Voyager Exits The Heliosphere

[Deepwater6]

http://science.time.com/2013/03/20/humanity-leaves-the-solar-system-35-years-later-voyager-offically-exits-the-heliosphere/?hpt=hp_t5

 

35 years and 11 BILLION miles later Voyager is either out of the solar system or very close to the end of the heliosphere. This is exciting stuff for space junkies myself included. This craft has truely gone where no one has gone before. Everyday it travels its gathering priceless information. Hopefully with the help of V-2 we will be able to clearly define the edge of our system in the near future.

[Deepwater6]

http://www.space.com/17458-voyager-spacecraft-explained-solar-system-infographic.html

 

Voyager infographic

[Eclogite]

I generally take exception to defintions of the solar system limits that hinge upon the boundary of the heliosphere. The Oort cloud comets are certainly under the gravitational influence of the sun and they are found an order of magnitude further out.

 

This observation does not detract from the achievements of the Voyager mission.

[CraigD]

Courteously, Webber, McDonald and the AGU made the paper behind yesterday's press, “Recent Voyager 1 Data Indicate that on August 25, 2012 at a Distance of 121.7 AU from the Sun, Sudden and Unprecedented Intensity Changes were Observed in Anomalous and Galactic Cosmic Rays”, available, at http://onlinelibrary.wiley.com/doi/10.1002/grl.50383/pdf :thumbs_up

 

It’s humorous, I think, that March 2013 may be immortalized as “when Earthkind left the solar system”, when, from what I gather, it's actually when the current Voyager team announced they were confident that the dramatic data they received in August 2012 shows this historic (at least in my book) event occurred then.

 

I recall feeling a happy sense of relief after reading about the 2012.65-2012.75 results, because I wasn’t sure a distinct heliopause boundary would be discovered before Voyager 1’s RTG-generated electric power dropped too low to power its transmitter, which I believe is estimated to be around 2025. 45 years after its launch, it looks like it made it with over 10 years life to spare.

 

It boggles my mind that this machine has kept working so well and so long. It’s outlived most, perhaps all, of the scientists, engineers and technicians who designed and built it. Yesterday’s paper’s coauthor, Frank B. McDonald, died 31 Aug 2012, age 87, having lived just long enough to see and report the 25 August findings.

 

Space exploration is truely a multi-generation endeavor.

[CraigD]

From this 20 Mar 2013 JPL press release, quoting JPL director Ed Stone:

"It is the consensus of the Voyager science team that Voyager 1 has not yet left the solar system or reached interstellar space. In December 2012, the Voyager science team reported that Voyager 1 is within a new region called 'the magnetic highway' where energetic particles changed dramatically. A change in the direction of the magnetic field is the last critical indicator of reaching interstellar space and that change of direction has not yet been observed."

So I'm back to worrying if Voyager 1 will last long enough to detect this indicator.

 

All appear to agree Voyager 1 left the heliopause around 25 Aug 2012. What's at issue now seems to me whether we should say the heliopause defines the heliosphere, or if a further boundary defined by the magnetic fields Stone mentions does.

Edited March 22, 2013 by CraigD
Fixed bogus future date :doh

[blamski]

 

All appear to agree Voyager 1 left the heliopause around 25 Aug 2013. What's at issue now seems to me whether we should say the heliopause defines the heliosphere, or if a further boundary defined by the magnetic fields Stone mentions does.

 

 

actually, i think that what's at issue now is how voyager managed to travel several months into the future.

[Deepwater6]

With the decrease of the solar wind and the drop in charged particle readings its pretty clear the craft has crossed a threshold, however Eclogite's point on the Ort cloud cannot be ignored.

[CraigD]

I generally take exception to defintions of the solar system limits that hinge upon the boundary of the heliosphere. The Oort cloud comets are certainly under the gravitational influence of the sun and they are found an order of magnitude further out.

Though technically every massive body is under the gravitational influence of every other massive body, I don’t think there’s enough data to conclude that most Oort cloud objects are properly part of the solar system.

