

After 35 years, Voyager nears edge of solar system - dirktheman
http://www.npr.org/2012/09/05/160609488/after-35-years-voyager-nears-edge-of-solar-system

======
gokhan
_So Stone can't say how long it will be before Voyager passes through it.

"I can't tell you whether it's days, months or years. I really can't tell
you," he said._

I'm not complaining, but that's why we hear this story over and over again,
every 3 months for the last 10 years.

~~~
dirktheman
It depends on your definition of ‘edge of solar sytem’, as there are many
definitions around. What amazes me the most is that we built something 35
years ago, shot it into space and it’s still going strong, sending radio
signals from a place so far away that it takes 16 hours to get here. They
supplied it with an 8-track disc that contains information about earth and
humanity.

To me, this speaks volumes about the brilliant naivety of that era, and I mean
naivety in the most positive way possible: an uncurbed enthousiasm where you
don’t see all the implications and problems on your path, but just execute.
Did they think about the fact that 8-track records would be outdated by the
time the Voyager would reach a destination where alien life would be possible?
It seems not. But they built the thing, and it’s still doing what is’s
supposed to do. This mindset has been missing for a long time, although the
new Mars Rover project has got my hopes up again.

~~~
alberich
> What amazes me the most is that we built something 35 years ago, shot it
> into space and it’s still going strong, sending radio signals from a place
> so far away that it takes 16 hours to get here.

I completely agree. I remember reading about Voyager 1 and 2 back in 1989,
when I was a just a child, and thinking how cool it was that humans could
build something to send into space and it could last so long. 23 years later,
it is even more impressive that it is still out there and kicking... and may
last another 10 years :) It is very impressive, to say the least.

~~~
slamdunc
One thing that really stuck in my mind when I heard the story was that, even
35 years later, "we're now a substantial fraction of a 'light-day' from the
Earth..."

With the term "light-years" most commonly mentioned (eg, from a few days ago:
[http://www.geek.com/articles/geek-cetera/astronomers-find-
su...](http://www.geek.com/articles/geek-cetera/astronomers-find-
sugar-400-light-years-from-earth-2012092/) ) I think hearing about light-hours
and light-days helps to put things a little more into perspective (though it's
all still mind-boggling).

------
noinput
> Voyager 1 can keep talking to Earth for about another decade. That's how
> long the plutonium that powers it should last. After it falls silent, it
> will still keep going. But it will be about 40,000 years before it wanders
> close to another star.

Something about that last paragraph that brings the whole article full circle
with lofty, child-like dreams. Makes me wonder if mankind will create the
technology (and find a way possible) to go out into deep space and pass
Voyager before that happens.

~~~
ChuckMcM
I am often inspired by the Voyager program because I see it as one where the
program planners did not put limits on themselves. And the fact that it would
be 40,000 years before the problem came close to another star was also
fascinating.

And then I consider that its only been in the last decade were we've been
looking at asteroids in an effort to identify potential disasters before they
happen. If some alien probe went through our solar system, it is only just now
that we would notice it at the size of Voyager, and then we wouldn't pay
attention because if it re-entered the atmosphere it wouldn't do significant
damage. Doesn't bode well for the aliens seeing it unless they are looking for
it.

------
kibwen
Additional reading:

"The heliopause is the theoretical boundary where the Sun's solar wind is
stopped by the interstellar medium; where the solar wind's strength is no
longer great enough to push back the stellar winds of the surrounding stars.
Voyager 1 is expected to cross the heliopause by 2014. The crossing of the
heliopause should be signaled by a sharp drop in the temperature of charged
particles, a change in the direction of the magnetic field, and an increase in
the amount of galactic cosmic rays."

<http://en.wikipedia.org/wiki/Heliosphere#Heliopause>

~~~
cstuder
And apparently the heliopause is already overdue:
[http://arstechnica.com/science/2012/09/missing-
voyager-1-yet...](http://arstechnica.com/science/2012/09/missing-
voyager-1-yet-to-find-the-boundary-line-of-the-solar-system/)

------
bbayer
Year 2012, human kind can get signals from 35 years-old spacecraft which is
passing edge of solar system.

Year 2012, I can barely have signal reception with my brand new smartphone at
my home.

------
anovikov
First time i heard that was 'Voyager was nearing edge of solar system' when i
was in high school.

~~~
Two9A
That's because there are many edges of the solar system.

The one you probably heard about was the termination shock, where the solar
wind goes subsonic. I forget how far out that is, but it's closer than the
heliopause.

From the graphs of radiation intensity, Voyager is either in a big bubble of
interstellar space trapped in the heliopause, or actually through and out the
other side. It's exciting either way.

~~~
danielweber
Query: how do you define "subsonic" in the near-vacuum of spce?

~~~
jessriedel
As you probably know, the "speed of sound" in an arbitrary medium is just the
speed at which disturbances in pressure propagate. For this to be well-
defined, the particles have to collide with each other often enough for there
to be collective disturbances (rather than just individual fast moving
particles). I would have thought that there was so much distance between
particles in interstellar space that they never collided, but apparently there
are often enough collisions to define a notion of sound. Here's wikipedia:

> The shock arises because solar wind particles are emitted from stars at
> about 400 km/s, while the speed of sound (in the interstellar medium) is
> about 100 km/s. (The exact speed depends on the density, which fluctuates
> considerably.) The interstellar medium, although very low in density,
> nonetheless has a constant pressure associated with it; the pressure from
> the solar wind decreases with the square of the distance from the star. As
> one moves far enough away from the star, the pressure from the interstellar
> medium becomes sufficient to slow the solar wind down to below its speed of
> sound; this causes a shock wave.

~~~
anovikov
Just curious why the speed of sound in interstellar medium depends on density,
while in the Earth atmosphere, it does not (it is nearly same as on surface,
around 10% smaller, on 100,000ft where there is hardly 2% of surface air
pressure).

------
CodeCube
Considering it's life expectancy is already about half over ... we should
launch another probe or two (perhaps in the opposite direction?). We have
better today these days and could probably build it to go for many decades
longer. The sooner we launch, the sooner our kids will have data.

~~~
dirktheman
We already did: the New Horizons is out there, too. But in the 60's and 70's
there was a lot more budget than these days...

~~~
CodeCube
oh cool, hadn't seen that. Hopefully the probe will keep going after its
initial mission to pluto has concluded.

------
brianmackey
Am I really the only person who hears about Voyager and immediately thinks of
"Star Trek: The Motion Picture"? At least reality is comporting with canon,
vis-à-vis V'Ger: <http://www.youtube.com/watch?v=gxAaVqdz_Vk>

------
jnazario
actually i was just reading on the SciAm blogs about this, and learned a bit
more about the edge of our solar system (and how the scientists involved in
this effort are tracking progress).

[http://blogs.scientificamerican.com/observations/2012/09/05/...](http://blogs.scientificamerican.com/observations/2012/09/05/nasas-
voyager-1-spacecraft-may-not-be-near-edge-of-solar-system-after-all/)

key comment: 'Decker and his colleagues conclude from the plasma measurements
“that Voyager 1 is not at present close to the heliopause, at least in the
form that it has been envisioned up to now.” '

just an interesting addendum to the story that NPR glossed over.

------
technotony
I love how old fashioned the images look. Even to me, 35 years on, we look
like untechnologically sophisticated... what a difference the microprocessor
makes!!

------
prawn
Amazingly, still 10-20,000 years from the Oort Cloud.

------
adrianwaj
At least now it can hit a worm hole and the Veloxi will know Earth's
inhabitable. Thanks NASA.

