Artist’s interpretation depicting the new view of the heliosphere. The heliosheath is filled with “magnetic bubbles” (shown in the red pattern) that fill out the region ahead of the heliopause. In this new view, the heliopause is not a continuous shield that separates the solar domain from the interstellar medium, but a porous membrane with fingers and indentations.Credit: NASA/Goddard Space Flight Center/ CI Lab
The Voyager probe has revealed that the heliosheath is not smooth as was once thought, but rather frothy.
The sun’s magnetic field spins opposite directions on the north and south poles. These oppositely pointing magnetic fields are separated by a layer of current called the heliospheric current sheet. Due to the tilt of the magnetic axis in relation to the axis of rotation of the Sun, the heliospheric current sheet flaps like a flag in the wind. The flapping current sheet separates regions of oppositely pointing magnetic field, called sectors. As the solar wind speed decreases past the termination shock, the sectors squeeze together, bringing regions of opposite magnetic field closer to each other. The Voyager spacecraft have now found that when the separation of sectors becomes very small, the sectored magnetic field breaks up into a sea of nested “magnetic bubbles” in a phenomenon called magnetic reconnection. The region of nested bubbles is carried by the solar wind to the north and south filling out the entire front region of the heliopause and the sector region in the heliosheath.
This discovery has prompted a complete revision of what the heliosheath region looks like. The smooth, streamlined look is gone, replaced with a bubbly, frothy outer layer.
This video is public domain and can be downloaded at: http://svs.gsfc.nasa.gov/goto?10790
Uploaded on Jun 9, 2011
Launched in 1977, Voyager 1 flew by Jupiter on March 5, 1979, and Saturn on November 12, 1980. The spacecraft has remained operational long enough for it to have crossed the termination shock in December 2004, and the heliopause on August 25, 2012 – entering interstellar space. Voyager’s radioisotope thermoelectric generator is continually degrading, and the spacecraft will cease functioning in the mid 2020’s. I plan on holding a wake.
Plot showing a dramatic decrease in the rate of solar wind particle detection by Voyager 1 (October 2011 through October 2012). Credit: NASA/JPL-CaltechThe Voyager 1 mission has provided mankind with a unique view of the edge of our solar system, but there is a lot more that could be learned that Voyager is not capable of providing. I would like to see a dedicated fleet of heliospheric exploration missions – robotic spacecraft that can explore our Sun’s magnetic environment in 3D.
As of February 2015, Voyager 1 was at a distance of 19.5 Billion Kilometers (130.5 AU) from the Sun.
Voyager Mission Infographic. Credit: NASA/JPL-Caltech