Post by Andrei Tchentchik on Jun 22, 2019 14:05:40 GMT 2
(.#203).- After 40 years, Voyager 2 will leave the Solar System.
After 40 years, Voyager 2 will leave the Solar System.
By Tristan Vey - Updated on 08/10/2018 at 19:14
The respective positions of the Voyager 1 and 2 probes with respect to the heliosphere. NASA / JPL-Caltech
NASA engineers have recorded a small burst of cosmic rays that suggests that the Voyager 2 probe, part in 1977, is approaching the border of the Solar System, crossed in 2012 by his big sister Voyager 1.
In August 2012, Voyager 1 became the first man-made object to leave the Solar System. It took a little more than a year for the scientific director of the program, the indestructible Ed Stone, 82 years old today, to agree to formalize the crossing of the symbolic barrier called heliopause that separates the zone of influence of the Sun, the heliosphere, and the interstellar medium. At the time, the researcher was waiting for a sudden change in the direction of the magnetic field that never came. He finally accepted the idea that the crossing of this border did not correspond exactly to the idea he had made of it.
Six years later, it's the second Voyager spacecraft that is about to take the leap after more than 40 years of interplanetary crossing. Starting the first two weeks ahead (contrary to what their numbering suggests), the Voyager 2 spacecraft was slowed down by its flight over Neptune in 1989. It is thus "only" 17.8 billion kilometers from the Earth against more than 21 billion kilometers for his big sister Voyager 1. Despite their distance, the two probes continue to operate thanks to their plutonium stack, with respectively 4 and 5 of their initial instruments in working order .
Voyager 2 always has its PLS instrument that will allow it to determine the density, temperature and movements of the interstellar gas in which our star moves. "This is a key measure that Voyager 1 could not achieve," said Rosine Lallement, astronomer at the Observatory Paris-Meudon who has long been part of the scientific teams of the mission. "It would be really great for Voyager 2 to get that done before they ran out of energy, that would be the dream end."
In a statement released Friday by NASA's Jet Propulsion Laboratory, US engineers announced that Voyager 2 would in turn approach the fateful border. Two instruments have indeed recorded a significant increase in the quantities of cosmic rays that hit it between the beginning of August and the end of August (at least another 5%). Part of this radiation, emitted among other things by the explosions of stars in the Milky Way, is in principle diverted by the bubble formed by the charged particles emitted by our star (which is more commonly called the solar wind). The closer we get to the "edges", the more we expect to receive cosmic rays.
An uncertain calendar
For the Voyager 1 spacecraft, it was only a few months before the heliopause crossing in May that the scientists had taken up this little start. But it is not sure that the Voyager 2 sensor knows exactly the same fate, at least not according to the same schedule. First of all, because she does not follow the same trajectory as her older sister. However, contrary to what its name indicates, the heliosphere is not a sphere. The Sun moves at high speed in the Milky Way and since the interstellar medium is not completely empty, it deforms the solar wind bubble. It is therefore possible that the transition zone traversed by Voyager 2 is a little thicker for example.
But that's not the only difference. The Sun has cycles of activities of an average duration of eleven years during which the quantity of charged particles emitted knows a minimum and a maximum. The boundaries of the heliosphere can thus move away or become closer over time. "We see a change in the environment of Voyager 2, there is no doubt about it," says Ed Stone. "We will learn a lot in the coming months, but we still do not know when we will hit the heliopause. We're not there yet, that's the only thing we're absolutely sure of. "
F I N .
After 40 years, Voyager 2 will leave the Solar System.
By Tristan Vey - Updated on 08/10/2018 at 19:14
The respective positions of the Voyager 1 and 2 probes with respect to the heliosphere. NASA / JPL-Caltech
NASA engineers have recorded a small burst of cosmic rays that suggests that the Voyager 2 probe, part in 1977, is approaching the border of the Solar System, crossed in 2012 by his big sister Voyager 1.
In August 2012, Voyager 1 became the first man-made object to leave the Solar System. It took a little more than a year for the scientific director of the program, the indestructible Ed Stone, 82 years old today, to agree to formalize the crossing of the symbolic barrier called heliopause that separates the zone of influence of the Sun, the heliosphere, and the interstellar medium. At the time, the researcher was waiting for a sudden change in the direction of the magnetic field that never came. He finally accepted the idea that the crossing of this border did not correspond exactly to the idea he had made of it.
Six years later, it's the second Voyager spacecraft that is about to take the leap after more than 40 years of interplanetary crossing. Starting the first two weeks ahead (contrary to what their numbering suggests), the Voyager 2 spacecraft was slowed down by its flight over Neptune in 1989. It is thus "only" 17.8 billion kilometers from the Earth against more than 21 billion kilometers for his big sister Voyager 1. Despite their distance, the two probes continue to operate thanks to their plutonium stack, with respectively 4 and 5 of their initial instruments in working order .
Voyager 2 always has its PLS instrument that will allow it to determine the density, temperature and movements of the interstellar gas in which our star moves. "This is a key measure that Voyager 1 could not achieve," said Rosine Lallement, astronomer at the Observatory Paris-Meudon who has long been part of the scientific teams of the mission. "It would be really great for Voyager 2 to get that done before they ran out of energy, that would be the dream end."
In a statement released Friday by NASA's Jet Propulsion Laboratory, US engineers announced that Voyager 2 would in turn approach the fateful border. Two instruments have indeed recorded a significant increase in the quantities of cosmic rays that hit it between the beginning of August and the end of August (at least another 5%). Part of this radiation, emitted among other things by the explosions of stars in the Milky Way, is in principle diverted by the bubble formed by the charged particles emitted by our star (which is more commonly called the solar wind). The closer we get to the "edges", the more we expect to receive cosmic rays.
An uncertain calendar
For the Voyager 1 spacecraft, it was only a few months before the heliopause crossing in May that the scientists had taken up this little start. But it is not sure that the Voyager 2 sensor knows exactly the same fate, at least not according to the same schedule. First of all, because she does not follow the same trajectory as her older sister. However, contrary to what its name indicates, the heliosphere is not a sphere. The Sun moves at high speed in the Milky Way and since the interstellar medium is not completely empty, it deforms the solar wind bubble. It is therefore possible that the transition zone traversed by Voyager 2 is a little thicker for example.
But that's not the only difference. The Sun has cycles of activities of an average duration of eleven years during which the quantity of charged particles emitted knows a minimum and a maximum. The boundaries of the heliosphere can thus move away or become closer over time. "We see a change in the environment of Voyager 2, there is no doubt about it," says Ed Stone. "We will learn a lot in the coming months, but we still do not know when we will hit the heliopause. We're not there yet, that's the only thing we're absolutely sure of. "
F I N .
