FW: "First Ark to Alpha Centauri" - the Screenplay!

JRS: In article <VA.00000308.0104ab3a.RemoveThis@mynameplus1.demon.co.uk.invalid>,
dated Sun, 28 Nov 2004 04:00:12, seen in news:alt.books.larry-niven,
Aidan Karley <aidan.RemoveThis@mynameplus1.demon.co.uk.invalid> posted :
 >In article <adbf5bc1.0411231953.3222dbbd.RemoveThis@posting.google.com>, AA
 >Institute wrote:
  >> I have read some articles that stipulate how comets (and
  >> presumably also some less dense asteroids) could break up on
  >> approaching within the "Roche Limit" around a planet under the
  >> gravitational tidal forces. Since my "First Ark to Alpha Centauri"
  >> concept is dependent on gravity assisted fly-by's of giant outer
  >> planets like Jupiter and Saturn for intial departure from our solar
  >> system, there is a serious danger of fragmentation!
  >>
 > Not a *huge* problem.
 > The Roche limit is flexible on, effectively, the tensile
 >strength of your material.

You are redefining the term there. The true limit is for the case where
the secondary is self-bound only gravitationally, and, in primary radii,
depends only on the ratio of densities.

But, indeed, for fly-bys it is the strength of ship and contents that
matters, in comparison with the tidal gradient. There will be no
problem with any normal ship passing any solar-system body.

 > ...
 > Anyone have a figure offhand for the diameters of the shepherd
 >satellites of Saturn's "F" ring? It's a few 10s of km IIRC, and in that
 >environment they probably suffer sufficient ablation to *need* to be
 >acquiring material at a rate similar to their ablation rate (otherwise
 >they'd not be noticeable). That gives a rough probe of the position of
 >the Roche limit for Saturn and material of "dirty snowball"
 >composition. Compared to the other engineering you propose, putting an
 >asteroid into an overgrown string bag to keep it together is not a huge
 >problem.

Saturn's density and radius are on record; the satellite densities will
be in the ice..rock range; and the calculation can be found at Web
<URL:http://www.merlyn.demon.co.uk/gravity3.htm#Roche> and elsewhere.

d = 2.423 R (P/p)^(1/3)

The period of the lowest non-fragmenting orbit of a gravitationally
self-bound spherical body is about 16.8 days, divided by the square root
of its SI density : 1.45E6 / Root(density), ten hours for Lunar density.

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demon.co.uk/> - FAQqish topics, acronyms & links;
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 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

In article <vKyX+SBJLjqBFw6L@merlyn.demon.co.uk>, Dr John Stockton wrote:
> You are redefining the term there. The true limit is for the case where
> the secondary is self-bound only gravitationally, and, in primary radii,
> depends only on the ratio of densities.
>
> But, indeed, for fly-bys it is the strength of ship and contents that
> matters, in comparison with the tidal gradient. There will be no
> problem with any normal ship passing any solar-system body.
>
Agreed, in the limit it is for two "light" particles in close
orbit. In practice the issue is about particles bound (however) into a
"body".

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

In article <vKyX+SBJLjqBFw6L@merlyn.demon.co.uk>, Dr John Stockton
wrote:
> the calculation can be found at Web
> http://www.merlyn.demon.co.uk/gravity3.htm#Roche and elsewhere.
>
> d = 2.423 R (P/p)^(1/3)
>
> The period of the lowest non-fragmenting orbit of a gravitationally
> self-bound spherical body is about 16.8 days,
>
The diagram and the text appear contradictory. Have you slipped
a "p" (either case, standing for rho = density) for an "r" somewhere?

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

JRS: In article <VA.0000031c.08194ca4.RemoveThis@mynameplus1.demon.co.uk.invalid>,
dated Mon, 29 Nov 2004 13:00:05, seen in news:alt.books.larry-niven,
Aidan Karley <aidan.RemoveThis@mynameplus1.demon.co.uk.invalid> posted :
 >In article <vKyX+SBJLjqBFw6L@merlyn.demon.co.uk>, Dr John Stockton
 >wrote:
  >> the calculation can be found at Web
  >> <a style='text-decoration: underline;' href="http://www.merlyn.demon.co.uk/gravity3.htm#Roche" target="_blank">http://www.merlyn.demon.co.uk/gravity3.htm#Roche</a> and elsewhere.
  >>
  >> d = 2.423 R (P/p)^(1/3)
  >>
  >> The period of the lowest non-fragmenting orbit of a gravitationally
  >> self-bound spherical body is about 16.8 days,
  >>
 > The diagram and the text appear contradictory. Have you slipped
 >a "p" (either case, standing for rho = density) for an "r" somewhere?

