What is really amazing is that the probe still operates after over 3 decades, which is a testament to the design team. It’s a SNAP to keep powered up though. – Anthony
Artist concept of Voyager near interstellar space. Image credit: NASA/JPL
From NASA JPL: (h/t to Dr. Leif Svalgaard)
PASADENA, Calif. – The 33-year odyssey of NASA’s Voyager 1 spacecraft has reached a distant point at the edge of our solar system where there is no outward motion of solar wind.
Now hurtling toward interstellar space some 17.4 billion kilometers (10.8 billion miles) from the sun, Voyager 1 has crossed into an area where the velocity of the hot ionized gas, or plasma, emanating directly outward from the sun has slowed to zero. Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars.
The event is a major milestone in Voyager 1’s passage through the heliosheath, the turbulent outer shell of the sun’s sphere of influence, and the spacecraft’s upcoming departure from our solar system.
“The solar wind has turned the corner,” said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. “Voyager 1 is getting close to interstellar space.”
Our sun gives off a stream of charged particles that form a bubble known as the heliosphere around our solar system. The solar wind travels at supersonic speed until it crosses a shockwave called the termination shock. At this point, the solar wind dramatically slows down and heats up in the heliosheath.
Launched on Sept. 5, 1977, Voyager 1 crossed the termination shock in December 2004 into the heliosheath. Scientists have used data from Voyager 1’s Low-Energy Charged Particle Instrument to deduce the solar wind’s velocity. When the speed of the charged particles hitting the outward face of Voyager 1 matched the spacecraft’s speed, researchers knew that the net outward speed of the solar wind was zero. This occurred in June, when Voyager 1 was about 17 billion kilometers (10.6 billion miles) from the sun.
Because the velocities can fluctuate, scientists watched four more monthly readings before they were convinced the solar wind’s outward speed actually had slowed to zero. Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 20 kilometers per second each year (45,000 mph each year) since August 2007, when the solar wind was speeding outward at about 60 kilometers per second (130,000 mph). The outward speed has remained at zero since June.
The results were presented today at the American Geophysical Union meeting in San Francisco.
“When I realized that we were getting solid zeroes, I was amazed,” said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again.”
Scientists believe Voyager 1 has not crossed the heliosheath into interstellar space. Crossing into interstellar space would mean a sudden drop in the density of hot particles and an increase in the density of cold particles. Scientists are putting the data into their models of the heliosphere’s structure and should be able to better estimate when Voyager 1 will reach interstellar space. Researchers currently estimate Voyager 1 will cross that frontier in about four years.
“In science, there is nothing like a reality check to shake things up, and Voyager 1 provided that with hard facts,” said Tom Krimigis, principal investigator on the Low-Energy Charged Particle Instrument, who is based at the Applied Physics Laboratory and the Academy of Athens, Greece. “Once again, we face the predicament of redoing our models.”
A sister spacecraft, Voyager 2, was launched in Aug. 20, 1977 and has reached a position 14.2 billion kilometers (8.8 billion miles) from the sun. Both spacecraft have been traveling along different trajectories and at different speeds. Voyager 1 is traveling faster, at a speed of about 17 kilometers per second (38,000 mph), compared to Voyager 2’s velocity of 15 kilometers per second (35,000 mph). In the next few years, scientists expect Voyager 2 to encounter the same kind of phenomenon as Voyager 1.
The Voyagers were built by NASA’s Jet Propulsion Laboratory in Pasadena, Calif., which continues to operate both spacecraft. For more information about the Voyager spacecraft, visit: http://www.nasa.gov/voyager . JPL is a division of the California Institute of Technology in Pasadena.
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Jeremy says:
December 15, 2010 at 7:59 am
There’s nothing in space that can’t be overcome.
What can’t be overcome is right here back on Earth…
Human pettiness, stupidity, and science illiteracy.
Dr. S thanks for the reply.
ENAs are of no consequence since they do not have a charge.
High latitudes (if coming back) charged particle would be guided by magnetic field (kind of to ‘aurora’ effect)
Sideway explanation sounds plausible except for:
Analysis of the data shows the velocity of the solar wind has steadily slowed at a rate of about 20 kilometers per second each year…
August 2007, when the solar wind was speeding outward at about 60 kilometers per second….
