Vger - the journey continues!

[Ralph]

Fans of ST1 will recognise "Vger" as Voyagers 1&2

I find it fascinating to check up on what man's furthest objects are up to

1977 technology is blazing the way at 38,000 miles per hour

and Voyager 1 is now at more than 3 times the distance of Earth to Pluto

So what do you reckon? Does man's two furthest objects inspire you as our galactic representatives carrying President Carter's message from Earth or worry you that some day some hungry aliens will identify an abundant source of food?

NASA's Jet Propulsion Laboratory has all the fascinating facts on our pioneers in the final frontier:

http://voyager.jpl.nasa.gov/mission/mission.html

and "fast facts" on here:

http://voyager.jpl.nasa.gov/mission/fastfacts.html

[Wayne]

Having been watching part of BBC's 1999 series:'The Planets' just recently, which icludes some stuff on Voyager, i think it's a pretty amazing achievement for 1970's technology.
Given the vast distances of space though, i think's more likely that they'll eventually run down before they get anywhere remotely near a nearby star. (Not that i'm an expert. I expect Jason's the man to ask) I expect they'll just drift through space forever. The chances of them being found by any other alien space travellers that may or may not exist, must be like the proverbial needle in a haystack. And a bloody big haystack at that!

[Rob McCow]

i think it's a pretty amazing achievement for 1970's technology.

It'd be a pretty stunning achievement for today's technology!

As for the Voyager probes, we've pretty much chucked them into the ether without any guidance. Like chucking a message in a bottle into the sea, I don't think we'll hear any more about it.

[Dirk Gently]

I don't think we'll hear any more about it.

I might be wrong but I thought we were still receiving information from both probes?
Voyager 1 is on the verge of leaving the Sun's* influence & going in to deep space if memory serves.






*That bloody newspaper gets everywhere!

[Wayne]

I might be wrong but I thought we were still receiving information from both probes?

Yes. So it says on Ralph's link. Although, what sort of information it doesn't say.
I wonder how long they'll keep transmitting for!

[Ralph]

I might be wrong but I thought we were still receiving information from both probes?

Yes you're totaly right. NASA compensate for the older technology by building better receivers on Earth so that they can continue to get the information sent back

Edited to add: which I see Wayne has answered

I think they'll just keep communicating with them Wayne for as long as possible.

[Dirk Gently]

Yes. So it says on Ralph's link.

You don't expect me to read his post AND click on the link do you?

[Ralph]

Some more info on the future for the Voyagers from the NASA site:

"The Future

Through the ages, astronomers have argued without agreeing on where the solar system ends. One opinion is that the boundary is where the Sun’s gravity no longer dominates – a point beyond the planets and beyond the Oort Cloud. This boundary is roughly about halfway to the nearest star, Proxima Centauri. Traveling at speeds of over 35,000 miles per hour, it will take the Voyagers nearly 40,000 years, and they will have traveled a distance of about two light years to reach this rather indistinct boundary."

40,000 years to get halfway to another star! Even if some passing tourist Alien picks up the message in 5000 years what will the home planet look like I wonder - will it even exist?! Will the message be relevant? Will it be the only evidence we actually ever existed? I hope not -it would seem sad to think it would all be over some day! The human race just a mere blip in the history of the Universe

"But there is a more definitive and unambiguous frontier, which the Voyagers will approach and pass through. This is the heliopause, which is the boundary area between the solar and the interstellar wind. When Voyager 1 crosses the solar wind termination shock, it will have entered into the heliosheath, the turbulent region leading up to the heliopause. When the Voyagers cross the heliopause, hopefully while the spacecraft are still able to send science data to Earth, they will be in interstellar space even though they will still be a very long way from the “edge of the solar system”. Once Voyager is in interstellar space, it will be immersed in matter that came from explosions of nearby stars. So, in a sense, one could consider the heliopause as the final frontier."

Starting to get over my head here but I get the general drift that they're currently moving into an new era in their exploration.

"Barring any serious spacecraft subsystem failures, the Voyagers may survive until the early twenty-first century (~ 2020), when diminishing power and hydrazine levels will prevent further operation. Were it not for these dwindling consumables and the possibility of losing lock on the faint Sun, our tracking antennas could continue to "talk" with the Voyagers for another century or two!"

So looks like we've ceraintly got another decade of reports to come - 45 years from any bit of technology is pretty marvelous

The facts on this section: http://voyager.jpl.nasa.gov/mission/didyouknow.html
are absolutely amazing - with enough money clearly 30 years ago we could have some pretty breathtaking technology! All for the price of one candy bar per annum since launch for each resident of the USA.

I love the way NASA have designed the site, they've really made it readable for ordinary folks

[WhiteCrow]

Yeah - the probes are never going to make it to another star system, however the whole putting a plaque on them, and details of the Earth was still a good idea, because it caught the public imagination.

