Voyager says goodbye to the solar system

The most distant man-made object - the Voyager 1 spacecraft - leaves the solar system

The most distant man-made object - the Voyager 1 spacecraft - leaves the solar system. Astronomers think that the spacecraft has reached the limit where the sun's influence begins to diminish. "This is a very exciting milestone," says Stamatios Krimigis of Johns Hopkins University in Laurel, Maryland. This is the first time a machine has left the cocoon of the Sun's atmosphere. Voyager 1 and its companion Voyager 2 were launched to the outer planets in 1977. Voyager 1 is currently about 90 astronomical units from the Sun (one AU Astronomical Unit is the distance between the Earth and the Sun). It is currently the most distant spacecraft in the solar system, having caught up with the Jupiter Pioneer 10 probe in 1998. Voyager 2 lingers behind, and is about 73 AU from the Sun. For years scientists thought that Voyager 1 was approaching the "final shock" of the solar system. This is the region where particles, moving at supersonic speeds and coming from the sun, pass through them through interstellar particles and slow down to speeds below the speed of sound. This region, which mostly symbolizes the edge of the solar system, should excite many particles and have a strong magnetic field.

When the Voyager spacecraft were launched, astronomers predicted that the "annihilation shock" would lie about 40 to 50 AU from the Sun. Even so, Voyager 1 has passed 60, 70 and 80 AU and still hasn't reached it. Now, finally, they found evidence that Voyager 1 is very close to it and may have even passed through it. In the summer of 2002, when Voyager 1 was at a distance of 85 AU from the Sun, it measured a sharp increase in the number of energetic particles over a six-month period. Krimigs and his colleagues say the data suggests Voyager went through an "elimination shock" that drifted back from her. It moves back and forth depending on the activity of the sun. However, a team led by Frank McDonald of the University of Maryland in College Park believes that Voyager is close to the shock but has not yet crossed it. The team notes that Voyager did not register a significant increase in the local magnetic field. Around 2020 Voyager is supposed to reach the "heliopause". At this point the influence of the sun fades completely, and interstellar space begins. Then astronomers will have their first opportunity to measure the magnetic fields and energetic particles of interstellar space.
Link to the original article in "New Scientist" (Hazel Mir)

Crossed the heliopause. And perhaps to John Noble Wilford's mother from John Noble WilfordDid the Voyager 1 spacecraft cross a turbulent region on the outskirts of the solar system? Scientists are divided

Since leaving Earth, more than 26 years ago, the Voyager spacecraft has traveled more than 13 billion km, a greater distance than any other spacecraft. It has now reached the outskirts of the solar system, but scientists are not sure what exactly it encountered there. By John Noble Wilford Since leaving Earth, more than 26 years ago, the Voyager spacecraft has traveled more than 13 billion km, a great distance More than any other spacecraft. Now it has reached the outskirts of the solar system, but scientists are not sure what exactly it encountered there. A team of scientists from Johns Hopkins University reported last week that according to the radio signals coming from the spacecraft, it apparently crossed the heliopause, a turbulent region near the "border" of the solar system ( According to astronomers, the term boundary is imprecise, as there is no clear point where the solar system ends). In the heliopause, the speed of the solar winds, which carry charged particles from the sun, is slowed down by their collision with material originating in the interstellar medium. No spacecraft has ever approached this area.
By John Noble Wilford Since leaving Earth, more than 26 years ago, the Voyager spacecraft has traveled more than 13 billion km, a greater distance than any other spacecraft. Now it has reached the outskirts of the solar system, but scientists are not sure what exactly it encountered there. A team of scientists from Johns Hopkins University reported last week that according to the radio signals coming from the spacecraft, it apparently crossed the heliopause, a turbulent region near the "border" of the solar system ( According to astronomers, the term boundary is imprecise, as there is no clear point where the solar system ends). In the heliopause, the speed of the solar winds, which carry charged particles from the sun, is slowed down by their collision with material originating in the interstellar medium. No spacecraft has ever approached this area, but another team of scientists disputes the conclusions of the first team. These scientists, who also analyzed data from Voyager, claim that the spacecraft is still far from the heliopause, although not very far. Both views were presented at a press conference at NASA headquarters in Washington and are the focus of two articles published last week in the journal Nature.

The team led by Dr. Stamatios Krimigis, from the Laboratory of Applied Physics at Johns Hopkins University, based its conclusions on two main findings: sharp changes in the speed of the solar wind - from supersonic speed to subsonic speed (due to the collision with material from the interstellar medium) - and changes in the particles carried by this wind. These changes took place beginning in August 2002 and lasted six months, after which the spacecraft reached an area where normal solar wind conditions prevailed. The researchers speculate that during that six months the spacecraft was in heliopause. During this period it traveled more than 650 million kilometers.

