Voyager memory still good at 35

How does memory on Voyager compare to other spacecraft or a modern smartphone?

Wednesday of this week marked the 35th anniversary of the launch of Voyager 1; its sister craft, Voyager 2, celebrated the 35th anniversary of its own launch last month. Right now, both space probes are still going strong hurtling through space and are getting close to the edge of the solar system; Voyager 1 is 11 billion miles from the sun and Voyager 2 9 billion miles away.

I don’t know about you, but 35 was right around the age where I started to find myself walking into a lot of rooms and saying, “Wait, why did I come in here?” That age seemed to mark the beginning of a slow decline in my memory which shows no sign of letting up with my 43rd birthday approaching later this year.

Wait, what was I writing about again? Oh yes, the Voyager spacecraft.

Unlike my brain, Voyager’s on-board memory seems to be as sharp as ever (despite needing the occasional reboot). Both Voyagers are relics of 1970’s technology, featuring computers with a whopping 68kB of memory, eight-track tape recorders and (I’m assuming) “Keep on Truckin’” mud flaps.

The stat about the on-board memory caught my eye. A measly 68kB to power each of those crafts through billions of miles of space and capture invaluable types and amounts of scientific data for three and a half decades, and they’re expected to keep functioning into the 2020’s, when their fuel finally runs out. Very unlike my first big-screen LCD TV that crapped out after only three years. Truly amazing!

Much like when I read about the lines of code that power the Curiosity rover up on Mars, this stat made me wonder how the Voyagers compare to historical and modern day technology, in terms of memory. So, I did a little noodling and Googling around (sorry, I don't Bing) and came up with the following chart:

memory_chart-600_0.jpg

ITworld/Phil Johnson

The amount of memory on each Voyager (68kB), as well as that on the Apollo 11 lunar and command modules (152kB) and the space shuttle (1MB) are dwarfed by that on the Curiosity’s on-board computer (256MB). But these are all blown out of the water by the memory such modern day devices as the iPhone 4S (512MB), the latest iPad (1GB) and the Samsung Galaxy S III (2GB) carry. Good thing the Galaxy S III has a lot more memory than the iPhone or Apple would probably sue them for copying.

What does this tell us? Well, the obvious main conclusion is that, gee, computing power sure has grown in leaps and bounds since 1977! Other than that, it reinforces the conclusion from my piece on the number of lines of code to power devices through the years: modern day gadgets like smartphones and tablets require a lot more computer power than do spacecraft that take men to the moon, rovers to Mars or eight-track players to the edge of the solar system. You just don’t need touch screens, pinch-and-zoom or speech recognition software to explore Saturn’s rings or drive around Gale Crater.

Now, what was I saying before I mentioned Voyager again? 

Notes/Data Sources:

Voyager - Combined memory for Computer Command System, Flight Data System and Attitude and Articulation Control System computers for Voyager 1 (Voyager 2 has identical systems). Source: http://voyager.jpl.nasa.gov/faq.html

Apollo - Combined on-board memory for Lunar Module Guidance Computer and Command Module’s Apollo Guidance Computer for Apollo 11. Source:http://www.doneyles.com/LM/Tales.html

Space Shuttle - Memory for the shuttle’s General Purpose Computer after 1991. Source:http://www.popsci.com/node/31716

Curiosity - Memory for the on-bord Rover Compute Element. Source:http://en.wikipedia.org/wiki/Curiosity_rover

iPhone 4S - Source: http://en.wikipedia.org/wiki/IPhone_4S

iPad - Memory for the 3rd generation iPad. Source: http://en.wikipedia.org/wiki/IPad

Galaxy S III - Memory for models available in North America, Japanese, and South Korea Source: http://en.wikipedia.org/wiki/Samsung_Galaxy_S_III

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