Voyager 1 Nearing the Heliosheath

Palomar · 2003-11-05 20:34:21

*This is an excellent resource with more information about Voyager 1 and its approaching heliopause, the heliosheath, bow shock and termination shock.

The final news segment on ABC Evening News mentioned Voyager 1 is traveling at a rate of nearly one million miles per day. The article above says 3.6 astronomical units per year.

Wow. Any comments on the article?

I'm going to keep Googling for this topic. If anyone else can contribute more info, that'd be great.

It's fascinating to me, how the heliosheath formed. Why did the solar wind create a bubble (scientific writers actually say "the sun blows a bubble")? Why not just an outflow of solar particles into space itself?

And V1 is still transmitting data back. I'm trying to find out how long it takes for the data to be downloaded/received by the scientists; anyone know? I checked the Yahoo! article (reposted below) twice; I don't see a reference to transmission time.

::EDIT:: Found an answer to the transmission-time question in an article linked in the 2nd post of this thread ("bow shock" article): "It continues to return what it learns via feeble radio signals sent over such a great distance that the messages take more than 10 hours to reach us -- even at the speed of light."

I'll keep looking...in the meantime, any input would be appreciated!

--Cindy

P.S.: The original article I posted in "New Discoveries *2*" thread:

http://story.news.yahoo.com/news?tm...._edge_1

*ANOTHER article:

http://story.news.yahoo.com/news?tm....emsedge

Palomar · 2003-11-05 20:44:17

[color=#810541:post_uid9]*Now I have another question about something in one of the articles that seems like a contradiction:

"Voyager 1 will eventually pass the termination shock and, barring catastrophe, other expected boundaries. That will put the craft in interstellar space. Scientists are eager to learn as much as possible during this first trip through the edge of the solar system before the machine runs out of fuel in about the year 2020, rendering it unable to communicate.

Voyager 2, launched in the same year, is about 70 AU away. Both robotic explorers are headed toward two other boundaries beyond the termination shock. The heliopause marks the region where the solar wind no longer exists and interstellar plasma rules. Then there is the bow shock, created by the entire heliosphere plowing through space. The bow shock is akin to the ripple of water raised by a boat's bow.

Previously, Voyager data was paired with observations from the Hubble Space Telescope (news - web sites) to find evidence that the outer shell, the bow shock, in fact exists as theory predicts.

Communications will be lost with both Voyagers before either can reach the bow shock."

*V1 will pass through the heliosphere soon, according to the Yahoo! articles and "Mark's Column" (he projected the year 2001 or 2003 for the event). The quote above says we should still be receiving info from V1 until 2020, when its fuel runs out. But the last line I quoted says "communications will be lost with both Voyagers before either can reach the bow shock (which obviously -isn't- going to take until 2020 to occur!)."

?

I presume this means a [/I]temporary[I] communications loss, which will be restored once V1 passes the boundary.

Robert Dyck, if you read this, can you please offer some insights?

--Cindy

P.S.: A good article devoted to the "bow shock":

http://www.space.com/science....15.html

::EDIT:: Reference to a phenomenon called "Fermi glow" in the "bow shock" article immediately above:

"Nearly 23 years after its launch, Voyager has been teamed with the Earth-orbiting Hubble Space Telescope and some scientists in Europe to help spot the glowing particles -- called the Fermi glow. The result, announced this week, is the first evidence that the solar system's bow shock is in fact real."

Whoa. Never heard of the "Fermi glow" before.[/color:post_uid9]

Palomar · 2003-11-06 11:44:05

"The nuclear-fueled probes should last to 2020."

*That's what one of the above-quoted articles says. Okay, V1 was launched in 1977. It's nuclear power will last until 2020, which means 43 years of functionality.

What kind of nuclear material is it powered with? And (going slightly off topic), if we one day do achieve manned spaceflight (beyond the solar system, I mean going waaaaay out), how will the nuclear power be replenished?

I'm still hoping someone will chime in, as well, on the two above posts. Talking to one's self is such a drag.

