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Voyager 1 Crosses The Termination Shock
Posted by
Hemos
on Wed May 25, 2005 01:03 AM
from the going-gentle-into-that-good-night dept.
from the going-gentle-into-that-good-night dept.
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."
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That Voyager is out there (Score:3, Funny)
Re:That Voyager is out there (Score:3, Interesting)
in other news... (Score:5, Funny)
Fixed article link (Score:5, Insightful)
The first link doesn't go anywhere useful. This link [agu.org] brings up the correct results for the session. You can also view the session details [agu.org].
2005 is shaping up to be quite the year! (Score:5, Interesting)
And excited.
The geek in me is excited about 2005. Methane oceans, rovers on Mars and private spaceflight? There's a lot that's scary going on in the world today. But when it comes to SPACEFLIGHT -- 2005 is shaping up to be a banner year!
Kudos to the Voyager team!
Re:2005 is shaping up to be quite the year! (Score:5, Funny)
Yeah, NASA might actually launch a shuttle this year.
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Re:2005 is shaping up to be quite the year! (Score:3, Funny)
Plus, the Autobots and Decepticons finally get new leaders!
Pity about Prime, though.
Woohooo! (Score:4, Interesting)
And death we never can doubt.
Time's cold wind, wailing down the past,
Reminds us that all flesh is grass
And history's lamps blow out.
But the Eagle has landed; tell your children when.
Time won't drive us down to dust again.
Cycles turn while the far stars burn,
And people and planets age.
Life's crown passes to younger lands,
Time brushes dust of hope from his hands
And turns another page.
But the Eagle has landed; tell your children when.
Time won't drive us down to dust again.
But we who feel the weight of the wheel
When winter falls over our world
Can hope for tomorrow and raise our eyes
To a silver moon in the opened skies
And a single flag unfurled.
But the Eagle has landed; tell your children when.
Time won't drive us down to dust again.
We know well what Life can tell:
If you would not perish, then grow.
And today our fragile flesh and steel
Have laid our hands on a vaster wheel
With all of the stars to know
That the Eagle has landed; tell your children when.
Time won't drive us down to dust again.
From all who tried out of history's tide,
Salute for the team that won.
And the old Earth smiles at her children's reach,
The wave that carried us up the beach
To reach for the shining sun.
For the Eagle has landed; tell your children when.
Time won't drive us down to dust again.
(c) 1975 - Leslie Fish
details (Score:3, Interesting)
Re:details (Score:5, Informative)
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Re:details (Score:5, Interesting)
Actually, "hot" (or temperature) is really describing the energy of the particles in the area. Inside the solar system, the solar wind is moving at pretty high speeds - wikipedia suggests energies of 500 KeV. Using the Boltzmann Constant we get 500,000 x 11,605 = 5.8 billion degrees K (Sounds a lot - can some astrophysacists check my figures please
Once you get to the termination shock, the solar wind is moving at much slower sub-sonic speeds. Not sure what energies we're talking about here but they're going to be a *lot* lower... A bit of googling suggests He energies somewhere around the 5.2 KeV area (5,200 x 11,605 = 60 million degrees K).
Of course, although the matter may be "hot", there isn't much of it - the low density of matter means that there isn't much "heat" (compare - a cigarette is "hot" (it's gonna burn you) whereas a central heating radiator is not as hot but generates more "heat" (it'll warm your room better than the cigarette because it's total energy output is much greater, even though it's temperature is less)).
Disclaimer: IANAAP (Astro-Physacist) so the above could be crap, but that is how I understand it.
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Re:details (Score:3, Interesting)
it did read like NASA will not pull the plug, how could they possibly. is the heat from Bush really that bad? could not Bush's NASA advisors sway him that this is some incredible data discovery over wasting money to put people on Mars in 40+ years?
Re:details (Score:5, Informative)
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.
Parent
Re:details (Score:4, Informative)
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.
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Termination Shock ... (Score:3, Informative)
http://en.wikipedia.org/wiki/Termination_shock
<i>In astronomy, the termination shock is theorised to be a boundary marking one of the outer limits of the sun's influence. It is where the bubble of solar wind particles slows down to below supersonic speed and heats up due to collisions with the galactic interstellar medium. It is believed to be about 100 Astronomical Units from the Sun.
The termination shock boundary fluctuates in its distance from the sun as a result of fluctuations in solar flare activity i.e. changes in the ejections of gas and dust from the sun.
