APOD: Behind Saturn (2016 Aug 01)

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Expand view Topic review: APOD: Behind Saturn (2016 Aug 01)

Re: APOD: Behind Saturn (2016 Aug 01)

by geckzilla » Wed Aug 03, 2016 7:20 pm

Dustdreamer wrote:
geckzilla wrote:
Dustdreamer wrote:It's a thing. Don't blame me for it, I only live here I didn't design the language. English, she is a law unto herself.
You're the only one here doing it. It's long been officially deprecated. Stop.
The practice has been "officially deprecated" by one US college and one US newspaper.
Which is a lot more than you have to work with as you tried to defend yourself by saying that's just how English works, which just isn't true. English evolves when a majority of people either naturally change their language or if they decide to consciously make the effort to change, such as once they realize it is sexist in an age when they are trying hard to promote diversity in STEM fields. Check out NASA's style guide: http://history.nasa.gov/styleguide.html
Manned Space Program vs. Human Space Program:

All references referring to the space program should be non-gender specific (e.g. human, piloted, un-piloted, robotic). The exception to the rule is when referring to the Manned Spacecraft Center, the predecessor to the Johnson Space Center in Houston, or any other official program name or title that included "manned" (e.g. Associate Administrator for Manned Spaceflight).
Note that I certainly don't hold it against anyone using it historically or for making historically correct references. It was a thing. It is no longer a thing. Things that aren't specifically covered by NASA's style guide are covered in The Chicago Manual of Style. I'd consider both NASA and The Chicago Manual of Style a much higher authority on the matter than you.

Re: APOD: Behind Saturn (2016 Aug 01)

by Dustdreamer » Wed Aug 03, 2016 6:48 pm

geckzilla wrote:
Dustdreamer wrote:It's a thing. Don't blame me for it, I only live here I didn't design the language. English, she is a law unto herself.
You're the only one here doing it. It's long been officially deprecated. Stop.
The practice has been "officially deprecated" by one US college and one US newspaper. That is almost so bad as saying that the BBC's insistence on never using quote-marks around the titles of books, films, plays and musical albums, never capitalising acronyms when they can be sounded out easily {Esa, instead of ESA}, never using those little dots to indicate initialisms or acronyms {RAF instead of R.A.F.} and other signs of a poor, Media Studies orientated education and massive intellectual laziness are all "officially Sanctioned" just because the B.B.C. says they are.

I heartily suggest you read the Wiki article on the Nimitz.

But you're [correct spelling, according to American Usenet postings, "your" being "officially deprecated" by many thousands of Americans] hostility is noted. I love the beauty, power and flexibility of the English language and I won't be amending my evil ways with her but I will be gone.

Now, how do I delete a userid?

Re: APOD: Behind Saturn (2016 Aug 01)

by neufer » Wed Aug 03, 2016 1:46 pm

neufer wrote:
<<If Cassini was in a circular orbit of velocity Vo then to be "sent out into open space" requires a velocity impulse of only [sqrt(2)-1]Vo as compared with a velocity impulse of -Vo in order to crash into Saturn.

For a Saturn crash to require a smaller velocity impulse (than the full escape option) requires the elliptical orbit aposaturn to be about 31/3 (= 2/[3-sqrt(8)] - 1) times perisaturn! Fortunately, Cassini is almost always this sort of a highly elliptical orbit. Hence, it roughly just as easy to crash into Saturn as to escape it...but pre-crash perisaturn orbits close to the rings are much more scientifically useful:

https://en.wikipedia.org/wiki/Cassini%E ... retirement
Actually... that's not quite true. :oops:

Elliptical orbits make it only slightly easier to crash than to leave the planet.

In the limit of the planet being much smaller than the orbit it is always easier to leave a planet than it is to crash onto a planet. At high eccentricities the velocity impulse required to escape the planet is about half the velocity impulse necessary to crash (i.e., being essentially the orbital velocity at the most distant point). Of course, with a finite sized planet it is not really necessary to reduce the orbital velocity at the most distant point to zero. (Interactions with moons can be used to make it easier both to leave and to crash onto a planet.) Since Cassini has never had a large velocity at aposaturn it has never been much of a problem to either leave Saturn or crash onto Saturn anytime one wished to.

Re: APOD: Behind Saturn (2016 Aug 01)

by neufer » Tue Aug 02, 2016 8:40 pm

Chris Peterson wrote:
Dan wrote:
Hello All...I'm just curious why Cassini has to be directed into the planet in September, rather than allowing it to continue gathering data from the planet? If the power source of the craft is depleted, why not just send it out into open space to travel for ever??