Initial speed is say 400km/s, down to 60km/s , i.e. down to 15% of the initial; there is definite de-acceleration. There is nothing around to pump more energy into SW, so de-acceleration would continue, regardless of direction, forward, sideways or backward. Eventually speed has to fall below the escape velocity, when gravity and solar ‘magnetic filled lines’ would come into play.
Would the solar wind had slowed to zero at that distance if it were active instead of spotless?
******
Monty says:
December 14, 2010 at 8:53 pm
@ur momisugly Jimash:
>Shouldn’t there be something between chemical rockets and flux-capacitor warp drives ?
If you find it, let me know.
******
The next logical step would be nuke-powered drives. Some kind of magnetohydrodynamic-type ion-drive using helium or hydrogen heated/ionized by a reactor? Even if it produced only a fraction of a gee, the constant acceleration over yrs would produce an impressive velocity.
Or construct a giant nozzle attached behind a ship & explode 1000-megaton nukes in the nozzle inlet. OK, you’d somehow have to survive thousands of gees of acceleration. A giant shock-absorber/spring connected between the nozzle and the living quarters?
Monty: That’s Project Orion.
But although the Logos is common, most people live as if they had their own private understanding.
Heraclitus of Ephesus
In interstellar space there is only miniscule gravity and no ‘medium’ resistance. Once craft is far away from the sun a powerful light source (fusion reactor placed in the focus of a parabolic mirror in the back of the craft; reactor could be ignited at suitable point along trajectory) should in principle quickly accelerate craft to velocity that can’t be matched by any other propulsion system (remember solar windmill toy). 20% speed of light should be achievable. NASA how about it, I have filed provisional patent application, ready to negotiate?
Wow ! 7 planets of the Proxima Centauri in 20 years (grow plants and raise chickens on the craft for food, just filing another PPA for that too) .
A government which completely prioritises financial values over the technical ability of their engineers to develop ,will cause stagnation. In the UK in the 1960’s our aerospace industry which built Concorde, the Harrier. Handley Page Victor was sacrificed for financial expediency. If the TSR2 had been built it would still be a cutting edge aircraft.
The NASA which produced Apollo and the Voyagers was simply the best.
Maybe it will take a space race with India or China for the accountants to lose power and the engineers given the opportunityto deliver the product.
But at least the Voyagers give something to aspire to.
A peer-reviewed paper, Physical Review Letters, “Contribution of Strong Discontinuities to the Power Spectrum of the Solar Wind” (2010), by Joseph Borovsky of Los Alamos National Laboratory states that the conventional model of the solar wind could be wrong.
Rather than being a homogeneous body of plasma, the solar wind could be cellular in structure made up of magnetic flux tubes:
From the Los Alamos press release: “Borovosky argues that the discontinuities are part of a structure to the solar wind that looks like spaghetti, with the discontinuities being the boundaries between adjacent noodles (magnetic tubes). In this concept, the wind plasma is structured rather than being homogeneous. He suggests that the spaghetti structure of the solar-wind plasma reflects the “magnetic carpet” on the surface of the Sun, with the spaghetti in the wind being loose strands of the magnetic carpet.”
http://www.lanl.gov/news/releases/understanding_of_solar_wind_structure_might_be_wrong_newsrelease.html
Much more investigation needs to be done to confirm or falsify the above conclusion.
But, if it turns out to be valid and the solar wind is, indeed, made up of “magnetic tubes”, it needs to be further investigated to determine how far out into interplanetary space these “magnetic tubes” travel away from the Sun.
Indeed, the question then arises, do these solar wind “magnetic tubes” travel all the way out to the heliosheath?
From the story in the post:
“Scientists suspect the solar wind has been turned sideways by the pressure from the interstellar wind in the region between stars…”
“The solar wind has turned the corner,” said Ed Stone, Voyager project scientist based at the California Institute of Technology in Pasadena, Calif. “Voyager 1 is getting close to interstellar space.”
The Voyager spacecraft does not have the capability to observe & measure whether the solar wind, charged particles, plasma, has a structure of “magnetic tubes”. But if the solar wind does have a structure of “magnetic tubes” at this distance from the Sun near the heliosheath, it suggests the possibility, that there is a “current” and is not simply “debris”.
