APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

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APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby APOD Robot » Sat Sep 08, 2012 4:06 am

Image Cosmic Rays at Voyager 1

Explanation: Launched on a grand tour of the outer planets in 1977, by good fortune the twin Voyager spacecraft were also headed in the general direction of the Sun's motion relative to nearby stars. Thirty five years later, Voyager 1 appears to be nearing the boundary of the Sun's heliosphere and interstellar space. Of course the heliosphere is the realm of the Sun defined by the influence of the solar wind and the Sun's magnetic field. But how can you tell when your spacecraft crosses the boundary into interstellar space? One clue would be a sudden increase in the detection of energetic cosmic rays. The high energy particles stream through interstellar space accelerated by distant supernovae in our galaxy, but are normally deflected or slowed by the heliosphere. Covering a 12 month period (September 2011 to 2012), this plot does show a dramatic increase in the rate of cosmic ray particle detection in past months by the Voyager 1 spacecraft. Voyager 1 is now 18 billion kilometers (17 light hours, 122 Astronomical Units) from the Sun and may soon be the first spacecraft from Earth to enter the realm of the stars.

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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Sinan İpek » Sat Sep 08, 2012 7:29 am

If Voyager were going to the nearest star, it would have been travelled 1/500th of its path.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Boomer12k » Sat Sep 08, 2012 7:55 am

Go, Voyager, Go!!!

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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby bystander » Sat Sep 08, 2012 9:45 am

And to think, it only took 35 years to get that far.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby nstahl » Sat Sep 08, 2012 9:49 am

It's amazing how rugged the components of those spacecraft have been. I wonder if, had the original mission been executed now, the components using modern electronics would last so long. And I wonder how the environment they're entering compares in exposure to high energy particles to what they experienced going by Jupiter, obviously for a much shorter time.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby rochelimit » Sat Sep 08, 2012 9:55 am

I wonder how many hours does it take for Voyager I to send these information back to Earth.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby bystander » Sat Sep 08, 2012 10:06 am

rochelimit wrote:I wonder how many hours does it take for Voyager I to send these information back to Earth.

APOD Robot wrote: Voyager 1 is now 18 billion kilometers (17 light hours, 122 Astronomical Units) from the Sun

About 17 hours.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby ritwik » Sat Sep 08, 2012 12:56 pm

APOD Robot wrote:Launched on a grand tour of the outer planets in 1977, by good fortune the twin Voyager spacecraft were also headed in the general direction of the Sun's motion relative to nearby stars.


last time i checked voyagers were going on opposite direction

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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Case » Sat Sep 08, 2012 1:54 pm

ritwik wrote:last time i checked voyagers were going on opposite direction

The Pioneer 10 and 11 are going roughly in opposite direction: 152° angular distance (Taurus/Scutum).
The Voyagers are going in very different directions (Ophiuchus/Telescopium), but I wouldn’t call those opposite directions: only 76° angular distance.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby south » Sat Sep 08, 2012 3:03 pm

About 17,500 years to go 1 lightyear? we are toast.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Chris Peterson » Sat Sep 08, 2012 3:09 pm

nstahl wrote:It's amazing how rugged the components of those spacecraft have been. I wonder if, had the original mission been executed now, the components using modern electronics would last so long. And I wonder how the environment they're entering compares in exposure to high energy particles to what they experienced going by Jupiter, obviously for a much shorter time.

No spacecraft use "modern" components. The nature of their design and validation process necessarily requires using components that are a number of years behind the state of the art. In general, I'd expect the same spacecraft, utilizing components available 30+ years later, to be somewhat more reliable than the original. We are better now at making electronics that can tolerate a space environment than we were in the 1970s.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby KellyBelly » Sat Sep 08, 2012 3:51 pm

It would be interesting to post an update about the change in speed that has happened to the Voyagers as they approach outer, outer space.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby ritwik » Sat Sep 08, 2012 4:11 pm

Case wrote:
ritwik wrote:last time i checked voyagers were going on opposite direction

The Pioneer 10 and 11 are going roughly in opposite direction: 152° angular distance (Taurus/Scutum).
The Voyagers are going in very different directions (Ophiuchus/Telescopium), but I wouldn’t call those opposite directions: only 76° angular distance.


hmm yes ..my bad

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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby emc » Sat Sep 08, 2012 4:24 pm

APOD Robot wrote:... may soon be the first spacecraft from Earth to enter the realm of the stars.

That struck a beautiful chord!

Are we seeing the cosmic bow wave May-Aug?
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby bystander » Sat Sep 08, 2012 5:18 pm

emc wrote:Are we seeing the cosmic bow wave May-Aug?

