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Is there an orbit that has always a direct line of sight with the mun (free field of view)?


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I have a commnet system active that works "up to" 3 Mega meter semi major axis. Now I wonder: can I add a single dish to this constellation to have a non intermittent communication with the mun? Or what is the minimum amount of satelites I need to do this?

 

I first tried to think of a polar orbit, however since the Mun is rotating, Kerbin will occlude half the orbit half the Munar cycle. So then i thought "how do I do this in my education", and the answer is "Use J2" pertubation, which obviously is absent.

 

So what is the better solution for ksp?

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1 hour ago, paul23 said:

Well that wouldn't solve the problem at all: since my current network doesn't extend that far. So then I'd have to have a satellite tracking that Mun trojan.

Comnet ranges depend on the sizes of both antennas, so just use a bigger antenna on your satellite(or, multiple stacking antennas, giving you an even larger virtual antenna).

As an added bonus, it could double as an interplanetary relay as well...

 

Edit:

Current network: 3Mm (Note: this is the range for a command pod connecting to the level 1 tracking station)

Mun: 12Mm

If you include a Communotron 16(the basic antenna) on your vessel, range increases to 31Mm for a level 1 tracking station, no need for a relay.

A level 2 tracking station can talk to command modules out to 15Mm

A Communotron 16-S  would not have any trouble reaching Kerbin from a Mun trailing orbit, but you may need it fairly close to the Mun to be able to reach it from command pods.

 

This page tells you how big an antenna you need to use based on your tracking station and how far you want to go:

https://wiki.kerbalspaceprogram.com/wiki/CommNet

Note how the 88-88 never needs a relay to reach a level 3 tracking station unless you have occlusion.  

 

Edited by Terwin
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Pics or diagram of your comnet? What is that distance you mentioned as a percent of Muns SMA?

A polar highly elliptical orbit will have line of sight most of the time if you can't do a pseudo L4 or L5 point

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Well I use remotetech/nerfed all ranges to the ground since I am not interested in "hey lets have it easy like stock is, and just use omnidirectional antenna's cause you can just stack them". Question isn't so much about what is the best antenna, but how to get visibility from "high kerbin orbit", and the minimum necessary satellites.

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I find that its efficient to keep a single satellite in a high polar orbit, and then dedicate an antenna on my geosynchronous satellites towards whatever mission I'm doing. Between the polar sat and at least 3 in geosynchronous orbit around Kerbin its 100% coverage. 

If you don't want a bunch of satellites, make them bigger and add more antennas. 

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There is no orbit in which a single satellite is never occluded by Kerbin from a given vantage point inside Kerbin's equatorial plane.

There are ways of mitigating the signal loss to the absolute minimum possible, such as utilizing an extreme tundra orbit (71km periapsis over one of the poles, apoapsis as high as the SoI will allow over the other). But that one requires a strong antenna, since the satellite will be way above or below the equatorial plane 98% of the time.

For circular orbits, the larger the orbit is the less frequently the occlusion will happen, but the longer the occlusion will last. On average, the total fraction of occluded time vs. visible time improves quite a bit with a large orbit, but on the very rare cases where there is an occlusion, you'll have to deal with 20-30 minutes of no signal. Also, the larger you make the orbit, the better the antenna must be, because it will swing farther out on the opposite side of Kerbin from your vantage point on the Mun.

However, you can have a guaranteed 100% uptime with two satellites. Does not matter if you arrange them in an equatorial orbit, or a polar orbit, or anything in between... the Mun will always be able to see at least one of two satellites if they are phased 180 degrees apart. An orbit as low as 500 km above Kerbin's surface is easily enough for this, assuming you can reach this distance from the Mun. If not, any higher orbit works just as well, up until a point where you get so close to the Mun's own orbit that the distance to a satellite phased 90° is approaching the distance to Kerbin again.

If you are concerned about occlusion, I'd go with the two-satellite solution. If you're concerned about cost, use one in as large a polar orbit as is practical, and accept that once in a blue moon you'll have a short blackout.

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20 hours ago, paul23 said:

I have a commnet system active that works "up to" 3 Mega meter semi major axis.

I guess it won't be long until you get better gear. Until then, do as KeranoKerman says and put one on a Mun-like orbit. It should be good for a game year or two until it falls into the moon.

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