Voyager 1, Painting by Mayank Chhaya
NASA’s Voyager 1 finally seems to be in the last stages of leaving our solar system to enter interstellar space. It has taken the spacecraft 36 years to get that far, far enough now for it to enjoy a more than 17-hour lag to communicate with NASA.
Although in March this year there was some speculation that Voyager 1 had left our solar system, it is only now that NASA is saying this: “Data from Voyager 1, now more than 11 billion miles (18 billion kilometers) from the sun, suggest the spacecraft is closer to becoming the first human-made object to reach interstellar space.”
“Research using Voyager 1 data and published in the journal Science today provides new detail on the last region the spacecraft will cross before it leaves the heliosphere, or the bubble around our sun, and enters interstellar space,” it says.
One of the most definite indications that the spacecraft is about to leave the solar womb is that it is now reporting a much higher rate of charged particles from outside the heliosphere than from inside it.
“Scientists have seen two of the three signs of interstellar arrival they expected to see: charged particles disappearing as they zoom out along the solar magnetic field, and cosmic rays from far outside zooming in. Scientists have not yet seen the third sign, an abrupt change in the direction of the magnetic field, which would indicate the presence of the interstellar magnetic field,” NASA says.
"This strange, last region before interstellar space is coming into focus, thanks to Voyager 1, humankind’s most distant scout," Ed Stone, Voyager project scientist at the California Institute of Technology in Pasadena, has been quoted as saying. "If you looked at the cosmic ray and energetic particle data in isolation, you might think Voyager had reached interstellar space, but the team feels Voyager 1 has not yet gotten there because we are still within the domain of the sun’s magnetic field."
“Scientists do not know exactly how far Voyager 1 has to go to reach interstellar space. They estimate it could take several more months, or even years, to get there. The heliosphere extends at least 8 billion miles (13 billion kilometers) beyond all the planets in our solar system. It is dominated by the sun’s magnetic field and an ionized wind expanding outward from the sun. Outside the heliosphere, interstellar space is filled with matter from other stars and the magnetic field present in the nearby region of the Milky Way,” NASA says.
For the better part of their journey since 1977, the two NASA spacecraft Voyager 1 and Voyager 2 have been the most distant human-made objects. Launched 16 days apart nearly 36 years ago, the two have seen and experienced space like nothing else that humans have created. Voyager 2 is about 9 billion miles (15 billion kilometers) from the sun and still inside the heliosphere.
"We saw a dramatic and rapid disappearance of the solar-originating particles. They decreased in intensity by more than 1,000 times, as if there was a huge vacuum pump at the entrance ramp onto the magnetic highway," says Stamatios Krimigis, the low-energy charged particle instrument’s principal investigator at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. "We have never witnessed such a decrease before, except when Voyager 1 exited the giant magnetosphere of Jupiter, some 34 years ago."
It is a sudden change in the direction of the magnetic field that would clearly tell us whether Voyager 1 is ‘outta here’, in so much as “out of” and “here” mean anything in the cosmic sense. If you see my painting of the spacecraft the light blue strokes are supposed to represent charged particles from inside our heliosphere and bluish yellow strokes from outside. It is a sudden change of direction of the magnetic field in this stage that we should wait for.
It is always sobering for the human race, quibbling over our trivial little preoccupations such as what constitutes marriage or privacy versus security or immigration or the falling gold prices or the rising dollar and other such assorted idiocies, to be reminded that even our relatively mediocre solar system extends at least 11 billion miles (18 million kilometers) in one direction. Our preoccupations cease to matter the moment there is a liftoff of spacecraft such as Voyager 1 and 2. So please, get your sense of scale and proportions before you launch into sanctimonious sermons. In short, these preoccupations are utterly, I mean really utterly, inconsequential. So much so that they do not even require stating.