September 13, 2013 - By today‚Äôs standards, the spacecraft‚Äôs technology is laughable: it carries an 8-track tape recorder and computers with one-240,000th the memory of a low-end iPhone. When it left Earth
36 years ago, it was designed as a four-year mission to Saturn, and everything after that was gravy.
This image obtained in 2002 from NASA
shows one of the twin Voyager spacecraft, launched in 1977.
But Voyager 1
has become ‚ÄĒ thrillingly ‚ÄĒ the Little Spacecraft
That Could. On Thursday, scientists declared that it had become the first probe to exit the solar
system, a breathtaking achievement that NASA
could only fantasize about back when Voyager was launched in 1977, the same year ‚ÄúStar Wars‚ÄĚ was released.
‚ÄúI don‚Äôt know if it‚Äôs in the same league as landing on the moon, but it‚Äôs right up there ‚ÄĒ ‚ÄėStar Trek‚Äô stuff, for sure,‚ÄĚ said Donald A. Gurnett, a physics professor at the University of Iowa and the co-author of a paper published Thursday in the journal Science about Voyager‚Äôs feat. ‚ÄúI mean, consider the distance. It‚Äôs hard even for scientists to comprehend.‚ÄĚ
Even among planetary scientists, who tend to dream large, the idea that something they built could travel beyond the Sun‚Äôs empire and keep grinding away is impressive. Plenty of telescopes gaze at the far parts of the Milky Way, but Voyager 1
can now touch and feel the cold, unexplored region in between the stars and send back detailed dispatches about conditions there. It takes 17 hours and 22 minutes for Voyager‚Äôs signals to reach NASA‚Äôs Jet Propulsion Laboratory
‚ÄúThis is historic stuff, a bit like the first exploration of Earth, and we had to look at the data very, very carefully,‚ÄĚ said Edward C. Stone, 77, NASA‚Äôs top Voyager expert, who has been working on the project since 1972. He said he was excited about what comes next. ‚ÄúIt‚Äôs now the start of a whole new mission,‚ÄĚ he said.
The lonely probe, which is 11.7 billion miles from Earth
and hurtling away at 38,000 miles per hour, has long been on the cusp, treading a boundary between the bubble of hot, energetic particles around the solar system and the dark region beyond. There, in interstellar space, the plasma, or ionized gas, is noticeably denser.
Dr. Gurnett and his team have spent the past few months analyzing their data, trying to nail down whether what they were seeing was solar plasma or the plasma of interstellar space. Now they are certain it was the latter, and have even pinpointed a date for the crossing: Aug. 25, 2012.
At a news conference on Thursday, NASA
scientists were a bit vague about what they hope to get from Voyager 1
from now on. The answer, to some extent, depends on what instruments continue to function as the power supply dwindles. Dr. Stone expects Voyager 1
to keep sending back data ‚ÄĒ with a 23-watt transmitter, about the equivalent of a refrigerator light bulb ‚ÄĒ until roughly 2025.
One hope is that Voyager 1‚Äôs position will allow scientists to more accurately study galactic cosmic rays, which are high-energy particles that originate outside the solar system. They would use the information to make judgments about what interstellar space is like at even greater distances from Earth.
In its heyday, Voyager 1
pumped out never-before-seen images of Jupiter and Saturn. But it stopped sending home pictures in 1990, to conserve energy and because there was no longer much to see. A companion spacecraft, Voyager 2, also launched in 1977, has stopped sending back images as well. Voyager 2 is moving in a different direction but is also expected to exit the solar system.
said, the Voyagers will pass other stars, coasting and drifting and being pulled by gravity. The next big encounter for Voyager 1, in around 40,000 years, is expected to be a dwarf star dispassionately known as AC+793888 in the constellation of Camelopardalis.
But already, Voyager 1
has achieved what Dr. Gurnett called ‚Äúthe holy grail of heliosphere research.‚ÄĚ Voyager 1
left the solar system the same month that Curiosity, NASA‚Äôs state-of-the-art rover, landed on Mars and started sending home gorgeous snapshots. Curiosity‚Äôs exploration team, some 400 strong, promptly dazzled the world by driving the $2.5 billion robot across a patch of Martian terrain, a feat that turned the Red Bull-chugging engineers and scientists of Building 264 of the Jet Propulsion Laboratory
campus into rock stars. By comparison, the Voyager mission looked like a Betamax in the era of Bluetooth.
The 12-person Voyager staff was long ago moved from the Jet Propulsion Laboratory
campus to cramped quarters down the street, next to a McDonald‚Äôs. In an interview last month at Voyager‚Äôs offices, Suzanne R. Dodd, the Voyager project manager, said that when she attended meetings in Building 264, she kept a low profile in deference to the Mars team.
‚ÄúI try to stay out of the elevator and take the stairs,‚ÄĚ Ms. Dodd said. ‚ÄúThey‚Äôre doing important work there, and I‚Äôll only slow them down.‚ÄĚ
At 52, Ms. Dodd is a relative newcomer to Voyager, first working on the mission in 1984. Now she and her team seem poised to return to the spotlight.
As the solar system‚Äôs edge grew tantalizingly close, NASA
asked the Voyager scientists to increase the amount of data collection. The problem: the 8-track data recorders from 1977 were not exactly bursting with extra space. Could Ms. Dodd even find anyone who specialized in that piece of technology and could coax it to record more?
‚ÄúThese younger engineers can write a lot of sloppy code, and it doesn‚Äôt matter, but here, with very limited capacity, you have to be extremely precise and have a real strategy,‚ÄĚ she said.
She was able to find her man: Lawrence J. Zottarelli, 77, a retired NASA
engineer. He came up with a solution. But would it work?
Mr. Zottarelli waited at Voyager mission control one afternoon last month to find out. The first of the newly programmed data dumps was set to come down. Ms. Dodd, Dr. Stone and Mr. Zottarelli watched two old Sun Microsystems computers like children watching for a chick to peck through an egg. ‚ÄúNine, eight, seven,‚ÄĚ Dr. Stone counted down.
‚ÄúEverything‚Äôs fine,‚ÄĚ said Mr. Zottarelli, flashing a thumbs up. ‚ÄúYou‚Äôre on your own now.‚ÄĚ
The relief was written all over Ms. Dodd‚Äôs face. ‚ÄúIt‚Äôs not easy flying an old spacecraft,‚ÄĚ she said.
Her eyes moved to Dr. Stone, who was peering at a computer through his trifocals.
‚ÄúThere are lots of old missions,‚ÄĚ he responded with a sly smile. ‚ÄúBut not many are doing exciting new things.‚ÄĚ