Thursday, September 26, 2013

V’Ger has Left the Solar System

A 1977 NASA picture of Voyager 2 with it's payload
I am old enough to have watched Star Trek in its original run on Thursday nights on a black and white TV. (When the show moved to Fridays I could no longer watch it before DVRs.) My husband and his brother can actually have meaningful conversations by quoting dialogue from episodes to covey ideas. So, I was delighted that a newly published paper makes the case that NASA's Voyager 1 spacecraft might have already entered interstellar space, the space between stars.

Interstellar space is filled with plasma, or ionized gas, that has a lower temperature than what is inside our solar bubble, also known as the heliosphere. Interstellar space is reportedly 10,000 degrees Fahrenheit (6,000 Kelvin). The solar bubble, the heliosphere, has temperature of about 2 million degrees Fahrenheit (1 million Kelvin).

A group of NASA scientists have developed a new model to analyze data from the Voyager Space crafts. The model described in a recently published paper is new and different from other models used previously to explain the data the Voyager spacecraft have been sending back from more than 11 billion miles (18 billion kilometers) away from our sun and claims that on Aug. 25, 2012, Voyager 1 entered the depletion region, where the magnetic field acts as a kind of "magnetic highway" allowing energetic ions from inside the heliosphere to escape out, and cosmic rays from interstellar space to zoom in.

The data collected by the minimal equipment on Voyager measure the level of fast-moving charged particles, mainly protons, originating from far outside the heliosphere, the level of slower-moving charged particles, also mainly protons, from inside the heliosphere and the direction of the magnetic field. The level of outside particles has increased dramatically, the level of inside particles fallen precipitously, as scientists watched. Both models of heliosphere and intersteller space agree that the spacecraft is closing in on the edge of interstellar space. According to traditional models of interstellar space scientists would need to see a change in the direction of the magnetic field to confirm that the spacecraft has sailed beyond the reach of the solar wind and finally arrived into the vast space between stars. The new model of interstellar space and the heliosphere does not require a change in magnetic field between the two.
Artist creation
NASA's Voyager project scientist, Ed Stone of the California Institute of Technology in Pasadena, explains:
"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. 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.”

If the new model of the data is correct that would mean that the interstellar magnetic field direction is the same as the magnetic field within the heliosphere, originating from our sun. As Voyager 1 continues in its mission and hopefully continues to be able to collect and send back data (despite a memory smaller than your phone), we will know if the magnetic field does change directions. The direction of the magnetic field, requires periodic instrument calibrations and complicated analyses. These analyses typically take a few months to return after the charged particle data are received on Earth, and the power remaining in Voyager is estimated to be another decade.

NASA's Voyager 2 spacecraft, the first Voyager spacecraft to launch on August 25, 1977, departed on a journey that would make it the only spacecraft to visit Uranus and Neptune and the longest-operating NASA spacecraft ever. Voyager 2 and its twin, Voyager 1, that launched 16 days later on Sept. 5, 1977, are still both operational. Voyager 2 is the longest-operating spacecraft, but has not traveled as far from home as Voyager 1. Voyager 2 has not yet reached the magnetic highway, though it has recently seen some modest drops of the heliosphere particle levels.
from NASA
If Voyager 1 has reached interstellar space then it is exploring a region no spacecraft has ever been to before.- I can’t resist- “Where No Man Has Gone Before.” In Star Trek The Motion Picture, the threat to the Enterprise (and Earth) is V’Ger, which the crew discovers at its center is actually Voyager 6, designed to collect data and transmit it back to Earth. Voyager 6 supposedly disappeared through a black hole.(Wouldn’t that be cool to have data from within a black hole.) The probe was found by inhabitants of a planet on the other side of the galaxy who discovered the probe's 20th century programming, which was to collect data and return that information to its creator and rebuild the probe and send it on its way.

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