Seems like we're still not sure it's left due to lack of agreement on what constitutes leaving:
However, Webber notes, scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system.
There was some great discussion on what "leaving" might mean. And several theories about how that might show up on the instruments. Each time the instrument readings changed the scientists asked the question "So does this mean we're outside?" and in the ensuing discussion concluded that Voyager was still travelling through the boundary layer. An astrophysicist at Berkeley described it like leaving the ocean, when you're coming up on the beach but your still being washed over by waves are you in the ocean or not? Sometimes are sometimes not? Hard to say if you've never seen a beach and the only communication you get back from your probe is "I'm wet!","I'm not wet!"
This is likely one of the last "we think we're outside" papers I suspect. From the paper:
"This large decrease of ACR was preceded by 2 precursor temporary decreasesstarting on July 28th and August 14th. Thus V1 may have crossed a boundary, which itself was very
sharp, at least 5 times during this time period"
>[Update/Correction (Mar. 19, 2013): I wrote the piece below after reading a press release from the American Geophysical Union (AGU) and after reading the professional science journal paper announcing the results. Just after posting this I received a press release from NASA/JPL quoting Ed Stone, the Voyager project scienist, saying "It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space.... [Emphasis mine.] I then received a follow-up press release from the AGU also backing off the claim of Voyager leaving the solar system.... So to be clear, the science of what I describe below is accurate enough, but the idea that Voyager 1 has left the building is not.
My guess, is that Voyager being declared "outside" the solar system will happen only after quite of bit of time has passed since it actually left. Like the Higgs Boson, there is data, there is analysis, and there are confidence intervals. One result may be that the instruments send back cosmic ray information that no theory can explain how that would be consistent with being inside the heliosphere. Or it may simply be that the environment stops changing. And after a while that non-changing result is accepted as being "outside" and then you can walk backwards in the data to figure out the first time you got that result (and consequently the last change you saw) and declare the exit that way.
Ed Stone, the project scientist and the nominal author of this press release, is 77 now. He was 41 when Voyager 1 launched (and he was project scientist then, too). You still see him around JPL and Caltech.
So it's out of the solar system - but is it in interstellar space?
Reading the Bad Astronomy blog entry got me thinking about the Oort Cloud - perhaps that is the real interstellar space (within the galactic plane) - beyond the Bow Shock and at a size of 1.5-3.0 LY with a spherical distribution, the cloud edge is closer to some of our nearest stars (notably Alpha Centauri, whose binary mass is 2 solar masses) than to the sun.
Perhaps the Oort Cloud is interestellar space - in which case, V1 hasn't gotten there yet.
Are you saying that our Oort Cloud potentially intersects with Oort Clouds of other stars? I didn't realize it was that big. Maybe interstellar space is ALL Oort Cloud, and we just haven't noticed because the masses are too small and cold to see (and obscured by closer stuff.) Maybe that's enough to make up the dark matter mass?
All four articles are talking about the same event that happened in August 2012. Today's article is a press release from the journal where the scientists published the data.
Anyone remember that science fiction story, where the first ship to leave the solar system shatters some shell. And that it's later discovered that all stars have the same shell, which is impermeable from the outside. Sort of an enforced prime directive by unknown powers? This reminded me of that, and despite many searches I'm not getting any hits.
Reminds me of the "celestial spheres" model of the universe where heavenly bodies (orbiting the earth of course) were "held up" because they were embedded into a sort of matryoshka series of crystal spheres made of a supposed 5th element, a solid æther.
Of course this model did little to explain retrograde motion.. ;)
Do we even have a clear boundary of where the solar system ends?
From what I gather as a layman, the answer to this is no, which in turn answers why Voyager has "left" numerous times. From the bit I've read Voyager has already forced some rethinking on what the edges of the solar system look like, and it may very well cause a few more.
If a spacecraft were to travel orthogonal to the plane on which planets orbit the sun, would it experience the heliosheath as it exits the solar system? For that matter, have there been any spacecraft launched that didn't travel on the orbital plane (ignoring earth-orbiting spacecraft)?
Yes, it would. The heliosphere is not spherical, but the solar wind exists in all directions. The orbital plane is due to conservation of angular momentum, a completely different phenomenon.
Maybe I'm just emotional today but the "Acknowledgments" section for the accepted journal was touching. I can only imagine what it felt like to complete the work of a good friend.
I want to say there has been some discussion about space travel to other worlds and "leaving too soon", ie - if you launch today, a space craft that launches to the same destination a year from now would beat you there, because the technology would have progressed to the point that the later ship was much faster.
If we were to launch a state of the art probe today, how long would it take to get to where voyager 1 is now after 35 years of travel?
About the same. New Horizons was faster at launch, but the real boosts come from gravitational assists.
Clever choices of orbits buy you speed - stealing an infinitesimal fraction of Jupiter's momentum is much more efficient than any propulsion technology in use. If that ever changes, then "too soon" will have become reality.
"New Horizons is often given the title of Fastest Spacecraft Ever Launched, although the Helios probes are arguably the holders of that title as a result of speed gained while falling toward the Sun. New Horizons, however, achieved the highest launch velocity and thus left Earth faster than any other spacecraft to date. It is also the first spacecraft launched directly into a solar escape trajectory, which requires an approximate velocity of 16.5 km/s (36,900 mph), plus losses, all to be provided by the launcher. However, it will not be the fastest spacecraft to leave the Solar System. This record is held by Voyager 1, currently travelling at 17.145 km/s (38,400 mph) relative to the Sun. Voyager 1 attained greater hyperbolic excess velocity from Jupiter and Saturn gravitational slingshots than New Horizons. Other spacecraft, such as Helios 1 & 2, can also be measured as the fastest objects, due to their orbital velocity relative to the Sun at perihelion. However, because they remain in solar orbit, their orbital energy relative to the Sun is lower than the five probes, and three other third stages on hyperbolic trajectories, including New Horizons, that achieved solar escape velocity, as the Sun has a much deeper gravitational well than Earth."