Just curious..
Cassini is gravitationally bound to Saturn. It can't be "sent out into open space" without using a big rocket engine and a huge amount of fuel- probably more than was used in its original launch from Earth. It can either be left in orbit, where it will eventually be perturbed and possibly hit a moon, or it can be allowed to fall while some control remains.
Click to play embedded YouTube video.
Actually... that's not quite true.

If Cassini was in a circular orbit of velocity Vo then to be "sent out into open space" requires a velocity impulse of only [sqrt(2)-1]Vo as compared with a velocity impulse of -Vo in order to crash into Saturn.

For a Saturn crash to require a smaller velocity impulse (than the full escape option) requires the elliptical orbit aposaturn to be about 31/3 (= 2/[3-sqrt(8)] - 1) times perisaturn! Fortunately, Cassini is almost always this sort of a highly elliptical orbit. Hence, it roughly just as easy to crash into Saturn as to escape it...but pre-crash perisaturn orbits close to the rings are much more scientifically useful:

https://en.wikipedia.org/wiki/Cassini%E ... retirement

Re: APOD: Behind Saturn (2016 Aug 01)

by Chris Peterson » Tue Aug 02, 2016 6:06 pm

Dan wrote:Hello All...I'm just curious why Cassini has to be directed into the planet in September, rather than allowing it to continue gathering data from the planet? If the power source of the craft is depleted, why not just send it out into open space to travel for ever??

Just curious..
Cassini is gravitationally bound to Saturn. It can't be "sent out into open space" without using a big rocket engine and a huge amount of fuel- probably more than was used in its original launch from Earth. It can either be left in orbit, where it will eventually be perturbed and possibly hit a moon, or it can be allowed to fall while some control remains.

Re: APOD: Behind Saturn (2016 Aug 01)

by Dan » Tue Aug 02, 2016 5:56 pm

Hello All...I'm just curious why Cassini has to be directed into the planet in September, rather than allowing it to continue gathering data from the planet? If the power source of the craft is depleted, why not just send it out into open space to travel for ever??

Just curious..

Re: APOD: Behind Saturn (2016 Aug 01)

by Chris Peterson » Tue Aug 02, 2016 1:49 pm

Guest wrote:
Chris Peterson wrote:Given that its velocity exceeds escape velocity, is it really correct to describe New Horizons as being in 'orbit'? Is there some nuance to the term orbit that I am missing? No criticism intended, just asking...
In common usage, we usually think of "orbit" as referring to a closed orbit. That is, one with an eccentricity of less than or equal to one: circular or elliptical. But the same orbital mechanics work when the eccentricity is greater than one, defining an open, or hyperbolic orbit. The shape of that orbit is still defined by the central mass of the system. In terms of the math, in terms of the technical usage, orbits are orbits whether they're open or closed. An object leaving the Solar System at greater than escape velocity is in a solar orbit until some other massive body becomes dominant, and then it would be seen as being in an open orbit around that body, not the Sun.

Re: APOD: Behind Saturn (2016 Aug 01)

by neufer » Tue Aug 02, 2016 9:36 am

Guest wrote:
Chris Peterson wrote:
New Horizons is currently moving away from the Sun at 14.5 km/s, in a part of the Solar System with a solar escape velocity of 6.7 km/s. There's no body out there massive enough to do more than slightly deflect the hyperbolic (nearly linear) orbit it's currently in.
Given that its velocity exceeds escape velocity, is it really correct to describe New Horizons as being in 'orbit'? Is there some nuance to the term orbit that I am missing?
https://en.wikipedia.org/wiki/Orbit wrote:
<<An orbit is the gravitationally curved path of an object about a point in space, for example the orbit of a planet about a star or a natural satellite around a planet. Orbits of planets are typically elliptical, and the central mass being orbited is at a focal point of the ellipse. Isaac Newton demonstrated that Kepler's laws were derivable from his theory of gravitation and that, in general, the orbits of bodies subject to gravity were conic sections.>>
(If New Horizons should accidentally crash into 2014 MU69 then it will be in Obit.)

Re: APOD: Behind Saturn (2016 Aug 01)

by Guest » Tue Aug 02, 2016 5:31 am

Chris Peterson wrote:
Dustdreamer wrote: Newby could be retrieved. All we need to do is slingshot her past her next target so she falls towards another falling rock then bounce her from rock to rock until one of the gravitational slingshots gives her an Earthward trajectory.
It might take a few centuries, and it would require us to find suitable rocks and ice-balls in appropriate orbits but those JPL guys are very, very good at this sort of stuff.
They got Voyager to Neptune using this technique, bouncing Newby around should be easy for them.

