Questions on Teleoperation

victoriatangoman wrote,

"
I don't think we're going to be having autobahn speeds on the moon,
so let's say the trucks are moving at 30 km/h.
"

Whoa! That sounds way, way too fast for teleoperation from Earth to
Moon. I suggest 6 km/h instead.

Ron

"victoriatangoman victoriatangoman@... 01/24/03 08:33 AM

I've been doing some thinking about tele-operation on the moon, or
at facilities located at L4/L5, which are the same orbital distance.
Of course for scenarios involving NEOs or facilities at L2, because
the distances would be greater, the questions I have would just
change in magnitude.

Here are my constants:

Distance to Moon = 384,400 km
Diamter of Earth = 12,756 km
Geo-Stationary Orbit = 6.6108 Earth radii (35,786 km)
Speed of light = 299,792 km/s

First question concerns time lag. Any operations on the moon or at
L4/L5 have to signals that traverse a distance of 768,800 km in an
ideal case with a link from the orbital facility straight to the
earthside teleoperation center. This involves a time lag of 2.5644
seconds.

In a non-ideal case, where the tele-operation center is on the side
of the Earth opposite the moon, and the signal is relayed through
one of three geo-stationary satellites, that adds another 73,028 km
(please check this distance independently as I'm not guaranteeing my
math) to each leg of the trip, thus the time lag is now extended to
3.0516 seconds. And of course, over the period of a day, the time
lag will vary between these two extremes.

If you're operating a lathe, a metal foundry, a welder, an orbital
transfer vehicle, a lunar dump truck, a lunar loader, etc, etc, etc
I wonder how you compensate for the time lag?

I don't think we're going to be having autobahn speeds on the moon,
so let's say the trucks are moving at 30 km/h. The time lag would
mean the truck would move 21.37 - 25.43 meters from when you either
ANTICAPTED the need to apply an action 1.5 seconds in advance, or
responded to a stimulus, to when that action was carried out.

I'm sure that you can create your own scenarios with any industrial
process you're familiar with.

What is the technological fix for this issue?

Second question concerns the signal beam steering for a constant
link between the orbital facilities and the Earth facility via the
geo-stationary satellites.

How accurate are constant link techologies? Can a beam be kept on
target and then switched to another satellite with no interuption of
service, or will all operations have a hiccup when the beam is
retargeted to another satellite?

Third question concerns integrity of data sent. Using the internet
as an example, how would packet loss be handled, wouldn't this
confirmation of data integrity just add to the time lag. On Earth,
we can pretty much think of the speed of light as instantaneous, so
requesting computer confirmation of data received doesn't involve
that much time lag, but with a round trip of 2.5 - 3.0 seconds for
this data integrity confirmation process, what happens to the
overall time lag? Will the data stream have to be designed to
operate like a CPU with multithreading and caches?

Fourth question concerns bandwidth. If we're having multiple
thousands of tele-operators, and some of them are using video feeds
in addition to machine data feeds, then how much bandwidth can a
transmitting facility handle? Will there have to be multiple dishes?
Can the beams be split over muliple frequencies without crossing
into other restricted frequencies? I have absolutely no clue about
the total bandwidth that thousands of tele-operators would require,
but I raise this question because of recent comments from the
satellite TV industry being concerned about having to carry HDTV
signals and predicting that they'll only be able to carry a small
percentage of existing channels. If we have a lot of video feeds, as
well as data, are we going to have to send up so many satellites as
to equal or surpass the entire satellite TV industry? Any insight
would be helpful.

I hope that someone can provide the answers I'm seeking.

TangoMan