"This is our first opportunity to directly examine the astonishing dynamic activity taking place in the far reaches of the solar system," Krimigis said. The information from Voyager shows that in addition to the change in the speed of the solar wind with the estimated entry into the heliopause, there was a 100-fold increase in the number of charged particles compared to the previous period. Some of the observed particles were different from the normal material carried by the solar wind, and hence probably came from outside the solar system. "When we saw all this, we were pretty sure we had reached the heliopause," said Dr. Louis Lanzerotti of Bell Laboratories, a research unit of Lucent Technologies.

The other team, led by Dr. Frank MacDonald of the University of Maryland, claims that it is possible that the spacecraft is close to the heliopause, but it has not yet crossed it. This conclusion is based on the strength and behavior of high-energy particles in Voyager 1's environment and the magnetic fields in the spacecraft's environment. According to the scientists, according to the models simulating the conditions in the heliopause region, the magnetic field around the spacecraft should have been stronger if it had actually reached this region. "It's just a matter of time," McDonald said, "but I think we'll know when we get there."

The lack of consensus among the team members did not bother other scientists studying the field. These scientists hypothesized that the models simulating conditions at the edge of the solar system, far from the nine planets, may be wrong or simplistic. "This means that there is something new to learn about the last book region of the solar system," said Dr. Edward Stone, senior Voyager project scientist and physicist at the California Institute of Technology.

In a review article in "Nature," Dr. Len Fisk, a space scientist from the University of Michigan who is not related to the research teams, wrote that he tends to agree with Krimigis' team's claim, according to which "the information obtained can be explained most plausibly if we assume that Voyager crossed the heliopause ". Fisk wrote that it is not surprising that the threshold of this region is not constant: the ebb and flow of solar activity, which occurs in 11-year cycles, probably causes changes in the location of the threshold.

Crossed the heliopause. And maybe not

By John Noble Wilford

Did the Voyager 1 spacecraft cross a turbulent region on the outskirts of the solar system? Scientists are divided

Since leaving Earth, more than 26 years ago, the Voyager spacecraft has traveled more than 13 billion km, a greater distance than any other spacecraft. It has now reached the outskirts of the solar system, but scientists are not sure what exactly it encountered there.

A team of scientists from Johns Hopkins University reported last week that according to the radio signals coming from the spacecraft, it apparently crossed the heliopause, a turbulent region near the "border" of the solar system (according to astronomers, the term border is imprecise, since there is no clear point where the solar system ends ). In the heliopause, the speed of the solar winds, which carry charged particles from the sun, is slowed down by their collision with material originating in the interstellar medium. No spacecraft has ever approached this area.

But another team of scientists disputes the conclusions of the first team. These scientists, who also analyzed data from Voyager, claim that the spacecraft is still far from the heliopause, although not very far. Both views were presented at a press conference at NASA headquarters in Washington and are the focus of two articles published last week in the journal Nature.

The team led by Dr. Stamatios Krimigis, from the Laboratory of Applied Physics at Johns Hopkins University, based its conclusions on two main findings: sharp changes in the speed of the solar wind - from supersonic speed to subsonic speed (due to the collision with material from the interstellar medium) - and changes in the particles carried by this wind. These changes took place beginning in August 2002 and lasted six months, after which the spacecraft reached an area where normal solar wind conditions prevailed. The researchers speculate that during that six months the spacecraft was in heliopause. During this period it traveled more than 650 million kilometers.

"This is our first opportunity to directly examine the astonishing dynamic activity taking place in the far reaches of the solar system," Krimigis said. The information from Voyager shows that in addition to the change in the speed of the solar wind with the estimated entry into the heliopause, there was a 100-fold increase in the number of charged particles compared to the previous period. Some of the observed particles were different from the normal material carried by the solar wind, and hence probably came from outside the solar system. "When we saw all this, we were pretty sure we had reached the heliopause," said Dr. Louis Lanzerotti of Bell Laboratories, a research unit of Lucent Technologies.

The other team, led by Dr. Frank MacDonald of the University of Maryland, claims that it is possible that the spacecraft is close to the heliopause, but it has not yet crossed it. This conclusion is based on the strength and behavior of high-energy particles in Voyager 1's environment and the magnetic fields in the spacecraft's environment. According to the scientists, according to the models simulating the conditions in the heliopause region, the magnetic field around the spacecraft should have been stronger if it had actually reached this region. "It's just a matter of time," McDonald said, "but I think we'll know when we get there."

The lack of consensus among the team members did not bother other scientists studying the field. These scientists hypothesized that the models simulating conditions at the edge of the solar system, far from the nine planets, may be wrong or simplistic. "This means that there is something new to learn about the last book region of the solar system," said Dr. Edward Stone, senior Voyager project scientist and physicist at the California Institute of Technology.

In a review article in "Nature," Dr. Len Fisk, a space scientist from the University of Michigan who is not related to the research teams, wrote that he tends to agree with Krimigis' team's claim, according to which "the information obtained can be explained most plausibly if we assume that Voyager crossed the heliopause ". Fisk wrote that it is not surprising that the threshold of this region is not constant: the ebb and flow of solar activity, which occurs in 11-year cycles, probably causes changes in the location of the threshold.