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Cassini Beams Back First Images from New Orbit

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Re: Cassini Beams Back First Images from New Orbit

#21

Post by IndianAstronaut »

prewett wrote: post #15
smegel wrote: post #2

I have to say I've been pretty disappointed with Cassini so far. Edit: reply was correct, I did in fact mean Juno.

Are you thinking of Juno perhaps? That's not a photo-mission. Cassini has: - found "sand" dunes, river channels, mountains, and lakes on Titan - landed a probe on Titan - photographed most of Saturn's moons - discovered gas jets on Enceladus and adjusted the mission to investigate and discovered that they are caused by tidal compression which squeezes out some of the subsurface ocean and forms one of Saturn's faint r…

Cassini is my favorite space mission. It has really changed our view of the solar system and beyond. Some of the most fascinating places are going to be moons of these gas giants.

Re: Cassini Beams Back First Images from New Orbit

#22

Post by ribasushi »

ajmurmann wrote: post #4

Every time I see photos of the big gas planets like this, I imagine earth orbiting the gas giant and feel very, very small and get what feels like mild vertigo from the overwhelming scale. This is truly wonderful

For me personally this is the definitive video of "practical scale". It doesn't go out of its way to dazzle me with larger and larger pieces of an incomprehensibly large puzzle. Instead it is a simple cause + potential effect, nothing more ;)

https://youtu.be/HFT7ATLQQx8?t=55

Re: Cassini Beams Back First Images from New Orbit

#24

Post by isfield »

prawn wrote: post #11
dyukqu wrote: post #10

Earlier quoted context omitted.

Well said. But, you know, with all its moons and rings, Saturn is way cool-looking than any other planet in our Solar System. That's why they called it that way, I guess.

Perhaps from a huge distance, but I think we win the title on any other scale. Earth is pretty stunning.

It's like the school playground arguments over which computer is better, the Amiga or Atari ST again. Only this time with planets. Imho Earth is better; it has a blitter... I mean liquid water oceans...

Re: Cassini Beams Back First Images from New Orbit

#27

Post by KineticLensman »

For people who are interested , check out Nasa's JunoCam project [0], which invites amateurs to conduct some of the target selection and image processing required on the imagery returned from Jupiter Space. It's also worth noting that JunoCam isn't one of the core scientific instruments on Juno. JunoCam is more like a public outreach initiative bolted on to the real mission, which is about studying the Jupiter's gravitational field, magnetosphere and atmospheric characteristics using a range of sensors. That doesn't of course detract from these wonderful images, but the primary science will not be based on JunoCam outputs

[0] https://www.missionjuno.swri.edu/junocam/processing/

Re: Cassini Beams Back First Images from New Orbit

#28

Post by ekimekim »

caycep wrote: post #26

the one concern i have - isn't the spacecraft fueled by a small plutonium reactor? there's no risk of it going Big-B Boom?

In short, no, there is no risk.

When we say a spacecraft is nuclear-powered, we're not actually referring to a reactor (with rare exceptions[1]), but instead to something called a Radioisotope Thermal Generator[2], or RTG for short.

Basically, an RTG contains radioactive material (material that undergoes constant, passive radioactive decay). This constant decay produces heat, which is then used to generate electricity via thermocouples. There's no feedback loop or active control needed, at its simplest an RTG is a solid hunk of metal with no moving parts.

There isn't physically enough of the radioactive material, let alone the precise materials, pressures, and other things needed for a proper criticality / runaway fission effect like an atomic bomb. It's actually much harder to make one than you think ;)

[1] https://en.wikipedia.org/wiki/Nuclear_power_in_space#Fission...

[2] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

Re: Cassini Beams Back First Images from New Orbit

#29

Post by jubes »

gewoonkris wrote: post #13

For those who are also wondering about the briefly mentioned hexagon-shaped jet stream: One hypothesis, developed at Oxford University, is that the hexagon forms where there is a steep latitudinal gradient in the speed of the atmospheric winds in Saturn's atmosphere. Similar regular shapes were created in the laboratory when a circular tank of liquid was rotated at different speeds at its centre and periphery. The mo…

I read the article and thought I must research into the hexagonal madness. Turned to comments, HN's transcendent consciousness wins again! Cheers gewoonkris.

Re: Cassini Beams Back First Images from New Orbit

#30

Post by mxvzr »

What amazes me the most about the Cassini mission is the drastic inclination changes they managed to achieve around Saturn (see the GIF in the hero section [1]). At first I thought the spacecraft must have had some serious delta-v budget, but in fact the bulk of it was provided by Titan [2] (noteworthy: this page also mentions the Cassini-Huygens communication issue that was uncovered during flight, for which the workaround was already mentioned on HN [3]). Truly amazing work from the navigation team.

[1] https://saturn.jpl.nasa.gov/news/2966/ring-grazing-orbits/

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

[3] https://news.ycombinator.com/item?id=12483579

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