The Voyagers were an amazing program, we've only recently been able to revisit Saturn, and Voyager 2 was the only visitor to Nepture and Uranus.

The planetary alignment was a once in a lifetime oppotunity, which I'm glad we managed to take advantage of. The planet were close enough to allow us to hop from one to another. These days we have to plan a complex maneouvre to just get to a single planet.

My personal favourite discovery was how Mimas looked like the Death Star ...

[shada pavlova]

I swear, alien are going to come to earth and steal all our plankton, thereby obliterating all life on earth.

[Ralph]

Well there's always Soylent Green as back up

[Jason Thompson]

The Voyagers were an amazing piece of space hardware, and did wonders for NASA's public image, but thyey almost never happened. There was a great deal of pessimsism about their success. They were designed and launched in a hurry (relatively speaking) when someone realised that the planets were suitably aligned to allow a probe to use gravity assistance to swing from one planet to another all the way out to Neptune (without gravity assist, the furthest any probe we could ever launch could get is Jupiter). They had a few years to design, build and launch the probes before the planets moved out of alignment and the mission became impossible for another century or so.

Not only did they succeed, they also bunged off a couple of extra probes beforehand to test the waters, so to speak. Voyager was the first probe to pass through the asteroid belt. Pioneer 10 and 11 showed it was possible to do that without running into a large lump of rock. Without the Pioneer probes at least one of the Voyagers would have been lost in Jupiter's huge radiation belts.

The Voyager probes increased our knowledge of the solar system exponentially. Most of what we know now about the outer planets we know thanks to Voyager. The best demonstration of how amazing they and the people who ran them were is that, after 12 years and billions of miles of flight, numerous course corrections, gravity assist manoeuvres, glitches, workarounds, and sleepless nights for the ground controllers, Voyager 2 passed Triton, it's final target, barely 9 seconds late.

The Voyagers are a landmark in space exploration, and they're still exploring. No, they'll never get to another star in any useful condition, but they're still sending information back on the nature of space beyond the outer planets. Amazing probes.

[Llordllama]

There's a great picture I remember having in one of my astrophysics books* as a kid which included in it's more speculative section a great picture of a one of the voyagers (or maybes Pioneer 10) looking as full of holes as a fine piece of emmental limping into orbit around Barnards star. There was a note to the effect that it would be more fragile than the rarest relics from prehistory thanks to interstellar radiation and dust ablation and that (relativistic velocity aside) any aliens trying to catch it would end up from atomic space dust.

So I think our plankton are safe!

[*erm, yes my first love folks-and why i currently support the Astrophysics dept here at sunny Leicester uni]

[Stuart Wallis]

I had an idea that they were still broadcasting; not long before he died, Carl Sagan went on TV with this photo showing a starscape and, in the middle, a small blue dot. He said, this photo was taken just after Voyager 1 passed beyond Pluto's orbit, and the blue dot was Earth. It was amazing that we've been photographed by something that's billions of miles away, and that we were able to get the photo as well.

[Ralph]

The Voyagers were an amazing piece of space hardware, and did wonders for NASA's public image, but thyey almost never happened. There was a great deal of pessimsism about their success. They were designed and launched in a hurry (relatively speaking) when someone realised that the planets were suitably aligned to allow a probe to use gravity assistance to swing from one planet to another all the way out to Neptune (without gravity assist, the furthest any probe we could ever launch could get is Jupiter). They had a few years to design, build and launch the probes before the planets moved out of alignment and the mission became impossible for another century or so.

I had no idea Jason that wthout the "gravity assist" the furthest the probes would have managed was Jupiter - I assumed somehow once you get an object moving in a vaccuum it would simply maintain it's momentum and keep going. It's great they managed to launch them in time - I just find the whole thing absolutely amazing and as Stuart says to get a picture let alone one of Earth from billions of miles away is just breathtaking!

[Jason Thompson]

I had no idea Jason that wthout the "gravity assist" the furthest the probes would have managed was Jupiter - I assumed somehow once you get an object moving in a vaccuum it would simply maintain it's momentum and keep going.

Remember one thing that is always acting on everything: gravity.

To maximise fuel efficiency in space, a spacecraft is accelerated to a great speed in a short time and then left to coast the rest of the way. If you can accelerate your spacecraft to 25,000mph it will be able to get far enough from Earth to be caught by the gravity of another object, but it will be constantly fighting Earth's gravity which will be slowing it down. The Apollo spacecraft, for example, got up to 25,000mph in a few minutes and coasted along to the Moon. By the time they entered the region where the Moon's gravity became dominant three days later, Earth's gravity had slowed them down to a mere 2,000mph. If it had been going any slower than 25,000mph it would have been slowed down and pulled back by Earth's gravity before the Moon could capture it.