The Voyager I spacecraft is believed to have passed termination shock in December 2004.</i>
Re:Termination Shock ... (Score:3, Funny)
So it's just a theory...?
more info (Score:5, Informative)
Re:more info (Score:5, Informative)
Given enough time. Interstellar space is incredibly empty. The pressure of interstellar gas (outside of the somewhat more dense nebula) is on the order of 10^13 times [wikipedia.org] less than Earth's atmosphere and since most interstellar gas is hydrogen or helium (both which are significantly lighter than the main ingredients of Earth's atmosphere), the drag of this medium is incredibly small.
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Re:more info (Score:3, Informative)
Funny (Score:5, Funny)
...and they want to cut funding?!?! (Score:5, Interesting)
Science just doesn't work when politics gets involved...
Re:...and they want to cut funding?!?! (Score:5, Insightful)
Science just doesn't work when politics gets involved... :(
On the other hand, science like this would never be funded with out politics. There's only a limited amount of money out there to fund endevours like this, and someone has to decide how to divy that money up. So who gets the money? Well you have to create a policy to decide where appropriate funds.... and now you've entered the relm of politics. Whether it's decided by elected senators on the floor of Congress or by a tribunal of society's leading scientists: scarcity leads to a policy of allocation which leads to politics. Can't avoid it.
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Re:...and they want to cut funding?!?! (Score:4, Informative)
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.
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What does it look like? (Score:4, Informative)
Re:What does it look like? (Score:4, Interesting)
http://antwrp.gsfc.nasa.gov/apod/ap031120.html [nasa.gov]
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This really makes me (Score:5, Interesting)
Re:This really makes me (Score:5, Interesting)
Just like all countries, we do good things and we do bad things. We have good politicians and we have bad politicians. We have good people and we have bad people. So, thanks again for your levelheadedness, in all seriousness, I really do appreciate it.
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Re:This really makes me (Score:5, Insightful)
The nearest we have in Europe is the European Space Agency [esa.int]. Now celebrating thirty years this has run some major programs and developed some excellent lauchers. Although it has a European Branding, my impression is that almost half the funding and most of the political drive has come from France, with very little in the way of contribution from the UK. If you ever get the chance and find yourself in South West France, check out the excellent Cité de l'Espace [cite-espace.com] museum near Toulouse. This is easily Europe's finest space museum with a wide range of information on space exploration and the European Space Program, inclding two Skylabs to walk through and a full size Ariane 5 rocket which dominates the skyline as you approach.
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Considering how much we spend on (Score:4, Insightful)
2006 budget:
Nasa: 16.5 billion
Education: 56 billion
HHS: 68.9 billion
Social Security: 540 billion
Medicare: 340 billion
Medicaid: 199 billion
Yeah, killing NASA would make a big dent.
Parent
Re:Considering how much we spend on (Score:5, Insightful)
Amen. The poster should be ashamed of themselves, and the moderates who modded you down as "flaimbait" for speaking the truth even more so.
1) Social Security isn't "welfare." We pay into the system, we get benefits out of the system. Social Security recipients are not getting "something for nothing," so to lump them in with welfare recipients is just plain Ignorant(tm) and Stupid(tm).
2) You want to discuss welfare, start by discussing the savings and loan bailout, the tax subsidies virtually every large corporation gets from state, local, and federal governments, and the immense amount of government pork in the defense budget which amounts to Yet Another Subsidy. The amount of tax dollars spent on corporate welfare, an appalling percentage of which goes directly to line the pockets of the very wealthy, dwarfs by an order of magnitude the amount of money being returned to those who've paid into the Social Security system, being paid to those who've paid into the Unemployment Benefits system, being returned to those who've paid into the Medicare and Medicaide system during their working lives, and yes, even those getting free handouts ('welfare') because they're too poor, too uneducated, lack resources, lack opportunity, or (in some cases, but not even close to all) are simply too lazy to work.
That doesn't change the fact that funding the space agency should be one of our top priorities, not one of our last, but to blame it on "welfare" is numerical nonsense--and to blame it on the modest, half-assed social programs we call Social Security and Medicare simply unconscionable right wing and, yes, fascist dogma. The Right in America has become so toxic it boggles the mind.
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Re:This really makes me (Score:5, Insightful)
Mars rovers?
Cassini-Huygens?
Hubble?
Chandra?
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Re:This really makes me (Score:5, Informative)
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...
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boundaries (Score:3, Interesting)
How many outer limits does the sun have and what are they ?
Now that's space! (Score:3, Interesting)
OMG ITS NOT IN THE BIBLE (Score:4, Funny)
OMG cut NASA's funding!
Re:OMG ITS NOT IN THE BIBLE (Score:4, Funny)
Ha, you don't have a very good translation do you?
It says right here after, "Thou shalt not pop-off around the corner for a pint," that, "Thou shalt enjoy thine termination shock so long as thou art not seen to be smug about the business. Thine undergarments must be clean at the time of the shocking of the termination. Thusly, shalt the word of the Snazzites be proven unworthy of the jigsaw-mongerer. And all will be well in Geziphalohn."