--Cindy :laugh:

RobertDyck · 2003-11-06 14:19:08

Ooh, my name was mentioned again. Well, in general the "bubble" is caused by solar wind. There is a very thin atmosphere of plasma in our galaxy caused by the accumulation of solar wind from all the stars. Our sun is orbiting the center of the galaxy. The interstellar plasma is generally orbiting the center of the galaxy as well, but not necessarily in the same orbit as our sun. Our sun is sending out solar wind in all directions. The solar wind pushes the interstellar plasma out of the way, but as the solar wind gets farther away from the sun it gets thinner and weaker. Eventually it gets so weak it can't push the interstellar gas out of the way. At that point the solar wind accumulates, with fresh wind delivered from our sun on the inside and interstellar plasma pushing from the outside. Well, the interstellar plasma doesn't "push", our solar system is pushing through it, but you get the idea.

Actually, close to the sun the solar wind is deflected by the sun's magnetic field so although the solar wind is relatively smooth near the sun's equator, at the poles it tends to follow twisty lines running out from the sun and generally bending toward the equator. The end of the lines that touch the sun move around as the gasses inside the sun churn about, and it takes time for the magnetic field lines to emanate out, so the lines bend like someone flicking the end of a skipping rope.

This is important for three reasons: First, it is the first time any measurements will be done outside our solar system. Measuring the tenuous plasma in space may be a bit esoteric, but it's something. Second, it will tell us what radiation is like in interstellar space. That could help people plan for interstellar voyages and better understand cosmic radiation. Cosmic radiation is high speed interstellar wind that gets into our solar system. How much is out there to start with? How does it get through the heliopause? Understanding cosmic radiation can help plan for radiation threats to interplanetary missions such as a manned mission to Mars.

The third reason is planning for an interstellar ramjet. Many years ago the British Planetary Society came up with a spaceship design they called the Daedalus which would scoop up interstellar plasma and feed it to a fusion engine. You may have heard science fiction stories talk about a Bussard collector, the idea originally came from the Daedalus. To keep mass down, a Bussard collector uses a big magnetic field to scoop up plasma rather than a physical cone. However, current mass estimates indicate there isn't enough interstellar plasma to support a nuclear fusion ramjet. The collector creates drag and the magnetic field takes power to maintain, if the plasma density is too low the thrust generated will not be enough to keep it going. Measurements from Voyager will confirm whether there really is too little interstellar plasma.

::Edit:: The heliosheath is that thickened accumulation of solar wind. The termination shock is the inside surface of the heliosheath, where fresh solar wind hits it. The heliopause is the outside surface where interstellar wind is stopped. However, the heliopause is not where our solar system first hits the interstellar wind. First contact is at the bow shock. Most of the interstellar wind passes through the bow shock, it isn't stopped until the heliopause, but the interstellar wind starts to get slowed between the bow shock and the heliopause so a very slight pressure builds up. The bow shock literally is a shock wave like the wave caused by a boat ploughing through water.

RobertDyck · 2003-11-06 14:23:33

One thing to worry about with RTGs is that the power is not steady over years. In the same time as the half-life of the nuclear material, the power generated will half. In that same time again the power will half again, so it will be a quarter of what you started with. Then it will half again so one eighth of what you started with. The power for Voyager is already so low that most instruments have to be turned off. It will continue to decrease until the radio doesn?t work any more, then it?ll be useless.

Palomar · 2003-11-06 14:59:30

Wow. Thanks for taking the time to reply to my posts, Robert. I genuinely appreciate it. I learned quite a bit, especially your description of solar wind ("twisty lines", solar poles, etc.), the ramjet, and the information in your 2nd post. It halves, huh? Hmmmmm.

You said: "Cosmic radiation is high speed interstellar wind that gets into our solar system. How much is out there to start with? How does it get through the heliopause?"

One of the articles' authors likened the heliosheath to the gestational placenta. It is an interesting question, how that cosmic radiation leaks through. I guess that's a mystery for greater minds than mine to solve. :;):

--Cindy

Christina · 2003-11-07 02:32:23

"The nuclear-fueled probes should last to 2020."
*That's what one of the above-quoted articles says. Okay, V1 was launched in 1977. It's nuclear power will last until 2020, which means 43 years of functionality.
What kind of nuclear material is it powered with?

The lastest press release says

the Voyagers were destined to explore regions of space where solar panels would not be feasible, so each was equipped with three radioisotope thermoelectric generators to produce electrical power for the spacecraft systems and instruments. Still operating in remote, cold and dark conditions 26 years later, the Voyagers owe their longevity to these Department of Energy-provided generators, which produce electricity from the heat generated by the natural decay of plutonium dioxide.

TJohn · 2003-11-07 07:39:01

This maybe off topic, but is Pioneer 10 also at the Heliopause just going in the opposite direction? I believe it was launched in the same year as Voyager 1.

