
Interstellar space even weirder than expected, NASA probe reveals - el_duderino
https://www.nationalgeographic.com/science/2019/11/interstellar-space-weirder-than-expected-nasa-voyager-2-reveals/
======
tectonic
From the last issue of Orbital Index
([https://orbitalindex.com](https://orbitalindex.com)):

> Today’s mind-blowing stat: Voyager’s transmitters use just 23 watts, roughly
> the same as an incandescent refrigerator bulb, yet we are able to interpret
> the 0.1 billion-billionth of a Watt that makes it to our 70 m dish from 11
> billion kilometers away. Both spacecraft are expected to last another 5
> years, until their plutonium batteries decay beyond usefulness and they
> drift with our golden record more or less forever among the stars.

~~~
ac29
23W with extremely high gain though. It was difficult to find a number, but
this source [0] gives the gain at 47dB (dBi or dBd isn't specified). With that
high of gain, the effective radiated power is over 1 million Watts (because it
is concentrated into a very narrow beam).

Also using phrases like "0.1 billion-billionth of a Watt" is misleading, and
not how radio signals are actually described. For example 0.1 million-
billionth of a Watt sounds pretty small too, but describes the power level of
a usable, and not particularly uncommon LTE signal level.

[0] [https://www.quora.com/How-can-Voyager-send-a-signal-
strong-e...](https://www.quora.com/How-can-Voyager-send-a-signal-strong-
enough-for-us-to-receive-in-spite-of-its-enormous-distance-from-us-And-how-
can-it-have-the-power-to-do-so-more-than-20-years-after-its-launch)

~~~
credit_guy
Great quora link, thank you for posting.

Here's a related thought: if we ever manage to send a probe to the closest
star, what a tough problem communication with home will be. The distance is
about 2000 times higher than where Voyager is now. So the signal will be about
4 million times weaker due to the quadratic attenuation alone, and maybe 100
million if we consider the absorption by the interstellar medium. On top of
that, when the probe will phone home, it's going to be a few seconds of arc
away from a phenomenally bright source of electromagnetic radiation: the star
itself.

You can fix this by using a bigger transmitting antenna (but Voyager's is
already 3.7m, not small at all), or a bigger receiving antenna (the current
ones are 20m). Or a stronger signal. But it appears we'd need to go from 23W
to GigaWatts .

One thing is sure: we won't be able to send a pound-size probe.

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badrabbit
[https://www.nature.com/articles/s41550-019-0920-y.epdf?refer...](https://www.nature.com/articles/s41550-019-0920-y.epdf?referrer_access_token=YptgbTqu4rf2cjJ19DEkl9RgN0jAjWel9jnR3ZoTv0NvQxyMvEHUqYz6PZPB2CM7MFEHtS7YS_M8EL0iadgrDtpis9Nbg7aE8i5f48BJtRqpVo6g6EhfPOkxvvTiWZBrb3t30tjLIs9ipt-
hgoHx1r14vKes_LXUzORiTwrA6hpkNY9rzwMx6AeFRldIcvs789A6jsgkU1QGpq0RFzR5xw%3D%3D&tracking_referrer=www.nationalgeographic.com)

Natgeo cuts off the article midway asking me o subscribe. Above is link to OC.

~~~
labster
Reader mode worked for me for the whole article.

TL;DR two data points (trajectories) is not enough to understand the dynamics
of the heliopause, as we saw different flow in each, but it’s all we got.

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mbillie1
I cannot imagine the feeling of pride you must have if you worked on the
Voyager program in any capacity. The first interstellar spacecraft, over 40
years old, and someone's still writing FORTRAN or ASM for it. So cool.

~~~
mmazing
And a non trivial chance that they will outlive everything else with any
association to humans and Earth.

~~~
JonathonW
If by "outlive" you mean "continue to exist"... the Voyagers have a finite
useful lifespan defined by the output of their RTGs, and that's expected to
drop below useable levels sometime around 2025 (for both craft). But they'll
still be out there, barring a random encounter with an asteroid or something.

~~~
fnord77
...while most things on earth will be burnt up when the sun swells in 5
billion years or so...

~~~
taf2
Interesting to imagine what are the odds that earth burns up before they might
be hit by a random rock

~~~
mmazing
I think that two grains of sand on beaches of the opposite ends of the Earth
are probably more likely to interact than a random rock and a tiny satellite
that has left the Solar System into interstellar space.

In fact, in about 40,000 years, Voyager 1 will pass within about 1.6 light-
years of the star Gliese 445. It's also likely that it's as close to a star as
Voyager 1 will be again, ever.

Space is pretty empty compared to Earth or even our own Solar System.

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felixyz
"It was amazing to work on this cutting-edge data from spacecraft that were
launched before I was born and still doing amazing science"

I'm equally amazed (as a non-scientist) when I reflect that reading about the
Voyager missions was one of the first things that opened up the infinite
wonders of science to me some thirty years ago, and here we are _still_
getting new data and new riddles to solve from those same probes.

~~~
beamatronic
Let’s launch some more, for the next generation to use.

~~~
rabidrat
Voyager 1 and 2 had to happen in a narrow window of time to take advantage of
favorable planetary alignments. If we launched something like this now, it
would take an order of magnitude more fuel and still not be able to go as
fast. The next window for exploring interstellar space so efficiently isn't
until 2150.

