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Voyager 2’s Discoveries from Interstellar Space

nytimes.com

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Re: Voyager 2’s Discoveries from Interstellar Space

#51

Post by russellbeattie »

ChuckNorris89 wrote: post #2

I'm amazed and still can't get my head around how today we can receive images and valuable data from a device which is currently lightdays away from us and was built with 60's technology & know-how and is operating well beyond it's expected lifetime. I raise my glass to the engineers who worked on this. Makes my daily programming tasks feel stupid in comparison. Edit: corrected, thanks for the numbers

I used to have it in my head that the Voyager probes were about as powerful as an Apple II computer. But it's hard to make a direct comparison as the probes have three computers made of two processors each, running at 1/20th or 1/6th the speed of an Apple. So it's not a one-on-one comparison in any way, but for discussion purposes:

An original Apple II used a MOS 6502 8-bit word CPU clocked at 1.023 MHz and typically had 4Kb to 48Kb of RAM. It ran about 500,000 instructions per second [1].

Computer Command System (CCS) - two 18-bit word interrupt-type processors with 4096 words each of plated wire memory. It ran about 25,000 instructions per second. [2]

Flight Data System (FDS) - two 16-bit word machine with modular memories and 8198 words each of memory. It ran about 25,000 instructions per second. [2]

Attitude and Articulation Control System (AACS) - two 18-bit word machines with 4096 words each of memory. The AACS ran about 80,000 instructions per second. [2]

So maybe the total amount of computing power is equal? The total memory on a Voyager was about 32K [3], and since the word sizes were bigger, theoretically they could access larger chunks of memory in a single instruction? What's for sure is that a single CCS is at least an of magnitude less powerful than an Apple II.

More info:

1) http://www.classiccmp.org/cini/pdf/Apple/Apple%20II%20Refere...

2) http://www.cpushack.com/space-craft-cpu.html

3) https://web.archive.org/web/20110721050617/http://voyager.jp...

Re: Voyager 2’s Discoveries from Interstellar Space

#52

Post by saagarjha »

mokus wrote: post #45
pm90 wrote: post #13

Earlier quoted context omitted.

"Why should I buy a computer today, when a computer in 10 years can do a ton more for less money?"

If you need to run a computation that is going to take 100 years with today’s computers, you probably should wait a bit to start it with faster computers.

Unless you can buy both, in which case you should start now and continue with the newer computer.

Re: Voyager 2’s Discoveries from Interstellar Space

#53

Post by klyrs »

aaroninsf wrote: post #42
klyrs wrote: post #39

Earlier quoted context omitted.

> EDIT: I don't understand the downvotes. Isn't this just fact? Nobody's questioning that fact (barring well-deserved pedantry about radio signals), but GP's claim was light days so the downvotes are probably about the nonsequitur.

OP edited after the fact (says as much)

lol timehackers. It made sense when I wrote it \o/

Re: Voyager 2’s Discoveries from Interstellar Space

#54

Post by outworlder »

flurdy wrote: post #12

I am always baffled by the conundrum of the futility of launching a spacecraft to go far away by our own ability to invent faster engines. Say it takes 300 years to get to Alpha Centauri. If you launch it you have 150 years to invent a spacecraft that goes twice the speed of the first one. Very likely. If you launch that one it will overtake the other one. Now you have 75 years to find an even faster engine. Launch i…

This is a fairly common trope in SciFi settings which have Generation Ships.

Some time after the ship gets launched (centuries, even), FTL gets developed. Then they either arrive and find a civilization at their destination, or they are considered to be off-limits and not to be messed with, depending on the setting.

That assumes such improvements are even possible.

At least for non-magical propulsion, we don't really need "faster" engines. Take whatever engine you want, let's say it can accelerate at a constant 1g. In less than 4 years(from an observer standpoint), you are at 97% of lightspeed. From your point of view, that would take less than two years.

If you can have an engine that can accelerate at a constant 1g for years (fueling it is left as an exercise for the reader), then you are all set. You can go anywhere in the galaxy inside a human lifespan – of course, assuming you don't care for the people left behind.

If you want to accelerate at more than 1g, there may be physiological issues.

Re: Voyager 2’s Discoveries from Interstellar Space

#55

Post by Aperocky »

ChuckNorris89 wrote: post #2

I'm amazed and still can't get my head around how today we can receive images and valuable data from a device which is currently lightdays away from us and was built with 60's technology & know-how and is operating well beyond it's expected lifetime. I raise my glass to the engineers who worked on this. Makes my daily programming tasks feel stupid in comparison. Edit: corrected, thanks for the numbers

Imagine the systems that they worked with.

