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Cassini will make its final close flyby of Saturn‘s moon Titan on April 21 (nasa.gov)
156 points by rbanffy on Apr 19, 2017 | hide | past | web | favorite | 47 comments



"Here's what we can do to change the world, right now, to a better ride. Take all that money we spend on weapons and defense each year, and instead spend it feeding, clothing and educating the poor of the world, which it would many times over, not one human being excluded, and we can explore space together, both inner and outer, forever, in peace."

What happens if you spend all your self-defense money on 'feeding, clothing, and educating the poor', and then a despotic nation which was spending 25% of it's GDP on military rolls over you?

The Cassini mission reminded me of the line "we can explore space together, both inner and outer, forever, in peace." and I thought I'd post the whole verse as it is as poignant today as it as ever has been.

What we can accomplish together in peace is breathtaking.

I'm pretty sure the "we" in the sentence is "humanity" not "my country". It is obviously a utopian message.

Okay....so humanity stops building weapons, and then a small group of people decide to build some weapons in secret, and can easily enslave humanity.

That doesn't sound like a great system.

The poor, uneducated and subjugated people of this "despotic nation" are the first folks we ought to feed, educate and look after.

Despots are created and thrive on the backs of hungry and hopeless citizens.

Okay, so we feed and educate some other nations people, so that nation can now afford to put 45% of it's GDP into weapons and military. I don't think that will accomplish what we want it to accomplish.

I agree with you, but do you think if we send a bunch of food to one of these despotic nations the people there would actually get fed? If you really want to feed and educate the world, you also have to police the world.

I'm not saying the US currently does either (feeds or polices the world), but just pointing out that spending the military budget on food will not change much.

The quote is about an ideal utopic society, and it would be humans as a whole, including that despotic nation, spending all the self-defense money.

I think you're supposed to hand them a Pepsi.

The problem seems to be that giving money does not solve problems all the time, and will not make everyone friendly towards you. US and EU have given billions if not trillions to Turkey, and it's still descending into dictatorship. It's regressing from a progressive society into a conservative one, probably more interested in religious laws than exploring space.

Considering they are ready to invade Syria and/or Kurdistan at the drop of a hat, I can see why their priorities are a bit askew.

Hmm, why does this remind me of "From each according to his ability, to each according to his needs"?

The dangerously seductive, utopian naivety of such statements rubs me the wrong way.

I wish all the kumbaya nature's-way-is-stupid-here's-my-brilliant-social-engineering-idea-instead people would collectively go and... try their social experiments elsewhere.

The idea that the status quo is "nature's way" is utterly wrong. Whatever we do as humans is "nature's way", as we are not separate from nature. Many different social structures have worked now and in the past. There is an enormous body of debate that our current system is terribly and perhaps fatally flawed (e.g. unable to act on climate change), so writing off people who want change as hippies that should go away is actually really rude.

Any example of a radically different social structure that has worked for humans in the past?

Btw I agree 100% that change is necessary and "natural". Vacuous hippie statements are not "it" though -- rational discourse and careful simulation is. This cannot be another "Oh, I had an idea in the bathtub, how about we try this ideology on the entire world's population?".

Given the room for disaster, and history's record of emotionally-loaded ideologies not backed by facts leading to such disaster quite reliably, that rhetoric is utterly unconvincing (as well as scary).

I don't think you are really understanding the context of the original quote. I would hope that most people with a reasonable thought process would recognize that building social structure is a very complex and difficult problem, but the path from here to "there", wherever "there" is requires "there" to be defined. I think the quote is talking about the ends, not the means. You seem to be talking about the means. The goal is building as peaceful, productive, happy, innovative, exploratory, fulfilled society as possible. Perhaps capitalism is our best mechanism at the moment, but as we evolve, we will hopefully get closer to that goal of not needing to spend money on war and being able to feed everyone, whether through better capitalism, or something else.

I see you're attempting to shift the goal posts :)

Instead of veiled insults, just re-read the original utopian quote. It's nothing like what you're describing. In fact, it's exactly the opposite -- a direct call to action.

That's a nice bit rhetorical judo. Disarming and ensuring that the bottom level of Maslow's hierarchy is met -> communism! The originator of that quote was anything but a communist.

I think you ought to think a little harder about what defense and military spending really is: welfare for engineers and those desperate or foolish enough to test their inventions. It's "from each ... to each ..." but under a different system of values.

So, there are a couple possible originators of that quote... 1 - Marx, who, obviously, was a Communist, in which case your statement is wrong 2 - Joseph Smith, who founded a classless commune. I think that invalidates your comment as well.

Is there someone else who you are thinking of as an originator who was "anything but a communist" as you put it? I'm more than willing to listen if there is.

They've been tried elsewhere, and they usually work out pretty well.

Countries that try them may not be utopias, but they do have consistently high citizen satisfaction scores.

Perhaps a little more realism and a little less moralising would be helpful.

To add: these science programs are good examples of collective action. Can anyone seriously imagine Facebook or Google paying for a project like Cassini?

>They've been tried elsewhere, and they usually work out pretty well.

To which one are you referring, China or North Korea?

Or maybe he's talking about the USSR, Cuba, or Venezuela. All bastions of progress and high standards of living.

I am a Communist, and I will say that a slogan is neither something to build your country upon, nor something to criticise a country on. No country has thus far managed to progress past capitalism, certainly not the ones you litsted nor the ones GP listed. Marx was referring to how life ought to be under Socialism, rather than an implementation of this principle under a capitalist system, which he believed was impossible.

To be fair, communist as described will never be able to exist - the furthest it will get is the USSR stage.

