NASA Voyager 1 enters unexplored territory at solar system’s edge
After more than 30 years of space journey, NASA’s Voyager 1 spacecraft has reached a distance of about 11 billion miles (18 billion kilometers) away from the sun and has entered uncharted regions between our solar system and interstellar space.
This region is called the “stagnation region” by the scientists. In this region gusts solar winds can be felt. Solat wind contains high-energy charged particles that stream from the sun that leak out into the space.
Ed Stone, Voyager project scientist at Caltech in Pasadena, Calif., said in a statement, “Voyager tells us now that we’re in a stagnation region in the outermost layer of the bubble around our solar system. Voyager is showing that what is outside is pushing back. We shouldn’t have long to wait to find out what the space between stars is really like.”
Stone added that having reached this stage in its journey, the Voyager 1 probe is currently the farthest manmade object from Earth, but has not yet reached interstellar space.
Voyager is still sending data of the heliosphere, which is a large bubble of solar plasma and solar magnetic fields that the sun blows around itself. This is enveloped by the turbulent layer of heliosheath. Beyond heliosheath begins the region of heliopause, the very edge of our solar system. With a speed of about 330 million miles (531 million km) every year, scientists are predicting that Voyager could cross the heliopause within a few months. But the precise moment when this will happen is difficult to pin down.
Stone said, “I can almost assure you that we will be confused when it first happens. This will undoubtedly not be simple. Nature tends to be much more creative than our own minds.”
Stone further elaborated, “Newton tells us the spacecraft will reach interstellar space. The question is, will we still be transmitting when that happens? No spacecraft has ever been there before. We continue to find our models need to be improved as we learn more about the complex interaction between solar wind and interstellar wind. The transition may not be instantaneous. There may be a turbulent interface, (and it) may take us months to get through a rather messy interface between these two winds.”
In April 2010, scientists found that the outward speed of solar wind had diminished to zero, hinting at the beginning of a new region.
Regarding this discovery Stone explained, “Once the wind slows down, the (magnetic) field lines get compressed and field intensity goes up. That’s precisely what we’ve seen now in the last year. Today, it’s about twice what it had been for the previous four years.”
Voyager 1 has been measuring energetic particles that originate from inside and outside our solar system since the past few years.
Rob Decker, a co-investigator on Voyager’s Low-Energy Charged Particle Instrument at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., explained in a statement, “We’ve been using the flow of energetic particles at Voyager 1 as a kind of wind sock to estimate the solar wind velocity. We’ve found that the wind speeds are low in this region and gust erratically. For the first time, the wind even blows back at us. We are evidently traveling in completely new territory. Scientists had suggested previously that there might be a stagnation layer, but we weren’t sure it existed until now.”
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