Of course there are other long-term missions we could be trying now; but it's
not quite so straightforward (due to the mechanics of space-time) as we're led
to believe.

For that matter, we could consider this whole anthropocene climate change
thing we're doing to be one long-term experiment. You're welcome, children of
the future, for all this wonderful data we're generating for you.

~~~
Already__Taken
It's what this sweet poster that hangs on my wall is for, first one in the
set: [https://www.jpl.nasa.gov/visions-of-the-
future/](https://www.jpl.nasa.gov/visions-of-the-future/)

~~~
noir_lord
I have one of those on my living room wall.

The Kepler 16b one.

The other wall has a cray supercomputer been serviced, a high res version of
this [https://www.extremetech.com/wp-
content/uploads/2014/10/cray-...](https://www.extremetech.com/wp-
content/uploads/2014/10/cray-1-nersc-disassembled.jpg)

It’s amazing I have a partner, it really is.

------
CriticalCathed
>And on the other side of the boundary, the interstellar medium is at least
54,000 degrees Fahrenheit, which is hotter than expected. However, this plasma
is so thin and diffuse, the average temperature around the Voyager probes
remains extremely cold.

I don't understand this. If the medium is 54,000 degrees wouldn't it have
incinerated the probes? How can an extremely diffuse plasma be 54,000 degrees
and yet also be extremely cold?

~~~
arbuge
Temperature relates to how fast atoms are moving. If they're moving very fast,
then we say it's very hot. Damage from high temperature however requires a
substantial quantity of those atoms, not just that they be moving quickly.

But there are very very few atoms in the interstellar medium. They are moving
very fast, but there are very few of them indeed.

To incinerate something, there would need to be a lot of atoms indeed moving
at high temperature. An isolated atom hitting the probe, even at relatively
high speed, won't be doing much incinerating.

It's like a sparrow hitting a building. Won't do much, even it's a fast-moving
sparrow. But a billion sparrows hitting it in unison - that might be a
problem.

~~~
Koshkin
But there once was this Diamond Mountain in Lower Pomerania...

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rogueSkib
Alt+Cmd+I -> Console -> closeOverlay()

~~~
exhilaration
That worked, but how did you find that particular method?

~~~
grumpy8
Not OP, but if you inspect the overlay, just right next to it there's a
<script> with a closeOverlay function. OP probably tried to inspect/delete DOM
element and found that function.

~~~
rogueSkib
Haha, yep, this. I hide a lot, but couldn't get scrolling to work, searched
for "scroll" and stumbled on that obviously named method :)

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lykr0n
I wonder if we'll someday launch a Voyager 3 & 4.

~~~
bpodgursky
One of the biggest problems is that NASA's Plutonium-238 stockpile is running
low, and is only barely being replenished (it was an artifact of nuclear
weapon production, at the time). Each of Voyager 1 and 2 used something like
15kg of it for their RTGs. Because they were so heavily powered, the half-life
won't power the craft down for decades.

The availability of Pu-238 is why European missions can't go past Jupiter
without coordinating with NASA -- politically is impossible for them to
produce nuclear spacecraft, but solar power becomes ineffective farther from
the sun.

But given that NASA has a limited Pu-238 stockpile, they're only stocking new
craft with the minimum necessary to hit the key science objectives.

There's (finally) a new program to produce more if it, but in very limited
quantities: [https://www.businessinsider.com/nasa-nuclear-battery-
plutoni...](https://www.businessinsider.com/nasa-nuclear-battery-
plutonium-238-production-shortage-2017-8)

~~~
mongol
Some years ago Sweden handed over 3kg plutonium to the US. They should have
given it to ESA instead.

[https://obamawhitehouse.archives.gov/the-press-
office/2012/0...](https://obamawhitehouse.archives.gov/the-press-
office/2012/03/26/fact-sheet-plutonium-removal-sweden)

~~~
baking
It needs to be Pu-238 which is not a typical component of nuclear waste.
[https://neutronbytes.com/2017/03/05/nasa-re-starts-
pu-238-pr...](https://neutronbytes.com/2017/03/05/nasa-re-starts-
pu-238-production-at-two-sites/)

------
mrabcx
I wonder if these probes may rather be captured by humans in a few hundred or
thousands of years and placed in museums back on earth. With faster space
travel techniques that is a possible scenario.

------
xz0r
I wonder if there is a documentary with visual explanations. It would be
amazing to watch and understand.

I recently saw a mind-bending documentary[0] titled "Timelapse of the future",
there's a brief mention of Voyager, it shows what happens to the universe in
the long run and how it ends.

[0]
[https://www.youtube.com/watch?v=uD4izuDMUQA](https://www.youtube.com/watch?v=uD4izuDMUQA)

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negamax
As I read this when listening to some rowdy drunk neighbors shouting. It's
such a perfect contrast to be in two worlds.

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walrus01
It is kind of weird to me that they say the Voyager craft are in interstellar
space, when their distance in AU from the sun is a great deal less than the
aphelion of Sedna's orbit and other sednoids.

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allard
a recent talk on the spacecraft and the project —
[https://youtu.be/H62hZJVqs2o](https://youtu.be/H62hZJVqs2o)

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soulofmischief
Most unsurprising headline I've seen in a while.

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RubenF
Interesting read. Thanks for sharing

