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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

#41

Post by ivan_gammel »

skissane wrote: post #28
rlpb wrote: post #6

Earlier quoted context omitted.

As far as I understand their speed mostly comes from gravity assists from Jupiter, so you'd have to wait for suitable orbital alignments and the basic technology for "much faster speed" doesn't exist.

> and the basic technology for "much faster speed" doesn't exist. Various forms of nuclear propulsion have been investigated. None of them are anywhere near ready for missions, but that seems to be more due to lack of investment in their development (and environmental/legal/regulatory/geopolitical/etc concerns) than any scientific obstacle. If NASA/etc were really serious about it (as in willing to spend multiple bil…

This probably can happen as soon as there’s some manufacturing and mining capacity beyond LEA, so that it’s safe to use nuclear technology without any environmental impact. Moon is an option here, so likely it’s 5-15 years after first Moon base is established (I‘d expect exponential growth of it).

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

#42

Post by krger »

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…

> I'm curious about the rationale behind this choice when nuclear power seems like a far superior option. Can someone shed light on this decision?

India’s plutonium has already been spoken for.

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

#43

Post by jordanb »

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…

A good reason is the lack of availability of the needed isotope (Pu238).

The Europa Clipper has a huge array of solar panels instead of an RTG due to the last of the available supply going into the New Horizons spacecraft.

Pu238 was a cast-off isotope from nuclear weapons development so it was more readily available during the cold war. We should be happy that it's scarce now.

Also solar panels have gotten a lot better than they were when Voyager was launched, but even today anything going out past Saturn is not going to be able to use solar energy.

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

#44

Post by YakBizzarro »

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…

Availability :) a RTG requires Plutonium 238, which needs to ne created almost on purpose in a nucleare reactor. Not all nations have this ability or they are running such expensive programs. Also in the USA they are reserved for programs where there is very little light available

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

#45

Post by floatrock »

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.

Isn't it something like space-reactor plutonium is a waste product from nuclear weapons production, and since we don't really make nuclear weapons at scale anymore, we aren't really making (refining?) plutonium anymore. And NASA has some amount on reserve, but they're rationing it out carefully. So the Clipper probe had to go with a massive solar array (100ft, the length of a basketball court) because they would rather save their plutonium for some future rover mission.

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

#46

Post by augusto-moura »

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…

I don't know the exact reasons why Vikram didn't get a fission reactor. But I can assume from similar missions:

1. Solar is pretty good as far as Mars and it gets worse as it travel further from the Sun. This is why most probes that travel past Mars need a nuclear reactor (Voyager, Pioneer, Cassini, etc). Going closer to the sun they get even better

2. Sending radioactive materials on rockets presents a risk and it is avoided if possible, lunar probes are usually cheaper and can still benefit from solar, so no need for nuclear. Imagine throwing plutonium in the atmosphere in the case of an accident

3. Nuclear reactors in probes are small and rely on decay radiation, they _usually_ have pretty small powet output, solar has a lot

4. And last but not least, price, solar is much cheaper than nuclear

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

#47

Post by datameta »

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…

Dead in 14 days? Was there a miscalculation that lead them to believe they could make one full night?

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

#48

Post by xpe »

mannykannot wrote: post #8
heresie-dabord wrote: post #4

> scientists and engineers back on Earth have increasingly had to deal with age-related maintenance issues There is perhaps unintended irony in that sentence, but it does evoke some Asimov stories in which human characters age while supporting technology.

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.

I would expect a mindful trade-off against total system mass and cost.

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

#49

Post by freeone3000 »

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…

Sure!

First, the nuclear power source is a giant hunk of plutonium. It is expensive to get, dangerous to use, and due to concerns about further refinement, is restricted internationally.

Second, it is toxic inherently — the source is continuously radioactive at a hazardous level to humans, plutonium itself has acute and long-term toxic effects aside from the radioactivity, and if a launch fails, the rtg will disintegrate and poison hundreds of miles (see Kosmos 954, which disintegrated over Canada)

Third, it is HEAVY. They produce 40W per kilogram. Solar panels produce three times that much on Mars, and can be folded compact for launch.

Voyager used an RTG because its planned mission took it far beyond where sunlight can generate power, and it could do so because it had the budget of NASA and plutonium from the Department of Energy.

Solar panels are way cheaper, lighter, easier to procure, easier to launch, and tend not to cause international incidents.

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

#50

Post by [deleted] »

floatrock wrote: post #45
selectodude wrote: post #39

Earlier quoted context omitted.

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.

Isn't it something like space-reactor plutonium is a waste product from nuclear weapons production, and since we don't really make nuclear weapons at scale anymore, we aren't really making (refining?) plutonium anymore. And NASA has some amount on reserve, but they're rationing it out carefully. So the Clipper probe had to go with a massive solar array (100ft, the length of a basketball court) because they would rath…

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