And, as Vukcevic stated: “These solar wind particles would be pulled back by Sun’s gravitation, not along the heliospheric sheet, but at the higher latitudes, forming a return current of protons, closing the loop, creating possibility of a feedback!”
Now, I don’t know about the gravitation angle, but if there is a “return current of protons [and possibly electrons, too]”, could this “return” current of charged particles pick up energy from the heliosheath region and then funnel energy back to the Sun?
Of course, it’s only a hypothesis, but since the reported observations & measurements have surprised scientists, might there be other surprises in store?
Only if we are willing to accept the surprises!
And, are willing to incorporate these “surprises” into our ideas — perhaps, even coming up with new ideas about solar system dynamics.
Again, from the story in the post:
“When I realized that we were getting solid zeroes, I was amazed,” said Rob Decker, a Voyager Low-Energy Charged Particle Instrument co-investigator and senior staff scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “Here was Voyager, a spacecraft that has been a workhorse for 33 years, showing us something completely new again.”
Science is about observation & measurement and, when appropriate, discarding old ideas and replacing the old ideas with new ideas that are consistent with new observations & measurements.
“There’s nothing in space that can’t be overcome.
What can’t be overcome is right here back on Earth…
Human pettiness, stupidity, and science illiteracy.”
– Guess God has set us an agenda to overcome the internal obstacles first before conquering Space. Makes sense actually – No point it taking it out with us to outer space and contaminating it as well. Also if we are to harness much greater forces than nuclear, it is just prudent that we also possess the maturity and restraint to use it wisely.
Jeremy says:{December 15, 2010 at 7:59 am}
“Even if it takes multi-generational spacecraft of asteroid-sized mass travelling at tiny fractions of c, it can be done, and if humanity can survive long enough without killing each other or falling victim to a solar-system disaster, it will be done. ”
The problem with multi-generational spacecraft theory is not whether it can be done but whether the reason to do so would survive through the generations. Imagine how horrible it would be for the generations that will live and die during the travel to know that their generation was one of many deemed to be expendable so that some future generation would be able to reach a goal that was established generations prior to them being born. Methinks they would rebel and change the mission to better suit themselves and their children. Eventually it will become a matter of do they want to continue rather than can they continue.
Leif Svalgaard says:
December 15, 2010 at 4:49 am
tallbloke says:
December 15, 2010 at 12:52 am
then they must surely accumulate at the boundary with the heliosheath.
And they do [in a fashion]. The result is called the ‘Hydrogen Wall’ which also contain interstellar ions. The whole shebang eventually slides off to the side and merges with the galactic medium.
Thanks Leif. So it sounds a little bit analogous to the way the Earth’s magnetosphere wards off the incoming solar wind, and deflects it round the outside. Maybe the heliosphere leaves a trail of plasma balls behind it like the Earth does, creating reconnection shocks which reverberate back into the solar system?
Sarc Ozy says:
December 15, 2010 at 10:05 am
……………
I think this Sarc Ozy bloke is a very clever guy. Looked at his website, lots of fun.
Tom in freakin cold Florida says:
December 15, 2010 at 12:18 pm
…Eventually it will become a matter of do they want to continue rather than can they continue.
How is there any rational alternative to continuing with the mission if your delta-V has already changed sufficiently to make it impossible to stop, turn-around, and head back?
Vijay says:
December 15, 2010 at 11:57 am
“There’s nothing in space that can’t be overcome.
What can’t be overcome is right here back on Earth…
Human pettiness, stupidity, and science illiteracy.”
Those last characteristics will be contrary to survival in the space environment.
Even with chemical rockets a low earth orbit/Luna/Mars civilization has travel times no worse than when empires were held together by sailing ships.
hotrod (Larry L) says:
December 14, 2010 at 4:21 pm
Djozar says:
December 14, 2010 at 1:58 pm
“Amazing! Any idea of how long we’ll be able to keep up communications, and the time lag involved?
If my math is right, the radio delay would be about 16.1222646012 hours, based on their 14.4 Billion Km distance or about .67 light days.
So somewhere between .67 and .86 light days.
