Ceilidh

Michael Zey
ing the heliosheath into a long, teardrop shaped structure. Image 2a shows the positions of the Voyager spacecraft in relation to these structures. NASA's Voyager 1 has reached the final frontier of our solar system, having traveled through a turbulent place where electrically charged particles from the Sun crash into thin gas from interstellar space. Astronomers tracking the little spaceship's 26-year journey from Earth believe Voyager 1 has gone through a region known as termination shock, some 8.7 billion miles (14 billion km) from the Sun, and entered an area called the heliosheath. 'Voyager 1 has entered the final lap on its race to the edge of interstellar space,' Edward Stone, Voyager project scientist at the California Institute of Technology, said in a statement released on May 24, 2005. (Reuters - Handout)

Voyager 1 reaches Edge of Solar System
Last update: May 28, 2005 at 6:27 PM
Voyager 1 in new territory
Guy Gugliotta,  Washington Post
May 29, 2005 VOYA0529

 

After a storied, 28-year odyssey, NASA's Voyager 1 spacecraft appears to have reached the edge of the solar system, a turbulent zone of near-nothingness where the solar wind begins to give way to interstellar space in a cosmic cataclysm known as "termination shock," scientists said last week.

"This is an historic step in Voyager's race," said physicist Edward Stone, the mission's chief scientist since Voyager 1 and its twin, Voyager 2, were launched in the summer of 1977. "We have a totally new region of space to explore."

Stone said that project scientists, working from models of a phenomenon never before directly observed, finally agreed that data from Voyager 1's tiny 80-kilobyte computer memory showed that the spacecraft had passed through termination shock to the "heliosheath," a frontier of unknown thickness that defines the border with interstellar space.

Stamatios Krimigis, another longtime Voyager scientist, said in a telephone interview that the spacecraft may remain in the heliosheath for perhaps 10 years but should easily survive, going dark only when its plutonium power source finally expires around 2020.

Voyager 1's "design mission" to Jupiter and Saturn lasted five years, then simply kept on going. Voyager 2 flew by Uranus and Neptune to complete a "grand tour" of the major planets and is now about 7 billion miles from the sun traveling at 63,000 miles per hour.

Voyager 1 broke away from the tour at Jupiter and headed for interstellar space. When it entered the heliosheath, it was 8.7 billion miles away -- the farthest any man-made object has ever traveled. Its speed is 46,000 miles per hour.

Krimigis said the solar wind, composed of fast-moving electrons, protons and other charged particles, has a magnetic field that prevents the interstellar wind from breaching the solar envelope, known as the "heliosphere," as the solar system travels through space.

The heliosheath is the heliosphere's outer frontier, a zone where the solar wind begins to dissipate. This process begins at termination shock and is marked by a sudden drop in the speed of the solar wind and a corresponding buildup in heat and the strength of the magnetic field. The effect is like traffic piling up on a freeway during rush hour.

Scientists first detected these symptoms in 2002, but they receded, then returned more strongly, only to recede again, a script not foreseen by the computer models.

"We've gone back and forth since then," Krimigis said. "But this time I guess we all agree."

Scientists estimated the speed of the solar wind dropped from 1.5 million m.p.h. to near zero.

Stone stressed, however, that this clash of cosmic forces has little effect on Voyager, since the amount of matter in the heliosheath is so meager.

PHOTO1Undated artist's concept illustrating where our solar system's final frontier, the heliosheath, fits in relation to our galaxy. The interstellar wind collides with the heliosheath and forms a structure called the bow shock (red and orange areas, forcing the heliosheath into a long, teardrop shaped structure. Image 2a shows the positions of the Voyager spacecraft in relation to these structures. NASA's Voyager 1 has reached the final frontier of our solar system, having traveled through a turbulent place where electrically charged particles from the Sun crash into thin gas from interstellar space. Astronomers tracking the little spaceship's 26-year journey from Earth believe Voyager 1 has gone through a region known as termination shock, some 8.7 billion miles (14 billion km) from the Sun, and entered an area called the heliosheath. 'Voyager 1 has entered the final lap on its race to the edge of interstellar space,' Edward Stone, Voyager project scientist at the California Institute of Technology, said in a statement released on May 24, 2005. (Reuters - Handout)

The heliosheath is the heliosphere's outer frontier, a zone where the solar wind begins to dissipate. This process begins at termination shock and is marked by a sudden drop in the speed of the solar wind and a corresponding buildup in heat and the strength of the magnetic field. The effect is like traffic piling up on a freeway during rush hour.

Scientists first detected these symptoms in 2002, but they receded, then returned more strongly, only to recede again, a script not foreseen by the computer models.

"We've gone back and forth since then," Krimigis said. "But this time I guess we all agree."

Scientists estimated the speed