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Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

smithsonianmag.com

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Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#51

Post by pkaye »

ghoomketu wrote: post #35

It's fascinating how Voyager 1, despite my lack of space knowledge, utilizes a nuclear power source for 40+ years, offering steady and reliable power without any moving parts that could degrade over time. In contrast, India's decision to rely on solar panels led vikram lander to be dead in just 14 days due to lack of sunlight (afaik). I'm curious about the rationale behind this choice when nuclear power seems like a…

RTGs need plutonium 238. I've read even US doesn't have a lot available. The Europa Clipper will be using solar panel for example. India could also use batteries and a standby mode during the 14 days without sunlight. But any extra weight would add to the launch cost. Maybe in future missions as they get confident with successful landing, they will have bigger lander that can survive the lunar night. Even the early Mars rovers from NASA were tiny and solar powered (ie Sojourner in 1997.)

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#52

Post by jonplackett »

arcbyte wrote: post #19
jonplackett wrote: post #17

Were engineers 50 years ago just much smarter than we are now? It’s pretty unbelievable that these things still work. Or is there something systemic about how they were able to achieve so much so long ago with basically no computers to help.

There was much less overall complexity (and capability). These engineers interacted directly with capacitors and circuits to accomplish their tasks. Integrated circuits enable a lot of modern society, but it also segregates engineering between fabrication time and everything afterwards.

I find that more analogue / mechanical type machines even more amazing in someways. Like how they say it ‘decided’ to switch to its backup radio. How are those decisions made on such basic hardware? I guess thinking mechanically is just a very foreign concept for me mostly making software

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#54

Post by TkTech »

selectodude wrote: post #39
ghoomketu wrote: post #35

It's fascinating how Voyager 1, despite my lack of space knowledge, utilizes a nuclear power source for 40+ years, offering steady and reliable power without any moving parts that could degrade over time. In contrast, India's decision to rely on solar panels led vikram lander to be dead in just 14 days due to lack of sunlight (afaik). I'm curious about the rationale behind this choice when nuclear power seems like a…

Using plutonium works great but there are two issues. 1) they don’t output that much power. Few hundred watts at most, and they decay at a fixed rate. 2) you need to get your hands on a decent amount of plutonium. Great for dirty bombs, hard to source.

Both Canada and the US have restarted production specifically to produce RTGs for NASA, but the process takes time to scale up and automate. It's gone up 4x in 4 years and continues to increase, so this is a problem that will eventually be "fixed".

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#55

Post by vikingerik »

grapesodaaaaa wrote: post #25
pupppet wrote: post #13

I didn’t realize the Voyagers relied on a once in a 175 year planetary alignment. What a lucky break technology had advanced to the point we could make use of it.

I’m trying to figure out why the alignment was so important. Wouldn’t it be possible to get a gravity assist in any alignment - albeit just taking a little longer to ping-pong across the system?

The scenario where a gravity assist doesn't work is if turning sharply enough would require your minimum planetcentric approach distance to be less than the radius of the planet - you'd crash into it instead.

This is why Voyager 2 couldn't also do Pluto - it would have needed to change course by roughly 90º at Neptune, which would have required going closer to the center of Neptune than Neptune's own radius.

The most unusual gravity-assist alignment that we did was for Pioneer 11 going from Jupiter to Saturn. The encounters were separated by roughly 120º of heliocentric longitude. Pioneer 11 used Jupiter to bend its path "up" out of the ecliptic plane and encountered Saturn on the way back "down". Nowadays we wouldn't bother doing that (we'd wait for a more direct launch window instead), but the purpose of this was to get preliminary Jupiter and Saturn encounters done in time before Voyager's launch window for the grand tour alignment.

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#56

Post by sumeno »

jfengel wrote: post #33
mannykannot wrote: post #8

Earlier quoted context omitted.

I like this quote: “We didn’t design them to last 30 years or 40 years, we designed them not to fail,” John Casani, Voyager project manager from 1975 to 1977, says in a NASA statement.

That doesn't seem helpful. Nothing lasts forever, and if you don't figure out when it's going to fail, it's going to be sooner rather than later.

Maybe the guy who helped launch the two manmade objects furthest from earth knows more about how to build space probes than you

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#58

Post by liamwire »

soulofmischief wrote: post #34
avereveard wrote: post #21

Earlier quoted context omitted.

They had lot less resources and knowledge to estimate the right amount of resilience for achieving the mission goals and erred on the side of cautions. You can see something similar happening in bridges, weight per meter load has come down considerably since the 60s because material understanding is much more advanced and they meed less margin for the same safety factor.

Our understanding of physics has also gotten much better, for example our understanding of tensegrity. https://en.wikipedia.org/wiki/Kurilpa_Bridge > The Kurilpa Bridge is a multiple-mast, cable-stay structure based on principles of tensegrity producing a synergy between balanced tension and compression components to create a light structure which is incredibly strong.

Delighted to see this here — the Kurilpa Bridge is less than 50 meters from my front door and is something to behold each time I get the chance to use it.

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#59

Post by leobg »

gdubs wrote: post #31

I'm reading Pale Blue Dot to my kids at night currently so this is really awesome. (The Voyager missions are described in excellent detail in ways that I never appreciated fully before.) It blows my mind that these are machines from the 8-track era. And they have fallbacks and redundancies that were completely ahead of their time.

Cool! I do the same thing with books like Asimov’s Earth and Space (science) or Lois Lowry’s Number the Stars (fictional history). What other books can you recommend?

Re: Voyager 1 breaks its silence with NASA via radio transmitter not used since 1981

#60

Post by gruturo »

Self-Perfection wrote: post #20
gruturo wrote: post #10

Earlier quoted context omitted.

Yes, but mostly no, also no, and, frankly, why would we. Yes: we could lift off a much heavier spacecraft, give it plenty of fuel, and many of its parts would be lighter than their 1970s equivalent, giving us lots of room for modern sensors No: the "battery" in the old ones is nuclear and it's going to be difficult to beat that (but not impossible: a nuclear stirling engine, either powered by fission or by decay, e.g…

We probably do not need to wait for ideal planets position to outrun Voyagers. We have ion thruster now with much higher specific impulse! Voyager-2 gained about 10 km/s at Jupiter, about 5 km/s at Saturn, about 2 km/s at Uranus, and lost about 2 km/s at Neptune. [1] Dawn spacecraft gained 11.5 km/s from ion thrusters. So just gravity assist maneuver just around Jupiter alone + massive tank for ion thrusters gas migh…

Unfortunately a gravity assist maneuver is almost "incompatible" with an ion thruster.

If you approach e.g. Jupiter you gain speed (it's pulling you in), which you then lose as you get away from it (as it's still pulling you in, meh). Gravity assists work because you use your chemical rocket right when you are closest and speed away, "robbing" Jupiter of the chance to claim the energy it lent you on approach.

Ion thrusters have very low thrust, so you would accelerate veeeeery slowly away from Jupiter's gravity well - and in this time it will keep affecting you and slowing you down, and the whole thing would be barely worth doing.

You could bolt on a very simple solid rocket booster just for the gravity assist, of course, but its ISP will be lower and you'll have to carry its mass until you can expend it.

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