Palomar · 2003-11-07 08:26:12

*Thanks Christina, for the information and link!

Hi TJohn: Good question. You got me curious, too, about Pioneer 10's whereabouts. I did some Googling, and found this:

"PIONEER 10 SENDS ITS LAST SIGNAL TO EARTH.

Bob Park, of the APS, brought us this poignant news item:

Its nuclear furnace has grown cold. Launched in 1972 on a two-year mission, the tiny 570-pound spacecraft was 30 years and 7.6 billion miles from home when it sent its last faint transmission on 22 January, 2003. The first spacecraft to venture beyond Mars, Pioneer 10 negotiated the unknown hazard of the asteroid belt to send back the first close-up images of Jupiter. It charted the currents of the solar wind to the very edge of interstellar space, while suffering the usual infirmities of old age: its mechanical limbs arthritic; its senses dimmed by the battering of radiation and micrometeoroids; circuits shut down to conserve energy. ---->Its last assignment was to find the heliopause, where the solar wind is offset by the galactic wind, but in April 1997 it was passed by a younger, faster Voyager spacecraft.<---- It was recalled to active duty by NASA's Deep Space Network as part a communications study in support of a future interstellar probe.

No matter, Pioneer 10 was expendable. Requiescat in pace.

As Carl Sagan and I once discussed, the engraved plaque aboard Pioneer 10, designed by Carl and Linda Sagan and Frank Drake, was intended to serve as a greeting to extraterrestrial civilizations, but Puritanical busybodies altered the illustrations of Homo Sapiens so that no reproductive means is to be seen on the female of our species, while the male is appropriately equipped. Strange?..

Though it's dumb and blind on its current path, Pioneer 10 will reach the giant red star Aldebaran, the eye of Taurus the Bull, more than two million years from now. Wow. Something we made and tossed up into the sky, though silent and helpless, will close in on this bulls-eye long after our species, as it is now, has ceased to exist ? at least in its present configuration."

I added those arrows in the text, by the way.

I found that tidbit from this web site; the long article the Pioneer 10 information was found in is dated 3/2003, so it's recent:

http://www.randi.org/jr/031403.html

--Cindy

Palomar · 2003-11-20 07:25:51

*Bless the good folks at Astropix. Today they give their readers a large, finely illustrated depiction of Voyager 1 nearing the heliosheath...along with bow shock, etc.; includes explanations as well, of course, and many links. I've seen ::tiny:: similar illustrations related to this story. You won't need a magnifying glass with this one. :;):

Click

--Cindy

::EDIT:: Here's another:

Heliosphere

Palomar · 2004-04-02 12:21:34

*Bless the good folks at Astropix. Today they give their readers a large, finely illustrated depiction of Voyager 1 nearing the heliosheath...along with bow shock, etc.; includes explanations as well, of course, and many links. I've seen ::tiny:: similar illustrations related to this story. You won't need a magnifying glass with this one. :;):
[http://antwrp.gsfc.nasa.gov/apod/ap031120.html]Click
--Cindy
::EDIT:: Here's another:
[http://antwrp.gsfc.nasa.gov/apod/ap020624.html]Heliosphere

*I wonder if space -within- the heliosheath/sphere is warmer than interstellar space?

This question keeps coming to mind as well.

--Cindy

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#1 2003-11-05 20:34:21

Re: Voyager 1 Nearing the Heliosheath

#2 2003-11-05 20:44:17

Re: Voyager 1 Nearing the Heliosheath

#3 2003-11-06 11:44:05

Re: Voyager 1 Nearing the Heliosheath

#4 2003-11-06 14:19:08

Re: Voyager 1 Nearing the Heliosheath

#5 2003-11-06 14:23:33

Re: Voyager 1 Nearing the Heliosheath

#6 2003-11-06 14:59:30

Re: Voyager 1 Nearing the Heliosheath

#7 2003-11-07 02:32:23

Re: Voyager 1 Nearing the Heliosheath

#8 2003-11-07 07:39:01

Re: Voyager 1 Nearing the Heliosheath

#9 2003-11-07 08:26:12

Re: Voyager 1 Nearing the Heliosheath

#10 2003-11-20 07:25:51

Re: Voyager 1 Nearing the Heliosheath

#11 2004-04-02 12:21:34

Re: Voyager 1 Nearing the Heliosheath

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