 

It’s critically important to understand that we know very little about the OC, and that common descriptions and graphical renderings of it, such as this NASA JPL (from the wikipedia article) one

[insert c:\temp\Kuiper_oort.jpg here]

are not actual images based on observational data, but constructed from the best, but loosely constrained, theoretical models of it. The data from which we extrapolate the structure and extent of the OC is from long period comets and a few (these 4) larger candidate OC opjects. OCOs are small and dimly lit – observing them at OC distances is so problematical that it’s never been done, and may never be done with near-Earth telescopes.

 

According to best current theory, the OC was formed from remnants of the protoplanetary cloud from which the Solar system formed, a cloud it may have shared with neighboring stars. The OC, then, although owing the origin of its structure to the formation processes of the solar system (best theory suggests OCOs were formed near the Sun, then ejected by interaction with the giant planets, so have shell structure) may be less of a distant solar system structure than one of the interstellar medium, not stuff of stellar systems, but the stuff between them. There’s no clear, uncontroversial consensus of the extent of the OC, suggesting that our Solar system’s overlaps those of neighboring stars. Small bodies passed from one stellar system may be commonplace OCOs.

 

Telescopy is increasingly able to image bodies near nearby stars, so somewhat counterintuitively, we know and are likely to increasingly know more about bodies around stars at distances of 10s or 100s of light years than about bodies at OC distances of about 1 ly. Though its hard to predict future technology, my guess is that to study OCOs, we’ll either need gigantic (10,000,000,000+ m²) near-Earth space-based telescopes, or smaller ones roaming OC space. It’s an exciting, though likely not fast-paced, future to imagine.

[Deepwater6]

http://www.space.com/22768-nasa-voyager-1-announcement-webcast.html

 

Hopefully at 2pm we will hear some clear news. As to confirmation of the first man made object to leave the solar system.

[CraigD]

As expected, NASA JPL has officially confirmed that Voyager 1 has left the solar system – that is, is beyond the heliopause, beyond where the movement of interstellar gas and plasma is little affected by the outflow from Sol.

 

Though the moment can’t be marked precisely, the generally accepted date is 25 Aug 2012 – the last year has just been “making sure” time. This makes sense, as previously, what appeared to be the true heliopause turned out to be the boundary of some newly discovered layer of the unexpectedly complex heliosheath, the “mixing area” between the heliosphere and interstellar space.

 

While amazed that Voyager 1 works at all after more than 36 years in space, and delighted that it not only is alive, but getting and sending valuable, never-before-had astrophysics data, it’s success gives me pangs of regret that there are not more like it headed in widely different directions.

 

Voyager 1 is 126 AU roughtly directly “upwind” relative to the heliosphere’s motion through the interstellar medium.

 

Voyager 2’s 103 AU about 30 off of Voyager 1’s course, but will run out of power before repeating Voyager 1’s penetration of the Heliosheath in a different location.

 

Pioneer 10, at 109 AU in nearly the opposite direction of Voyager 1 and 5 years older, has a good suite of particle detection instruments, but died (that is, lost communication with Earht) in 2003. Pioneer 11, now at 89 AU, was last heard from in 1995.

 

Then there’s the baby of our 5 extra-solar spacecraft, launched in 2006 New Horizons, but its Pluto flyby trajectory is in roughly in the same direction of Voyager 1and slower that it. New Horizons also has a smaller Pu-238 RTG power source than the Voyagers (250 vs 470 W at time of launch, so won’t be able to stay in communication as long.

 

Imagine how much more complete a picture of the heliosphere we could be getting if we had launched more than 2 of the voyagers, or launched even better ones, since the 1970s?

 

It makes me wistful to remember the 1979 Star Trek: The Motion Picture, which predicted the launch of Voyager 6 in 1999. Even if the science of that movie was crap, and the fiction not much better, it’s optimism was uplifting, and leave me feeling like real history owes me and the rest of a few generations of trekies/ers another half-dozen or so Voyagers!

 

Source: the heavens-above.com webpage Spacecraft escaping the Solar System has a nice graphic and chart of the 5 extra-solar spacecraft.