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."

Update wiki with new information

[Dancin_Santa]

The wikipedia entry claims that The Voyager I spacecraft is believed to have passed termination shock in February 2003.

I'd do it, but my wiki privileges have been revoked temporarily. I can't imagine why.

Re:Update wiki with new information

[wkohse]

Wikipedia just says that it is believed to have crossed the termination shock, whereas "Dr. Ed Stone presented clear evidence that Voyager 1 crossed the termination shock last December. It was skepticism in 2003, now its been confirmed as true.

MOD PARENT UP FOR GOOD LINK

[Infinity Salad]

The link in the topic post is bunk.

Re:Update wiki with new information

[Spy Hunter]

That belief appears to be old and busted. The new hotness is that Voyager 1 has recently passed through the termination shock into a new region called the "heliosheath". Here's more info, pictures, and even movies, straight from the source [nasa.gov] (a much, much better link than the article provided).

Termination Shock ...

[bushboy]

Yep, had no idea what it was (so much for my Space Geek Badge)

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:details

[downsize]

if NASA does not terminate the project [washingtonpost.com] 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 [wikipedia.org] 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)

Voyager

[Fuji Kitakyusho]

I have been intermittently following the voyager program with some interest. Much more detail is available at the NASA JPL website, including transcripts of communication efforts with the spacecraft, as well as info about the program and the spacecraft themselves. It's quite the interesting story, given that the program was never expected to continue as long as it has.

Re:details

[helioquake]

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.

more info

[Ichigo Kurosaki]

the bbc http://news.bbc.co.uk/1/hi/sci/tech/4576623.stm [bbc.co.uk] 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."

Re:Uh... really old?

[Jugalator]

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."

What does it look like?

[astromog]

For those who want to know what a termination shock looks like: Clicky. [nasa.gov]

Particles, yes, large masses, no.

[Anonymous Freak]

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.)

Star Trek

[Anonymous Coward]

Remember VGER (Vee-jer)?
Yeah, that was a highly advanced AI hell-bent on destroying the Earth because it's disappointed in us as creator-figures.
So the story goes it evolved into that from Voyager 6 after we told it to gather all information in the universe.
Maybe I should be worried?

Re:more info

[Ichigo Kurosaki]

The Voyage wont accually be traped because it is primarily using inertia to propel it self. If you think back to Newtonian physics in order to stop the voyager you would either need a pulling or a pushing force that is greater then the force of the moving object. Since it has breached the termination shock the gravity from the solar system is not suffiecient to prevent it from leaving. And the solar winds do not present enough drag (D=Cd*A * .5 * r * V^2) on the frontal area of the craft to sufficently stop it. The solar winds will not push it back do to there velocity and mass are not sufficient to overcome the force. It will enter deep space.

Re:details

[helioquake]

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.

Re:Particles, yes, large masses, no.

[hubie]

A gas floating around in space has a speed of sound associated with it, which is the speed a disturbance propagates through the gas (due to the gas molecules bumping into each other down the line). This is the same way a sound wave propagates through the atmosphere. The medium that the sound waves travel in is the gas itself.

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:2005 is shaping up to be quite the year!

[rsynnott]

And in this "banner year" for space travel, Voyager is at significant risk of becoming a budget cut, apparently, to indulge Bush's moon-lust.

Re:...and they want to cut funding?!?!

[EvilTwinSkippy]

Actually no.

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.

Re:more info

[khallow]

Right, but according to the diagram there is wind in deep space also. Thus given long enough the probe should either come to a stop and start going backwards, or continue going forward while changing direction more and more.

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.

Distances, etc

[Alien54]

Actually, I am an advocate of using the earth's lunar distance as a measure of interplanetary diastance. It has the advantadge of seeming to be more intuitive. People think they know how far away the moon is. It is somewhat intuitive. After all, they see the Moon out there in the sky many nights.

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 = about 384 kilometers and 1 au = 150 million kilometers.

Thus typical distances [nasa.gov] can be rendered in LD

• Sun to Mercury = 97 LD
• Sun to Venus = 273 LD
• Sun to Earth = 390 LD
• Sun to Mars = 585 LD
• Sun to Jupiter = 2,028 LD
• Sun to Saturn = 3,700 LD
• Sun to Uranus = 7,400 LD
• Sun to Neptune = 11,700 LD
• Sun to Pluto = 15,400 LD

• One Light Second = 0.78 LD
• One Light Minute = 46.8 LD
• One Light Hour = 2,811 LD
• One Light Day = 67,453 LD
• One Light Year = 24,636,644 LD

• 1 au = 390 LD
• 90 au = 35,100 LD
• 100 au = 39,000 LD

  Current Voyager 1 & 2 Data [nasa.gov]

• Voyager 1 from Sun = 36,997.4 LD
• Voyager 2 from Sun = 29,596.4 LD

With apologies for rounding errors

Re:more info

[MindStalker]

Everything being equal wind from stars in all directions will equalise themselves and should provide zero force in any direction. And I believe the probe is above terminal velocity to leave the system.

