Slashdot Mirror
Voyager 1 Crosses The Termination Shock
SubstormGuy writes "In a scientific session at the AGU meeting in New Orleans this morning, Dr. Ed Stone presented clear evidence that Voyager 1 crossed the termination shock last December. The scientists in the room applauded when the announcement was made."
if NASA does not terminate the project to favor Bush's push to put humans on Mars, the Voyager 1 has enough power to last another 15 years (2020). in that case, they should be able to retain enough data to calculate what is going on in the heliosheath and beyond. I don't think 'hot' is used to describe a location that is 7 billion miles from the sun :-} .. but they should be able to calculate a close temperature based on the distance and magnetic fields among many other factoring (IANAS)
do you have shinyfeet?
The termination shock is basically where the wind of the sun meets "the wall" -- as known as interstellar medium.
You know about the solar wind. It's basically a stream of particles flowing out of the Sun's atmosphere at a supersonic speed. The particles would cruise radially out of the Sun and go on and on and on...until it meets a clump of gas associated with semi-primodial stuffs that the Sun and other neighboring stars were made out of. Imagine that the Sun is sitting in a void of space (the emptiness was due to the solar wind sweeping out the material around it).
Anyway, as the particles in the solar wind nears the wall, the particles in the solar wind begins to "feel" the presence of a wall. It's like a wind hitting a building and twirl near the wall of the building. A similar thing happens here and the sensors on board Voyager can sense the motion of these particles "twirling" around. In this case, these particles are slowing down and that's what Voyager I has detected.
As for the precise timing? I don't think there is a clear signature of the "termination" point. It might have been in 2003 or in Dec 2004. In the astronomical standpoint, the distinction is, I believe, not so meaningful.
Phew. That's alot to write. I'd better go to bed now.
the bbc http://news.bbc.co.uk/1/hi/sci/tech/4576623.stm has some more info on this. You should know that they are not 100% it has crossed the termintation shock. "Some researchers thought the probe had arrived at the shock; others thought it still had some way to go. Now, at the 2005 Joint Assembly meeting organised by the American Geophysical Union, space scientists say they are confident - and agreed - that Voyager has gone beyond the termination shock and is flirting with deep space. Predicting the location of the termination shock was hard, the researchers say, because the precise conditions in interstellar space are unknown. Also, changes in the speed and pressure of the solar wind cause the termination shock to expand, contract and ripple. The most persuasive evidence that Voyager 1 has crossed the termination shock is its measurement of a sudden increase in the strength of the magnetic field carried by the solar wind, combined with an inferred decrease in its speed. This happens whenever the solar wind slows down."
Just goes to show that maybe a source that ANYONE can stick any random crap into might not be the most reliable.
Not really, in this case it showed that an article that's out of date may not be correct. I mean, the new information was just now announced. To clarify, these articles now seem to be correct according to my source, and read:
- "Scientists at the Johns Hopkins University Applied Physics Lab believe that Voyager entered the termination shock in February 2003."
- "Evidence presented at the AGU meeting in New Orleans in May 2005 by Dr. Ed Stone suggests that the Voyager I spacecraft passed termination shock in December 2004."
Beware: In C++, your friends can see your privates!
For those who want to know what a termination shock looks like: Clicky.
Except the solar wind slows down due to it 'running in to' interstellar particles. Larger objects are less affected by these subatomic particles, and can keep much more of their momentum.
Likewise, a solar sail isn't like a nautical sail. Once the momentum has been imparted, you need to apply energy to SLOW it down. On a sailboat, when the wind stops, the friction with the water slows you down. In interstellar space, when you don't have any solar 'wind' to power you, you just keep going...
I also have a problem with the use of the term 'subsonic'. When there is no medium for sound waves to travel in, how do you define 'subsonic'? (I don't mean you personally, I mean the schmuck that decided to use that term in this context originally.)
Another non-functioning site was "uncertainty.microsoft.com."
The purpose of that site was not known.
Supersonic means just that -- particles moving faster than the LOCAL speed of sound. It varies slightly at a distance, as you might imagine.
Don't think too much. Generally speaking there is the presence of a "shock" where a supersonic flow turns into subsonic one. That's why you hear about these words often when talking about heliopause.
Intersteller space is a giant unknown. We still can't account for a large portion of the Universe's mass (depending on which comsmolgical model you follow.)
Interstellar space is also teeming with leftovers from the formation of this chunk of the Universe. We are also still trying to track down another mass that is screwing up our calculations for the orbit of the outer planets. One of these probes might actually be able to give us a better measurement of it.
Just because it's black and cold does not a boring place make.
"Learning is not compulsory... neither is survival."
--Dr.W.Edwards Deming
Where are we now? There's almost nothing in the pipeline and NASA's sucking every dime out of science to feed the shuttle and ISS programs. We've got another decade of good stuff from existing probes, but after that we better hope ESA, Japan and China take up the slack.
Major Probes from the past 3 years:
-Deep Impact
-Gravity Probe B
-Messenger
-MER's
-Spitzer Space Telescope
Major probes slated for launch in next 3 years:
-MRO
-Dawn
-Mars Phoenix Lander
-Kepler
Right...
The correct terminology for this is superalphonic(sp?) There is a similar phenomena with solar wind and the earth's atmosphere, a bow shock is created, much like a rock in a stream. The solar wind is superaphonic in the reference frame of the earth. Very interesting stuff. http://www-istp.gsfc.nasa.gov/istp/outreach/ has some good info.
This page has been linked to from Slashdot and is getting a lot of vandalism so I've protected it. I'm going to bed, so if someone else wants to unprotect it later that's fine. CryptoDerk 06:59, May 25, 2005 (UTC)
I guess you should have suggested updating it with relevant, truthful information.
Extra medication for all!