[HN Gopher] Juno skims the cloud tops of Jupiter
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Juno skims the cloud tops of Jupiter
Author : lelf
Score : 123 points
Date : 2022-06-04 17:15 UTC (5 hours ago)
(HTM) web link (www.nasa.gov)
(TXT) w3m dump (www.nasa.gov)
| arriu wrote:
| It's really a shame they didn't put better imaging equipment on
| Juno. The argument being that little science would be gained from
| it. I'd argue secondary effects would have made it worth the
| weight.
| sephamorr wrote:
| You have to be careful what you ask for - I certainly like
| pretty pictures myself, but one of the reasons that Juno is so
| successful as a scientific mission is because it was kept to
| the barebones and managed scope so aggressively. With Juno ($1B
| for an outer planets mission) we got Flagship mission-quality
| science for a New Frontiers price. There's a good interview
| with Mark Wolverton on Planetary Radio that discusses how this
| happened.
| 0daystock wrote:
| bliteben wrote:
| so that google can be the only crawler that is allowed
| [deleted]
| leephillips wrote:
| I was surprised to hear that. I visit nasa.gov frequently, and
| I've never seen this nonsense.
| _jal wrote:
| It is pretty easy to set off if you control your browser much
| (privacy-enforcing proxies, ad blockers, etc.).
|
| I haven't seen it with NASA, but I'm currently doing
| something that trips CF's verify-your-humanity bullshit on
| third party sites a lot. Haven't yet figured out what upsets
| it.
| Sebguer wrote:
| To prevent bots from causing bandwidth costs to be insane?
| xixixao wrote:
| Can someone run this through ML to create a smooth animation?
| dylan604 wrote:
| Why? Just 3D animate it using other imagery from NASA/ESA
| probes to map to a sphere and then fly the camera over it in
| what ever fashion you want your pretty pictures. You're
| confusing scientific data with pretty pictures for the sake of
| being pretty pictures.
| [deleted]
| swayvil wrote:
| What's the definition of a planet's atmosphere edge? Does it just
| keep on thinning out to a light year and beyond or is there a
| clear transition?
| ceejayoz wrote:
| Bit of both. https://climate.nasa.gov/news/2919/earths-
| atmosphere-a-multi...
|
| 99.99997 percent is below 100km, but the exosphere is
| considered to go as far as 10k, and maybe further:
|
| > A February 2019 study using data from the NASA/European Space
| Agency Solar and Heliospheric Observatory (SOHO) spacecraft
| suggests, however, that the farthest reaches of Earth's
| atmosphere -- a cloud of hydrogen atoms called the geocorona --
| may actually extend nearly 391,000 miles (629,300 kilometers)
| into space, far beyond the orbit of the Moon.
| WalterGR wrote:
| How much time elapses in that time-lapse?
|
| Edit: Two hours of real-time Jupiter:
| https://www.youtube.com/watch?v=GPMK_6-QrIg
| pjscott wrote:
| In case anybody was wondering "Why is the frame rate so lousy?"
| the answer is that the probe only has about 325 bits per second
| of downlink on average.
|
| https://en.wikipedia.org/wiki/Juno_(spacecraft)
| sgt wrote:
| Would it be possible to extrapolate frames in between to give
| one smooth flyover?
| giantrobot wrote:
| Yes but it will _look_ like there 's extrapolated frames. I'm
| sure you'll see something like that in a YouTube video or
| something on the Discovery channel but I don't see the point
| of NASA doing that.
| shrx wrote:
| Nitpick: you interpolate data between two known points
| (frames), and extrapolate beyond the first or last known
| datapoint.
| Cthulhu_ wrote:
| And are there additional images in the probe's storage that
| will be transferred over the coming... years?
| skohan wrote:
| What's the limiting factor on bandwidth constraints for probes
| like this? Is it the power of the probe? Is it the distance
| from earth?
|
| I wonder if you could build a mesh network of satellites/probes
| out farther into the solar system to get better connectivity
| for projects like this.
| rich_sasha wrote:
| The limiting factor is power/distance^2 basically, which
| determines the signal/noise ratio, which determines the
| bandwidth.
|
| A mesh network sounds fun, though you'd have to have a fair
| few probes, as their orbits wouldn't be in sync. Also that
| far from the sun, solar panela don't cut it and you need
| nuclear thermal generators, which have a finite lifespan.
| lifeisstillgood wrote:
| Basic science is the foundation stone of the past 200 years of
| human progress - and if anyone out there wants to put "double the
| science budget just because" on their manifesto they can have my
| vote.
|
| I am so glad we live in an age where this is possible, and that
| it is celebrated and respected.
|
| Fantastic.
| holoduke wrote:
| 210,000 kilometers per hour. Almost 60km/40mi per second. Amazing
| speed when you think about it. Wonder if there would be any time
| dilation noticable if the craft ever gets captured and brought
| back to earth.
