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Thirty-five years after launch, Voyager 1 set to exit solar system

Now some 11 billion miles from the sun, Voyager 1 is approaching interstellar space.

How long does it take to fly to the edge of the solar system? At least 35 years.聽Voyager聽1聽is there now, carrying 1970s-era technology that might make your jaw sag 鈥� computers with 8,000 words of memory and 8-track tape recorders.

Those of us who can remember popping the Allman Brothers into the 8-track tape deck can identify with聽Voyagers聽1聽and 2 鈥� a couple of nearly old fogies. But these NASA stalwarts are set to make space history. Again.

Wednesday marks the 35th anniversary of聽Voyager聽1鈥檚 launch to Jupiter and Saturn.聽Voyager聽2 marked its 35th anniversary on Aug. 20.

鈥淭hey were the first fully automated spacecraft that could fly themselves,鈥� Ed Stone, chief聽Voyager聽project scientist, told the Los Angeles Times in an interview Tuesday. 鈥淭hey were the peak of technology.鈥�

Now the聽Voyagers聽are on their way to becoming the first human-made objects ever to enter interstellar space 鈥� that yawning black gap between the stars.

Since its launch,聽Voyager聽1聽has traveled billions of miles 鈥� it is now 11 billion miles from the sun.聽Voyager聽2 is not far behind, at 9 billion miles from the sun.

According to NASA, both spacecraft have spent the last five years exploring the outer layer of the heliosphere, 鈥渢he giant bubble of charged particles the sun blows around itself.鈥�

Suzanne Dodd,聽Voyager聽project manager at NASA鈥檚 Jet Propulsion Laboratory in La Canada Flintridge, Calif., said the two spacecraft were in great shape, considering they had flown through Jupiter鈥檚 鈥渄angerous radiation environment鈥� and had endured the frigid temperatures of space for decades.

鈥淲hen聽Voyager聽was launched, the space agency itself was only 20 years old,鈥� noted Stone, who also is a longtime physics professor at the California Institute of Technology. 鈥淲e always hoped we would reach interstellar space.鈥�

Scientists didn鈥檛 just hope for it. They planned for it. The spacecraft鈥檚 CRS 鈥� Cosmic Ray Subsystem 鈥� was intended specifically for use in interstellar space, Stone said.

鈥淚t was able to measure many things鈥� along the journey, Stone said, 鈥渂ut its prime purpose was determining the interstellar spectrum of cosmic rays.鈥�

Stone has been with NASA鈥檚聽Voyager聽project since the beginning, and he鈥檚 excited.

鈥淭his is a major milestone,鈥� he said. 鈥淭his will be the first spacecraft to enter interstellar space. We鈥檒l know exactly how big this bubble is.鈥�

There are estimates on the size of the bubble, which is described in one Associated Press report as a hot and turbulent area created by a stream of charged particles from the sun. Interstellar space begins somewhere from 11 billion to 14 billion miles from the sun.

So any day now聽Voyager聽1聽could exit the bubble and cross over into interstellar space. Any day 鈥� week, month or, perhaps, year.

鈥淰oyager聽travels a million miles a day,鈥� Stone said, 鈥渂ut a million miles out of a billion miles is a very tiny little sliver.鈥�

Once the spacecraft does cross over, it can measure the strength and direction of the magnetic field that鈥檚 pressing against the outside of the plasma bubble, Stone said. And the intrepid newbie can take 鈥渜uality measurements鈥� of cosmic rays, including the ionized rays that are unable to enter our solar system.

鈥淔or the first time,鈥� the scientist said, 鈥渨e鈥檒l be able to measure the intensity of these cosmic rays that can鈥檛 get in.鈥�

The聽Voyagers鈥� original goal, as the AP wrote, was to tour Jupiter and Saturn. They sent back data on Jupiter鈥檚 big red spot and Saturn鈥檚 rings. They discovered erupting volcanoes on the Jupiter moon Io; saw hints of an ocean below the icy surface of Europa, another Jupiter moon; and found signs of methane rain on the Saturn moon Titan.

Voyager聽2 journeyed to Uranus and Neptune. It鈥檚 the only spacecraft to fly by these two outer planets.

How much longer can the two聽Voyagers聽last?

They have enough electrical power to last until 2020, Stone said. The team behind the spacecraft will begin to turn off instruments at that point to reduce power needs. The last instrument will likely be shut off in 2025.

鈥淭hen, they will orbit the center of our galaxy essentially forever,鈥� he said.

鈥斺赌斺赌�

漏2012 Los Angeles Times

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