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Long-distance surface-trips by Transrapid instead of rovers

Posted by: Ekkehard Augustin - Sun Apr 03, 2005 3:34 pm
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Long-distance surface-trips by Transrapid instead of rovers 
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Post    Posted on: Tue Apr 12, 2005 2:34 pm
If the satellite would orbit at above the lunar equator exactly it cannot be prevented that there are times during which the telescope looks to the satellite.

As far as I know the telescope will be used for observations at a range of frequencies.

Different to Pioneer 10 the satellite will be extremely close to the Moon. Compared to the distance of Pioneer 10 the satellite will be nearly ON the Moon. So it may be that it doesn't matter if the satellite will have or use a directional antenna.

To exclude disturbation as sure as possible it is best to use laser communication.

But all this is a little bit off-topic in between - laser or radio isn't of significant meaning for long distance transportation questions.



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Post    Posted on: Tue Apr 12, 2005 2:47 pm
I still think that a radio link would be no problem. Observations are simply not scheduled during the 0.001% of the time the satellite in the way. Interference, even at this close range, can easily be avoided with good design. Lasers would work too.

The SETI detection of Pioneer was not interference. They were testing the SETI receiver by intentionally targeting the Pioneer signal.
http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179273

And I agree that the whole discussion is a little off topic.


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Post    Posted on: Tue Apr 12, 2005 4:48 pm
campbelp2002 wrote:
Even very badly designed receivers emit only a very small amount of noise. A well designed receiver on a satellite many kilometers away will not be detectable at all.


This statement is not necessarily true. Satellites are not designed in the same way as equipment used on Earth. On Earth equipment must comply with commercial EMC emission limits determined by the country they are used in (the FCC set these in the US and the EU in Europe), military equipment must meet military specifications. In space no such rules apply because the equipment is so far away from anything it might interfere with and the only real concern is whether it can function without causing itself a problem. For this reason satellites normally have a specific EMC requirement based upon what its internal components can tolerate, this normally leads to satellites that are much more rf emissive than normal household equipment.

A satellite manufacturer will only be interested in reducing rf noise levels if it creates a problem for him. Radio astronomers or other people are not normally considered when defining an EMC spec for a satellite so this may be a problem in the scenario being discussed. This is not to say that it would be impossible to design a quiet satellite, just that it is not normally a consideration and may cause additional problems.

Any receiving antenna has the ability to transmit rf emissions at a range of frequencies (granted at lower levels outside its normal operating range) generated as internal noise by onboard equipment.

I have tested electronic components destined for use on satellites that would not meet any kind of civil or military spec but were deemed to be acceptable for space use.

Another point is that I'm not sure you could just turn a satellite completely off as it probably needs to send telemetry signals to keep position and check whether you are trying to talk to it to switch itself on again.

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Post    Posted on: Tue Apr 12, 2005 5:41 pm
The relay in question will be an integral part of the radio telescope system, not some generic communication satellite. Any noisy design will not win the contract. Also, the telescope is a very directional antenna pointed well away from the satellite and listening on a different frequency. The relay would have to be pretty noisy to be a problem under those circumstances.
And any telemetry would be aimed at the control center on the other side of the Moon or on Earth and not at the telescope. If you need a period of EXTREME quite, just command the satellite to sleep for a specified time.


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Post    Posted on: Tue Apr 12, 2005 5:55 pm
Aiming is subjective over such a long distance and a radio beams of over 10GHz are likely to have a footprint of a few kilometers at least, lasers would be better.

I thought that EXTREME quiet was the reason for going to the moon in the first place. :)

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Post    Posted on: Tue Apr 12, 2005 6:10 pm
Andy Hill wrote:
I thought that EXTREME quiet was the reason for going to the moon in the first place.
OK, you got me there.

But I still think a quite enough RF relay would be easy to build. The transmitted signal would be aimed at the control center on the other side of the Moon from the telescope, not just a few km away. A separate and very quite receiving system on an independent antenna would do all the listening. For sending commands to the telescope, a 3rd dedicated antenna connected to a transmitter that is powered down when not sending commands would be used. The point is that the telescope operators also control the relay. They send signals when they need to and tell it to be quite the rest of the time. They can't tell the BBC to stop broadcasting when they want to make an observation on Earth!


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Post    Posted on: Thu Apr 14, 2005 11:25 am
Last Saturday I mentioned that transportation on the lunar surface may have to go over hills and mountains as well as crossing valleys. I imagine that it may be easier to enable this by the beam of a Transrapid because such a beam required one pylon in distances of several meters only and not to cover each squaremeter of the track.

Currently this seems to become a more relevant and more actual question because of a concrete finding. The article "Perfect Spot Found for Moon Base" ( www.space.com/scienceastronomy/050413_moon_perfect.html ) says that at the rim of the Peary crater at the lunar Northpole the sun never sets and that it could be a good place to install a lunar station.

Now it is hard for me to imagine that the CEV or any other lunar vehicle wouldland at the rim because it is not broad enoughl (does someone know, how broad?). The vehicle would land in the plane below the rim I suppose. In that case equipment would have to be transported uphill - the equipment for the station perhaps but the solar cell equipment at least.

