Voyager 1 - let the calculations begin!

[dwight]

Has it officially exited the Solar system?

http://www.space.com/17966-voyager-spacecraft-solar-system.html

How cool.

[Kiwi]

Even more important than the numbers:  Did it give a little jump as it went through?









[With thanks to Mike Collins's sense of devilment for that bit of Apollo 8 and Apollo 11 obscurity, Carrying the Fire, Cooper Square Press edition, 2001, pages 423 and 424 (originally published 1974).]

[ka9q]

Has it officially exited the Solar system?

Well, I suppose it depends on what you define as the boundary of the Solar System. I guess the boundary of the sun's magnetic field is as good a definition as any. But you could also say that it doesn't really end until you're experiencing more gravity from an object outside than inside, and that won't happen for quite some time. The Oort Cloud extends something like halfway to Alpha Centauri.

[Glom]

When it reaches the boundary, we'll know.

[dwight]

Two years ago we were at Tidbinbilla and saw the tracking of Voyager 2. There was a time listed next to the spacecraft's name - 27, and that was how many hours were required for the signal to reach earth. So our loveable little probes are just over 1/364th of a light year from us.

[ka9q]

Wow, only 1/1,419th (approximately) of the way to Alpha Centauri.

If it were headed in that direction, that is.

[ka9q]

Two years ago we were at Tidbinbilla and saw the tracking of Voyager 2. There was a time listed next to the spacecraft's name - 27, and that was how many hours were required for the signal to reach earth.

Wait, that must be the round trip light time. As of 9 Sep 2012, Voyager 1 was 121.798 AU from the sun and Voyager 2 was only 99.077 AU from the sun. That's 16.89 and 13.7 light-hours respectively.

So Voyager 1 (the faster of the two) is only 1/2,269th of the way to Alpha Centauri. If it were headed in that direction.

[ka9q]

Trivia question: in the inertial reference frame where the sun is at rest, which currently has the highest velocity?

a. Voyager 1
b. Voyager 2
c. me (or you, for that matter)

[smartcooky]

Trivia question: in the inertial reference frame where the sun is at rest, which currently has the highest velocity?

a. Voyager 1
b. Voyager 2
c. me (or you, for that matter)

Heliocentric speeds

a. Voyager 1 - 17.3 km/s
b. Voyager 2 - 15.4 km/s
c. me (or you) - 29.9 km/s*

* this will depend on where you are on the Earth. You will be moving fastest on the night side near the ecliptic and slowest on the days side near the ecliptic.

Of course this all pales into insignificance when you consider the sun, planets and voyagers are all travelling around the galactic centre at over 200 km/s, and the galaxy itself is speeding through the universe at over 6000 km/s in the direction of something called The Great Attractor

[ka9q]

Correct! (Was it that obvious?)

6,000 km/s is cooking. That's 2% of c!

You mentioned our galactic speed, which suggests another trivia question, one I haven't actually investigated. Although the Voyagers (and Pioneers, and New Horizons) are on solar system escape trajectories, they do not have enough velocity to escape the galaxy. But suppose one encounters another star many thousands of years from now. Could it provide enough of a gravity assist to eject it from the galaxy? How big a star and how close would the approach have to be? Assume the star is moving along with Sol in the same direction around the galactic center at 200 km/s.

[Echnaton]

And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down here on Earth.

[smartcooky]

Galactic escape velocity (at the Sun's radius) is about 1000 km/s. The Voyagers are travelling at less than 2% of that.

Would take an enormous gravitational assist (massive star & close pass) to increase their velocity by a factor of 500. More likely several passes close to several massive stars.

And pray that there's intelligent life somewhere up in space,
'Cause there's bugger all down here on Earth.

[smartcooky]

Just had a friend call into my shop; one who was in the Canterbury Astronomical Society with me many years ago. I put the question to him.

He said that the formula would require F^BS + F^CA (f---ing Big Star + F---ing Close Approach)

Seriously, he did suggest that Voyager might get the required gravitational assist by flying close to the event horizon of a large black hole, if it could survive the tidal forces and the colossal dose of X-Rays and /or Gamma Radiation.