See? Plain as day.
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Re:OMG ITS NOT IN THE BIBLE (Score:4, Funny)
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Re:Uh... really old? (Score:3, Funny)
Re:Uh... really old? (Score:5, Interesting)
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Re:Uh... really old? (Score:4, Funny)
Ahhh..
You know about the secret 8-track installation on Voyager too, huh?
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Re:Really Dangerous: Chinese Military (Score:3, Insightful)
Thanks for playing, AC! but why not check some of the manifests for Shuttle flights; and whether the astronauts have security clearances; etc. The notion that NASA is "entirely civilian" is
Re:Uh... really old? (Score:5, Informative)
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."
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Re:It happened ages ago? (Score:3, Interesting)
You have: 100 au
You want: light years
* 0.0015812845
/ 632.39726
You have: 0.0015812845 years * 2
You want: hours
* 27.722488
/ 0.036071799
Distances, etc (Score:3, Informative)
The Nasa Near Earth Object site includes this unit in their online data [nasa.gov] since newspapers used to freak out on a regular basis when they were using only decimal AU for distance measurements. A lunar distance = abo
Re:Update wiki with new information (Score:5, Insightful)
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Re:Update wiki with new information (Score:3, Interesting)
Re:cool (Score:5, Insightful)
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Particles, yes, large masses, no. (Score:3, Informative)
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
Re:Particles, yes, large masses, no. (Score:3, Informative)
You get a shock wave when you have a bunch of matter traveling at supersonic speeds that then at some point slow to subsonic speeds. That is what is going on here.
Re:Power source (Score:5, Insightful)
While this is true, my basic problem is that most people opposed to RTGs can't understand this statement in context. The environmental impact statement of this project is particularly useful. Its in this PDF [nasa.gov] on page 19. But let's analyze that statement anyway, piece by piece.
1) An "accident" could have released material, but it was unlikely. The containers were tested under explosions, fires, shrapnel, reentry heat, and impact. The RTGs were tough enough that they could hit concrete at terminal velocity and release only a minscule amount of fuel (0.22 grams).
2) Yes, Plutonium is "highly toxic". But most people complaining about the RTGs don't worry about "toxic". They worry about "nuclear explosion" or "fallout". Of course, none of those can result from the failure of an RTG. 10kg of toxic material (only a fraction of which would actually be released in a failure) is hardly your biggest worry. I'd be more worried about the thousands of pounds of very nasty fuel in solid rocket boosters.
3) The fuel in the RTG's isn't plutonium, its plutonium dioxide. This is an important difference, because the latter is very stable, almost inert (it was believed to be completely inert until 1999), and is insoluable in water. It also has a very high melting temperature and an even higher vaporization temperature. The net result is that the mechanisms through which it can enter the environment in the event of an accident are very limited. Basically, it would have to be bulverized and become airborne. Pulverizing 10kg of a hard material encased in a strong, unrestrained container, with just a single explosion is non-trivial. The physics of the situation tend to make the container just fly away and land in the dirt.
So basically, an accident was exceedingly unlikely, and even if it did happen, release was unlikely, and even if that happend, you had bigger things to worry about at that point.
You can operate on a basis of reasonable risk management
It's not "reasonable risk management". It's "not caving in to complete paranoia".
assuming the general public is entirely ignorant of physics
The general public *is* ignorant of physics.
I'm sure there are plenty of people in the "general public" who have studied more physics and bio/chemistry than you have.)
Well that's fine and good, and I don't doubt that biology and chemistry can tell you that plutonium will cause poisoning and cancer. However, biologists and chemists are not engineers or environmental scientists. They cannot tell you the probability of an RTG failing in an explosion, nor can they tell you the environmental mechanisms through which plutonium could spread even in the case of a failure. Nor can they tell you what sort of population impact such a spread would have anyway. Finally, they are not trained to make risk assessments of this nature. Engineers build bridges (and planes and cares and buildings), that thousands of people trust their lives too every day, without a second thought, using the exact same risk assessment mechanisms the NASA folks used. If you're going to question the NASA folks, the intellectually honest thing to do would be to grill the guy who designed your car about what risks he took with your life.
I agree that people sometimes go way overboard with their resistance to anything nuclear, but that attitude was instilled in them, or their parents, pretty forcefully.
Most parents are people, and most people are stupid, therefore most parents are stupid. Is having stupid parents supposed to be an excuse for being ignorant?
And it doesn't help the situation one bit, when the only response when concerns are raised is "go away, you are ignorant"
What if "you are ignorant" is the correct answer? I do not buy the idea that it is the du
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