In the 1970s, dealing with primitive electronic systems, often without screen and most definitely without a full OS.

Goosebumps. To imagine that the tech phenomenon that we can only regard as recent (2000-) but there are people from as far as 30 years back before that, working on things that have lasting impact to us.

I recently read bwk's Unix history and memoir, it's a great read, to see many of these pioneers being old and passed away is a great sadness.

Re: Voyager 2’s Discoveries from Interstellar Space

#56

Post by srathi »

flurdy wrote: post #12

I am always baffled by the conundrum of the futility of launching a spacecraft to go far away by our own ability to invent faster engines. Say it takes 300 years to get to Alpha Centauri. If you launch it you have 150 years to invent a spacecraft that goes twice the speed of the first one. Very likely. If you launch that one it will overtake the other one. Now you have 75 years to find an even faster engine. Launch i…

It is covered in this Wikipedia article. It is called 'the incessant obsolescence postulate'. https://en.wikipedia.org/wiki/Interstellar_travel

"It has been argued that an interstellar mission that cannot be completed within 50 years should not be started at all. Instead, assuming that a civilization is still on an increasing curve of propulsion system velocity and not yet having reached the limit, the resources should be invested in designing a better propulsion system. This is because a slow spacecraft would probably be passed by another mission sent later with more advanced propulsion (the incessant obsolescence postulate)"

Re: Voyager 2’s Discoveries from Interstellar Space

#57

Post by Aperocky »

outworlder wrote: post #54
flurdy wrote: post #12

I am always baffled by the conundrum of the futility of launching a spacecraft to go far away by our own ability to invent faster engines. Say it takes 300 years to get to Alpha Centauri. If you launch it you have 150 years to invent a spacecraft that goes twice the speed of the first one. Very likely. If you launch that one it will overtake the other one. Now you have 75 years to find an even faster engine. Launch i…

This is a fairly common trope in SciFi settings which have Generation Ships. Some time after the ship gets launched (centuries, even), FTL gets developed. Then they either arrive and find a civilization at their destination, or they are considered to be off-limits and not to be messed with, depending on the setting. That assumes such improvements are even possible. At least for non-magical propulsion, we don't really…

I personally believe that it is easier to put human/whatever consciousness in a computer than it is to achieve FTL.

Not that the former is easy, but the latter is basically impossible. After the former is achieved, we can basically coast on sleep for eternities.

Re: Voyager 2’s Discoveries from Interstellar Space

#58

Post by kolinko »

mlthoughts2018 wrote: post #27
ChuckNorris89 wrote: post #2

I'm amazed and still can't get my head around how today we can receive images and valuable data from a device which is currently lightdays away from us and was built with 60's technology & know-how and is operating well beyond it's expected lifetime. I raise my glass to the engineers who worked on this. Makes my daily programming tasks feel stupid in comparison. Edit: corrected, thanks for the numbers

Yeah but did they use Agile methods and have good team velocity as they burned down the backlog? If not, how can we really be sure the project was a success?

Agile shares a lot in common with practices mentioned in „Mythical man-month”, which in turn was based on the good practices from the Voyager era.

Also, extreme programming was based in part on the TDD from Mercury program, iirc.

Having said that - yes, cargo cult agile sucks, we all know that.

Re: Voyager 2’s Discoveries from Interstellar Space

#59

Post by hedvig »

srathi wrote: post #56
flurdy wrote: post #12

I am always baffled by the conundrum of the futility of launching a spacecraft to go far away by our own ability to invent faster engines. Say it takes 300 years to get to Alpha Centauri. If you launch it you have 150 years to invent a spacecraft that goes twice the speed of the first one. Very likely. If you launch that one it will overtake the other one. Now you have 75 years to find an even faster engine. Launch i…

It is covered in this Wikipedia article. It is called 'the incessant obsolescence postulate'. https://en.wikipedia.org/wiki/Interstellar_travel "It has been argued that an interstellar mission that cannot be completed within 50 years should not be started at all. Instead, assuming that a civilization is still on an increasing curve of propulsion system velocity and not yet having reached the limit, the resources shou…

>assuming that a civilization is still on an increasing curve of propulsion system velocity

I think this is the error

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