The Voyager 1 deep space probe may - finally - be about to leave our solar system, according to reports.
The craft was launched in 1977, and is speeding away from the Earth at 38,000 miles an hour.
It's now about 121au away from the Earth - about 121 times the distance of the Earth from the Sun. In 1990 its cameras were switched off, and in 2004 it entered the edge of the area where the Sun's particles reach - the 'heliosphere' - indicating it was close to leaving the solar system entirely.
If it does leave the solar system the achievement will be huge. No other object made by humans has crossed that barrier, and it was not always clear that Voyager 1 would make it that far.
But nobody is sure just how thick or dense the heliosheath - the edge of the heliosphere - really is. And since 2004 the data it sends backs about nearby particles has indicated it was getting ever closer.
According to a Nasa scientist interviewed by the Atlantic, it may be about to leave.
Just... not quite yet.
Recently speculation the barrier had been crossed erupted after the probe detected an increased level of cosmic particles which usually get blocked by the heliosheath.
But The Atlantic points out, the fact the levels are still rising mean the craft hasn't quite crossed the divide.
"But we don't know," said the former head of Nasa's Jet Propulsion Lab and Voyager's project scientist Edward Stone. "I mean this is the first time any spacecraft has been there."
"We're looking at our data every day -- we listen to these spacecraft every day, for a few hours every day," he added. "It's very exciting from a scientific point of view, when you're seeing something that nobody's seen before."