Planetary rovers, SETI and other musings, was Re: update.356 (fwd)

[Jim Choate <ravage@ssz.com>]

Hi Steve,

Can I forward your questions to another technology list I support as well as
the local high performance rocketry group I'm involved in? I believe
they would be intriqued by your questions.

Forwarded message:

> Date: Tue, 27 Jan 1998 19:56:33 -0800
> From: Steve Schear <schear@lvdi.net>
> Subject: Planetary rovers, SETI and other musings, was Re: update.356 (fwd)
> 
> >ANOTHER VERSION OF QUANTUM TELEPORTATION is

[text deleted]

> I wonder how far off use of this technique for interplanetary rovers might
> be (10 years, 20 years)?  Remote (Earth) rover manipulation is tedious at
> best due to several minutes (or an hour or more to the outer planets) of
> propagation delay.

As I understand the process you don't get around the speed-of-light issue
because the control channel still needs to be sent via radio or laser or
whatever. This was discussed in the in the original teleportation
announcement. However, I don't see anything that would keep you from syncing
two atomic clocks and then using them to make the changes in sync, this
should allow the imposition of the speed of light only on initiation and
occassion syncronization. I'll have to beg ignorance on specifics as I
haven't had the time to really dig into specifics. I haven't even read the
primary references to date.

> Autonomous rovers need enough smarts built-in to handle
> unexpected situations, a non-trivial problem.  An alternative is to
> establish a link using entangled photons. If a simple approach to saving
> these entangled states during signal transit, in both directions, were
> found instantaneous communication and simplified remote control would be a
> reality.

Agreed. It would also solve many terrestrial problems as well.

> Of course one needn't stop there.  If entangled states could be stored for
> several years, instantaneous communication with neighbooring stars is a
> real possibility.  Coupled with advances in mind-machine science it might
> someday be possible to explore, first-hand, our local portion of the galaxy
> without leaving earth, or upload/download one's consciouness to vessels in
> remote locations.

True, but it would be boring compared to being there first person. I do
support robot exploration as a precursor to manned exploration.

> Speaking of which, do the current SETI programs check for signal modulation
> using polarization.

>From what little I have delved into this, most signals coming in from 'out
there' as well as from satellites are circularly polarized. This is the
reason that the antennas have those curly-ques on them (look like a
cork-screw sorta). The last time I even messed with extra-terrestrial
signals was the SL-9 impacts. I worked with several amateur groups using plane
(flat rectangular) loop antennas to measure the increase in the background
noise in various bands (we used a HP spectrum analyzer at my site) during
the impacts. What we saw was a 'jump' across the band of several db's just
at the time-of-flight times we expected. The assumption being this was
caused by the impacts. We monitored 1MHz to 10MHz. I found it pretty
impressive. We got, if memory serves, around 6 of the large impacts.

>  If we've discovered this trick, sure so have other
> intelligent life forms.  Most natural sources of radiation tend to
> unpolarized, so a rapidly flucuating polar modularion might easily appear
> to be noise.

I'll have to disagree, all forms of E-M radiation that I am aware of are
polarized to some frame of reference. The E-M fields after all are
orthogonal. The question is which field you want to pick as a reference
and the relationship of source to sensor. Circularly polarized (ie the
fields rotate around the axis of transmission at some rate) are about the
only sort that would appear essentialy the same irrespective of reference
frame.


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