I don't think so, but it is possible. Can you be more explicit about
which part of the text, and what contradiction you see?

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demon.co.uk/> - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm; quotes.htm; pascal.htm; &c, &c.
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 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

In article <YuCa3aCKO3qBFwfx.TakeThisOut@merlyn.demon.co.uk>, Dr John Stockton wrote:
> > The diagram and the text appear contradictory. Have you slipped
> >a "p" (either case, standing for rho = density) for an "r" somewhere?
>
> I don't think so, but it is possible. Can you be more explicit about
> which part of the text, and what contradiction you see?
>
Maybe "contradictory" isn't the right word. "Confusing" would be
better. I don't know what you're using for an HTML editor (the header
element "<META NAME="MSSmartTagsPreventParsing" content="TRUE">" would
suggest some form of MSWord, but I've never tried using that for editing
HTML), but the code it generates for some situations appears to not work.
You say: "<p>Consider a large primary, radius <i>R</i>, density <font
face="Symbol">R</font>,"
and it renders as
> Consider a large primary, radius R, density R,
>
which sort-of makes it difficult to follow your working in the rest of the
article. I initially suspected something similar between the "p" and one
or several "rho" values representing densities.

Your page states "<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01
Transitional//EN" "http://www.w3.org/TR/html4/strict.dtd">", but the
"font" tag is deprecated in HTML 4.01 and is *not* supported under the
strict DTD.
Headaches keeping up with these things. Have you tried running your
code past the validator at http://validator.w3.org ?

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

JRS: In article <VA.0000033c.1dfb35b5.TakeThisOut@mynameplus1.demon.co.uk.invalid>,
dated Fri, 3 Dec 2004 19:00:07, seen in news:alt.books.larry-niven,
Aidan Karley <aidan.TakeThisOut@mynameplus1.demon.co.uk.invalid> posted :
 >In article <YuCa3aCKO3qBFwfx.TakeThisOut@merlyn.demon.co.uk>, Dr John Stockton wrote:
   >> > The diagram and the text appear contradictory. Have you slipped
   >> >a "p" (either case, standing for rho = density) for an "r" somewhere?
  >>
  >> I don't think so, but it is possible. Can you be more explicit about
  >> which part of the text, and what contradiction you see?
  >>
 > Maybe "contradictory" isn't the right word. "Confusing" would be
 >better. I don't know what you're using for an HTML editor (the header
 >element "<META NAME="MSSmartTagsPreventParsing" content="TRUE">" would
 >suggest some form of MSWord,

Certainly not. I use plain-text editors; mostly PFE but others when
they have a needed capability. Every byte in the file is personally
chosen, typos apart.

 > but I've never tried using that for editing
 >HTML), but the code it generates for some situations appears to not work.
 >You say: "<p>Consider a large primary, radius <i>R</i>, density <font
 >face="Symbol">R</font>,"
 >and it renders as
  >> Consider a large primary, radius R, density R,

You need to say what system you are using. Probably you do not have
Symbol font available to you - Symbol-P is RHO - but that should be a
clear enough indication that what you see as R should be spoken as
*either* Arr or Row. Likewise there is arr & row, and elsewhere pee and
pie, and O-umlaut and Root.

Perhaps you missed the note at the top of gravity3.htm, just below the
table of contents?

I use MSIE4, in which the preferred representation for such characters
(something like ᇗ or Ρ) is not implemented. The only way that
I can see those characters here is by Symbol font, which works for a
substantial majority of users; I refuse to write in a manner that I
cannot read, for obvious reasons, and that outweighs my general
preference for conformance with modern W3-class standards.


