Interstellar space even weirder than expected, NASA probe reveals
nationalgeographic.com
nationalgeographic.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.
I don't have the data, but if you want to calculate the rate of sublimation, you need to look at the vapor pressure of various metals at interstellar temperatures.
But they're in interstellar space. I imagine high-energy collisions (with hydrogen atoms or loose protons) would be a more likely cause of evaporation, and I don't know the numbers for that.
Will the craft be radiating heat away from itself?
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...
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.
Natgeo cuts off the article midway asking me o subscribe. Above is link to OC.
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.
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.
I don't really see it as tragic or sad, more like ... liberating.
Those sorts of thoughts remind me to not waste this precious time that we are lucky enough to have at all.
In truth, they'll be orbiting the galactic centre in an orbit somewhat offset from the Solar System. The Milky Way will have completed about 20 rotations. No idea what the resulting offset would be, but all but certainly somewhere within the galactic disk itself.
Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is.
I liked Neil deGrasse Tyson's description of how what we call space is still ridiculously close to our planet and how far away everything else actually is, using a standard classroom globe for scale: https://youtu.be/Tt0uV5d8tss?t=99
I wonder how long the gold-plated records will last.
Tyranny of the rocket equation strikes again.
That can be solved with a much larger ion drive, which will be much cheaper to launch (along with appropriate amounts of propellant) using Starship (or its future successors). And if a wealthy individual that has everything wants to retrieve that golden record for his personal collection, and is willing to spend a couple billion on it, well I'm sure that Musk's great grandkid will be more than willing to oblige.
https://www.wolframalpha.com/input/?i=2*sqrt%28122AU+%2F+%28...
Such a device could cross the distance in a few weeks.
Now we only have to go to project rho and build one fitting rocket design ;).
I might have a rudimentary understanding of electronics and digital design and could write Assembly and kind of understand the full toolchain from A to Z, but on a modern computer (hardware, BIOS, OS, programming language...etc) there is no hope.
Everything is a trade-off. If I had to write code for a probe today I would opt for the absolute simplest hardware and software so there is a lot less room for error.
A lot of modern complexity is kind of incidental. We need to deal with GUIs, protocols, out of order execution, parallel and concurrent programming. The core of things didn't change that much, you store a bunch of things in memory, you sort then, you search things, you move them to disk storage, you retrieve them and so on.
If you wanted to run a factory floor and the machines in it just by using either assembly or C and our knowledge of a bunch of algorithms, it would probably work, but without all the advantages we leverage by modern technologies. Instead of "Select ProdOrders where....", considering we once have done a bunch of "create table" and "create index", we would have to manually define the disk structures layouts by hand, hand write sorting routines for each one. It would take armies of programmers, but a single iphone would suffice for all IT needs of a large multinational bank. The user interface would be terrible, you'll need speacialized operators for simply entering data on the system, or extracting results.
But in a space probe, you don't need to care about user interfaces, ever-changing business requirements, nice integration points, so you could probably get away with a very simple and primitive time-sharing os, in a single-threaded CPU, by using only C and a barebones standard library, dropping from time to time to inline assembly.
Actually it is an interesting imagination exercise. It makes me think that even if a catastrophic event happened like an EMP, we would probably be using computers again to help rebuild the world in less than 20 years. As long as we had people with the knowledge to deal with the basics.
https://voyager.jpl.nasa.gov/golden-record/whats-on-the-reco...
Some of the music selection they added to the golden record is actually really ... good. I think it captures a good cross section of Earth.
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.
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.
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-...
It’s amazing I have a partner, it really is.
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?
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.
It doesn't make intuitive sense to me but I do understand the explanation.
I don't think we'll see a dedicated interstellar probe for a long time. It just takes too much energy to get out that far in a reasonable amount of time without radical designs or a big leap in propulsion technology.
(Not that we're anywhere near having a rocket factory on the moon... but maybe one could be assembled and fueled in orbit?)
Which you can't. So that's a no for the moon, but something from orbit could make sense.
Have a staging area and just accumulate tons of fuel from multiple launches.
Of course you can.
> By atomic composition, the most abundant element found on the Moon is oxygen. It composes 60% of the Moon's crust by weight, followed by 16-17% silicon, 6-10% aluminum, 4-6% calcium, 3-6% magnesium, 2-5% iron, and 1-2% titanium.
