Ladies and Gentlemen Voyager 1 Has Left the Solar System

[BadBrain]

Per NASA's press release ( http://www.nasa.gov/mission_pages/voyager/voyager20120614.html ) of 14 June 2012, interstellar cosmic rays are striking the spacecraft at an increased rate. Voyager 1 has already encountered solar wind moving laterally with respect to the solar surface, and even in net retrograde motion with respect to the solar surface, which would mean that she's passed through the limit of solar influence capable of deflecting the interstellar medium, and has observed the interstellar medium deflecting solar influence. If the density of charged particles in the vicinity of the spacecraft has INCREASED, then this can only mean that she is currently in the "bow shock", which is where interstellar winds would tend to pile up in front of the solar system as it flies through interstellar space. (Think of a ship passing through the water: water is incompressible, so the energy of the ship passing through the water can only be expressed as a shift in the volume of the water immediately adjacent to the ship's bow (the "bow wave"). In a similar fashion, interstellar winds would tend to pile up in front of the solar system as an expression of aerodynamic pressure/aerodynamic drag.) If she's within the "bow shock", then she's within the interstellar medium, and no longer within the solar system.

Just think of that! An object crafted by human hands is now flying in interstellar space, outside the solar system! Elvis has truly left the building!

Three cheers for Voyager 1:

Hip! Hip! HOORAY!
Hip! Hip! HOORAY!
Hip! Hip! HOORAY!

 

[DaveC426913]

That's way cool.

 

[SHISHKABOB]

Awesome!

 

[OmCheeto]

Wow. That sucker was launched the year I graduated from high school. What the hell has kept it going?

google google google

Voyager 1 has three large radioisotope thermoelectric generators (RTGs). Each RTG contains 24 pressed plutonium-238 oxide spheres. The heat from the spheres generated about 157 watts of electric power at the launch, with the remainder being dissipated as waste heat. Hence there was a total of about 470 watts of electric power provided by the three RTGs.

The power output of the RTGs does decline over time, but the RTGs of Voyager 1 will continue to support some of its operations through about 2025.

13 more years!

That is freaking awesome. I'll be 66 years old, and probably ready for the permanap myself.

:zzz:

 

[Ivan92]

Oh my damn...that is incredible!

 

[DaveC426913]

What the hell has kept it going?

[STRIKE]In space, it just coasts, so...[/STRIKE]

 

[Antiphon]

The most shocking thing is that we can pick up a 24 Watt transmitter from this distance. I still can't believe it.

 

[Pengwuino]

Well they better hurry up and get it back soon...

 

[Anna Blanksch]

That. Is. AWESOME! Hip Hip Hooray!

 

[rethipher]

I'm glad at least some of our race views this as important. This is the epitome of what our curiosity is capable of!

 

[Storm89]

It is quite a feat, but I can't help but think what we could achieve today. Although it's a bit of a vast distance to catch up to...

 

[Pkruse]

I remember that launch. The roads were packed with thousands of protesters objecting to the nuclear payload. That craft has a nuclear reactor onboard for power. Too far away from the sun to use solar power.

 

[Ryan_m_b]

I remember that launch. The roads were packed with thousands of protesters objecting to the nuclear payload. That craft has a nuclear reactor onboard for power. Too far away from the sun to use solar power.

It's not a nuclear reactor, its a radioisotope thermoelectric generator. The difference as I understand it is that the first involves induced chain reactions of nuclear fission and the latter is harvesting energy from the heat produced by continuous radiation.

 

[Astronomyboy]

Wow :)

 

[Whovian]

I know I'm a bit late, but awesome!

 

[lisaray]

O Wow it was great...didn't even knew about this.

 

[Pkruse]

I know that a RTG is not a nuclear reactor, but it is commonly called that in the press, and we who worked with them would also sometimes call it that, even though we knew better.

I worked in the lifting, handling, and installation into the spavecraft, so I was not one of the guys who got to see them on the inside.

The radioactive material is only a passive heat source. It warms a bunch of thermocouples, which generate a voltage and current.

 

[BadBrain]

O Wow it was great...didn't even knew about this.

I should have stated clearly in my original post that my statement on this matter represents a minority report, as the NASA people still say passage through the heliopause is yet to come. My statement is in accord with the criteria laid out for measuring passage through the heliopause and into the bow wave, which have clearly been satisfied per the measurements to which I refer in my original post.

 

[mfb]

It is quite a feat, but I can't help but think what we could achieve today. Although it's a bit of a vast distance to catch up to...

For every distance, there is an ideal time to launch a probe to reach the destination :). For up to ~200 AU (and maybe more), I think Voyager will be first. And after that, I doubt that there are many interesting targets within 4 light years.

 

[Dotini]

...I doubt that there are many interesting targets within 4 light years.

Every once in a while I've heard it said that the Oort cloud is part of the solar system, presumably traveling along with us a light year or so off. I've also heard from NASA that the heliopause defines the limit of the solar system. Who's right? Is it a fact or merely a surmise that the Oort cloud really even exists? What would it mean if it doesn't exist? Could Voyager, or any device, make the trip to the Oort cloud and still keep on ticking? What sorts of instruments would be needed to verify the Oort cloud?

Respectfully submitted,
Steve

 

[mfb]

The Oort cloud is an area where (afaik) no objects are known today - and even if the cloud exists with objects of relevant mass, they would be so sparse that a mission will never hit one by chance. If we detect some objects there, they might become a target for a future mission.

