Why is Stefano Uranus so much more common than other defense fissures?

[Clowee]

It seems like every time I log into to play, and go looking for a defense fissure, the only choice is Stefano on Uranus.  I see this fissure spawn way more than other defense fissures.  Sometimes I log in, and it appears to have been up for 3+ days straight.  Other defense nodes like Io or Belenus seem to be exceptionally rare.  Is it just me noticing this? 

Last night it was up every time I logged in.  Today I logged on 3 times with several hours between and it's still up.  I notice this enough to see a weird pattern.  I would like some other defense maps to spawn just as regularly to add variety 😞

[QueenofYandxre]

^{I noticed this too, hun. You're not the only one, don't worry. I like to run defense fissures to keep cracking relics to stock pile up on Prime parts for ducats (cause of Baro's visits). And, while I do enjoy the defense on Stefano, Uranus, it's not my fave mission. I would also prefer another defense fissure elsewhere on the Star Chart.}

[taiiat]

Defense/Interception on Grineer Sealab is highly common because:

Grineer Sealab is restricted from being used for Void Tears due to the Archwing restriction and Void Tears are not allowed to require the use of Archwing. so the entire Tileset is blocked, however the Defense/Interception Tiles do not require Archwing, and because of this, those two specific Missions represent the entire shared probability that all of the Missions on Uranus would have provided to the Void Tears' Randomization.

or in short, those two Missions (Grineer Sealab Defense/Interception) because of a Tileset restriction, just those two, represent almost 10% of the entire Solar Map in terms of valid Mission Nodes for Void Tears.
any other single Mission Node would have a probability weight more around 2-3%, for context.

Edited January 3, 2020 by taiiat

[yarl5000]

I think it is a combo of the relic range, most of Uranus being flagged as arch wing submersible so I don't think those can be candidates for relic missions to spawn that cause it to be the most common def at that tier. 

[Clowee]

what i'm having a hard time wrapping my head around is that, when I posted this, the Map had 18 minutes left on it.  It briefly despawned, and now it's back again 😞

It's like they cycle this map/planet 10x more than others. Why not a defense on Pluto, or earth, or any other planet?  It almost looks like a glitch or something that's making the game select this mission way more than other planets and defense nodes