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Started by mongers, September 05, 2012, 03:57:28 PM

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mongers

It seems the Voyager spacecraft are on the verge of entering interstellar space :cool:



Quote
Voyager's 35th birthday gift: One-way INTERSTELLAR ticket

Veteran space probe bores outward into the deep void

By Brid-Aine Parnell • In Space • At 10:22 GMT 5th September 2012

As NASA's Voyager probes complete their 35th year of operation, Voyager 1 has sensed a second change in the surrounding expanse of obsidian nothingness - just as scientists predicted would happen before the craft enters interstellar space.

Since June, Voyager 1 has detected galactic cosmic rays in rapidly escalating amounts, one of three criteria that must be satisfied before boffins are sure the probe has left the heliosphere, which is the outer shell of the bubble of charged particles around our Sun.

Now, as well as observing these high-energy particles streaming into the bubble, Voyager 1, launched in September 1977, has also sensed a decrease in the amount of lower-energy particles streaming out of our solar system, another sign that the spacecraft is nearing the breakthrough into interstellar space.

The final change in Voyager 1's environment that NASA's Jet Propulsion Lab's scientists hope to see soon is the direction of the magnetic fields, which will change from running east-west to running north-south. The team is crunching the latest numbers received from the probe - now at least 11.1 billion miles from Earth - to see if this may in fact have already happened.

....

Rest of interesting artlcle here:

http://m.theregister.co.uk/2012/09/05/voyager_35_year_anniversary/

"We have it in our power to begin the world over again"

Tamas


Barrister

Weird.

I was just today reading an article that said, despite the predictions, that Voyager I has NOT passed the edge of the solar system.

QuoteMissing: Voyager 1 yet to find the boundary line of the Solar System
Spacecraft finds zero solar wind speed near expected Solar System boundary.

by Matthew Francis - Sept 5 2012, 11:00am MDT
PHYSICAL SCIENCES SPACE
61

Voyager 1 spacecraft during assembly.
JPL/NASA
Since today marks the 35th anniversary of the launch of the Voyager 1 spacecraft, it seems appropriate to commemorate the mission—and to note how it continues to provide data about the far edges of the Solar System.

Where exactly are those edges of the Solar System? According to theory, the boundary of the Solar System is marked by a region known as the heliopause, where the solar wind—particles streaming from the Sun—meets the plasma of interstellar space. In this region, beginning about 90 times the distance from Earth to the Sun, models predicted that the solar wind's particles would be deflected by the interstellar material, much as water is pushed aside by the bow of a ship.

However, new measurements provided by the venerable Voyager 1 probe have failed to find the expected flow, deepening the mystery of the boundary between our Solar System and interstellar space. This adds to an earlier surprise, when Voyager's instruments measured zero outward velocity in the solar wind, a measurement that has now held constant for over two years. In a Nature paper, Robert B. Decker, Stamatios M. Krimigis, Edmond C. Roelof, and Matthew E. Hill concluded that Voyager 1 is not actually close to the heliopause, despite expectations. The researchers further suggested that the models for interactions between the solar wind and interstellar plasma may require reevaluation.

The solar wind is a plasma: a mixture of electrons and (mostly) protons streaming out from the Sun. This flow varies a lot over time, based on the solar cycle, but its particles consistently move outward, or radially.

At some point, the wind will necessarily run into the material in the region between stars. This contains more plasma, along with non-ionized atoms and molecules, which are collectively known as the interstellar medium (ISM).

By any reasonable theory, when the solar wind meets the ISM, there should be a transition. The usual model describes the solar wind carving out a region in the ISM known as the heliosphere, and the place where the solar wind is deflected by the pressure from the ISM is the aforementioned heliopause.

In April 2010, Voyager 1 reached a point about 113 AU from the Sun and saw the solar wind velocity began slowing down dramatically. (1 AU, or astronomical unit, is the average distance from Earth to the Sun, which is about 150 million kilometers.) This discovery led to speculation that the craft was reaching the heliopause.

