A Space & astronomy forum. SpaceBanter.com

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Astronomy Misc
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

"Pioneer anomalous acceleration" and Cassini



 
 
Thread Tools Display Modes
  #42  
Old November 14th 03, 09:14 AM
Jonathan Silverlight
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini

In message , Jim
Greenfield writes
(Steve Willner) wrote in message
...
In article ,
Jonathan Silverlight writes:
A Busssard ramjet, as you may already know. Doesn't work, for all sorts
of reasons.


Hard to build, no doubt, but "doesn't work?" Why not? Are you
thinking of the mythical "ramjet speed limit?"


Is there any chance of surmising from the design of Cassini whether a
sustantial differential in the EMR emmission is in one direction?
I suspect tumbling would be the most likely outcome, rather than
linear accelleration.


I don't think so. That's what this argument is about. Anderson et al.
seem to be saying they can't model the emission accurately enough, while
Bertotti et al. seem to disagree. The "thermal thrust" is really, really
tiny and isn't something the mission planners have to worry about. It
just affects very small and possibly non-existent things like the
Pioneer anomaly. The results say _something_ is pushing against
Cassini's direction of movement, and emission from the spacecraft is the
most likely cause, since most of it is facing away from Earth behind the
main dish antenna.
--
Rabbit arithmetic - 1 plus 1 equals 10
Remove spam and invalid from address to reply.
  #43  
Old November 14th 03, 11:44 PM
Jim Greenfield
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini

Jonathan Silverlight wrote in message ...
In message , Jim
Greenfield writes
(Steve Willner) wrote in message
...
In article ,
Jonathan Silverlight writes:
A Busssard ramjet, as you may already know. Doesn't work, for all sorts
of reasons.

Hard to build, no doubt, but "doesn't work?" Why not? Are you
thinking of the mythical "ramjet speed limit?"


Is there any chance of surmising from the design of Cassini whether a
sustantial differential in the EMR emmission is in one direction?
I suspect tumbling would be the most likely outcome, rather than
linear accelleration.


I don't think so. That's what this argument is about. Anderson et al.
seem to be saying they can't model the emission accurately enough, while
Bertotti et al. seem to disagree. The "thermal thrust" is really, really
tiny and isn't something the mission planners have to worry about. It
just affects very small and possibly non-existent things like the
Pioneer anomaly. The results say _something_ is pushing against
Cassini's direction of movement, and emission from the spacecraft is the
most likely cause, since most of it is facing away from Earth behind the
main dish antenna.


Thanks (for the egg on my face re my ignorance)

Jim G
  #44  
Old November 15th 03, 10:53 AM
George Dishman
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini


"Steve Willner" wrote in message
...
In article ,
Jonathan Silverlight

writes:
A Busssard ramjet, as you may already know. Doesn't work, for all sorts
of reasons.


Hard to build, no doubt, but "doesn't work?" Why not? Are you
thinking of the mythical "ramjet speed limit?"


Isn't it to do with the problems of getting hydrogen
to fuse. Most practical attempts use heavier isotopes.
I found this in a quick scan on Google but there is
bound to be something more detailed around (skip the
text quoted and above it):

http://www.asa3.org/archive/asa/200007/0217.html

George


  #45  
Old November 17th 03, 06:33 AM
Jim Greenfield
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini

"George Dishman" wrote in message ...
"Steve Willner" wrote in message
...
In article ,
Jonathan Silverlight

writes:
A Busssard ramjet, as you may already know. Doesn't work, for all sorts
of reasons.


Hard to build, no doubt, but "doesn't work?" Why not? Are you
thinking of the mythical "ramjet speed limit?"


Isn't it to do with the problems of getting hydrogen
to fuse. Most practical attempts use heavier isotopes.
I found this in a quick scan on Google but there is
bound to be something more detailed around (skip the
text quoted and above it):

http://www.asa3.org/archive/asa/200007/0217.html

George


Cart the fuel source along if absolutely necessary, but early Murray
River steamboats were so successful because they could collect their
fuel straight off the bank

Jim G
  #46  
Old November 17th 03, 08:45 PM
George Dishman
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini


"Jim Greenfield" wrote in message
om...
"George Dishman" wrote in message

...
"Steve Willner" wrote in message
...
In article ,
Jonathan Silverlight

writes:
A Busssard ramjet, as you may already know. Doesn't work, for all

sorts
of reasons.