 

[BadBrain]

Every once in a while I've heard it said that the Oort cloud is part of the solar system, presumably traveling along with us a light year or so off. I've also heard from NASA that the heliopause defines the limit of the solar system. Who's right? Is it a fact or merely a surmise that the Oort cloud really even exists? What would it mean if it doesn't exist? Could Voyager, or any device, make the trip to the Oort cloud and still keep on ticking? What sorts of instruments would be needed to verify the Oort cloud?

Respectfully submitted,
Steve

Steve:

There's no conflict between those two contentions, as the heliopause lies beyond the Oort Cloud, enveloping a region known as the Heliosheath where only charged particles exist. The Heliosheath might be thought of as the Solar System's fuselage, resisting the dynamic pressure of the Interstellar Medium as the Solar System flies through it. In addition to a bow wave, the Heliosheath also has a "stern tail", giving the Solar System overall the shape of a teardrop or drop tank.

 

[Dotini]

...the heliopause lies beyond the Oort Cloud

Dear BadBrain,

Due to my hobbyist status and the august nature of the Physics Forum, I've never had the temerity to attempt a scientific correction of any statement I've ever found in the Physics Forum. However, I will do so now.

My research indicates the heliopause is being found a bit over 100 AU from the Sun.
Additional research shows the hypothesized Oort cloud is thought to be about a light year distant.

100 AU is about 15 billion kilometers
http://en.wikipedia.org/wiki/Heliosphere

1 light year is roughly 10 trillion kilometers (or about 6 trillion miles).
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question19.html

Therefore, if my research and math are correct, the heliopause is well inside any Oort cloud, and my questions remain completely unanswered. I will continue looking into this small matter and let you know what I find.

Respectfully submitted,
Steve (distantly related to Kepler!?) :)

 

[DaveC426913]

I am not schooled on the specifics, but I think Dotini is correct. I understood that the Oort cloud in principle includes all objects out to the edge of Sol's gravity well, which extends halfway to Centauri.

 

[arabianights]

isn't the new boundary of solar system the Oort cloud? which is 1 ly and Voyager is still inside solar system by that definition.

 

[BadBrain]

Steve:

Thanks for the correction!

 

[BadBrain]

Steve:

I did a little further research of my own, and I found that the existence of the Oort Cloud may be irrelevant to a discussion of whether or not the Heliopause constitutes the outer edge of the Solar System, as the minor planet (if that's what she is) 90377 Sedna, undoubtedly part of the Solar System, has an aphelion of 937 AU, and a perihelion of 76.361 AU, which means that, barring the highly unlikely prospect of her orbit being perfectly aligned with the Heliopause's Tail Cone, she spends most of her orbit beyond the Heliopause.

I feel like I don't know anything anymore!

EDIT:

The Heliosphere now appears not to have a tail, per Cassini and IBEX. Boy do I feel like the dunce of the forum!

 

[PhilDSP]

Very interesting! But now where is the solar system heading towards? Can a rough direction be estimated?

 

[DaveC426913]

Very interesting! But now where is the solar system heading towards? Can a rough direction be estimated?

The Solar system is orbiting our galactic core; one revolution every 260 million years.

Actually, wiki has some interesting figures on its movement in the page's sidebar:
http://en.wikipedia.org/wiki/Milky_Way

 

[Dotini]

The Solar system is orbiting our galactic core; one revolution every 260 million years.

Many stars are found in the four arms of the Milky Way galaxy (duh). I think ours is a bit of an oddball, because instead of residing in one arm, it orbits through all four.

Respectfully,
Steve

 

[DaveC426913]

Many stars are found in the four arms of the Milky Way galaxy (duh). I think ours is a bit of an oddball, because instead of residing in one arm, it orbits through all four.

Respectfully,
Steve

I am not sure that makes it an oddball. I believe the spiral arms are not fixed structures, but density variations, like the bars.

I should get a reference for that though.

 

[BadBrain]

I am not sure that makes it an oddball. I believe the spiral arms are not fixed structures, but density variations, like the bars.

I should get a reference for that though.

Yep!

I'm thinking "zones of resonance" to describe the arms.

 

[PhilDSP]

Actually, wiki has some interesting figures on its movement in the page's sidebar:
http://en.wikipedia.org/wiki/Milky_Way

The Apex of the Sun's Way, or the solar apex, is the direction that the Sun travels through space in the Milky Way. The general direction of the Sun's Galactic motion is towards the star Vega near the constellation of Hercules, at an angle of roughly 60 sky degrees to the direction of the Galactic Center.

Does this mean that since Voyager is encountering the solar system's bow wave (so to speak) where energy streams at an angle normal to the solar system's trajectory (solar apex), that Voyager's trajectory is within the hemisphere pointing at the star Vega and presumably closer towards Vega than the outer rim of the hemisphere?

 

[DaveC426913]

Does this mean that since Voyager is encountering the solar system's bow wave (so to speak) where energy streams at an angle normal to the solar system's trajectory (solar apex), that Voyager's trajectory is within the hemisphere pointing at the star Vega and presumably closer towards Vega than the outer rim of the hemisphere?

You could define such a hemisphere with Vega at its centre - but it would be a hemisphere 25 light years in radius and be dotted with a dozen other, closer stars. I don;t see what physical significance it would have.

 

[JamesEllison]

That is truly amazing :D three cheers for Maths!