Duna communications network

[Opsium]

Hello,

I'm fairly new to ksp and have recently sent my first interplanetary mission to Duna. My ship consisted of four landers with 1 RA-2 relay on each and another RA-2 relay on top. Things were fine till I began landing the landers. I landed two and began the process of deorbiting the third lander when all the sudden i had no probe control. After a bit of fiddling I decided to research relay strength (before this i had never left kerbin soi so not having enough signal strength was not a problem.) I found what i needed and made it. I then made the rocket to get it there. Unfortunately i could not recreate the success of my first Duna mission. 

So, i guess what i am asking for is tips on getting to Duna and having a satellite in high enough orbit to maintain a constant connection to Kerbin without spending a ton of delta-v circularizing.

[bewing]

"Getting to Duna"? That usually just requires picking a good launch window. As I understand it, anything from day 20 to day 236 works OK, with increasing quality -- with day 236 being extremely good. Are you already familiar with launch window calculators and deltaV maps?

As far as putting up a relay goes: it sounds like you only lost control/comms when you lost your line-of-sight connection to Kerbin. So the easy answer to fixing that is to just wait until daylight over the targeted part of Duna before you deorbit each lander. Kerbin is always on the daylight side of Duna, so you'd always have LOS if you wait until daylight. If you really want to bounce through a relay in orbit so that you have constant comms -- then the relay has to sit on the night side of Duna. And it's best if it stays out of Ike's SOI (to avoid slingshots), so a fairly polar orbit is best. And you want the orbit to have a really high Ap (at the edge of Duna's SOI), so that it stays in that spot for a long time before quickly completing the rest of its orbit. If you really really want constant comms, then you need at least 4 relay sats -- which gets to be a total PITA. My personal preference is to not bother with any relay sat at all, and just do everything when my landers have LOS.

 

 

[Xd the great]

You need relays. With RA 100 antennas. 

[mystifeid]

For initial forays, I'm with @bewing - LOS is fine. In a career though it pays to research the M700 survey scanner relatively quickly to enable finding the highest ore concentrations. This goes on a sat in polar orbit and it might as well have a relay antenna on it. Add another one in a polar orbit around Ike. When you get a contract for a station orbiting Duna it might as well have a relay antenna too. Add another one orbiting Ike. After researching the Sentinel Telescope contracts will be offered to place them in Kerbol orbit. Hey, throw relay antennae on all of them.

Sooner or later you end up with more relays floating around than you can poke a stick at.

[Laie]

On 8/25/2018 at 9:13 PM, Opsium said:

So, i guess what i am asking for is tips on getting to Duna and having a satellite in high enough orbit to maintain a constant connection to Kerbin without spending a ton of delta-v circularizing.

That's several questions and I'm not sure what your really want to know...

For starters, single relay satellite simply cannot provide 24/7 coverage on the entire body. The again, you don't need 24/7 -- you only want it to be there when you do your landing. Assuming that both your lander and the relay are in different orbits around Duna, you just need to wait a little for a good alignment.

Or as Bewing said, you don't need any relay at all but can just wait until your landing site is about facing Kerbin. That works as long your lander has an Kerbin-reaching antenna that will operate during atmospheric entry.

The ultimate method of saving delta-V is to not circularize at all:

1. send probe with powerful relay on a fly-by of Duna. A rather high flyby, halfway to Ike or thereabouts.
2. have a detachable lander on said probe, with a small amount of delta-V
3. some ten days before the flyby, detach the lander and send it on a collision course with Duna. This maneuver takes perhaps 10 m/s. You maybe don't need no engine at all, possibly the decoupler's push will suffice.
4. The lander enters the atmosphere while the fly-by zooms past overhead, providing relay service.
5. By the time the fly-by relay gets out of range (over the horizon, whatever) the lander is on the ground and can unfold it's own long-range antenna. Now it no longer needs a relay.

This sounds frantic, but isn't. The relay can easily provide coverage for an hour, prolly enough to bring down a lander in the mean time.  But as with all maneuvers, doing it for the first time will be a bit of a learning experience.

Edited August 27, 2018 by Laie

[TheFlyingKerman]

Because Duna has the same side always facing Ike an alternative is to have a relay orbiting Ike, assuming you confine your operation to that part of Duna (which is more interesting).