — do they come from the solar wind? Or Earth’s own ionosphere? — as well as to find out what powers the belts’ variations in size and gives the particles their extreme speed and energy. Increased knowledge about Earth’s radiation belts will also help in the understanding of the plasma environment that pervades the entire Universe.

Read: What Are The Radiation Belts?

Ultimately the information gathered by the RBSP mission will help in the design of future science and communications satellites as well as safer spacecraft for human explorers.

The satellites are slated to launch aboard a United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station no earlier than 4:08 a.m. EDT on August 24.

Find out more about the RBSP mission here.

Video/rendering: NASA/GSFC.

Incoming! CME On Its Way Toward Earth

As you read this, a huge cloud of charged solar particles is speeding toward our planet, a coronal mass ejection resulting from the X1.4-class flare that erupted from sunspot 1520 on July 12. The CME is expected to collide with Earth’s magnetic field on Saturday, potentially affecting satellite operations and tripping alarms on power grids, as well as boosting auroral activity. It’s on its way, and all we can do is wait. (Thank goodness for magnetospheres!)

Actually, the effects from the incoming CME aren’t expected to be anything particularly dramatic. NOAA is predicting a geomagnetic storm level raging from G2 to G4, which although ranges from “moderate” to “severe” a G2 (Kp = 6) is most likely, according to Dr. C. Alex Young from NASA’s Goddard Space Flight Center.

[Read: What Is a CME?]

“A G2 level storm can cause some power fluctuations that may set off some voltage alarms for power companies,” Dr. Young told Universe Today. “Damage to transformers is possible for longer events, but unlikely. Satellite companies may have to make some orbit corrections for their satellites, and at higher latitudes where there are aurora they can be some disruption of high frequency radio broadcasts.

“All in all the effects should be minor,” he concluded.

And this may not be the last we hear from 1520, either.

“Its complexity has decreased but it is still large and has a ‘delta’ configuration,” added Dr. Young, “when there is opposite polarity magnetic field of the umbra within the penumbra of the sunspot. This is an unstable configuration that is indicative of larger releases of energy, lots of flares — in particular M and X flares.”

Below is a computer model of the CME from Goddard Space Weather Center. Impact with Earth is expected on 7/14 at 10:20 UT (+-7 hrs), 6:20 am EDT.

Auroras may be visible at lower latitudes this weekend, so check the NOAA’s updated auroral oval map to see if visibility extends into your area over the next several nights. Hopefully aurora photographers around the world will be able to get some great photos of a summer sky show!

You can keep up with the latest news on solar activity on Dr. Young’s blog, The Sun Today. And of course, stay tuned to Universe Today for more updates on any noteworthy space weather!

The video below uses SDO AIA footage in 131(teal), 171(gold) and 335 (blue) angstrom wavelengths, and shows the X1.4 class flare erupted from the center of the sun on July 12, 2012 at 12:52 PM EDT. Each wavelength shows different temperature plasma in the sun’s atmosphere. 171 shows 600,000 Kelvin plasma, 335 shows 2.5 million Kelvin plasma, and 131 shows 10 million Kelvin plasma. The final shot is a composite of 171 and 335 angstrom footage.

Top image: illustration of a CME about to impact Earth’s magnetosphere (NASA). Model animation: NASA/GSFC. Video courtesy NASA/SDO and the AIA science team.

UPDATE: The CME took a bit longer to arrive than expected, but impact with Earth’s magnetic field was detected at around 1800 UT (11 a.m. PDT/2 p.m. EDT), activating a geomagnetic storm. According to SpaceWeather.com: At the moment, conditions appear favorable for auroras over high-latitude places such as Canada, Scandinavia, Antarctica and Siberia. It is too early to say whether the storm will intensify and bring auroras to middle latitudes as well.

New Computer Simulations Show Earth’s Spaghetti-Like Magnetosphere

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A new computer simulation is showing Earth’s magnetosphere in amazing detail – and it looks a lot like a huge pile of tangled spaghetti (with the Earth as a meatball). Or perhaps a cosmic version of modern art.