Data from IBEX back in May 2012 suggests bow shock does not exist. The sun is not moving fast enough to create one. Recent results from Voyager can be found here.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby MountainJim » Sat Sep 08, 2012 5:26 pm

When Voyager runs out of gas, how long will it take the sun to catch up with it?
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby ta152h0 » Sat Sep 08, 2012 6:44 pm

what is a cosmic ray ?
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Chris Peterson » Sat Sep 08, 2012 7:55 pm

ta152h0 wrote:what is a cosmic ray ?

A high energy particle, from about 1 GeV and up. Most are protons, there are also some helium nucleuses, and a fraction are heavier nucleuses or free electrons.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Guest » Sat Sep 08, 2012 11:19 pm

MountainJim wrote:When Voyager runs out of gas, how long will it take the sun to catch up with it?

I think Voyager doesn't use any "fuel" to propagate its movement. Its nuclear battery is just for its electronics.

By the way, I wonder how Voyager and Earth communicate. It's so tiny and so distant... How can we receive its radio signals?
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Chris Peterson » Sun Sep 09, 2012 2:06 am

MountainJim wrote:When Voyager runs out of gas, how long will it take the sun to catch up with it?

Voyager is traveling greater than the solar escape velocity with respect to the Sun. It's never coming back, and it's not using any fuel. It will just coast away from us forever- at least, until it falls under the influence of some other massive body.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Chris Peterson » Sun Sep 09, 2012 2:06 am

Guest wrote:By the way, I wonder how Voyager and Earth communicate. It's so tiny and so distant... How can we receive its radio signals?

Slow data rates and very big, very high gain antennas.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby 500pesos » Thu Sep 13, 2012 12:50 pm

Will we be able to continue receiving a signal from V1 even if/when it enters the heliosphere of a different star? (not very soon of course but it's bound to happen sometime, right?)
What information are we getting from V1 about the areas it's going through?
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby neufer » Thu Sep 13, 2012 2:04 pm

500pesos wrote:
Will we be able to continue receiving a signal from V1 even if/when it enters the heliosphere of a different star? (not very soon of course but it's bound to happen sometime, right?)
http://en.wikipedia.org/wiki/Voyager_1#Power wrote:
<<Voyager 1 has three large radioisotope thermoelectric generators (RTGs). Each RTG contains 24 pressed plutonium-238 oxide spheres. The heat from the spheres generated about 157 watts of electric power at the launch, with the remainder being dissipated as waste heat. Hence there was a total of about 470 watts of electric power provided by the three RTGs. The power output of the RTGs does decline over time (plutonium-238 is a radioactive isotope of plutonium with a half-life of 87.7 years.), but the RTGs of Voyager 1 will continue to support some of its operations through about 2025. Voyager 1 is not heading towards any particular star, but in about 40,000 years it will pass within 1.6 light years of the star AC+79 3888, which is at present in the constellation Camelopardalis. That star is generally moving towards our Solar System at about 119 km/s .>>

The Low-Energy Charged Particles, Cosmic Ray Subsystem, Magnetometer, and Plasma Wave Subsystem instruments are still operational.

500pesos wrote:
What information are we getting from V1 about the areas it's going through?
http://en.wikipedia.org/wiki/Voyager_1 wrote:
    Year End of specific capabilities as a result of the available electrical power limitations
    ..................................................................................................
    2007: Termination of plasma subsystem (PLS)

    2008: Power off Planetary Radio Astronomy Experiment (PRA)

    2010: Terminate scan platform and Ultraviolet spectrometer (UVS) observations

    2015: Termination of Data Tape Recorder (DTR) operations (limited by ability to capture 1.4 kbit/s data using a 70 m/34 m antenna array. This is the minimum rate at which the DTS can read-out data.)

    2016 (approx): Termination of gyroscopic operations

    2020: Start shutdown of science instruments (as of October 18, 2010 the order is undecided but the Low-Energy Charged Particles, Cosmic Ray Subsystem, Magnetometer, and Plasma Wave Subsystem instruments are expected to still be operating)

    2025–2030: Can no longer power any single instrument.
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Re: APOD: Cosmic Rays at Voyager 1 (2012 Sep 08)

Postby Chris Peterson » Thu Sep 13, 2012 2:55 pm

500pesos wrote:Will we be able to continue receiving a signal from V1 even if/when it enters the heliosphere of a different star? (not very soon of course but it's bound to happen sometime, right?)
What information are we getting from V1 about the areas it's going through?

Besides the fact that the probe will have no power long before that, there is also the problem that all of the electronics will have been destroyed by cosmic rays after just a few hundred years. We do not know how to build an electronic device (or anything that has complex moving parts, like an antenna aiming system) that can operate for thousands of years.
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