Now if we develop warp drive in another 33 years we will be able to run it down in less than 2 days travel at light speed ;)”
I assume you are talking about the time lag for TWO way communication as I get half that for ONE way communication not including the miniscule time dilation effects. No idea how long it can keep sending and receiving though. In English units 10.8 Billion miles divided by 386,000 mps.=7.77hours
I worked on the telemetry software for Voyager back in 1975-76 at JPL. I asked the question one day at a meeting with some of the scientists: “When will one of the probes reach another star?” The answer I got back was, “About 250,000 years it will get close to one.” (They told me which one, but I don’t remember what it was.)
Jeremy says:
December 15, 2010 at 12:55 pm
“How is there any rational alternative to continuing with the mission if your delta-V has already changed sufficiently to make it impossible to stop, turn-around, and head back?”
Who said anything about turning around and heading back? I just said they would change the mission to suit themselves and not worry about someone else’s dreams from generations past.
Minor points re the forgoing: I always thought that the nearest star (besides Sol) to Earth was Proxima Centuri, not Alpha Centuri. It would seem that Proxima is now considered part of a three-star Alpha system:
http://hypertextbook.com/facts/KathrynTam.shtml
but it is still listed as closer.
There have been numerous SF stories and novels written about multiple-generation starships sent out from Earth to colonize deep space. Many concern possible social pathologies of such small, self-contained worlds, notably Heinlein’s Orphans of the Sky, wherein the inhabitants have completely forgotten the purpose of the mission, and do not even understand that they are on a spaceship:
http://en.wikipedia.org/wiki/Orphans_of_the_Sky
Lastly, I am enormously impressed that we have engineers and scientists here who actually worked on or were associated with the Voyager program. It is a testament to the quality of this blog and our tireless host.
/Mr Lynn
Erratum: For ‘Centuri’ read ‘Centauri’. Proofread, darn it! /Mr L
Some of you got it wrong with regards to the speed of the solar wind.
They measured a solar wind speed of zero relative to the sun itself.
Suppose you are in a car going 100 Mph on the road. Suppose there is no wind today so the air doesn’t move. People inside the car will measure a wind speed of 100 Mph (exactly the speed of the car) wich means that the wind speed is effectivly zero.
Jim G,
That would be 186,000 miles/s, not 386,000 miles/s, for a little more than twice that time.
Mark
Tom in freakin cold Florida said: (December 15, 2010 at 12:18 pm) Imagine how horrible it would be for the generations that will live and die during the travel to know that their generation was one of many deemed to be expendable so that some future generation would be able to reach a goal that was established generations prior to them being born.
It would be horrible for us, Tom, but I feel it would not be horrible for those who were born to it. I doubt any of my grandchildren will ever long for the freedom of the family farm which was so important to me. It does not even seem important to my children, not born there and not really moved by my nostalgia. Life aboard a spacecraft, if that was all one had ever known, would be as sweet to them as the endless paddocks (fields, meadows) were to me — although it was not long before the bus trip into High School that I began to want the city (Paree?).
I really doubt they would feel “expendable” but more likely that this was just life. For the original parents it would be extremely difficult, as it would be in a different way to those who were alive when the destination was reached — but for those who’s lifetimes were bounded by the walls of the ship I would expect as much content and discontent as we Earthlings experience right now.
As to the flux capacitor warp drive…that was tongue in cheek, please try to read between the lines.
@ur momisugly Mike, yes my heart wants us to go there, but I feel we are not ready. As Leif pointed out, we have many unresolved problems here…, Carl Sagan came to the same conclusion in the end. As to your early world empire analogies, I feel we are still at the skin boat level, paddling around in a back bay somewhere. We haven’t even developed the lateen sail yet. Clipper ships or at least long boats are needed, and many of those early colonies failed….
I am familiar with project Orion etc. Unfortunately politically and economically infeasible. Remember that colonies were to make money. The oceans are right here and we have only barely begun to utilize them. Space is much farther and much more daunting than the ocean. I build things for a living and therefore you must excuse my pragmatism.
The frontier for this century is biology…IF we can keep the dead enders in a check.
I seem to have confused Jeremy and Mike B in my last post. Also should read dead enders in check…although in a check seems to be the current strategy.
My apologies.