Chris is going to give us pages of why this is a ludicrous idea. :)
New Horizons is currently moving away from the Sun at 14.5 km/s, in a part of the Solar System with a solar escape velocity of 6.7 km/s. There's no body out there massive enough to do more than slightly deflect the hyperbolic (nearly linear) orbit it's currently in.
Hi Chris,

Given that its velocity exceeds escape velocity, is it really correct to describe New Horizons as being in 'orbit'? Is there some nuance to the term orbit that I am missing? No criticism intended, just asking...

Re: APOD: Behind Saturn (2016 Aug 01)

by Ann » Tue Aug 02, 2016 5:24 am

neufer wrote:
Dustdreamer wrote:
geckzilla wrote:
Please stop anthropomorphizing spacecraft and using feminine pronouns. They're not women.
True, they are not women, they are not even alive. However, they are either ships or aircraft and both of those are, by tradition, commonly referred to with the feminine pronoun in English.

Planets, stars, galaxies, moons and even the falling rocks variously termed "Asteroids", "Minor Planets" or "Dwarf Planets" are also feminine, even those, such as Jupiter, whose names are most certainly male. Even countries and cities can be female.
http://www.grammarphobia.com/blog/2010/12/ships.html wrote:
<<The personification of nonliving nouns (e.g., ships or nations) as “she” has fallen out of common usage. It’s now generally considered quaint or poetic. The Chicago Manual of Style (16th edition), as well as the style books of the Associated Press and the New York Times, recommend using “it” or “its” to refer to ships. In 2002, Lloyd’s List, the 276-year-old London-based shipping newspaper, officially dropped the gender personification and now refers to ships with the pronouns “it” and “its” instead of “she” and “her.”>>
In Swedish, the Sun has traditionally been thought of as a female being. And the Moon has been considered male, maybe because there is a "man in the moon". Now no one would refer to the Sun as "she" or the Moon as "he", of course.

Interestingly, the word "människa" - "human being" - has been regarded as feminine. It is in fact still acceptable in Sweden to say "människan, hon" = "a human being, she".

In English-speaking countries, people say "man, he".

Ann

Re: APOD: Behind Saturn (2016 Aug 01)

by Chris Peterson » Tue Aug 02, 2016 2:28 am

Dustdreamer wrote: Newby could be retrieved. All we need to do is slingshot her past her next target so she falls towards another falling rock then bounce her from rock to rock until one of the gravitational slingshots gives her an Earthward trajectory.
It might take a few centuries, and it would require us to find suitable rocks and ice-balls in appropriate orbits but those JPL guys are very, very good at this sort of stuff.
They got Voyager to Neptune using this technique, bouncing Newby around should be easy for them.

Chris is going to give us pages of why this is a ludicrous idea. :)
New Horizons is currently moving away from the Sun at 14.5 km/s, in a part of the Solar System with a solar escape velocity of 6.7 km/s. There's no body out there massive enough to do more than slightly deflect the hyperbolic (nearly linear) orbit it's currently in.

Re: APOD: Behind Saturn (2016 Aug 01)

by neufer » Tue Aug 02, 2016 2:24 am

Dustdreamer wrote:
geckzilla wrote:
Please stop anthropomorphizing spacecraft and using feminine pronouns. They're not women.
True, they are not women, they are not even alive. However, they are either ships or aircraft and both of those are, by tradition, commonly referred to with the feminine pronoun in English.

Planets, stars, galaxies, moons and even the falling rocks variously termed "Asteroids", "Minor Planets" or "Dwarf Planets" are also feminine, even those, such as Jupiter, whose names are most certainly male. Even countries and cities can be female.
http://www.grammarphobia.com/blog/2010/12/ships.html wrote:
<<The personification of nonliving nouns (e.g., ships or nations) as “she” has fallen out of common usage. It’s now generally considered quaint or poetic. The Chicago Manual of Style (16th edition), as well as the style books of the Associated Press and the New York Times, recommend using “it” or “its” to refer to ships. In 2002, Lloyd’s List, the 276-year-old London-based shipping newspaper, officially dropped the gender personification and now refers to ships with the pronouns “it” and “its” instead of “she” and “her.”>>

Re: APOD: Behind Saturn (2016 Aug 01)

by geckzilla » Tue Aug 02, 2016 1:34 am

Dustdreamer wrote:It's a thing. Don't blame me for it, I only live here I didn't design the language. English, she is a law unto herself.
You're the only one here doing it. It's long been officially deprecated. Stop.