Re:boundaries

[Anonymous Coward]

From wikipedia : "In astronomy, the termination shock is theorised to be a boundary marking one of the outer limits of the sun's influence."

How many outer limits does the sun have and what are they ?

Well we wont know until we exceed them them!

Seriously though, the ultimate limits of the solar system are usually thought to be the distance from the sun that phenomena it generates becomes indistiguishable from the surrounding stars.

Think about a pond with many pebbles thrown into it, all somewhat close to each-other. Near the point of each impact the ripples will be distinct, but as the go out each set of ripples interacts and interferes with the neighboring set of ripples.

Now when it comes to stars in our galaxy, the solar wind is one type of "ripple". The termination shock would signify the point were the solar wind interacts with the sum of the surrounding star's solar winds. This is considered one of the logical places to say the Sun no longer has dominate influence, and so it is not part of our solar system.

You can use similar thinking but with different solar phenomena, so that's how you can end up with different limits. For example, a city like Chicago or London has set geographical and legal city limits. However, we often include the suburbs or other metropolitan areas when talking about such cities. These are different than the real geographical limits, but for some purposes they are just as valid.

Re:This really makes me

[dtolman]

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...

Re:Power source

[jnik]

Cassini does not have a reactor. Both Cassini and Voyager are powered by radiothermal generators (RTG's). It's a small can of plutonium that produces heat (thus power) through natural radioactive decay processes. It is not a reactor--no fission.

Re:That Voyager is out there

[lukehan]

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/ [nasa.gov] has some good info.

Mod Parent -1 Uninformed

[Anonymous Coward]

Wrong.

The FY2006 U.S. Military budget is projected to be 419.3 billion according to:

http://www.armscontrolcenter.org/archives/001203.p hp [armscontrolcenter.org]

Being 120 billion LESS than the Social Security Ponzi Scheme, it is hardly "more than every other program combined"

Re:This really makes me

[Anonymous Coward]

Yeah, it's so much more important than sustainable food production so most humans have enough to eat and drink; so much more important than shelter and sanitation; so much more important than renewable non-polluting energy sources. Yay US.

Unfortunately I've already modded this topic, so I'm posting anonymously.

I think a lot of people don't understand just how much benefit they get from the space program. Things they have to develop to get something to work in space trickles into everyday life later on. Probably the biggest is that in order to get a craft into space, computers needed to be scaled down. So anything computerized that fits in your hand or your car got it's start in that miniaturization drive.

For other things we have because of that, check here [nasa.gov] and here [nasa.gov].

Having spent an entire day in the front seat of an old chevy on bad roads, probably this is my favorite development: Memory foam came from the space program. (Originally called T-foam.) It was used in seats on the shuttle. It was later used in wheelchairs because it could be molded to fit the individual's form, thus preventing problems from pressure points that people with twisted frames suffered from before.

I'm just waiting for them to put it in replacement truck seats now.

Re:Update wiki with new information

[craash420]

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.

Re:Considering how much we spend on

[brianerst]

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.

Are you nuts? An order of magnitude more? Do you even know what "order of magnitude" means?

According to government figures [whitehouse.gov], the total gross domestic product (GDP) of the US will be 12.9 trillion dollars ($12,900 billion). This is the total economic output of the nation.

Social Security ($540 billion), Medicare ($340 billion) and Medicaid/SCHIP ($199 billion) alone add up to $1.079 trillion (1,079 billion) - and that's leaving out traditional "welfare". That's almost 10% of GDP.

You're claiming an "order of magnitude" more in corporate welfare? $10.79 trillion? What kind of tax breaks are you thinking of here? Apparently, you believe that the government should take 100% of GDP in taxes and simply redistribute it as it sees fit, because that $11+ trillion that doesn't go to SS, Medicaid/Medicare is all "corporate welfare".

Dude, even Ralph Nader [citizen.org] only puts corporate welfare at $200 billion - only about a fifth as much as is spent on the big three social programs.

You seem to have been bit by the "numerical nonsense" bug yourself. Maybe you meant an order of magnitude less? You'd at least be in striking distance then...

I suppose, of course, that those are just "fascist facts". I'm sure you can figure out some way to link the approximately 10% of GDP paid out in the above services to fundamentalist Christian tithing of 10% of income to the church to "prove" how Amerikkka is becoming a theocratic dictatorship.

The rest of us learned to put down the bong when we started getting paranoid.