From "The West Wing", around one of the last times Voyager left the solar system:
"Voyager, in case it's ever encountered by extra-terrestrials, is carrying photos of life on Earth, greetings in 55 languages and a collection of music from Gregorian chants to Chuck Berry. Including "Dark Was The Night, Cold Was The Ground" by '20s bluesman Blind Willie Johnson, whose stepmother blinded him when he was seven by throwing lye in is his eyes after his father had beat her for being with another man. He died, penniless, of pneumonia after sleeping bundled in wet newspapers in the ruins of his house that burned down. But his music just left the solar system."
It's pretty amazing how far we've extended our reach, if not our grasp.
The song might have left the solar system, but it's not arrived in the UK yet:
"This video contains content from PEDL, SME, PRS CS, AdShare MG for a Third Party and Warner Chappell, one or more of whom have blocked it in your country on copyright grounds."
If the record is ever recovered and studied by aliens, I'd love to hear the RIAA try to explain to a star-hopping intergalactic civilization why they can't share it amongst themselves because it hasn't been licensed for their "region".
With our luck, they'll be Vogons and vaporize our entire planet for infringing on their patent for watering lawns with a garden hose.
Several commenters are joking about how many times they've heard this before, but NASA goes into great detail about why it was so difficult to measure and what new information helped them decide for sure. Here's a small excerpt:
"The particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere. Density of this sort is to be expected in interstellar space."
Read their account of how an "unexpected gift from the sun" helped them. It's not long and quite fascinating, and some little tidbits like this are pretty intriguing to me:
"By the time the signals get to Earth, they are a fraction of a billion-billionth of a watt."
I agree with everyone who is tired of the "Voyager has left the solar system" PR game, but I'll point out that the latest announcement is data confirming last year's Aug. 25, 2012 exit date, not a new exit. That is, they have new data showing that the previous departure was "real".
If the universe is continually expanding, does that mean we are trying to hit a moving target? Probably sounds like a stupid question, but I honestly want to know.
The Hubble constant is 67.8 (km/s)/Mpc. That means that something one Mega-parsec (Mpc) away will appear to recede at about 70 km/s. Our galaxy is about 35 kpc across.
Voyager is currently 0.0006 parsecs from Earth, moving at 17 km/s.
Given this distance, we find that the cosmological effect alters the apparent velocity of Voyager by 4.2x10^-8 km/s. This is only 1 part in 4x10^8, which is probably too small to measure.
There may be general-relativistic corrections to the spacecraft clocks, however, and computation of its trajectory may involve general-relativistic dynamics. So some of the often-ignorable effects probably do add up.
Of course, the surrounding volume is also expanding with the same rate, so from that point of view, there is no effect.
The expansion of the Universe is irrelevant in this case. Our galaxy is gravitationally bound, so things (stars, planets, etc) within it do not follow Hubble's law. So there will be no modification to Voyager's distance from earth as a result of the Universe's expansion.
Even nearby galaxies don't obey Hubble's law. Andromeda, for example, is moving towards us, despite the overall expansion of the universe. In this case, it is due to the gravitational attraction between it and our galaxy.
You are offering a more sophisticated take on the matter. At non-cosmological scales, metric expansion (i.e., the Hubble law) is not occurring because of bulk gravitational attraction.
The arithmetic I did is a tool illustrating the scale that is needed to make metric expansion operative. The arithmetic has the advantage of giving a quantitative idea how far away Earth-Voyager is from the necessary scale.
> The arithmetic I did is a tool illustrating the scale that is needed to make metric expansion operative.
You might revisit the wording then. As it's written it implies that with arbitrarily increased measurement precision, we could measure an effect of the Hubble Flow on Voyager's movement. But even with arbitrary precision we'd never measure an effect from the Hubble Flow on Voyager's motion because the expansion of the Universe isn't contributing to the relative motion between Earth and Voyager.
Nice example. GPS is another case; to get the most out of the data requires very careful modeling, including tidal effects, Earth mass density, and GR corrections. (E.g., https://gipsy-oasis.jpl.nasa.gov/index.php?page=software)
A better title would be "number of times NASA has described a fascinating new discovery made with Voyager I as 'leaving the solar system'." The issue is with the headline writers who avoid words like "heliopause", "heliosphere", and "interstellar plasma".
But every one of those hash marks still indicates a region of space that humanity has explored for the very first time.
Although the heliosphere is variable the size of the solar system is not expanding due to universal expansion, which is only witnessed on a very large scale. The solar system is gravitationally bound much like our galaxy and local group.
I'm not certain that NASA has made such a strong claim before. Usually it's "Things are weird", or "New indications of the heliopause", etc. It's been about a year since these wiggles turned up; perhaps now the experts are satisfied.
> Stone discussed with the Voyager science group whether they thought Voyager 1 had crossed the heliopause. What should they call the region were Voyager 1 is?
> "In the end, there was general agreement that Voyager 1 was indeed outside in interstellar space," Stone said. "But that location comes with some disclaimers - we're in a mixed, transitional region of interstellar space. We don't know when we'll reach interstellar space free from the influence of our solar bubble."