> nature's-way-is-stupid-here's-my-brilliant-social-engineering-idea-instead

So then instead of trying to change the world for the better, we ought to just submit to a naturalistic fallacy and live our lives in ignorance of the ways society could be better organised? It seems like you're criticising Communism based on this quote, which is in fact supposed to show how life ought to be under Socialism, rather than how we ought to implement it with capitalism.

What gives you the ideat that capitalism is "nature's way"? This couldn't be further than the truth.

Sorry to be off-topic, but I really do despise the "stressed" narration voice of STEM media these days.

Am I the only one here who misses the balanced, informed, steady and smooth narration of Carl Sagan et al of yesteryear STEM media? Now all I hear is this over-ambitious, over-animated, low-content, and stressed voice with absurdly long pauses. Almost like somebody is shouting at you.

BBC are terrible for it in the UK, it seems like a race to the bottom. Whoever can superficially appear the most terribly "passionate" about whatever they're talking about gets the job...

Cassini rocks though, what an achievement for mankind the whole saga has been!

People need to feel excited: https://www.youtube.com/watch?v=sGUNPMPrxvA

They're going to fly between the planet and it's rings - but how? I was watching a show on Voyager 1 where they had originally thought about doing the same, but were glad they didn't. When Voyager got close enough to image the rings, there was quite a bit of debris between the planet and the rings. Apparently, it was enough to ensure the destruction of the spacecraft. Do they now know enough about that debris field, and now have accurate enough "control" (calculated by astrodynamics), to avoid a collision?

From this NASA link [1] it looks like when Cassini crosses through the plane of the rings, it does that almost at a right angle. The width of the rings is at most 1km, and at a speed of about 20km/s, each crossing will take at most 0.05s. The average distance between rocks in the rings is a few meters (and Cassini is about 4m by 6m), so even if Cassini crossed the rings themselves the probability of a crash would be about 50%. The average distance between space debris in the space between rings and between rings and the planet is probably hundreds of times lower, so I would think that the probability of a crash is very small, easily less than 1% per crossing. For Voyager, a crash probability in the neighborhood of 1% was most likely unacceptable, but for a spacecraft scheduled to be destroyed on 15-Sept-2017, this is probably ok.

[1] https://saturn.jpl.nasa.gov/mission/spacecraft/navigation/

Now that the primary objectives of the mission are completed, they are engaging in more and more dangerous orbits to gather even more data. If they do have a mission ending strike.. it goes out doing science.

From what I remember, the plan was Voyager crossing the Cassini division and they were glad when they realized it was not as particle free as we used to think at the time. The region between the planet and the inner ring is much cleaner.

Cassini has been around Saturn for a long time now and I don't think there will be too many surprises on its final cruise.

And, if there are, Cassini will just have discovered a new way to destroy space probes.

Even if they're taking huge risks going through a debris field, they're destroying the craft soon after anyway. If it actually is risky, it's probably worth the risk.

They're going to do it 22 times over 24 days before the descent into Saturn. The only thing I can think of is that the 2,000 km gap is close enough to avoid the debris, and perhaps they couldn't have calculated that close a fly-by with Voyager 1 with the knowledge and technology of the day.

It might have been a trajectory limitation. A major goal for Voyager 1 was to fly by Titan, and it may not have been possible to both fly through the gap and fly past Titan given the limited fuel available.

They might not have known the gap was there, either. Much of what is now known about the structure of Saturn's rings was first discovered by the Voyagers.

Is it possible that there is a rock big and fast enough to divert Cassini someplace undesirable, such as leaving a streak through a ring, crashing into a moon, or perturbing something else from its natural state?

Cassini is very small, compared to pretty much everything around Saturn. So, no. You could drop a billion Cassini spacecrafts into the rings without perturbing anything.

I don't mean that Cassini will shift a moon from its orbit, but the introduction of foreign materials, for example, could change things.

Perhaps I'm putting too much emphasis on the naturally pristine state of things around Saturn, but I've read that also is a priority of researchers, at least in some circumstances.

"its rings"

And there are gaps that have been identified, but they don't care if the spacecraft gets destroyed now, so that's why they're doing these bold maneuvers now

re "its rings". I'm never quite sure whether to correct grammar/spelling or not in HN comments. On the one hand I know there are lots of people here for whom English is a second language and who might find it useful. On the other hand, I don't want to appear dickish. At work I generally ask my non-native-English-speaking colleagues if they want me to point out errors and then act accordingly. And every now and then one of them challenges my correction and I discover I'm wrong ;-)

As a non-native speaker, I think there are some classes of errors like confusing homophones that native speakers are much more likely to make, e.g. "could of", their/there/they're, or even the above-mentioned its/it's. The latter two are covered very extensively in lessons, and "could of" is just so absurd to anyone who's had to study to learn the language that it doesn't even compute.

I've generally decided not to comment on people's spelling and grammar on HN because it doesn't really add to the discussion. I do sometimes make a point of italicising the correct spelling in my response if I have something substantial to add to the discussion :)

Yeah I concede correcting some mistakes might get annoying sometimes

But as a non-native speaker myself the homophone mistakes really bother me (though I concede native speakers are likely to make these kind of mistakes in their native language - and I include myself in this)

But it's a continuing effort, however I noticed this kind of mistake has increased in past years. I suspect autocorrect is to blame

Good idea. Thanks.

It will be on a ballistic trajectory into Saturn, which will happen debris collision or not, so what does it matter?

Can they somehow ensure this 22 orbits in advance (e.g. using Titan's gravity to change the trajectory slightly on each orbit)?

The amount of data and images Cassini has collected over the years is really something extraordinary.

Here's a collection of such images: https://www.nasa.gov/mission_pages/cassini/images/index.html

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