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Remote tech signal delay landings


Teutooni

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As part of my unmanned mission to Moho, I decided to include landing gear on the low-altitude probe and try landing it. The whole mission included 3 probes on different altitudes fitted with communications equipment and different science instruments and SCANsat sensors, so the landing part was just an afterthought. With nearly 4 minutes of signal delay introduced by the remote tech mod, I didn't think much of my chances.

When everything else I could gather was done, it was time to try this. After a small deorbit burn, I instructed the probe to orient surface retrograde and burn for 1000m/s (all the fuel that was left) and throttled the engine to 0%. Then a few seconds later I instructed the probe to throttle engine to 10%, thinking there would be a 4 minute delay. Turns out there is no delay when you manually right-click an engine and adjust it's throttle. Manually adjusting the throttle in real-time would have made the landing trivial, if the probe was designed to land (centre of mass was off, and delta-v was short some 50m/s). It was the roughest landing I have ever done, hitting the ground 50-60 m/s and spinning wildly as I tried to burn the engine at 100% throttle every time the spinning probe pointed retrograde. Lost all of the solar panels, but by some miracle the extended communications antenna as well as all the science instruments survived - I think the spinning landing gear managed to absorb most of the shock.

What do you think of this? Is it cheating to ignore the signal delay on throttle? Should there not be an automated landing protocol in a probe that is 4 light-minutes away? How would you balance landing a far-away probe so that it would be suitably challenging but not require excessive manual calculations?

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Cheating is a matter of perspective in single player games. It's your game and only your game so you are free to play it how you want. We don't really have any of the "known" methods for remote landing in the game. Satellites don't land, the only landing of remote probes we do in the real world is for rovers like Curiosity, which was done by a sort of drop ship.

And then there was Spirit and Opportunity that landed inside a giant balloon structure and bounced for miles before stopping.

Edited by Alshain
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Real-life soft landers (Surveyor, Viking, Phoenix, Curiosity) have onboard software that uses radar altimeter data to control their engines. If you can find a large enough mostly-flat area to aim for, you can do something similar with kOS. That's the purist's way to do auto-landing. If you need to avoid or correct for a substantial slope, it helps to have additional rangefinders in more directions than straight down, which kOS is a release or two away from being able to read (although there's a usable part at http://forum.kerbalspaceprogram.com/threads/86062-WIP-Plugin-Parts-LaserDist-0-2-for-KSP-0-24-Alpha whenever kOS catches up).

The other option is MechJeb. With default settings, MJ can control a probe without signal delay as long as a connection is present. The problems are that MJ's landing autopilot is sometimes quirky and that some people prefer not to have MJ's other features available.

What some people might like is a "landing guidance sensor" part that has a reasonably reliable terminal-descent autopilot but not the rest of MechJeb.

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Games frequently end up in situations where "realism" to the letter in one respect destroys realistic outcomes. This sounds like one of those times to me. Signal delay is realistic, but without the appropriate systems to allow some autonomy, it makes realistic probes impossible as landings are not remotely controlled with insane delays, the orbiters are designed (as said above) to measure altitude, and land by themselves.

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Games frequently end up in situations where "realism" to the letter in one respect destroys realistic outcomes. This sounds like one of those times to me. Signal delay is realistic, but without the appropriate systems to allow some autonomy, it makes realistic probes impossible as landings are not remotely controlled with insane delays, the orbiters are designed (as said above) to measure altitude, and land by themselves.

I think landing with kOS best captures the "all you can do is wait to find out whether it worked" excitement of a real-life autonomous landing. But it's not for everybody. Some people can't run it with other mods that are higher priority. Others just don't find writing programs fun. Turning off signal delay and doing what a more sophisticated computer would do is a perfectly fair way to simulate an autonomous landing if it's what works for you.

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Writing a program is fine, but real landers have altitude information, it's not all time-based. Needlessly harder, is not "realistic." Yeah, doing it manually makes more sense (no delay).

kOS can already read altitude above the ground directly below you, which is good enough to start playing with altitude-based autoland scripts on flat ground.

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