Voyager 1 has been traveling for about a year through plasma between stars
nasa.gov
nasa.gov
"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.
"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."
With our luck, they'll be Vogons and vaporize our entire planet for infringing on their patent for watering lawns with a garden hose.
"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."
Check my math but one billionth of a Watt is 1 nW. So one billion-billionth of a Watt is 1 atto Watt?
The noise floor of the Goldstone Observatory is truly incredible.
There was a xkcd comic about this @ http://xkcd.com/1189/
But every one of those hash marks still indicates a region of space that humanity has explored for the very first time.
Result: speed of universe expansion between sun and voyager 1 is about 43.74 µm/s. Small enough to ignore.
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.
Oh, they certainly do: http://www.cosmosmagazine.com/news/pioneer-anomaly-solved/
I don't think any other space mission has ever had a chance to worry about that level of detail.
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.
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.
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.
> "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.
http://www.jpl.nasa.gov/news/news.php?release=2013-278
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.
"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."
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.
Probably not what you're thinking of... It sounds like something Asimov would have written but nothing comes to mind.
Would like to read.
(Oh, and they show that colonizing the universe would be surprisingly easy. This has obvious implications re: the Fermi paradox.)
[1] http://www.sciencedirect.com/science/article/pii/S0094576513...
Where can I find Voyager data?
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)
http://en.wikipedia.org/wiki/Plasma_receiver
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:
http://www.nytimes.com/2013/09/13/science/in-a-breathtaking-...
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.)
THEN I will consider it news...
Even because some scientists consider even the oort cloud (that is hell far) still part of solar system anyway.
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.
Besides, have you ever seen any data from interstellar plasma before? Well they have, now.
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.
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.
Heaven forbid NASA do something as inconvenient as sending out a press release about its copious new discoveries in our solar system.
Because discovering new things is actually more important than drawing arbitrary lines.
That's the definition of how the general public interacts with a piece of news.
But NASA hasn't said so before, and hasn't released a press release saying so before - why do you blame them for the headlines general media ?
(and if you read this press release it's about Voyager entering interstellar space, not leaving the solar system)
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.
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.)