| ericbarrett wrote:
| Similarly I wonder if there was any detectable heating from
| kinetic interaction with dust and trace atmosphere. 60 km/sec
| is _fast!_
| orbital-decay wrote:
| Not sure about the composition of atmosphere at those exact
| altitudes on Jupiter, but aerodynamic heating was a serious
| concern during Cassini's close Titan flybys, and that's
| "just" at ~6.3km/s max. IIRC the closest one was the T-70 at
| 880km; a lot of work has been done to make sure it won't
| tumble or overheat. (Titan's low gravity makes its dense
| atmosphere reach very far, so 880km is really low)
| pvg wrote:
| Relativistic effects are measurable with accurate enough clocks
| in earth satellites (or even just taking a clock to a mountain)
| and correction is necessary in systems with finicky time
| requirements like GPS.
|
| Incidentally, the relative speed you can napkin math estimate -
| an object in orbit flying that close to the planet is going to
| have escape-velocity-ish speed. It's around 60km/sec for
| Jupiter.
| atoav wrote:
| By now I think they managed to measure relativistic effects
| of clocks that are a few milimeters apart in terms of
| distance from earths gravitational center.
| pvg wrote:
| Sufficiently clever experimentalists also pulled this off
| in about 20 meters in 1959, the clever bit being ditching
| the clocks entirely:
|
| https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experimen
| t
| dmd wrote:
| > taking a clock to a mountain
|
| http://www.leapsecond.com/great2005/tour/
| cmroanirgo wrote:
| Fantastic! Has this been shared on HN before?
|
| > _We would come back about 20 ns older compared to her
| [the wife who stayed behind]._
|
| >= _Or, the other way to look at it (since this is
| relativity after all), is that she would become 20 ns
| younger than us upon our return. Note to husbands: this
| could be a useful gift idea for your wife._
| pvg wrote:
| It has, in the HN equivalent of the Archean eon
|
| https://news.ycombinator.com/item?id=598090
| belter wrote:
| They also did the First Atomic Clock Wristwatch...
|
| http://leapsecond.com/pages/atomic-bill/
| rococode wrote:
| It's about 0.01% the speed of light, which is definitely fast
| enough to have a measurable impact. Even ISS astronauts
| experience a tiny amount of time dilation (on a millisecond
| level) and they move at much slower speeds.
| Crontab wrote:
| I've read that time moves a tiny bit slower on Earth than it
| does in space and that it affects satellites. I wonder how much
| difference there is for something like the Voyagers, which has
| been in space since the 70's, and us on the ground.
| arghwhat wrote:
| As a point of reference, our solar system orbits our galaxy at
| approximately 4 times that speed at 828 megameters per hour, so
| 210 megameters per second isn't _that_ big a deal in the grand
| scheme of things...
| _Microft wrote:
| Kilometer is the largest SI-prefixed variation of meter that
| is commonly used (among physicists that I know). I would
| rather suggest that you use scientific notation if you do not
| want to deal with large numbers of kilometers.
| arghwhat wrote:
| We don't stop at millimeters or kilowatt, so there is
| really no reason to stop at kilometer when megameter is
| more appropriate.
|
| Scientific notation is also fine, but "210 megameter" is in
| my opinion easier to read than "2.1 * 10^8 meters",
| especially for the casual reader.
|
| So while I respectfully make note of your feedback, I
| strongly disagree and stand by my choice of units. :)
| ksaj wrote:
| Given how hard it is to convince most Americans to use
| prefixed metre measurements instead of inches, feet,
| yards and miles, I think it would be even harder to
| convince the world that a megametre, picometre, etc is
| the way to go.
|
| Not that I don't agree (I fully do!), the ease of using
| multiples of 10 is way easier. But it is very difficult
| to introduce change to the masses, no matter how sensible
| it is.
|
| The US is one of the only countries on the planet that
| still fully stick to the old system. And they're also one
| of the only countries that spell 'meter' instead of
| 'metre.' For everyone else in the world, 'meter' is a
| measuring gauge or tool, and so is everything that rhymes
| with 'thermometer' except for the American pronunciation
| of 'kilometre' that too many have adopted up here.
|
| Likewise, adult Canadians still use pounds at the gym and
| their body weight, and feet/inches for their height.
| Young people are far more reasonable about measurements
| these days.
|
| Change is hard, and seems to get really messy when
| everyone goes in different directions from the start.
| arghwhat wrote:
| > 210 megameters per second
|
| Oops, _megameters per hour.
|
| 210 Mm/s is a _very* big deal, with the speed of light being
| around 299 Mm/s.
| andrekandre wrote:
| > 210,000 kilometers per hour.
|
| that would get you to the moon in about one and a half hours...
| crazy (cool)
| belter wrote:
| They are noticed in the Parker Solar Probe. At closest approach
| it get's to 590,000 kilometers per hour (aprox 360,000 mph)
|
| "Parker Solar Probe passing extremely close to the Sun; what
| relativistic effects will it experience and how large will they
| be?":
| https://physics.stackexchange.com/questions/348854/parker-so...
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