Re: APOD: Behind Saturn (2016 Aug 01)

by Dustdreamer » Tue Aug 02, 2016 12:55 am

geckzilla wrote:Please stop anthropomorphizing spacecraft and using feminine pronouns. They're not women.
True, they are not women, they are not even alive. However, they are either ships or aircraft and both of those are, by tradition, commonly referred to with the feminine pronoun in English.
Even ships with masculine names, such as U. S. S. Nimitz and which are actually named after masculine humans, such as Admiral Nimitz, are considered to be female -ish.
The robots we drop around, onto and into planets and moons are spaceships - a type of ship, or unmanned aerial vehicles - a type of heavier than air flying machine, both of which classes of instrumentality are usually give feminine pronouns.
It has nothing to do with anthropomorphism, it is simply a correct use of the language.

Planets, stars, galaxies, moons and even the falling rocks variously termed "Asteroids", "Minor Planets" or "Dwarf Planets" are also feminine, even those, such as Jupiter, whose names are most certainly male. Even countries and cities can be female.

It's a thing. Don't blame me for it, I only live here I didn't design the language. English, she is a law unto herself.

Re: APOD: Behind Saturn (2016 Aug 01)

by geckzilla » Tue Aug 02, 2016 12:27 am

Please stop anthropomorphizing spacecraft and using feminine pronouns. They're not women.

Re: APOD: Behind Saturn (2016 Aug 01)

by Dustdreamer » Mon Aug 01, 2016 11:03 pm

Chris Peterson wrote:
Dustdreamer wrote:
Chris Peterson wrote:So the only viable option to avoid contamination of the system is to crash into that planet.

Why?
What would the problem be with trying to force the probe into so nearly a low polar orbit of Saturn as the remaining fuel can achieve? That way, Cassie can image Saturn and The Rings for us for a while and she will eventually drop to the "surface" of her own volition when atmospheric drag takes her down?
I don't think anybody is comfortable leaving a spacecraft in orbit that cannot be controlled. And FWIW, changing orbital eccentricity tends to be expensive. It's likely that putting Cassini into a nearly circular orbit well inside the ring system is either not possible with the remaining fuel, or would use so much that the remaining science mission would be impacted.
Also, has no one at NASA/JPL read "Encounter With Medusa", by Clarke? If they are imaginative enough to dream that alien bugs might live on Titan and Europa, Mimas and Io so Jovian and Saturnian orbiters must avoid those places, don't they consider that Jupiter and Saturn, too may have indigents?
Not a problem, because the entry velocity is so high that anything biological remaining on the craft will be completely burned away. Lumps will not survive. The same can't be said for crashing into a moon.
Cool, thanks, but what about a refuelling tanker? Maybe with some updated electronics boxes and a better camera?

Yes, I know, Cassini-2 would be faster and vastly cheaper and would give us more Science. But it's a shame that we have to keep expending these robots when they have given us so much.

I just had a brilliant idea ... something truly amazing and paradigm shattering ... we could send a human engineer to update and refuel Cassie.
I volunteer.
I'll even supply my own screwdriver sets.

Re: APOD: Behind Saturn (2016 Aug 01)

by Dustdreamer » Mon Aug 01, 2016 10:46 pm

heehaw wrote:
hardware dealer wrote: if a space craft cannot be recovered then it should not be sent off.

Ummmm.... New Horizons?
Newby could be retrieved. All we need to do is slingshot her past her next target so she falls towards another falling rock then bounce her from rock to rock until one of the gravitational slingshots gives her an Earthward trajectory.
It might take a few centuries, and it would require us to find suitable rocks and ice-balls in appropriate orbits but those JPL guys are very, very good at this sort of stuff.
They got Voyager to Neptune using this technique, bouncing Newby around should be easy for them.

Chris is going to give us pages of why this is a ludicrous idea. :)

Re: APOD: Behind Saturn (2016 Aug 01)

by Boomer12k » Mon Aug 01, 2016 10:26 pm

They grow up sooooo fast....

But really...."TO PROTECT LIFE"?????????? Gimme a break.....

