Antique Voyager Technology

sea_stuart writes with a story from the Tidbinbilla space tracking station, outside Canberra, Australia. It is still communicating with the two Voyager spacecraft 30 years after they were launched and 18 years after Voyager 2 passed close by Neptune. Here's a little background on Voyager 1 and Voyager 2. "The bank of computers that would look at home in black-and-white episodes of Doctor Who cannot be junked... [T]he 1970s hardware is now our world's only means of chatting with two robot pioneers exploring the solar system's outer limits. Today Voyager 1 is humanity's most remote object, 15.5 billion kilometers from the sun. Voyager 2 is 12.5 billion kilometers from it. Both continue beaming home reports, but now they are space-age antiques. 'The Voyager technology is so outmoded,' said Tidbinbilla's spokesman, Glen Nagle, 'we have had to maintain heritage equipment to talk to them.'"

Comments

Re:Useful information?

[fr4nk]

From the Wikipedia article:

If Voyager 1 is still functioning when it finally passes the heliopause, scientists will get their first direct measurements of the conditions in the interstellar medium.

This contradicts wikipedia

[Anonymous Coward]

Wikipedia says that it was possible for amateur radio operators to receive data:

On March 31, 2006, the amateur radio operators from AMSAT Germany tracked and received data from Voyager 1 using the 20 m dish at Bochum with a long integration technique. Its data was checked and verified against data from the Deep Space Network station at Madrid, Spain. AMSAT-DL article in German; ARRL article in English. This is believed to be the first such tracking of Voyager.

Re:32 bits a second

[Anonymous Coward]

Actually, they haven't been using 30bps all the way. The transmit rate has been reduced due to the decreasing signal power that is received at earth, but maybe also due to the reduced power output of the RTGs, but have been able to increase it from the planned rates due to upgrades to the receiving equipment.

At Saturn, they were transmitting at 115200 bps, at Jupiter 44800bps, 29900bps at Neptune and 21600bps at Uranus. There are multiple different transmit modes, with varying power requirements and different receiver requirements. The high rates given above were only possible by combining multiple antennas, so in cruise mode, they have to make do with much lower data rates. There's more documentation here, and, while I haven't found anything about the ground station computers that are used, here's an interesting article about the onboard computers of the voyager spacecraft.

Re:Science for the man on the street

[pv2b]

Let's assume (assumption number one) they mean the voltage of the received signal in the antenna is 20 billion times weaker than a watch battery.

Now, a watch battery is approximately 3 volts in voltage, if I recall correctly. 3 / 2e10 == 1.5e-10 V -- so if that's what they meant by signal strength, they're getting a voltage of 150 picovolts somewhere in the antenna.

P = U^2 / R. If we assume (assumption number two) they've got their antenna matched to 50 Ohm wherever they connect their antenna to their equipment. (1.5e-10)^2 / 50 = 4.5e-22 W == 450 yoctowatts. (That, incidentally, is also how far down the SI prefixes go. :-)

You wanted to know how many picowatts that is... well, that's 4.5e-10 picowatt -- or -184 dBm. This is probably the power they get in their connector after their antenna.

Or, in other words, 20 billion times weaker than a hypothetical watch battery that emits a RF signal at 3 Volt transmitting into a 50 ohm antenna. ;-)

This, of course is assuming that's what they meant. They could have meant something else arbitrarilly entirely.

Re:Pictures

[Whiteox]

Pic here (from a post above) about half way down the page: http://www.hq.nasa.gov/office/pao/History/computer s/Ch6-2.html

A 16 bit computer with 128 registers and an 8k memory. Pretty good as in 1977 I was playing Star Trek (simple grid system)on an IBM at uni with 8k. The Voyager was cutting edge at the time.

Re:Photos

[FeebleOldMan]

I couldn't find any pictures of the Voyager computer banks, but I found these pictures of old computer banks from the Viking era, which is about a year or two before the Voyager program. The Voyager computer banks would probably look something like this.

Re:I worked on this project

[rimcrazy]

Cassinni is using the same transponders as Voyager. They were "left over" from the original build. The loop caps were replaced. The problem somewhat discussed above is it took FOREVER to qual all of the devices used for the electronics. Once they were finally qualified, they were obsolete. In the case of this specific transponder we (Motorola) actually had to convince TI to restart one of their LSTTL fab lines (for you young whippersnapers you can Google what that is) because we needed some replacement parts and these were qualified and rad-hard so we could not replace them with anything else.

On the Anti-aging we see it all around where US companies are out-sourcing so much technology and the old farts are all being "right sized" or simply retire. In one sense a deep understand of old technology at some point becomes immaterial (Who needs an SXN7 or an AU25.....google that too!) but if the basic problem solving skills are gone to then we are in deep shit if we ever need to do something ourselves.

Re:I've got an old dell they can use...

[Mr2cents]

After reading further in the wikipedia articles, I found this paragraph:

On March 31, 2006, the amateur radio operators from AMSAT Germany tracked and received data from Voyager 1 using the 20 m dish at Bochum with a long integration technique. Its data was checked and verified against data from the Deep Space Network station at Madrid, Spain. AMSAT-DL article in German; ARRL article in English. This is believed to be the first such tracking of Voyager. There you have it. That old equipment isn't the only thing that can communicate wit V'ger. Probably just a reporting eager to romantisize a story.