Voyager is executing a series of roll manoeuvres to get one of its instruments into the optimum position to measure particles sweeping away from the Sun.
Controllers at the US space agency’s Jet Propulsion Laboratory in Pasadena, California, report a perfect response from the probe.
“I liken Voyager to an old car,” said project manager Suzanne Dodds. “It’s got simple electronics, not a lot of fancy gadgets – but because of that it can operate for longer; it’s not as finicky.”
And as Voyager 1 passes through the heliosphere boundary – where Nasa’s IBEX spacecraft recently found unexpected evidence of structure – it’s still returning unique scientific data. From the Nasa press release
In June 2010, when Voyager 1 was about 17 billion kilometers (about 11 billion miles) away from the sun, data from the Low Energy Charged Particle instrument began to show that the net outward flow of the solar wind was zero. That zero reading has continued since. The Voyager science team doesn’t think the wind has disappeared in that area. It has likely just turned a corner. But does it go up, down or to the side?
“Because the direction of the solar wind has changed and its radial speed has dropped to zero, we have to change the orientation of Voyager 1 so the Low Energy Charged Particle instrument can act like a kind of weather vane to see which way the wind is now blowing,” said Edward Stone, Voyager project scientist, based at the California Institute of Technology, Pasadena. “Knowing the strength and direction of the wind is critical to understanding the shape of our solar bubble and estimating how much farther it is to the edge of interstellar space.”
Voyager engineers performed a test roll and hold on Feb. 2 for two hours, 15 minutes. When data from Voyager 1 were received on Earth some 16 hours later, the mission team verified the test was successful and the spacecraft had no problem in reorienting itself and locking back onto its guide star, Alpha Centauri.
The Low Energy Charged Particle instrument science team confirmed that the spacecraft had acquired the kind of information it needed, and mission planners gave Voyager 1 the green light to do more rolls and longer holds. There will be five more of these maneuvers over the next seven days, with the longest hold lasting three hours 50 minutes. The Voyager team plans to execute a series of weekly rolls for this purpose every three months.
The success of the March 7 roll and hold was received at JPL at 1:21 a.m. PST (4:21 a.m. EST) on March 8. But it will take a few months longer for scientists to analyze the data.
“We do whatever we can to make sure the scientists get exactly the kinds of data they need, because only the Voyager spacecraft are still active in this exotic region of space,” said Jefferson Hall, Voyager mission operations manager at JPL. “We were delighted to see Voyager still has the capability to acquire unique science data in an area that won’t likely be traveled by other spacecraft for decades to come.”
As the BBC report adds
“It counts the particles and measures their direction,” explained Suzanne Dodds. “This will give us a much better picture of what’s happening with the solar wind close to the heliopause (the “official” edge of the Solar System). It could be that as we do these measures we see its direction change. All we have out there is models and every time we get data the models don’t quite fit what Voyager sees, and then we have to update the models.”
Voyager’s next destination – interstellar space.