If that was true, then the solar wind particles should be deflected in the transverse or meridional direction. Voyager's instruments happen to be good at measuring outward, or radial, flow velocity, so the spacecraft had to be reoriented five times over a 10-month period so that it could determine the meridional velocity of solar wind particles.

Two years of data revealed that the meridional velocity was 3±11 kilometers/second, or between -8 and +14 km/s. (Negative velocity in this case represents flow in the opposite direction expected by theory.) In other words, while the most likely velocity value is 3 km/s—within the instrumental limits, the flow is zero. That's certainly nowhere close to the predicted value of approximately 25 km/s.

Unlike the earlier "Pioneer anomaly," these data don't appear systematic: the five separate measurements were all consistent with zero meridional flow, but varied widely in most likely value.

These results are troublesome for several reasons. The thickness of the region where Voyager 1 has measured low radial velocity is now at least 7.5 AU (and counting). In that region, there has been very little fluctuation in the solar wind, even though we know the solar wind should vary strongly in time, thanks to the solar cycle. Additionally, combining the three components of the solar wind velocity shows the shape of the flow to be very different from what we expected.

The authors concluded that the heliopause either differs radically from theory, or Voyager is still not close to it. Both of these scenarios would require another look at the model for the solar wind-ISM interaction, since the current calculations don't explain the strange reduction in solar wind velocity or the direction of flow. It's possible the edge of the Solar System is farther out still—and might look very different from what we expected.

Nature, 2012. DOI: 10.1038/nature11441  (About DOIs).

http://arstechnica.com/science/2012/09/missing-voyager-1-yet-to-find-the-boundary-line-of-the-solar-system/

So take that Mongers!
Posts here are my own private opinions.  I do not speak for my employer.

FunkMonk

Godspeed, heavenly voyager.  :cry:
Person. Woman. Man. Camera. TV.

Barrister

That being said, are we sure it's a good idea to be sending space probes out into space like this?

What if it gets flung through a black hole, encounters an advanced machine race, and returns to destroy us all?
Posts here are my own private opinions.  I do not speak for my employer.

Phillip V

Quote from: Barrister on September 05, 2012, 04:08:45 PM
That being said, are we sure it's a good idea to be sending space probes out into space like this?

What if it gets flung through a black hole, encounters an advanced machine race, and returns to destroy us all?
Worth it.

Eddie Teach

To sleep, perchance to dream. But in that sleep of death, what dreams may come?

Habbaku

Quote from: Phillip V on September 05, 2012, 04:12:01 PM
Quote from: Barrister on September 05, 2012, 04:08:45 PM
That being said, are we sure it's a good idea to be sending space probes out into space like this?

What if it gets flung through a black hole, encounters an advanced machine race, and returns to destroy us all?
Worth it.

We should be sending as many as possible.
The medievals were only too right in taking nolo episcopari as the best reason a man could give to others for making him a bishop. Give me a king whose chief interest in life is stamps, railways, or race-horses; and who has the power to sack his Vizier (or whatever you care to call him) if he does not like the cut of his trousers.

Government is an abstract noun meaning the art and process of governing and it should be an offence to write it with a capital G or so as to refer to people.

-J. R. R. Tolkien

FunkMonk

Quote from: Barrister on September 05, 2012, 04:08:45 PM
That being said, are we sure it's a good idea to be sending space probes out into space like this?

What if it gets flung through a black hole, encounters an advanced machine race, and returns to destroy us all?

That's so ridiculous. Not even in the movies would something this crazy happen.  :rolleyes: :rolleyes:
Person. Woman. Man. Camera. TV.

crazy canuck

Quote from: Barrister on September 05, 2012, 04:08:45 PM
That being said, are we sure it's a good idea to be sending space probes out into space like this?

What if it gets flung through a black hole, encounters an advanced machine race, and returns to destroy us all?

Bah, they probably wouldnt even be able to pronounce voyager properly.