The magnetosphere is formed by the Sun’s magnetic field interacting with Earth’s own magnetic field. When charged particles from a solar storm, also known as a coronal mass ejection (CME), impact our magnetic field, the results can be spectacular, from powerful electrical currents in the atmosphere to beautiful aurorae at high altitudes. Space physicists are using the new simulations to better understand the nature of our magnetosphere and what happens when it becomes extremely tangled.

Using a Cray XT5 Jaguar supercomputer, the physicists can better predict the effects of space weather, such as solar storms, before they actually hit our planet. According to Homa Karimabadi, a space physicist at the University of California-San Diego (UCSD), “When a storm goes off on the sun, we can’t really predict the extent of damage that it will cause here on Earth. It is critical that we develop this predictive capability.” He adds: “With petascale computing we can now perform 3D global particle simulations of the magnetosphere that treat the ions as particles, but the electrons are kept as a fluid. It is now possible to address these problems at a resolution that was well out of reach until recently.”

It helps that the radiation from solar storms can take 1-5 days to reach Earth, providing some lead time to assess the impact and any potential damage.

The previous studies were done using the Cray XT5 system known as Kraken; with the new Cray XT5 Jaguar supercomputer, they can perform simulations three times as large. The earlier simulations contained a “resolution” of about 1 billion individual particles, while the new ones contain about 3.2 trillion, a major improvement.

So next time you are eating that big plate of spaghetti, look up – the universe has its own recipes as well.

The original press release from Oak Ridge National Laboratory is here.

Moon’s Mini-Magnetosphere

Many objects in the solar system have strong magnetic fields which deflect the charged particles of the solar wind, creating a bubble known as the magnetosphere. On Earth, this protects us from some of the more harmful solar rays and diverts them to create beautiful aurorae. Similar displays have been found to occur on the gas giants. However, many other objects in our solar system lack the ability to produce these effects, either because they don’t have a strong magnetic field (such as Venus), or an atmosphere with which the charged particles can interact (such as Mercury).

Although the moon lacks both of these, a new study has found that the moon may still produce localized “mini-magnetospheres”. The team responsible for this discovery is an international team composed of astronomers from Sweden, India, Switzerland, and Japan. It is based on observations from the Chandrayaan-1 spacecraft produced and launched by the Indian Space Research Organisation (ISRO).

Using this satellite, the team was mapping the density of backscattered hydrogen atoms that come from solar wind striking the surface and being reflected. Under normal conditions, 16-20% of incoming protons from the solar wind is reflected in this way.

For those excited above 150 electron volts, the team found a region near the Crisium antipode (the region directly opposite the Mare Crisium on the moon). This region was previously discovered to have magnetic anomalies in which the local magnetic field strength reached several hundred nanotesla. The new team found that the result of this was that incoming solar wind was deflected, creating a shielded region some 360 km in diameter surrounded by a “300-km-thick region of enhanced plasma flux that results from the solar wind flowing 23 around the mini-magnetosphere.” Although the flow bunches up, the team finds that the lack of a distinct boundary means that there is not likely to be a bow shock, which would be created as the buildup becomes sufficiently strong to directly interact with additional incoming particles.

Below energies of 100 eV, the phenomenon seems to disappear. The researchers suggest this points to a different formation mechanism. One possibility is that some solar flux breaks through the magnetic barrier and is reflected creating these energies. Another is that, instead of hydrogen nuclei (which composes the majority of the solar wind) this is the product of alpha particles (helium nuclei) or other heavier solar wind ions striking the surface.

Not discussed in the paper is just how valuable such features could be to future astronauts looking to create a base on the moon. While the field is relatively strong for local magnetic fields, it it still around two orders of magnitude weaker than that of Earth’s. Thus, it is unlikely that this effect would be sufficiently strong to protect a base, nor would it provide protection from the x-rays and other dangerous electromagnetic radiation that is provided by an atmosphere.

Instead, this finding poses more in the way of scientific curiosity and can help astronomers map local magnetic fields as well as investigate the solar wind if such mini-magnetospheres are located on other bodies. The authors suggest that similar features be searched for on Mercury and asteroids.