But the 25,000mph is only the speed required to escape the Earth's gravity. There's another body exerting a gravitational influence on everything in the solar system: the Sun. Even if your spacecraft can escape Earth's influence, it can't escape the Sun's. Because of limitations on payload and fuel efficiency we can get a probe directly to Jupiter, but it can't go fast enough for Saturn to capture it before the Sun's gravity pulls it back in again. What the gravity assist manoeuvre does is use Jupiter's gravity and its momentum as it moves along its orbit to tug the spacecraft and slingshot it further out. In accelerating the spacecraft Jupiter is slowed somewhat, but due to the vast difference in mass the effect is hugely significant for the spacecraft but negligible for the planet. Voyager 2 used gravity assist on all four outer planets in sequence, and that was only possible because they were aligned in such a way that it could be thrown by Jupiter to a location where Saturn would be a few years later to catch it and swing it out to Uranus and so on. The cumulative effect of all these slingshots is that Voyager is now going fast enough to escape the Sun's gravity, but it didn't get there by the fuel we gave it.

Gravity assist is a standard technique now, allowing much lower fuel requirements, thus increasing the useful payload in terms of science return. It takes longer for your probe to get where you want it, but it can do much more work when it gets there.

[Wayne]

Interesting stuff Jason.
One of the other things that impressed me on watching 'The Planets' docu was the mathematical timing of the whole thing.
I can't remember the exact words, but it was to do with the way the planets were aligned. They timed it perfectly so that the probe would be able to photograph all the outer planets on it's journey. One of the scientists said it wouldn't be possible to do it again in our lifetime before they were all aligned correctly again.

[SiHart]

This thread has been really interesting. It's really good to hear that the probes are still going on their way and functioning fine!
I'll have to borrow The Planets from work again sometime and give it another watch. It was brilliant both times I've seen it.


Si xx

[Jason Thompson]

Absolutely right. They also said, if I recall, that last time it happened Thomas Jefferson was US President, and he screwed it up!

The New Horizons probe has used the gravity assist method to swing it out to Pluto. Pluto is further out than all the other outer planets, but New Horizons will miss them entirely because they are not aligned properly for it to pass them and use their gravity to accelerate itself even more.

(As an interesting aside, Neptune was actually further out than Pluto at the time of the Voyager mission, since Pluto has a highly eliptical orbit that brings it closer to the Sun than Neptune for a short time, and so, since no Kuiper Belt objects were discovered until a few years later, Voyager 2 visited the furthest known object in the solar system at that time.)

[Wayne]

There's some interesting stuff about the space race in The Planets as well.
Just lots of history & background info going right back to the Nazi's V2 rocket technology, through to Sputnik, Gagarin, & eventually the moon landings of course. Throwing up allsorts of interesting things i didn't know.
Like the Russians contacting Jodrell Bank to inform them about one of their probes to the moon. They blasted the thing up there, but they didn't have the technology to track it. Ironic considering the whole iron curtain political situation. And the Russians were furious because they were the last ones to get the images that it sent back, which were in the British newspapers first.
Also, there was a bloke who went up into space via a helium balloon! I never knew that! And he simply bailed out from above the atmosphere, (i think) & eventually parachuted back to earth! Balls of steel!

[Ralph]

I was really interested there reading your comments Jason about the "gravity assist" - thanks!

I enjoy the BBC series "The Planets" because it explains things in terms that can be understood without having a scientific background and allows you thereby to participate in the excitement of the various developments in learning about our Solar System. I'm still struck with awe over the Space Race and the achievement of Man getting to the Moon. In 1977 as a teenager I was really excited when the first pictures came back from the probe on Mars - I recall some of the newspapers having a full front page picture declaring "This is Mars"

[Antony Cox]

Was 'The Planets' the one with Sam Neil presenting/narrating?

[Wayne]

Was 'The Planets' the one with Sam Neil presenting/narrating?

Samuel West it says on the dvd.

[Ralph]

The web page below provides a good description of the series and each individual episode:

http://www.tvfactual.co.uk/planets.htm

I think it was more indepth than the Sam Neill series but in fairness I haven't seen that one.

[MacNimon]

Heather Couper also presented a series called 'The Planets' a while back, along with it's follow-up 'The Universe'. And Ms Couper is much nicer on the eye than Sam Neill, Samuel West or Patrick Moore...

and btw, an excellent site (or more specifically, the free download available on the site) worth a look from anyone who's interested, is Microsoft's World Wide Telescope. You'll be able to download software similar to Google Earth except it's about outer space. Photos, videos, maps...and it's all geared towards the general public rather than scientific types. I can highly recommend it