 >which sort-of makes it difficult to follow your working in the rest of the
 >article. I initially suspected something similar between the "p" and one
 >or several "rho" values representing densities.

I've now scanned the whole web site, and made it so that Symbol font is
used only for single characters; the set used is
&OGRAVE; &OUML; E H M P Q R W X Z
in either upper or lower case. MiniTrue could be used by a reader to
substitute all of those 11..22 usages into preferred form (I don't know
all the preferred codings myself).


 > Your page states "<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01
 >Transitional//EN" "http://www.w3.org/TR/html4/strict.dtd">", but the
 >"font" tag is deprecated in HTML 4.01 and is *not* supported under the
 >strict DTD.
 > Headaches keeping up with these things. Have you tried running your
 >code past the validator at <a style='text-decoration: underline;' href="http://validator.w3.org" target="_blank">http://validator.w3.org</a> ?

I validate off-line with W3's TIDY, currently of 1 Nov 2003; everything
passes on all pages, except for demonstrations of errors. There is a
problem with many external test services; the authors get carried away
in their enthusiasm, and tend to include superfluous code which crashes
my browser or computer.

It's the best I can do at present; my site does require, of a reader, a
minimum degree of compatibility with my MS IE4. Outside of nit-seeking
web-authoring newsgroups, you are the first person who has reported the
problem.

Thanks for your interest.

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
I find MiniTrue useful for viewing/searching/altering files, at a DOS prompt;
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 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

> Shane Paul <snafu.DeleteThis@fubar.com> wrote:

> > The asteroid would have to have a high nickel-iron content. Greg Bear used
> > Juno in Eon, to create the Thistledown. He only spun it to .6g.
> > Now, if we could just get that magical corridor to infinity stuck onto the
> > end of it, we got it made!
>
<snip>

I really hate to chop and change things around... but a Celestial
"Titanic" conjours up all sorts of frightening images of a shipwreck,
plenty of doom and gloom when the vessel might collide with an icy
comet whilst sailing in the dark waters of the distant Oort cloud that
circles the Sun half way between us and Alpha Centauri.

Therefore, the final name of my ship for this epic, *first* ever
voyage to Alpha Centauri, is going to be called the "Centauri
Princess". That's final!

Abdul Ahad
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

In article <7D0Cc$HK0bsBFwoh@merlyn.demon.co.uk>, Dr John Stockton wrote:
> >element "<META NAME="MSSmartTagsPreventParsing" content="TRUE">" would
> >suggest some form of MSWord,
>
> Certainly not. I use plain-text editors; mostly PFE but others when
> they have a needed capability. Every byte in the file is personally
> chosen, typos apart.
>
That's how I cut my own HTML, when I need to. But it does beg the
question of where the header META tag came from.

> You need to say what system you are using. Probably you do not have
> Symbol font available to you
>
I do have a Symbol family of typefaces available and installed. But
your web page says to use a strict HTML 4.01 DTD in which the FONT tag is
deprecated (you're meant to use CSS instead), so a standards-compliant
browser both OUGHT TO and should ignore your "<FONT .... >" constructs
since they're not an accepted part of HTML 4.01 (strict).

> Perhaps you missed the note at the top of gravity3.htm, just below the
> table of contents?
>
I saw it, but because it mis-rendered similarly to the rest of the
page, it doesn't really help.

> I use MSIE4, in which the preferred representation for such characters
> (something like ᇗ or Ρ) is not implemented.
>
MSIE4 is not (and never has been) a standards-compliant browser. I
hear that development of the IE line was stopped several years ago. I
thought that some of the IEs handled Unicode character entities though.

> You need to say what system you are using.
>
Firefox on Linux and Windows at different times. Also available for
Mac.

> The only way that
> I can see those characters here is by Symbol font, which works for a
> substantial majority of users;
>
Declining majority.

> I refuse to write in a manner that I
> cannot read, for obvious reasons,
>
I know that feeling. I'm a caver - that is a torch in my pocket
(regardless of whether I'm pleased to see you). <G>

> Outside of nit-seeking
> web-authoring newsgroups, you are the first person who has reported the
> problem.
>
I appreciate the difficulty of staying within standards, as the
standards develop. I'm a little surprised that your code didn't show some
orange flags with "TIDY", but that's life. Ultimately, if you're going to
be doing equations, then you really need to look at MathML. But again, the
defunct IE product line doesn't (TTBOMK) know how to render MathML.

