By analyzing data from the probe, a team of researchers identified a new continuous signal that would allow measurement of the density of the interstellar plasma that passes through it.
It launched in September 1977, two weeks after the twins Voyager In Figure 2, the Voyager 1 probe is currently the most distant human artifact from Earth (22.8 billion km or 152.8 astronomical units). After the flyby of Jupiter (March 1979) and Saturn (November 1980), the probe took a path outside the ecliptic, the orbital plane around which all the planets orbit, and out of the solar system. On August 25, 2012 the first investigation became Prof. Get out of the sun’s atmosphere, The plasma bubble that surrounds the sun, thus entering interstellar space. Of the many devices on board, only four are currently active, including the plasma wave system (PWS) that continuously measures the electron density in space traversed by two antennas 10 meters long.
In the recent years that Voyager 1 has covered 30 astronomical units in interstellar space, PWS has continued to send valuable data back to Earth which, in conjunction with sporadic turbulent phenomena, has allowed local density measurements.
In particular, only 8 events were recorded due to the plasma waves generated by the sun.
“Unfortunately, we only discover one per year,” said Stella Koch-Acker, of Cornell University in Ithaca (New York) and lead study published in the journal. nature. “Based on these rare events only, we would get a map of the density of intersecting space very poorly.”
This was precisely the starting point for investigating the available data in more detail, and looking for an item that could fill in the gaps in the measurements. Through further filtering of the received signals, starting in mid-2015, an increasingly faint but steady signal was identified, regardless of large cosmic disturbances.
“It’s basically one tone, with a very narrow bandwidth,” says Stella Koch Ocker. “We hear it varies over time, but it is precisely this variation in frequency that allows us to determine how the density of space changes.”
The new signal has been called Plasma wave emission (Plasma Wave Emission) is a similar known phenomenon that can be observed in the Earth’s upper atmosphere directly related to the electron density present.
“This new discovery will allow us to constantly monitor the density of space that Voyager 1 traverses, regardless of solar activity.”
Tracking the signal back to 2012, it was observed that the mean plasma density began to slowly rise, reaching a value forty times higher than the first measurements in 2015 that remains constant to this day.
After 44 years of mission, Voyager 1 continues to do science, giving us new discoveries for a greater understanding of the universe. This will be possible as long as the power produced by the generator X ray On board, which is expected to run out at the end of the decade, will suffice. Then, the probe will silently travel through the Milky Way, reaching the first branches of the Oort Cloud in 300 years, take another 30,000 to cross it and then continue in the direction of the constellation Ofphiuchus.