:---[===] *

Re: APOD: Behind Saturn (2016 Aug 01)

by ShaileshS » Mon Aug 01, 2016 10:20 pm

Chris Peterson wrote:
Catalina wrote:How is NASA insuring that NO microbes are planted on Mars with all of the rovers making soft landings and cruising such distances on the martian surface?
They aren't. Because they can't. They do their best to sterilize what they can, but it's quite possible that some living microbes have made it to the surface of Mars. Luckily, that's a very inhospitable place for Earth life, so it's improbable that anything would survive long. But not impossible.
Who knows, maybe some would survive and 10-20 yrs down the road, folks visiting from earth would "discover" new life on Mars (yeah, right !) and some human beings will be elated (as in "Finally, we found LIFE somewhere else") and some would predict the doom soon (as in "This confirms there's aliens out there more intelligent than us who'd come and destroy us soon !"). No one knowing that time (or would realize that time) that these were left there (and survived) by our own missions 10-20 yrs back.

Re: APOD: Behind Saturn (2016 Aug 01)

by Chris Peterson » Mon Aug 01, 2016 9:23 pm

Catalina wrote:How is NASA insuring that NO microbes are planted on Mars with all of the rovers making soft landings and cruising such distances on the martian surface?
They aren't. Because they can't. They do their best to sterilize what they can, but it's quite possible that some living microbes have made it to the surface of Mars. Luckily, that's a very inhospitable place for Earth life, so it's improbable that anything would survive long. But not impossible.

Re: APOD: Behind Saturn (2016 Aug 01)

by Catalina » Mon Aug 01, 2016 9:20 pm

How is NASA insuring that NO microbes are planted on Mars with all of the rovers making soft landings and cruising such distances on the martian surface?

Re: APOD: Behind Saturn (2016 Aug 01)

by Chris Peterson » Mon Aug 01, 2016 8:17 pm

Dustdreamer wrote:
Chris Peterson wrote:So the only viable option to avoid contamination of the system is to crash into that planet.

Why?
What would the problem be with trying to force the probe into so nearly a low polar orbit of Saturn as the remaining fuel can achieve? That way, Cassie can image Saturn and The Rings for us for a while and she will eventually drop to the "surface" of her own volition when atmospheric drag takes her down?
I don't think anybody is comfortable leaving a spacecraft in orbit that cannot be controlled. And FWIW, changing orbital eccentricity tends to be expensive. It's likely that putting Cassini into a nearly circular orbit well inside the ring system is either not possible with the remaining fuel, or would use so much that the remaining science mission would be impacted.
Also, has no one at NASA/JPL read "Encounter With Medusa", by Clarke? If they are imaginative enough to dream that alien bugs might live on Titan and Europa, Mimas and Io so Jovian and Saturnian orbiters must avoid those places, don't they consider that Jupiter and Saturn, too may have indigents?
Not a problem, because the entry velocity is so high that anything biological remaining on the craft will be completely burned away. Lumps will not survive. The same can't be said for crashing into a moon.

Re: APOD: Behind Saturn (2016 Aug 01)

by Dustdreamer » Mon Aug 01, 2016 8:00 pm

Chris Peterson wrote:So the only viable option to avoid contamination of the system is to crash into that planet.


Why?
What would the problem be with trying to force the probe into so nearly a low polar orbit of Saturn as the remaining fuel can achieve? That way, Cassie can image Saturn and The Rings for us for a while and she will eventually drop to the "surface" of her own volition when atmospheric drag takes her down?

Also, has no one at NASA/JPL read "Encounter With Medusa", by Clarke? If they are imaginative enough to dream that alien bugs might live on Titan and Europa, Mimas and Io so Jovian and Saturnian orbiters must avoid those places, don't they consider that Jupiter and Saturn, too may have indigents?
I would.
Sure, burning up could crispy-fry everything terrestrial but it might not. Lumps might survive.
Do we really want to find Earthman-type bugs in the airs of Saturn in a few centuries?

Also, in the realm of "Trek" and "Dr. Who", refuelling tanker? :)

Re: APOD: Behind Saturn (2016 Aug 01)

by Chris Peterson » Mon Aug 01, 2016 2:34 pm

Animal of Stone wrote:It seems to me that after we have finished exploring our neighbours we plunge our devices into them. Could they not be programmed to explode somewhere in deep space or directed away from our planets and into deep stellar space.
There is no way for a probe like this to get out of Saturn orbit. Gravitationally, it is essentially a part of Saturn. So the only viable option to avoid contamination of the system is to crash into that planet.

Re: APOD: Behind Saturn (2016 Aug 01)

by Fred the Cat » Mon Aug 01, 2016 2:31 pm

What became of Emily's "crazy" idea? Will "plunging through a point just outside the narrow F ring (the edge of the main rings)" give more information about the rings? After re-reading the "The Grand Finale" perhaps that is the plan. :?:

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