I found the remains of IE in the bowels of my machine (it's damned
difficult to get rid of all traces of it), and the 'Symbol' font usage
does show up there (but capital Rho, unicode 0x03A1) looks identical to
the default text font's capital P (0x0050), which is headache-inducing
again.
It's pushing 02:00, and I've things to do tomorrow. Today.
Whatever.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

JRS: In article <VA.00000350.2a367eba.TakeThisOut@mynameplus1.demon.co.uk.invalid>,
dated Mon, 6 Dec 2004 04:00:19, seen in news:alt.books.larry-niven,
Aidan Karley <aidan.TakeThisOut@mynameplus1.demon.co.uk.invalid> posted :
 >In article <7D0Cc$HK0bsBFwoh@merlyn.demon.co.uk>, Dr John Stockton wrote:
   >> >element "<META NAME="MSSmartTagsPreventParsing" content="TRUE">" would
   >> >suggest some form of MSWord,
  >>
  >> Certainly not. I use plain-text editors; mostly PFE but others when
  >> they have a needed capability. Every byte in the file is personally
  >> chosen, typos apart.
  >>
 > That's how I cut my own HTML, when I need to. But it does beg the
 >question of where the header META tag came from.

No doubt I saw something in News that I took to mean that it would be a
Good Thing to have that tag, and by use of keyboard and mouse I somehow
caused it to appear in every page.


  >> You need to say what system you are using. Probably you do not have
  >> Symbol font available to you
  >>
 > I do have a Symbol family of typefaces available and installed. But
 >your web page says to use a strict HTML 4.01 DTD in which the FONT tag is
 >deprecated (you're meant to use CSS instead), so a standards-compliant
 >browser both OUGHT TO and should ignore your "<FONT .... >" constructs
 >since they're not an accepted part of HTML 4.01 (strict).

Can you suggest a better DTD for me to use? I (almost) only use FONT to
get Symbol, site-wide, and could use style for the remainder (not worth
Cascading) - example <URL:http://www.merlyn.demon.co.uk/js-anclk.htm>.


  >> Perhaps you missed the note at the top of gravity3.htm, just below the
  >> table of contents?
  >>
 > I saw it, but because it mis-rendered similarly to the rest of the
 >page, it doesn't really help.

It's only meant to show the existence of the situation ...


 > I appreciate the difficulty of staying within standards, as the
 >standards develop. I'm a little surprised that your code didn't show some
 >orange flags with "TIDY", but that's life.

Well, it could not do that; I use command-line TIDY, from a batch file
(so I just type TRY, and all *.htm in the current directory dated after
TRY was last run in that directory are checked); therefore, results are
monochrome. It does say "No warnings or errors were found.".


 > I found the remains of IE in the bowels of my machine (it's damned
 >difficult to get rid of all traces of it), and the 'Symbol' font usage
 >does show up there (but capital Rho, unicode 0x03A1) looks identical to
 >the default text font's capital P (0x0050), which is headache-inducing
 >again.

Indeed. But I cleverly do not use either P or p as symbols in that
section. (For me, BTW, italic RHO and P are readily distinguishable, by
their slant, and normal RHO and P are *just* distinguishable.)

--
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Web <URL:http://www.merlyn.demon.co.uk/> - w. FAQish topics, links, acronyms
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 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

In article <oNEmfbJPOGtBFwzq RemoveThis @merlyn.demon.co.uk>, Dr John Stockton wrote:
> >browser both OUGHT TO and should ignore your "<FONT .... >" constructs
> >since they're not an accepted part of HTML 4.01 (strict).
>
> Can you suggest a better DTD for me to use?
>
The way I read the standards, HTML 4.01 (transitional) would be better
(deprecated elements are allowed, as long as they're used correctly' "strict"
implies no use of deprecated elements). AIUI. IANA[HTML]Lawyer.