Magnetic North Pole

The movement of Earth's north magnetic pole across the Canadian arctic, 1831--2001 (Geological Survey of Canada)

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The Earth has a magnetic field, known as the magnetosphere, that protects our planet from the particles of the solar winds. One point of that field is known as the Magnetic North Pole. The Magnetic North Pole is not the geographic North Pole; it is actually hundreds of miles south of the geographic North Pole and north of Canada.

Hundreds of years ago, European navigators believed that the needles of compasses were attracted to some “magnetic mountain” or “island” thought to be located in the far north. Some also believed that the needles could be attracted to the Pole Star, which is part of the Ursa Minor constellation and has long been used in navigation. One English philosopher, William Gilbert, proposed that the Earth acts like a giant magnet; he also was the first person to state that the Earth’s magnetic field points vertically downward at the Magnetic North Pole. It took hundreds of years before scientists came to properly understand our planet’s magnetic field, although this is known to be correct now.

All magnets have two poles, like the “plus” and “minus” signs found on batteries. Instead of these locations being named plus and minus though, they were named the North and South Magnetic Poles. It is toward the Magnetic North Pole that your compass points not the geographic North Pole, which makes sense considering it utilizes magnets to determine direction. At the Magnetic North Pole, the magnetic fields points down vertically; in other words it has a 90° “dip” toward the Earth’s surface. The counterpart of the Magnetic North Pole is the Magnetic South Pole. Because the Earth’s magnetic field is not perfectly symmetrical, the magnetic fields are not antipodal. That means that if you draw a straight line between them, it does not pass through the Earth’s center. It is off by approximately 530 km. The North and South Magnetic Poles are also known as Magnetic Dip Poles because they “dip” at a 90° angle towards the Earth.   

The Magnetic North Pole continues to move around. According to the Geological Survey of Canada, which routinely studies the Magnetic North Pole, the pole moves as much as 40 km per year. It also moves daily. Every day, the Magnetic North Pole has an elliptical movement of approximately 80 km from the average point of its center. That means when you are using a compass, you have to be aware of the difference between magnetic north and geographic north.

Universe Today has articles on Earth’s magnetic field and modeling the Earth’s magnetic field.

For more information, check out the Magnetic North Pole and geomagnetism.

Astronomy Cast has an episode on Earth.

References:
Earth’s Inconstant Magnetic Field
Earth’s Magnetic Field and its Changes in Time

Branson Wants to Fly Space Tourists into the Northern Lights

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For his next big plan for the private space industry, Richard Branson is thinking up new ways to excite affluent space tourists: flying them into the biggest lightshow on Earth, the Aurora Borealis. Although the New Mexico Virgin Galactic Spaceport isn’t scheduled for completion until 2010, the British entrepreneur is already planning his next project intended for cruises into the spectacular space phenomenon from an Arctic launchpad.

Located in the far north of Sweden (in the Lapland province), the small town of Kiruna has a long history of space observation and rocket launches. The Arctic location provides the town with unrivalled views of the Aurora Borealis as it erupts overhead. The Auroral lightshow is generated by atmospheric reactions to impacting solar wind particles as they channel along the Earth’s magnetic field and down into the thickening atmospheric gases.

Once a view exclusive only to sounding rockets, this awe inspiring sight may in the future be seen from the inside, and above, by fee-paying space tourists as they are launched into space from a new spaceport, on the site of an existing base called Esrange. Although launching humans into an active aurora holds little scientific interest (if it did, it would have probably been done by now), it does pose some prudent health and safety questions. As Dr Olle Norberg, Esrange’s director, confidently states: “Is there a build-up of charge on the spacecraft? What is the radiation dose that you would receive? Those studies came out saying it is safe to do this.” Phew, that’s a relief.

The chance to actually be inside this magnificent display of light will be an incredible selling point for Virgin Galactic and their SpaceShipTwo flights. As if going into space were not enough, you can see and fly through the atmosphere at it’s most magnificent too.

Source: The Guardian Unlimited