1970s Voyager 1 Spacecraft Conducts Interstellar Experiments

When NASA’s Voyager 1 space probe launched on 5 September, 1977, its mission was to explore Jupiter and Saturn and help scientists learn more about our solar system. Thirty-six years later, Voyager 1 is still providing discoveries.

NASA recently learned that Voyager 1, which has now traveled more than 15.8 million miles from Earth, has moved so far from our planet that it is now in what is called interstellar space, or a region of our solar system, where it has come into contact with particles that were released by stars other than our sun.

Interstellar space

That’s significant, according to NASA, because it means that the Voyager 1 probe is now in contact with particles in an area of the solar system that’s beyond our sun and the planets that revolve around it. For scientists, it means that the space probe is being bathed in interstellar space plasma that is 40 times as dense as particles seen during the earlier parts of its travels.

“Scientists were wowed about this because no spacecraft has been there before,” Enrique Medina, Voyager 1’s guidance and control manager at NASA’s Jet Propulsion Laboratory in Pasadena, California, told eWEEK. “Only in the simulation models that scientists use have we been able to predict what’s out there. Now, we’re going to know more and find out whether the models match reality.”

Medina, who joined the Voyager project in 1986, said that scientists only learned about Voyager 1’s interstellar space activities in late August 2013, after data that was recorded by the probe a year ago – back in August 2012 – was downloaded, analysed and prepared for use. The delay in getting the information was due to a complex system that’s used to record and retrieve data on an on-board tape recorder, which is actually an old eight-track tape recorder, which wasn’t old when it was placed aboard the space probe before its launch, said Medina.

“We have been in it for a year and we are recording” the information, he said. “Scientists are deciphering the data, and they are going to be writing papers for years to come. It hasn’t left our solar system,” Medina said of Voyager 1. Instead, it is just collecting new data and information from areas of our solar system that are farther from the pull of our sun.

Another reason that it took so long to discover that the transition had been made into interstellar space is that the space probe’s on-board plasma experiment, which could have detected the changes earlier, has been broken since 1980, he said. Another experiment system on the spacecraft, called a plasma wave experiment, had to be used, and because it gives different information, the discovery took longer to make.

1970s technology

“We found a way, and it’s amazing,” said Medina. “Voyager 1 is one of the most robust pieces of hardware that’s ever been built” and sent into space.

The equipment aboard the probe was powerful when it was launched, but in comparison with today’s technology, it is incredibly outdated. There are three computers on board, along with three duplicate back-up computers, for a total of six. Those six machines have a total of 68KB of memory, compared with a typical 16GB smartphone in 2013 that contains about 235,000 times more memory, according to Medina.

One of the computers is used for telemetry data, while another sends and receives sequences detailing what NASA wants to do on the craft. The remaining computer system is the attitude and articulation control system (ACS), which Medina calls “my baby”. That computer controls the actual movement of Voyager 1 and keeps it pointed toward the Earth.

“I deal with it, I program it, and when there are problems, I reprogram it. We’re here every day and we get data on the Voyagers on the average of six to eight hours a day from each one,” he said, adding that Voyager 2 is also still in space, on a trajectory that will have it reaching interstellar space in the next two to three years.

Five of the original 11 experiments built into Voyager 1 are still operational, 36 years after the mission began, said Medina. A camera was shut off in 1990 when it was no longer needed in a power-saving move. The spacecraft, which is powered by nuclear fuel, plutonium 238, only has enough fuel to operate the remaining experiments through 2020. At that point, scientists will have to shut down the experiments. By 2025, only enough fuel will remain to simply fly the probe, without any operating experiments, he said.

“At that time, we either go and engineer a monitoring mission with no data or we shut it off,” said Medina.

Continuing mission

“This is just another phase,” Medina said of the craft’s travels through interstellar space. “This is not the end of the mission, by any stretch of the imagination. We’re trail-blazing unknown territory.”

In August, NASA’s Curiosity Mars rover celebrated its one-year anniversary on the Martian surface as the space agency looks forward to more discoveries as the rover begins its second full year of exploration.

So far, the rover and its two-year planned mission have brought back several significant finds to scientists back on Earth, including the discovery of evidence that ancient Mars could have supported life, according to NASA.

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Originally published on eWeek.