Something just a little bit remarkable happened last week.
Launched on September 5th, 1977, Voyager 1 visited Jupiter in 1979 and Saturn 1980, sending back marvellous photos and data from both. The craft is not fitted with brakes and has been sailing out of the solar system since, most recently encountering a “roar” caused by a coronal mass ejection. The circumstances in which the sound was detected led boffins to believe the probe has definitively left the solar system.
As of last Tuesday, the craft's journey ticked over another small milestone: it's now 18 light hours from the Sun.
Here's the craft's Tweet from last Monday.
Sister ship @NASAVoyager is 17 hrs 59 mins 55 secs of light-travel time from Earth (2014:293:120000:1L)— NSFVoyager2 (@NSFVoyager2) October 20, 2014
And here's its Wednesday report.
Sister ship @NASAVoyager is 18 hrs 00 mins 03 secs of light-travel time from Earth (2014:294:120000:1L)— NSFVoyager2 (@NSFVoyager2) October 21, 2014
NASA measures both Voyagers distance from the Sun, rather than Earth, because our home planet's orbit means we're sometimes closer to the probes. Measuring distance from the Sun therefore gives a more objective way of tracking the spacecrafts' progress.
The Voyager Mission Operations and Status Report page lags the probes' journey by about a month, but the most recent report from the week ending September 19th found “performance was nominal” for instruments and flight systems aboard Voyager 1.
The probe looks to be putting about three light minutes between itself and Sol each week, as it hurtles towards who knows and perhaps – just perhaps – someone or something capable reading its famous cargo of a golden record that attempts to explain its origins. ®