Hard to build, no doubt, but "doesn't work?" Why not? Are you
thinking of the mythical "ramjet speed limit?"


Isn't it to do with the problems of getting hydrogen
to fuse. Most practical attempts use heavier isotopes.
I found this in a quick scan on Google but there is
bound to be something more detailed around (skip the
text quoted and above it):

http://www.asa3.org/archive/asa/200007/0217.html

George


Cart the fuel source along if absolutely necessary,


Sure, but it wouldn't be a ramjet then.

but early Murray
River steamboats were so successful because they could collect their
fuel straight off the bank


The hydrogen in space is almost entirely the plain vanilla
flavour that takes more energy to contain than you get out.
Disappointing, but that's the problem in a nutshell.

George


  #47  
Old November 18th 03, 12:34 PM
Volker Hetzer
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini


"George Dishman" schrieb im Newsbeitrag ...
The hydrogen in space is almost entirely the plain vanilla
flavour that takes more energy to contain than you get out.
Disappointing, but that's the problem in a nutshell.

Maybe that's so with current technology, but since all those stars
seem to manage all right I think it's just so that we haven't figured
out a working concept yet.

Lots of Greetings!
Volker
  #48  
Old November 18th 03, 03:03 PM
[email protected] \(formerly\)
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini

Dear Volker Hetzer:

"Volker Hetzer" wrote in message
...

"George Dishman" schrieb im Newsbeitrag

...
The hydrogen in space is almost entirely the plain vanilla
flavour that takes more energy to contain than you get out.
Disappointing, but that's the problem in a nutshell.


Maybe that's so with current technology, but since all those stars
seem to manage all right I think it's just so that we haven't figured
out a working concept yet.


We have a working concept, allright. We just don't have a container for
the created neutrons. Magnetic bottles don't do a very good job with
uncharged particles. The stars use gravity, which cares only for mass.
Neutrons have mass...

David A. Smith


  #49  
Old November 18th 03, 03:11 PM
Volker Hetzer
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini


(formerly)" dlzc1.cox@net schrieb im Newsbeitrag news:OEpub.8850$vJ6.5695@fed1read05...
Dear Volker Hetzer:

"Volker Hetzer" wrote in message
...

"George Dishman" schrieb im Newsbeitrag

...
The hydrogen in space is almost entirely the plain vanilla
flavour that takes more energy to contain than you get out.
Disappointing, but that's the problem in a nutshell.


Maybe that's so with current technology, but since all those stars
seem to manage all right I think it's just so that we haven't figured
out a working concept yet.


We have a working concept, allright. We just don't have a container for
the created neutrons. Magnetic bottles don't do a very good job with
uncharged particles. The stars use gravity, which cares only for mass.
Neutrons have mass...

Exactly my point.

Lots of Greetings!
Volker
  #50  
Old November 18th 03, 08:37 PM
George Dishman
external usenet poster
 
Posts: n/a
Default "Pioneer anomalous acceleration" and Cassini


"Volker Hetzer" wrote in message
...

(formerly)" dlzc1.cox@net schrieb im Newsbeitrag

news:OEpub.8850$vJ6.5695@fed1read05...
Dear Volker Hetzer:

"Volker Hetzer" wrote in message
...

"George Dishman" schrieb im Newsbeitrag

...
The hydrogen in space is almost entirely the plain vanilla
flavour that takes more energy to contain than you get out.
Disappointing, but that's the problem in a nutshell.


Maybe that's so with current technology, but since all those stars
seem to manage all right I think it's just so that we haven't figured
out a working concept yet.


We have a working concept, allright. We just don't have a container for
the created neutrons. Magnetic bottles don't do a very good job with
uncharged particles. The stars use gravity, which cares only for mass.
Neutrons have mass...

Exactly my point.


And mine, it is a problem, it is not impossible, or
"It's just engineering (tm)" as a manager would say.

George (Dilbert) Dishman


 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 05:03 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 SpaceBanter.com.
The comments are property of their posters.