> So, would the team say Voyager 1 has left the solar system? Not exactly - and that's part of the confusion. Since the 1960s, most scientists have defined our solar system as going out to the Oort Cloud, where the comets that swing by our sun on long timescales originate. That area is where the gravity of other stars begins to dominate that of the sun. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it. Informally, of course, "solar system" typically means the planetary neighborhood around our sun. Because of this ambiguity, the Voyager team has lately favored talking about interstellar space, which is specifically the space between each star's realm of plasma influence.
I tend to agree with their rationale, but they may just be pressed with time (remaining power on Voyager 1) and want conclusion. They can't wait 300 - 30,000 years.
For the series something went wrong: The CPUs inside this spacecraft run at just 0.25Mhz.
"The Voyager spacecraft computers are interrupt driven computer, similar to processors used in general purpose computers with a few special instructions for increased efficiency. The programming is a form of assembly language."
"The master clock runs at 4 MHz but the CPU’s clock runs at only 250 KHz. A typical instruction takes 80 microseconds, that is about 8,000 instructions per second. To put this in perspective, a 2013 top-of-the-line smartphone runs at 1.5 GHz with four or more processors yielding over 14 billion instructions per second."
Is it just me, or is anyone else fascinated by the idea that we receive data from a device that is 12 billion miles away at a rate of 20 bytes a second? How do they deal with the problem that there is most likely to be a lot of interference in the form of other planets, magnetic waves, solar flares, random gamma rays, etc?
It's not just you ... it is fascinating. I would love to have a good chat over some beers or coffee with some of the engineers and scientists that built this :)
A more interesting event will be when crewed spacecraft "pass" the Voyagers. Betting this won't happen is basically betting that humanity will destroy itself.
I read a great book a long time ago.. wish I could remember the name.
Basically, sometime in the future, Earth is dying, so everyone has to leave to some faraway planet within 100 years.
The first intrepid explorers leave at T-100 years, expecting to be the first to arrive. A few years later a new craft leaves that can travel faster and will get there sooner. This goes on and on until it comes down to a betting game of how late can you wait until leaving, while still being the first to arrive (and thus claim ownership/leadership, etc.), with people coming up with all kinds of hair-brained schemes on the best time to actual leave.
IIRC, it kind of turned a little into Hitchhikers Guide kind of ridiculous near the end.
There's an interesting recent paper [1] by Stuart Armstrong and Anders Sandberg about the feasibility of colonizing the entire visible universe. Among other things, they conclude that as long as you can reliably expect technology to keep progressing, it pays to wait and keep investing in R&D instead of launching too early.
(Oh, and they show that colonizing the universe would be surprisingly easy. This has obvious implications re: the Fermi paradox.)
IIRC there was something in Hyperion about this, but it wasn't a focus, just some back-story on why Martin Silenus was brain-damaged for some time after his emigration from Old Earth. (Bad cryo on a slow-ass spaceship.)
Probably not what you're thinking of... It sounds like something Asimov would have written but nothing comes to mind.
A question for the physicists or people that know about the subject: does plasma affect circuits? I read somewhere that alpha particles do affect them. I'm just curious. It might well be a stupid question. Pardon for my ignorance.
1) The electronics on board Voyager (and all spacecraft we've launched) are pretty well shielded.
2) The density of the plasma in interplanetary (now interstellar) space is very, very low. What Voyager is measuring is not the direct particles, but the oscillations of them. (Radio waves)
Don Gurnett @ the U. of Iowa has been a part of many of these missions - plasma receivers have been on nearly every major mission since Voyager. (Esp. Galileo to Jupiter and Cassini to Saturn.)
Here's a link to the research group at the U. of Iowa (the same group that published today's paper in Science) - there are some good introductory articles on the instruments and the physics behind them:
To expand on #2, the environment around Voyager 1 is significantly lower pressure and density than the most extreme ultra-high-vacuum conditions humans have ever managed to create on Earth.
“These younger engineers can write a lot of sloppy code, and it doesn’t matter, but here, with very limited capacity, you have to be extremely precise and have a real strategy,” she said.
In general you're right to mistrust the oft-repeated headline. But this is actually a big deal. Voyager I really is exploring a new part of space for the first time.
It's also worth noting that Voyager I entered interstellar space well over a year ago, but that only now have we been able to confirm that fact. So if it seems like this has been repeated a lot lately, it's because the scientists have been sifting this data for a long time before they could be sure. (Again, this is uncharted territory for the human race.)
It's likely you would be dead before then. Voyager 1 after 36 years is about 127 AU away. The oort cloud is believed to be at least 50,000 AU away [0]. So you'll have to wait about another 14,000 years.
"Pass" being a pretty generous term, coming within 1.7 light-years, or over 500 times farther than its lifetime distance from Earth/Sol to today. It's like driving from New York to San Francisco and calling some spot in Kansas "passing the moon".
All of the Solar System outbound spacecraft aren't expected to pass within, say, the planetary disc range of any known stars at any calculable future time. Space is really freakin empty.
You mean the hypothetical oort cloud? Because we don't know where that is either. This is news because they have confirmed their hypothesis again. This is how science works. It's not just one experiment and then it's time go home.
