Robert McNees
The Voyager 1 space probe was launched from Cape Canaveral #OTD in 1977, a few weeks after Voyager 2.
Now it's the most distant human-made object – about 14.96 billion miles from Earth, racing away from us at 38,000 miles per hour with respect to the Sun.
Images: NASA/KSC/JPL
Robert McNees
Voyager 1’s outbound trajectory took it by Jupiter in 1979, then past Saturn the next year.
This time lapse of the Jupiter approach consists of 66 frames, take once per Jovian day. Look carefully for moons darting past, shadows flickering across the face of the planet.
Credit: NASA/JPL
Robert McNees
Voyager 1 discovered three new moons (Prometheus, Pandora, and Atlas) shepherding Saturn's A- and F-rings.
It also uncovered a wealth of new information about basic properties of Saturn's moon Titan, from size to atmospheric composition.
Image: NASA/JPL-Caltech
Robert McNees
The trajectory that gave Voyager 1 the best view of Titan (a mission priority) sent it out of the ecliptic and towards interstellar space.
Ten years later, in 1990, Carl Sagan suggested that the probe should point its camera back at the solar system for a family portrait.
The sixty frame mosaic captured by Voyager 1 on Valentine's Day of 1990 shows Jupiter, Earth, Venus, Saturn, Uranus, and Neptune.
https://voyager.jpl.nasa.gov/galleries/images-voyager-took/solar-system-portrait/
Image: NASA/JPL-Caltech
Robert McNees
The frame containing Earth shows a dramatic optical artifact because we are near the Sun in the camera's field of view.
That's the Pale Blue Dot. Suspended in a sunbeam, captured from a distance of 40 AU by a probe out on the edge of darkness.
After that, mission scientists turned off Voyager 1's cameras to save power.
Image: NASA/JPL
Robert McNees
By 1998, Voyager 1 was at 68 AU, further out than Pioneer 10.
Around 2004, at about 94 AU from the Sun, it crossed the termination shock and entered the heliosheath.
And in 2012, at 121 AU from the Sun, Voyager 1 crossed the heliopause and entered interstellar space.
Robert McNees
But Voyager 1 hasn't left the solar system. At 161 AU, its current distance from the Sun is a fraction of Sedna's 936 AU aphelion (though it is currently further out than the minor planet).
And it's nowhere near the inner edge of the Oort cloud, thousands of AU from the sun.
This chart shows Voyager 1's location in 2013, with distance from the sun plotted on a log scale. It is at roughly the same place today, since the next step on the scale jumps from 100 to 1000 AU.
Image: NASA/JPL-Caltech
Robert McNees
So even though Voyager 1 has a long way to go, I wouldn't fault anyone for describing it as being at "the edge of the solar system."
It’s the fastest and most distant thing humans have ever made, it’s okay to sound a little dramatic.
Robert McNees
When we receive data from Voyager 1, we’re picking up a signal sent about 22 hours and 19 minutes.
Of all the objects humans have hurled into space, Voyager 1 is the closest to being one full light-day away from us.
The speed of light is 3 x 10⁸ m/s, and Voyager 1 is traveling at about 38,000 mph with respect to the Sun. A few conversions turns that into about 0.5 light-hours per year. So we're a little over three years away from Voyager 1 being one full light-day away from us.
Robert McNees
Six of the probe’s scientific instruments have been powered down. The other four will be shut off over the next few years. When it reaches a distance of one light-day we’ll still be able to communicate with it, but it won't have much to say.
Voyager 1 will remain in range of our Deep Space Network for some time after that. Eventually, though, it won't be able to muster enough power for a detectable signal, and will quietly sail off into darkness.
https://voyager.jpl.nasa.gov/downloads/
Image: NASA/JPL-Caltech
Robert McNees
@transponderings They're all rotating the same way. The appearance of rotating in different directions is a result of capturing frames at fixed intervals while they move at slightly different speeds.
There's not too much variation in the speeds, though. Depending on whether you use polar or equatorial bands, the day varies by about 5 or 10 minutes. Another definition (used by IAU) is rotational period of the planet’s magnetosphere.
Anna Nicholson
@mcnees How do astronomers arrive at the length of a day for a gas giant?
There are various bands of fluid rotating in different directions in the time-lapse video
Given the relatively static nature of the Great Red Spot in Voyager 1’s photographs, I’m guessing that the rotational period of this well-known feature is (or was at the time) used as the rotational period of the planet as a whole, i.e. the length of a Jovian day
Or is the composition of Jupiter sufficiently well understood that it’s possible to calculate the moment of inertia of the planet about its rotational axis?
andrybak
@mcnees it's the same as the series of discoveries of water on Mars. Every time it's actually something new and different from the previous instances, but it inevitably gets oversimplified to just "Breaking news: water on Mars!"
GJ Groothedde 🇪🇺
@mcnees It's humbling knowledge that this is still only 0.35% of the distance to the nearest star.
bouriquet
@mcnees I graduated from college in 1977, now almost retired. Voyager 1 has been traveling during my entire career. Likely that the folks tracking it are not those who began after the launch.
Jennifer Wojcik
@mcnees I was 5. Wow.
PetrichorLove
@mcnees one of my all time favourite pictures, thank you 😊
Eric Carroll
@mcnees
Updates are available daily via @NSFVoyager2 and
@Voyager1 accounts.
xs4me2
Yes there we are, and we could share all we have with everybody so all would be happy and in unison with nature… instead mankind is the only animal that has created models and means to suppress their kind and reason some are mediocre because of skincolor or beliefs, and go to war committing planned murder and destruction on its own kind.
We do not deserve this pale blue dot…
Amanda Grace
@mcnees I love how we’re even littering in SPACE though.
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