Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Voyager 1 Cruising on a ‘Magnetic Highway’

05.12.2012
Johns Hopkins Applied Physics Laboratory Scientists
See Charged Particles Taking ‘Exit Ramp’ to Interstellar Space

NASA’s Voyager 1 spacecraft has encountered a new region on the outskirts of our solar system that appears to be a magnetic highway for charged particles. Scientists believe this is the final region Voyager has to cross before reaching interstellar space, or the space between stars.

Scientists call this region the magnetic highway because our sun's magnetic field lines are connected to interstellar magnetic field lines. The connection has allowed lower-energy charged particles that originate from inside our heliosphere – the bubble of charged particles the sun blows around itself – to zoom out, and higher-energy particles from outside to stream in.

Before entering this region, the charged particles bounced around in all directions, as if trapped on local roads inside the heliosphere. Thinking the particles might be colliding against the gaseous boundary of the solar system, scientists operating Voyager’s low-energy charged particle detector wondered if the spacecraft had reached the last stop before – or even crossed into – interstellar space. Data indicating that the direction of the magnetic field lines has not changed, however, leads the Voyager team to infer that this region is still inside the solar bubble.

The new results will be described today at the American Geophysical Union meeting in San Francisco.

"If we were judging by the charged-particle data alone, I would have thought we were outside the heliosphere," says Stamatios Krimigis, principal investigator of the Low-Energy Charged Particle (LECP) instrument, based at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "In fact, our instrument has seen the low-energy particles taking the exit ramp toward interstellar space. But we need to look at what all the instruments are telling us and only time will tell whether our interpretations about this frontier are correct. One thing is certain – none of the theoretical models predicted any of Voyager’s observations over the past 10 years, so there is no guidance on what to expect."

Since December 2004, when Voyager 1 crossed a shockwave known as the Termination Shock, the spacecraft has been exploring the heliosphere's outer layer, called the heliosheath. Here, the stream of charged particles from the sun – known as the solar wind – abruptly slowed down from supersonic speeds and became turbulent. Voyager 1's environment was consistent for about five and a half years, but then the spacecraft detected that the outward speed of the solar wind slowed to zero. The intensity of the magnetic field also began to increase.

“The solar wind measurements speak to the unique abilities of the LECP detector, designed at APL nearly four decades ago," Krimigis says. “Where a device with no moving parts would have been safer – lessening the chance a part would break in space – our team took the risk to include a stepper motor that rotates the instrument 45 degrees every 192 seconds, allowing it to gather data in all directions and pick up something as dynamic as the solar wind. A device designed to work for 500,000 ‘steps’ and four years has been working for 35 years and well past 6 million steps.”

In fact, for the past several months, the entire Voyager spacecraft was commanded to rotate periodically by 70 degrees so the LECP instrument could measure the solar wind flow in the up-down direction, or north-south according to the ecliptic plane on which the planets orbit the sun. In theory, with the flow in the ecliptic plane having dropped to zero, the plasma should have been headed north at Voyager’s position. But the measurements, reported Sept. 6 in the journal Nature, showed that the flow was consistent with zero. “This was a real surprise,” says LECP Co-investigator Rob Decker, of the Applied Physics Laboratory (APL), “because most models were expecting the northward speed to be at least as high as 25 kilometers per second.”

A New Region

Around May 14, LECP also measured a sudden, 5-percent increase in cosmic rays – high-energy particles coming in from the galaxy – followed by a similar increase on July 28. This second increase was accompanied by a decrease (by a factor of 5) in the low-energy particles, but this only lasted for four days. A few days later the same up-and-down exchange occurred, but on Aug. 25 the instrument recorded an even larger increase in cosmic rays – bringing the total increase since the end of March to about 30 percent.

The intensity of particles that have an even lower energy than the cosmic rays dropped by more than a factor of 1,000 below that observed since Voyager 1 first entered the heliosheath. LECP scientists agree with their colleagues that Voyager has entered a new region, but perhaps is not yet out of the heliosphere. Decker says that the distribution of lower-energy particles suggests a magnetic field direction of about 110 degrees to the direction pointing away from the sun, but in the ecliptic plane, not drastically different than the direction of about 90 degrees inside the heliosphere.

"We believe this is the last leg of our journey to interstellar space,” says Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena. “Our best guess is that it's likely just a few months up to a couple years away. The new region isn't what we expected, but we've come to expect the unexpected from Voyager."

Voyager 1 and 2 were launched 16 days apart in 1977 and, between them, visited Jupiter, Saturn, Uranus and Neptune. Voyager 1 is the most distant manmade object, about 11 billion miles (18.5 billion kilometers) away from the sun. Voyager 2 is about 9 billion miles (15 billion kilometers) away from the sun. While Voyager 2 has seen some gradual changes in the charged particles, they are very different from those seen by Voyager 1. Scientists do not think Voyager 2 has reached the magnetic freeway.

The Voyager spacecraft were built and are operated by the Jet Propulsion Laboratory, a division of the California Institute of Technology. The LECP instrument was designed and built at the Johns Hopkins University Applied Physics Laboratory with NASA funding. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington. For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager. For more on the Low-Energy Charged Particle detector, visit: http://sd-www.jhuapl.edu/VOYAGER/index.html.

The Applied Physics Laboratory, a not-for-profit division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit www.jhuapl.edu.

Michael Buckley | Newswise
Further information:
http://www.nasa.gov/voyager

More articles from Physics and Astronomy:

nachricht Introducing the disposable laser
04.05.2016 | American Institute of Physics

nachricht New fabrication and thermo-optical tuning of whispering gallery microlasers
04.05.2016 | Okinawa Institute of Science and Technology (OIST) Graduate University

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nuclear Pores Captured on Film

Using an ultra fast-scanning atomic force microscope, a team of researchers from the University of Basel has filmed “living” nuclear pore complexes at work for the first time. Nuclear pores are molecular machines that control the traffic entering or exiting the cell nucleus. In their article published in Nature Nanotechnology, the researchers explain how the passage of unwanted molecules is prevented by rapidly moving molecular “tentacles” inside the pore.

Using high-speed AFM, Roderick Lim, Argovia Professor at the Biozentrum and the Swiss Nanoscience Institute of the University of Basel, has not only directly...

Im Focus: 2+1 is Not Always 3 - In the microworld unity is not always strength

If a person pushes a broken-down car alone, there is a certain effect. If another person helps, the result is the sum of their efforts. If two micro-particles are pushing another microparticle, however, the resulting effect may not necessarily be the sum their efforts. A recent study published in Nature Communications, measured this odd effect that scientists call “many body.”

In the microscopic world, where the modern miniaturized machines at the new frontiers of technology operate, as long as we are in the presence of two...

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

New fabrication and thermo-optical tuning of whispering gallery microlasers

04.05.2016 | Physics and Astronomy

Introducing the disposable laser

04.05.2016 | Physics and Astronomy

A new vortex identification method for 3-D complex flow

04.05.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>