Besides, have you ever seen any data from interstellar plasma before? Well they have, now.
No kidding, That's about the 6th time I've read about it these last two years. WHY doesn't NASA begin by establishing WHAT is it exactly that makes a solar system official "boundary" before producing press releases every time they find something interesting in the readings sent to them by Voyager.
ADDENDUM : Ahem, Thanks for the downvotes, but the inner workings of space discovery are not the subject of my comment. As an engineer, I'm more than mindful of the back & forth & general messiness of discovery, peer-reviews, control groups, & the like. I'm talking about press releases & headlines targeted towards the GENERAL PUBLIC. A public that has a lot less of an appetite, patience or time to follow NASA's inner deliberations or the intricacies of the scientific method. The fact that this is the 5th or sixth time that they've heard that "Voyager has left the solar system" might leave them a little bit confused.
Uhh ... that's exactly what they are doing: attempting to establish what the boundary even looks like. We thought we knew what the boundary would look like (even though we have never been there before). It turned out we were wrong. In science, that's good thing.
Some people may not want to hear anything until the science is over, but I think a lot of us actually enjoy being on the inside of the scientific process for a change.
Yes, NASA released research and related press releases in the past corresponding to new, unexpected data from Voyager that led to "[discovery of] a new region of the heliosphere that we had not realized was there" as well as "[leaving] researchers without a working model for the outer Solar System." [0]
Heaven forbid NASA do something as inconvenient as sending out a press release about its copious new discoveries in our solar system.
This is about confirming that their detection of the heliopause was in fact correct. Also, new data.
From the article:
Voyager 1 does not have a working plasma sensor, so scientists needed a different way to measure the spacecraft's plasma environment to make a definitive determination of its location. A coronal mass ejection, or a massive burst of solar wind and magnetic fields, that erupted from the sun in March 2012 provided scientists the data they needed. When this unexpected gift from the sun eventually arrived at Voyager 1's location 13 months later, in April 2013, the plasma around the spacecraft began to vibrate like a violin string. On April 9, Voyager 1's plasma wave instrument detected the movement. The pitch of the oscillations helped scientists determine the density of the plasma. The particular oscillations meant the spacecraft was bathed in plasma more than 40 times denser than what they had encountered in the outer layer of the heliosphere. Density of this sort is to be expected in interstellar space.
> WHY doesn't NASA begin by establishing WHAT is it exactly that makes a solar system official "boundary" before producing press releases every time they find something interesting in the readings sent to them by Voyager.
Because discovering new things is actually more important than drawing arbitrary lines.
the inner workings of space discovery are not the subject being discussed here. As an engineer, I'm more than mindful of the back & forth & general messiness of discovery, peer-reviews, control groups, & the like.
I'm talking about press releases & headlines targeted towards the GENERAL PUBLIC. A public that has a lot less of an appetite, patience or time to follow NASA's inner deliberations. The fact that this is the 5th or sixth time that they've heard that "Voyager has left the solar system" might leave them a little bit confused.
The general public is footing the bill, there is nothing wrong with giving the general public some periodic status updates. This could really only get confusing if you read no further than the headlines.
People who read no further than headlines will have trouble regardless. The solution to that is not "release fewer press releases so that people have fewer opportunities to be confused".
Gen pop don't get smarter if you don't make them think. Confusion can be useful and in this case likely a good bit of medicine. Grade school education level of understanding on anything is pretty useless and implying that they cant do better insults pretty much everyone. Hence the d/v's.
Part of NASA's job is to generate excitement and interest in the sciences and exploration in general, as well as to Congress who can dictate NASA's budget on a whim. Unfortunately, when they talk to the media that Voyager appears to have "left" the solar system, the general media misinterpret things and ignore some of the scientific process behind it -- the same phenomenon leads to headlines about 'X cures cancer!'.
Through this semi-public process, NASA has given the public exposure to the amazing Voyager mission that's been running for longer than many Americans have even been alive, and opened public discussion and amazement for several successive years.
I only hope there are classrooms with students eagerly plotting the trajectory of Voyager or any other missions on graph paper, sitting on the edge of their seats waiting for the next set of data to be released by NASA. Every new bit of information can open an entirely new topic to their minds, a new topic for them to dig into every public resource, article, and book they can get their hands on. (That was me, some years ago, but I digress.)
What do you suggest? Should they have launched a probe to discover what features to expect at the edge of the solar system? I know you're entitled to 100% accurate info, dammit, but perhaps a refresher on how the scientific method works would be helpful.
"Voyager, in case it's ever encountered by extra-terrestrials, is carrying photos of life on Earth, greetings in 55 languages and a collection of music from Gregorian chants to Chuck Berry. Including "Dark Was The Night, Cold Was The Ground" by '20s bluesman Blind Willie Johnson, whose stepmother blinded him when he was seven by throwing lye in is his eyes after his father had beat her for being with another man. He died, penniless, of pneumonia after sleeping bundled in wet newspapers in the ruins of his house that burned down. But his music just left the solar system."
It's pretty amazing how far we've extended our reach, if not our grasp.