landing without control

[king of nowhere]

I would like to land on duna with an automated probe (actually a big mining rig; for long reasons i sent the crew away and i would like to land it anyway and refuel so it's ready when, in a couple of years, another ship arrives and may desperately need the fuel), yet i realized a problem.

the probe has a communotron 88, it will get broken by aerodinamic forces during reentry. so i must fold it.

at this point, though, i have no more control on the probe. and i selected the "no control without signal" option; I can't even use the basic control of throttling up and down.

so, i will reenter atmosphere. then i will need to deploy parachutes, and that can be done authonomously, here is the first problem, though, in the probe orientation:  i need to keep it pointed radially, or or makes too little drag and it will crash on the ground before it can deploy the chutes. but after the chutes are deployed, i must turn it retrograde, because the chutes give it a massive tug that would rip the ship apart if it's not pointed retrograde.

and then i must use the rockets to slow down to finish landing, of course. which i can't do without control.

i will have probably around 500 m/s available after reaching Duna. enough for some manuevers, not for a full rocket braking. going to ike and landing there is also not an option, nor is sending a relay, for other weird reasons that mostly amount to self-imposed challenge.

i am using kerbalism, and it gives some additional automated options, but they are triggered by events like "enter atmosphere" or "landed". and they won't let me point radial/retrograde anyway.

 

In short, I can't think of any way to land this thing without breaking the rules of my challenge. i may get away with not landing, it will really depend on how much fuel will be left on the other ship arriving to duna in the future.

anyway, can you think of a way to land without control?

[Daedalus3000]

Maybe KoS would work? I’ve never used this mod and I think you need to physically attach a KoS part  to your ship for it to work, but I know you can program stuff with this without a blatant autopilot.

[king of nowhere]

38 minutes ago, Daedalus3000 said:

Maybe KoS would work? I’ve never used this mod and I think you need to physically attach a KoS part  to your ship for it to work, but I know you can program stuff with this without a blatant autopilot.

i don't know what is KoS.

More importantly, I don't know if it would be compatible with kerbalism.

Even more importantly, I can't attach new parts to my ship, it's currently making the Dres-Duna transfer

[paul_c]

I can't remember how I did it but I think I sent a big multi-part ship to Duna/Ike with a relay or two. Relay detaches, flies to a high orbit, then the lander only needs a small aerial to do it. It would also be possible with a much more scaled-down relay (possibly even with no fuel/engine) if you left it in (low) orbit then immediately went for the landing so you remained underneath it and in its range.

Also for the 1st career, everything that went to Duna had a relay on it too, even if it wasn't asked for. After 3-4 sats there is a semi-useful comms network available for use.

The other option is you could just chance it - the atmosphere on Duna is thin and it might not break off, especially if its retrofired and/or the chutes come out early?

[king of nowhere]

43 minutes ago, paul_c said:

I can't remember how I did it but I think I sent a big multi-part ship to Duna/Ike with a relay or two. Relay detaches, flies to a high orbit, then the lander only needs a small aerial to do it. It would also be possible with a much more scaled-down relay (possibly even with no fuel/engine) if you left it in (low) orbit then immediately went for the landing so you remained underneath it and in its range.

Also for the 1st career, everything that went to Duna had a relay on it too, even if it wasn't asked for. After 3-4 sats there is a semi-useful comms network available for use.

 

as i said, that's not an option. i am on a grand tour mission, can't launch support missions. actually, a relay that does not interferes with the mission is a bit of a grey area, but anyway, i choose to read the rules as no launching relays after the start.

i didn't prepare for this scenario because it was never predicted that the ship in question would ever be unmanned, or far from the mothership in the first place. but at some point i realized i had to change plans, and that eventually led to my mining rig to be sent to dres and abandoned in its orbit.

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The other option is you could just chance it - the atmosphere on Duna is thin and it might not break off, especially if its retrofired and/or the chutes come out early?

that's what i will try if i can't find any better way.

if that won't work, i'll just keep it in orbit, and hope the 50 tons of fuel it could transfer in an emergency would not make the difference between success and failure when the mothership comes back to duna and it will need to slow down enough before aerocapture

[bewing]

In general, Duna is extremely forgiving when it comes to reentry. So your antenna may well survive a normal reentry. If not, you will certainly be able to deploy the antenna while you are still above the ground. Do a test to find out what the antenna can take. Don't just guess what its limits are.

Second, you don't necessarily need to remain Radial. Get your rocket to spin before reentry. Spinning is almost as good as holding radial.

Do you care where you land? If you just lower your Pe to 20km altitude, and spin, you will lose a very large amount of speed before you impact. Make sure your Ap is just above the atmosphere, too. But your target will basically be random.

Did you pack any drogue chutes? On Duna they deploy at quite high speeds.

[Snark]

11 hours ago, king of nowhere said:

the probe has a communotron 88, it will get broken by aerodinamic forces during reentry. so i must fold it.

If you're open to the idea of using mods, you could use this mod of mine that was designed for precisely this type of scenario. 

 

[king of nowhere]

On 1/30/2021 at 11:33 PM, Snark said:

If you're open to the idea of using mods, you could use this mod of mine that was designed for precisely this type of scenario. 

 

i tried first aerobraking without, and the antenna broke easily. then i used this mod, and it went really well. good job