Re: Ranging and Pioneer

[Jonathan Silverlight]

In message <mt2.1-19034-1154204421@sshserv.aei.mpg.de>, Oz
<Oz@farmeroz.port995.com> writes
>Richard Saam <rdsaam@att.net> writes
>>The New Horizon space craft somewhat fits this description.
>>The New Horizon project people
>>are well aware of the Pioneer deceleration Anomaly
>>and are making every effort to replicate it.
>
>Unfortunately the only comment seems to be on
>
>http://www.boulder.swri.edu/pkb/
>
>in
>
>New Horizons 2 Concept Overview (Feb 2005)
>
>Which is a powerpoint document I cannot read.
>
>Could you give some indication of what they can do on the anomalous
>pioneer acceleration?
>

Are you sure that's the right document? I don't see anything about the
Pioneer anomaly (though the mission looks well worth flying !)
Unfortunately, it seems that the New Horizons design isn't suited to
this experiment - as Charles Francis (Oh No) has already noted in this
thread, the emission from the RTGs is likely to produce thrust which
can't easily be modelled (I must admit I don't understand why Cassini
had this problem, despite having it explained to me elsewhere. The
Italian relativity experiment on Cassini achieved residuals which were
much lower than from the Pioneers, which seems to show that they
modelled the heat emission very well).
BTW, why can't you read Powerpoint documents? There's a free viewer from
Micros**t.


[[Mod. note -- I rather doubt the free viewer works on Macs, GNU/Linux
systems, or any of the less common non-microsoft OSs around...
-- jt]]

[Richard Saam]

Jonathan Silverlight wrote:
> In message <mt2.1-19034-1154204421@sshserv.aei.mpg.de>, Oz
> <Oz@farmeroz.port995.com> writes
>
>>Richard Saam <rdsaam@att.net> writes
>>
>>>The New Horizon space craft somewhat fits this description.
>>>The New Horizon project people
>>>are well aware of the Pioneer deceleration Anomaly
>>>and are making every effort to replicate it.
>>
>>Unfortunately the only comment seems to be on
>>
>>http://www.boulder.swri.edu/pkb/
>>
>>in
>>
>>New Horizons 2 Concept Overview (Feb 2005)
>>
>>Which is a powerpoint document I cannot read.
>>
>>Could you give some indication of what they can do on the anomalous
>>pioneer acceleration?
>>
>
>
> Are you sure that's the right document? I don't see anything about the
> Pioneer anomaly (though the mission looks well worth flying !)
> Unfortunately, it seems that the New Horizons design isn't suited to
> this experiment - as Charles Francis (Oh No) has already noted in this
> thread, the emission from the RTGs is likely to produce thrust which
> can't easily be modelled (I must admit I don't understand why Cassini
> had this problem, despite having it explained to me elsewhere. The
> Italian relativity experiment on Cassini
> achieved residuals which were
> much lower than from the Pioneers, which seems to show that they
> modelled the heat emission very well).

A summary of Space Craft Specification are as follows:

Typical Refs:
http://spaceprojects.arc.nasa.gov/Space_Projects/pioneer/PN10&11.html#spacecraft
http://en.wikipedia.org/wiki/New_Horizons
http://www.esa.int/SPECIALS/Cassini-Huygens/SEM9D2HHZTD_0.html

Pioneer New Horizon Cassini-Huygens

Mass 241 kg 470 kg 5712 kg

Moment of Inertia 588 kg m^2 401 kg m^2 ?
around spin axis

antenna diameter 2.74 m 2.1 m 4 m

estimated area 4.30 m^2 3.30 m^2 6.28 m^2
normal to
sun/earth

Mass/Area 56 kg/m^2 142 kg/m^2 909 kg/m^2

Area/Mass .01786 m^2/kg .00702 m^2/kg .00110 m^2/kg

Radiated
RTG Power 5 Kw 5 Kw ?

One hypothesis is that space object deceleration
is proportional to space object Area/Mass.
(Area is that projected towards observer)

The very small Cassini-Huygens area/mass ratio
may be an indication why no anomalous deceleration
was detected on this platform.

The New Horizon space craft Area/Mass ratio
although smaller than Pioneer Area/Mass ratio
is much larger than Cassini-Huygens Area/Mass ratio
and worthy of investigation in regards to anomalous deceleration.

As noted by Jonathan and Charles Francis

http://www.daviddarling.info/encyclopedia/P/Pioneer_anomaly.html

"the emission from the RTGs is likely to produce thrust which
can't easily be modeled"
because of New Horizon RTG being close
to centroid instrument package as evidenced
by New Horizon small Moment of Inertia around spin axis
relative to Pioneer Spacecraft.

"can't easily" does not mean 'can't be done'
I am sure the New Horizon Team will make every effort to do it.
There will be plenty of time to analyze data
through space craft active and sleep modes.

http://pluto.jhuapl.edu/mission/mission_timeline.html

The anamolous deceleration effect should begin to be apparent now
while nearing Jupiter rendevous in February 2007
and continue at a constant value past
Pluto (July 2015),
Kuiper belt (2016 - 2020)
and beyond.

This constant deceleration effect should be observable
within changing power (RTG and others)
radiation pressure characteristics
of the New Horizon space craft.

The above space craft physical data
are estimates from web pages only.
If someone has better data,
I would appreciate having it,
particulary
a radius of gyration for each spacecraft
and more precise projected area & mass numbers.

Richard Saam