For that matter, why did anyone buy computers when waiting just a little longer brought cheaper, faster, and better computers?
Well, for one thing, if nobody bought computers, they wouldn't have gotten any faster, since no one would have built them. And if nobody launched space probes, they wouldn't have gotten faster, because no one would have made them.
Well, since most of the speed is from slingshot gravitational interactions, there's 2 parts to it.
* How well are the planets aligned
* How well can you exploit that
Some of the current probes have done multiple flybys of inner solar system bodies to boost speed to reach the outer planets. Voyager 1 and 2 had a relatively direct route to take advantage of a once in a lifetime alignment of the outer planets.
Maybe someone with experience in the field of communications and space can clarify my doubts: how we can improve the flow of data transmission to Earth? Imagine a string of satellites that communicate with each other so that the message reaches the earth faster distributed way. Now it seems that communications between satellites and Earth are slower and it has greater delays.
Maybe I'm not understanding your question, but adding intermediate satellites/probes wouldn't improve the speed of communications. The limiting factor is the speed of light. Adding additional hops in between would just add a slight processing delay, but definately not change the overall latency. Voyager is very far away and it's going to take a while to talk to it no matter what you do.
Just kidding. But more seriously, intermediate satellites could possibly improve the transfer rate of information by acting as signal boosters. However, they would have to span substantial fractions of space between points to be useful. We only have a few spacecraft between earth and voyager. I.e. new horizons boosts voyager's signal back to earth (cassini maybe?). And in voyager's case it's probably irrelevant given how old the hardware is and how weak the power source has become.
"The Voyager team is aware of reports today that NASA's Voyager 1 has left the solar system," said Edward Stone, Voyager project scientist based at the California Institute of Technology, Pasadena, Calif.
I don't think this is anything new? We've had reports for over a year that Voyager has been getting anomalous readings. Whether or not that indicates having "left the solar system" is still a matter of debate (unless this article is trying to say that the debate has been settled), although it's certainly still exciting.
When it is finally agreed that it has left (which presumably will occur within the next year or two), What Then?
I'm not hopeful that we'll be surprised in a major by the data coming from outside the heliosphere; to be honest I'm a bit worried that a lack of novelty will increase public apathy - 'We made it out! ...and that's all folks, shows over.' It's a bit like the moon landings; having been there and run out of convincing reasons to go back, we're heading back to that situation of no living person having walked on the surface of another world (http://xkcd.com/893/).
Props to Elon Musk etc., but I'm not all that optimistic about private enterprise just filling this niche.
I'm sniping this from a reddit comment, but I'm also now (jokingly) hoping that Voyager just ends up hitting a spherical wall that's covered in painted stars and galaxies. Could you imagine the ridiculousness of that, and the conversations that would occur? Ah the potential hilarity...
Just this morning I listened to the Voyager Engineering Team on an old NPR Radio Lab episode where the crew mentioned that every day they check their Google Alerts to see if Voyager has left our solar system. I imagine their celebrating today.
CORRECTED PRESS RELEASE
Please note that the headline on this release has been changed to better represent the findings reported in the study. New title - "Voyager 1 has entered a new region of space, sudden changes in cosmic rays indicate"
Besides ‘oh, how many times it will left it?’, I wonder why many find someone's (another) whining about google reader or new bugs in rails more interesting than this.
The Voyager project scientist at Nasa's Jet Propulsion Laboratory, Ed Stone, said he wanted to see a reorientation of the magnetic fields around the probe before declaring it to be in interstellar space. This was a "critical marker", he added. "…that change of direction has not yet been observed."
Beyond the discussion of 'how many times it has left already' I wonder what's the next Voyager spacecraft.
New Horizons certainly looks like it's going to help, it's a flyby mission to Pluto, and it's going faster than Voyager 1/2 apparently (haven't checked)
With modern equipment and transmission technology, hopefully it will help solve part of the mystery (or get its circuits fried with excess radiation outside of the solar system - too far fetched?)
It was faster at launch, but V1 has gained more momentum.
From wikipedia: ' However, it will not be the fastest spacecraft to leave the Solar System. This record is held by Voyager 1, currently travelling at 17.145 km/s (38,400 mph) relative to the Sun. Voyager 1 attained greater hyperbolic excess velocity from Jupiter and Saturn gravitational slingshots than New Horizons '
Only if it were a timeline, put alongside services that we use every day--I'd like to see the uptime on Curiosity or something next to this quarter's cloud outage.
How is Voyager able to transmit such a great distance, even after all these years? Hasn't its battery died yet? Also how does it power its sensors (to measure radiation and such)?
Radio. Voyager is nuclear powered (Thought not in the sense you're probably thinking. It's a nuclear source and a thermoelectric cell.), and many (most?) of the instruments are still functioning and sending signals back.
It really is quite astounding when you think about it! Launched in 1977, traveled through the solar system, and still functioning!
- https://news.ycombinator.com/item?id=4867577 (106 days ago)
- https://news.ycombinator.com/item?id=4619731 (165 days ago)
- https://news.ycombinator.com/item?id=4483757 (195 days ago)
Seems like we're still not sure it's left due to lack of agreement on what constitutes leaving:
However, Webber notes, scientists are continuing to debate whether Voyager 1 has reached interstellar space or entered a separate, undefined region beyond the solar system.