"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?"

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.

Jim G

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
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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

"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

"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

"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

"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

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

(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

"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