You have oxygen. You have aluminum. You can now make a solid rocket. There's some magnesium there too if you want to use that instead.
Not exactly. You have aluminium oxide, which you could split into aluminium and oxygen using huge amounts of energy, like we do on earth.
Helium-3 could be interesting, though.
I believe that this is wrong.
The Earth weighs 5.96e+24 kg and has radius 3.37e6 meters. The Sun weighs 1.98e30 kg and our orbit has radius 1.496e11 meters. That means that the potential well for getting away from Earth is about 11,800,000 joules/kg while for getting out of the Sun's gravity well is about 882,800,000 joules/kg. Assuming that I did the math right, that's about 7.5 times as hard.
It therefore takes a lot more energy to climb out of the Solar System than it does to climb out of Earth's gravity well. Voyager got a LOT of energy from those gravitational slingshots.
A probe has to launch from the surface of the earth. But counterintuitively the probes start out already in solar orbit, even before they're launched -- because the earth is in solar orbit. More than half the energy required to achieve escape velocity is needed just to get into a roughly circular relatively low orbit around the gravitating body you're trying to escape from, and by virtue of being launched from the earth the probes get that velocity for free. Furthermore, the earth's orbit isn't really "low" with respect to the sun. We're fairly far out there, so the fraction of the energy needed to go from earth orbit to a solar escape trajectory is even less.
Put another way: a probe launched from the earth gets no help leaving earth's gravity well. But once it does it gets a huge automatic gravity assist from the earth itself as it enters solar orbit.
It takes a lot of energy to escape Earth's gravity well. It takes a comparatively tiny amount to escape the Sun's, as a sibling poster pointed out. It would be actually harder to visit, say, Mercury, as you now have to shed all the energy Earth has given you for free, in order to "fall" into the Sun's well.
Voyager wanted to visit multiple planetary bodies – changing orbital parameters is not cheap. But if all it wanted was to get out of the system, burning straight out would probably be cheaper (in Delta-V terms). The closer to Earth the better, for the Oberth effect.
https://www.nasa.gov/mission_pages/station/expeditions/exped...
It would be cheaper in fuel terms, and require less thrust, but it'd also require us to manufacture propellant on the lunar surface and fly everything we can't build there from Earth (and landing on the Moon is purely propulsive).
It's entirely a political problem. There is no will to fund such a mission, and what's worse is that in the US funding is approved year by year.
[0] https://www.spacex.com/sites/spacex/files/starlink_press_kit...
[1] http://ngpdlab.engin.umich.edu/electric-propulsion/krypton-H...
The question then becomes: what instruments would you put on this that would tell us something the Voyager probes have not? What is your mission beyond "making something go even further away from us"?
1: https://www.skyandtelescope.com/astronomy-news/100-million-f...
Depending on the mission there's no doubt other alignments that would give the gravity assist.
To put it into perspective, Voyager 1 has a current speed of 17 kilometers per second. So the Dawn craft has most of that trip covered without gravity assists if it wanted. AFAIK there's nothing stopping us from loading up some craft with more fuel and larger ion engines except for launch weight. And even then, if we mastered orbital refueling we could surpass that.
As it stands, the craft can carry approximately the same amount of Delta-V that the rocket that got it into space. Equivalent to tons of fuel from chemical rockets.
And the Earth has 30 km/s, yet we don't get Voyager "for free" and then some just from LEO. You can't compare speeds in different parts of the gravity well against each other because then you're ignoring the dv required to get from here to there.
"I think of the oak beams in the ceiling of College Hall at New College, Oxford. Last century, when the beams needed replacing, carpenters used oak trees that had been planted in 1386 when the dining hall was first built. The 14th-century builder had planted the trees in anticipation of the time, hundreds of years in the future, when the beams would need replacing. Did the carpenters plant new trees to replace the beams again a few hundred years from now?"
I sincerely hope we do launch more deep space probes in the near future, for our collective far future selves.
Not all such decisions are short-sighted.
Edit: I think it's been shown elsewhere that it is not the date that you launch the next probe that is important, but the speed at which it travels.
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...
Of course you can't stockpile radioactive materials for too long. Their very nature limits their shelf life. So constant production is necessary if you want to use it on missions.
https://obamawhitehouse.archives.gov/the-press-office/2012/0...
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.