> >standards develop. I'm a little surprised that your code didn't show some
> >orange flags with "TIDY", but that's life.
>
> Well, it could not do that; I use command-line TIDY, from a batch file
> (so I just type TRY, and all *.htm in the current directory dated after
>
Sorry, "metaphorical" orange flags. "Warnings", not "errors".

> Indeed. But I cleverly do not use either P or p as symbols in that
> section. (For me, BTW, italic RHO and P are readily distinguishable, by
> their slant, and normal RHO and P are *just* distinguishable.)
>
I understand that OO.org (OpenOffice.org) has HTML options in it's
"writer" module which will do MathML output. Might be worth following up, as
you work with entities that "are" `big rho', `little rho' etc, not just some
random collection of bits that may or may not resemble a "rho" on your
screen.
ISTR encountering a MathML2GIF module somewhere which would take a but
of MathML code and generate a GIF (PNG?) of the output as a fall-back for
MathML-less browsers.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

JRS: In article <VA.0000035d.2f5c0399.RemoveThis@mynameplus1.demon.co.uk.invalid>,
dated Tue, 7 Dec 2004 04:00:05, seen in news:alt.books.larry-niven,
Aidan Karley <aidan.RemoveThis@mynameplus1.demon.co.uk.invalid> posted :
 >In article <oNEmfbJPOGtBFwzq.RemoveThis@merlyn.demon.co.uk>, Dr John Stockton wrote:
   >> >browser both OUGHT TO and should ignore your "<FONT .... >" constructs
   >> >since they're not an accepted part of HTML 4.01 (strict).
  >>
  >> Can you suggest a better DTD for me to use?
  >>
 > The way I read the standards, HTML 4.01 (transitional) would be better
 >(deprecated elements are allowed, as long as they're used correctly' "strict"
 >implies no use of deprecated elements). AIUI. IANA[HTML]Lawyer.

I've saved the page as <URL:http://www.merlyn.demon.co.uk/g3.htm> with
the beginning being

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/transitional.dtd">
rather than ...html4/strict.dtd">

Is that better?

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demon.co.uk/> - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm; quotes.htm; pascal.htm; &c, &c.
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 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

In article <piYWU0K80ZtBFwBh RemoveThis @merlyn.demon.co.uk>, Dr John Stockton
wrote:
> I've saved the page as http://www.merlyn.demon.co.uk/g3.htm with
> the beginning being
>
> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
> "http://www.w3.org/TR/html4/transitional.dtd">
> rather than ...html4/strict.dtd">
>
> Is that better?
>
Doesn't seem to help.
Beyond my knowledge of HTML/CSS I'm afraid.

--
Aidan Karley,
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay! 

JRS: In article <VA.00000364.33dd7cee RemoveThis @mynameplus1.demon.co.uk.invalid>,
dated Wed, 8 Dec 2004 01:00:05, seen in news:alt.books.larry-niven,
Aidan Karley <aidan RemoveThis @mynameplus1.demon.co.uk.invalid> posted :
 >In article <piYWU0K80ZtBFwBh RemoveThis @merlyn.demon.co.uk>, Dr John Stockton
 >wrote:
  >> I've saved the page as <a style='text-decoration: underline;' href="http://www.merlyn.demon.co.uk/g3.htm" target="_blank">http://www.merlyn.demon.co.uk/g3.htm</a> with
  >> the beginning being
  >>
  >> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
  >> "http://www.w3.org/TR/html4/transitional.dtd">
  >> rather than ...html4/strict.dtd">
  >>
  >> Is that better?
  >>
 > Doesn't seem to help.
 > Beyond my knowledge of HTML/CSS I'm afraid.

OK. I'm considering a process to scan all new *.htm files for the use
of a Symbol character, converting it to an &name; or &#digits; sequence,
with the output file *.html, but difficulties keep appearing.

I never have understood why HTML/Web, being started at CERN, did not /ab
initio/ have a representation for maths symbols, including Greeks, in
which case earlier browsers would have implemented them.

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 MIME. ©
Web <URL:http://www.merlyn.demon.co.uk/> - FAQqish topics, acronyms & links;
some Astro stuff via astro.htm, gravity0.htm; quotes.htm; pascal.htm; &c, &c.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: FW: "First Ark to Alpha Centauri" - the Screenplay!