Musing about spaceflight concepts and originality...

[Guest]

I've been doing a new save and making designs from the ground up since breaking ground launched, before that I hadnt played Kerbal for a while. Anyway, I spent all night last night going down the rabbit hole of designing a mission to the Mun, and so needed to design and test a lander which soon became a system of Munar exploration involving a orbital tanker stage which the lander could use as a DV source to make orbital changes to explore different areas and to re-dock with and refuel for more missions. This system seems very similar to the Lunar Gateway plan NASA is going ahead with, with using the orbiter to take the lander into different high inclination orbits like a tugboat, and I wondered how much of the physics of the problem determined my solution or how much of the things currently being done in spaceflight have coloured my thinking. (This wasnt actually the thing that started me thinking about that, this was >>) After I had the Mun mission vehicles designed and tested I then needed to make a rocket to get them to orbit and since I like to optimize the launch I did a lot of iterating to find the right combination of fuel and engines to get a nice lazy gravity turning launch profile to orbit and after more hours than I'd like to admit, I ended up with something that is pretty much the SLS... Although it has 4 SRBs.  

So after all my tinkering and thinkering I ended up with basically a copy of an SLS and something essentially the same as the Lunar Gateway system.

Just the musings of an imaginationless copycat   

 

[Epicdreamer]

Copycat maybe. But at least you're a bit closer to understanding how the SLS and Lunar Gateway came to be. In a (Kerbal) way you went through the same development proses yourself. Nice read, thanks!

[Xavven]

KSP inspired me to go read about real missions undertaken by NASA and the Soviet Space Program, and while KSP isn't the highest fidelity spaceflight simulator, there's enough realism and simulation in it that many IRL solutions turn out to be optimal solutions in KSP too. It's no coincidence that you've copied some of NASA's ideas.

[Ratwerke_Actual]

This is reminiscent of most cars resembling one another when all were designed in a wind tunnel.

The mathmatics take them all in the same direction.

This effect may be magnified in KSP by having fixed part choices.

[cantab]

Partly yes, I think that despite some unrealistic aspects to KSP, a lot of it is the same problems, so the same solutions. Partly it may be unconscious (or even conscious) art imitating life. And there's the KSP part selection.

 

[Geschosskopf]

23 hours ago, Dale Christopher said:

So after all my tinkering and thinkering I ended up with basically a copy of an SLS and something essentially the same as the Lunar Gateway system.

Just the musings of an imaginationless copycat   

Very pretty rocket and an entertaining story of convergent evolution.

I think NASA stole the idea from KSP as this method has been used in the game for years .  The usual KSP approach, however, is not to use the refueling station as a tugboat but to put it in a highly inclined, non-synchronous orbit.  Thus, the station will eventually pass over ever point of the world's surface so you can land wherever you want, provided you don't mind waiting for it to rotate under your path.  The lander then makes relatively minor inclination changes as needed going down and up.  This burns less fuel than making major plane changes with the combined mass of the lander, the station, and all the extra fuel, so the spare fuel lasts longer, allowing more landings.

 

[Guest]

13 hours ago, Geschosskopf said:

The usual KSP approach, however, is not to use the refueling station as a tugboat but to put it in a highly inclined, non-synchronous orbit.  Thus, the station will eventually pass over ever point of the world's surface so you can land wherever you want, provided you don't mind waiting for it to rotate under your path.  The lander then makes relatively minor inclination changes as needed going down and up.  This burns less fuel than making major plane changes with the combined mass of the lander, the station, and all the extra fuel, so the spare fuel lasts longer, allowing more landings.

This sounds great! and yer I didnt like dragging around the whole deltaV source just so it would pass over my landing spot, but I wasnt thinking about putting it in an orbit that would naturally pass over the whole surface, hmmmm. The downside of needing to wait until the orbiter was back into the correct plane might be annoying, If I'm understanding it correctly it would be approximately once per month that you could optimally redock the lander? (I'm not familiar with exactly how this works, (I'm imagining that you'd be reliant on the moon's orbital period to present different parts of its face to your orbiter or something) I'll do some tinkering in kerbal to see if I can figure it out!

Edited June 10, 2019 by Guest

[AngrybobH]

19 minutes ago, Dale Christopher said:

If I'm understanding it correctly it would be approximately once per month that you could optimally redock the lander?

The muns day is 6 days 2 hours 36 minutes and 24.4 seconds (according to the wiki). Your landing site would line up with the plane of the orbiter twice in that period. This is not a direct rendezvous because the station would not necessarily be right there but you would be launching into it's plane. Rendezvous from there should be fairly easy on the fuel.

Edited June 10, 2019 by AngrybobH

[Geschosskopf]

11 minutes ago, Dale Christopher said:

This sounds great! and yer I didnt like dragging around the whole deltaV source just so it would pass over my landing spot, but I wasnt thinking about putting it in an orbit that would naturally pass over the whole surface, hmmmm. The downside of needing to wait until the orbiter was back into the correct plane might be annoying, If I'm understanding it correctly it would be approximately once per month that you could optimally redock the lander? (I'm not familiar with exactly how this works, (I'm imagining that you'd be reliant on the moon's orbital period to present different parts of its face to your orbiter or something) I'll do some tinkering in kerbal to see if I can figure it out!

The lander is necessarily going to get behind the station due to slowing down to land.  This is true whatever the station's inclination is.  So, if the station is in an equatorial orbit and you land on the equator, you have to wait like 3/4 of the station's orbital period to get back up.  If the station is in an inclined orbit so you land off the equator, you' have a choice.  Get back up immediately after landing (assumes no more than flags and footprints while down) and doing a plane change with the lander as required to catch up with the station, or wait some multiple of 1/2 a local day until the station's orbit comes back overhead.  It's only 1/2 a local day because the lander can take off north or south as needed.  But this can be quite long for tide-locked moons at considerable distances from their primary.  Thus, I usually build such landers (and have enough extra fuel--including mono) on the station to cover the lander boosting much higher than the station and making a 45^ plane change to dock.  This has always proved to be excessive over-engineering but I've haven't left a Kerbal stranded from lack of fuel since 2013 and don't want to do so again.  But, given the 1.7.1 emphasis on long rover trips, planning for a long time on the ground seems necessary now.