system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] why didn’t thanos send his entire army to earth through space instead of sending some through the tesseract portal?

there were two stones that he knew about on earth so I don’t know why he would be impatient instead of bringing down his full might upon the planet.
gpt
The Bifrost was down.  After Thor destroyed Asgard's rapid response transport, the Nine Realms descended into chaos.

Thanos sought to use the opportunity to get in quickly and grab his prize.  He used Loki as a proxy so it wasn't obvious that he was behind it.  Odin used Dark Energy to send Thor in response to resolve what he saw as a family squabble.

Had Thanos mounted a large-scale invasion, he would have had to conquer all of the intervening space.  Powerful systems and empires, including Asgard, would have noticed and mobilized to stop him.  The campaign would have ground on for months or years.  

He didn't care about those systems, though.  He just wanted the Infinity Stones.