And if these solar cells were those ones to provide the electricity for a radio telescope at the far side hills and mountaines as well as valleys are closer to an actual relevant topic too. Transportation will have to go up and down them and the equipment to be transported will be heavy often.



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Post    Posted on: Thu Apr 14, 2005 12:21 pm
While it is necessary for the solar array to be up on the rim, the actual base and landing pad might be better to be sited in the crater near possible lunar ice deposits. Power could be beamed to the base from the rim, making constantly hauling equipment, people and resources up the crater wall unnecessary.

This would be better for logistics but maybe not so good because of the much lower temperatures that might be at the crater floor. Also the base might require additional power for life support systems to deal with the harsher temperature swings in the crater and need to be maufactured from different materials to cope with the cold.

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Post    Posted on: Thu Apr 14, 2005 12:46 pm
The requirement of transportation uphill seems to be there at all.

And I would add another thought: landing at least seems to require sunlight as long as there is no electrical light installed.

Landing inside Peary crater or any other polar crater even may cause the evaporation of water deposites - so the landing site and launching site shouldn't be inside such a crater.

So there seem to be two reasons at least to land and launch outside polar craters, to install solar cells at the rim of polar craters and to get water from inside the polar craters - resulting in the requirement of transporation uphill from the landing site to the rim, downhill from the rim into the inner side and reverse: At least some water will be required outside the crater.

Water deposites may be a reason to land or launch never in shadows but to look for water there.



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PS. Besides - isn't it possible that somewhere at the moon ice is hidden meters below the surface in non-polar regions too? Ice ressources that can be detected by equipment like that of Mars Express only? Or has such equipment already been applied to search for ice?


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Post    Posted on: Thu Apr 14, 2005 12:57 pm
Ekkehard Augustin wrote:
PS. Besides - isn't it possible that somewhere at the moon ice is hidden meters below the surface in non-polar regions too? Ice ressources that can be detected by equipment like that of Mars Express only? Or has such equipment already been applied to search for ice?
No equipment capable of detecting ice that deep has been sent to the Moon, as far as I know.


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Post    Posted on: Thu Apr 14, 2005 1:08 pm
Interesting - if we are right there shouldn't be any landing/launch sites at locations where lunar ice deposites could be destroyed or the access to them barred by the sites.

In between I thought of the diameter of Peary crater - 73 kilometers. Water may have to got from the total of its shadowed area - which means transportation over distance a martian rover never has gone. The weight of water per transport may be significant because one man needs at least one liter of water per day. There will be several men at the station and some equipment too will require water- and it's designed to be a permanent station.

Still it's not sure that a station will be placed at the Northpole - but currently it will be tried to get water from the poles. Long distance transportation trips again appear to be a relevant topic.



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Post    Posted on: Wed May 18, 2005 10:21 am
In between there is an article that containes a consideration of long distance surface trips: "Not So Picture Perfect: Proposed Lunar Landing Site Has Drawbacks" ( www.space.com/adastra/adastra_lunarsite_050517.html )

It says

Quote:
... the search for the eternal light brings with it the inherent drawbacks of: putting us in very small local areas surrounded by much more challenging polar terrain, putting us where we have no, or greatly reduced, access to iron and other industrially essential elements more abundant in mare regolith. Both poles are highland areas.

putting us in a place from which it is hard to travel overland to anywhere else still needing to have a power storage system on top of a more massive system of solar arrays linked by cable around the polar mountain or rim crest having to set up shop in relatively non-flat areas. Laying out the extended solar power array system in mountain terrain, involves high risk to personnel and equipment. ...


In mentions too tha David Schrunk has worked out a concept that includes a railroad - Peter Kokh recommends Schrunk's book. But it may be that Schrunk simply didn't think of Transrapid/maglev. Perhaps I will write and e-mail to Peter Kokh to ask him what he thinks about my Transrapid-thought.



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Post    Posted on: Tue May 31, 2005 9:26 am
It seems that the extra mass required for a lunar rail system means that rovers are much more viable to transport people across the moon's surface.

http://www.thespacereview.com/article/380/1

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Post    Posted on: Tue May 31, 2005 10:21 am
I read it but still have to think about it. My own point was mass transportation of mining products and products of manufacturing - a topic Peter Kokh focused on too.

Passenger transportation over long distances wasn't my focus yet - currently I suppose that I would prefer space vehicle for this purpose. But for transportation of masses of lunar mining products for ISRU I wouldn't.

I suppose a lunar Transrapid to be faster than a rover - in this case it would have advantages if time is the problem. The advantage would have to outweigh the disadvantage in mass, material, installation costs and so on. I could imagine that the lower gravity would simplify the technology - not that much pylons required and so on.



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Post    Posted on: Tue May 31, 2005 11:58 am
Ekkehard Augustin wrote:
I read it but still have to think about it. My own point was mass transportation of mining products and products of manufacturing - a topic Peter Kokh focused on too.


I'm not sure that there will be a need for this, large manufacturing facilities will probably ship most products off moon rather than for local use. The smaller quanties used on the lunar surface can be transported by rover or bases will grow up around those resources and not need large quanties moved.

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