Bon Voyage Voyager 1!
 

Okay, strictly speaking Voyager 1 left the Earth 34 years ago, however the spacecraft is about to make another milestone--it is about to become the first object crafted by humans to leave the Sun's influence.

The solar system does not just encompass the planets, it is actually the entirety of the Sun's influence both gravitational and (in a limited sense) electromagnetic*. Voyager 1, at ~11 billion miles from the Sun is already out further than any other object made by humans. It is past the outermost planets, it is out beyond the Kuiper belt and is close to what is known as the heliopause which is where the 'boundary' of interstellar space is considered to be. When it crosses that boundary, it will no longer be in the solar system and will truly be out in interstellar space.

http://www.popsci.com/science/articl...-new-data-says

Cheers
Aj

I realize I didn't explain the *.

The solar system does not just encompass the planets, it is actually the entirety of the Sun's influence both gravitational and (in a limited sense) electromagnetic*.

So, strictly speaking if some alien life form looks up at the sky and sees a twinkling star that is our Sun, then the Sun has influenced it in the electromagnetic spectrum. However, that's not what I'm talking about here. Rather, I'm talking about things like the solar wind which is just charged particles disgorged from the Sun. For the sake of accuracy, it has to be said that the electromagnetic influence of the Sun extends as far as it can be detected (assuming, for the moment, that there are other someone's out there to do the detecting). But once an object has passed the heliopause it is well and truly beyond the influence of its home star.

Cheers
Aj

a couple of questions for you.

1) do we have contact with voyager 1? i.e. receive transmitted data

2) once it moves beyond the heliopause, will we be able to maintain contact? (assuming we have it now)

3) how freakin' cool is this?

Yep, both Voyager 1 and 2 are still transmitting and will continue to do so for ~10 years or so. The signal is so faint, at this point, that it is less powerful than a digital watch battery.

Yes. It is *amazing* what you can do with a 20 watt transmitter! :) We should continue to get signals back until its power fails around 2020 or so. At this point it is so far away that it takes hours for a transmission from Voyager to reach Earth. For purposes of comparison--light moves at ~182,282 miles per second in vacuum. At that speed it takes a signal to the Moon about 1.5 seconds to go one way. It takes light from the Sun 8 minutes to reach us. You get an idea how far away that is. It also gives you an idea of how huge our solar system is--when Voyager was passing Jupiter in 1998, it took nine *hours* for a signal to get to the Earth.

So cool that it is beyond words how groovy it is! This is pretty impressive stuff for a bunch of glorified chimpanzees to pull off. :)

cheers
Aj

thanks, Aj. do you have any idea what sorts of data are collected and transmitted? also, what sort of use can we put that info to?

There's actually quite a large number of instruments on the spacecraft.

It's measuring the strength of the cosmic wind. This is going to be important if we ever want to get off this planet on a permanent basis. As it has made passes by the planets it has sent back information on their composition, given us information on the radio signals coming from Jupiter and Saturn*, and is now telling us quite a bit about the outer parts of the solar system.

It has allowed astronomers to have a better idea of not just what the other planets are made of but what their atmospheres**, ionospheres, gravity fields, etc. are like. Because of Voyager we know quite a bit more about the rings of Saturn than we otherwise would, as well as having discovered things about a couple of Jupiter's larger moons that ground based telescopes would never have revealed. For example, Io is a hellhole. It is so close to Jupiter and the tidal forces of Jupiter are so strong that the volcanic activity on Io is because Jupiter keeps pulling at its mantle. Europa, we've discovered, has ice--it appears to be water ice with some ammonia and methane and possibly even some sulfur. Now, what's interesting about that is that underneath that ice there *may* be liquid water. Where there is liquid water, life has a chance to get started. We know, from environments here on Earth, that very, very simple creatures can live quite happily underneath ice packs.

A lot of the value that has been gained from the Voyager has been in giving NASA the expertise to build better and better robotic missions. Cassini, the Mars rovers, are all descendants of Voyager. A lot of what we are doing in space (as opposed to Earth orbit) is still in the 'basic science' stage. Meaning that we are still trying to figure out what is going on at a very basic level. The difference between the two is best explained this way:

Newton describes how gravity works. That is the basic science. Building a rocket that can escape Earth's gravity is engineering. Newton described how gravity works at the end of the 16th century, at that point building a ship to fly to the moon was largely (not entirely) a matter of engineering solutions. Without the basic information, though, of how to calculate if the Earth has X mass and you want to escape its gravitational pull you have to provide this amount of thrust, no rocket would ever have gotten out of the atmosphere except by peer, dumb luck.


*Jupiter and Saturn put out radio signals. Around Jupiter, this is caused by a cloud if ionized gases from Io that get captured by the big planet and then become part of its magnetosphere (the planet's magnet field). The particles get charged and start sending out radio signals. You can hear the radio signal here. It's important to note that these radio signals are purely a function of physics and that there's no intelligence involved.

**It's important to note here that at no point does Voyager enter the atmosphere, it merely uses a spectrometer to measure what wavelengths are absorbed and reflected back. Since any chemicals in an atmosphere will be opaque to certain wavelengths, transparent to others and reflective to still others, if you can see what the spectral lines are like then you can tell what the atmosphere is made of. That is how we can tell what stars that are millions of light years from Earth are made of--in fact, it's how we first discovered what the Sun was made of.

Cheers
Aj