For two reasons:
First, as this guy said above:
To put that another way, some of the things you're saying are confusing to us and that's making it hard to help you.
That's not necessarily your fault. You're new, so this is understandable. My only point is, when you're new to any game, it's better to post screenshots than to try to describe what you saw. You could be new to Minecraft and having trouble, but if the Minecraft forum gets confused about what you're asking, they won't be able to help.
Second reason: if I try to help you by showing you how to do this mission, there's a very, very good chance that you're gonna say, "that's not the same kind of mission I had."
On the other hand, you know where you got the mission, so all you have to do is go back there and find a duplicate. Minor factions tend to give the same mission over and over again for a few weeks, until the system state changes. So you could find a duplicate mission and take a screenshot. I probably can't do it.
I've described it pretty thoroughly enough, have I not? I'm busy doing other things in game right now and am not gonna fly all the way across the galaxy to try and find the same mission I don't even remember the name of or where it took place(think I got it somewhere near pichi wang? Was trying to work on rep with a minor faction there after an earlier issue where I picked up a bunch of CZ kill missions, only for there to be zero CZ's in said system, forcing me to abandon them all and tank my rep).
Word for word, step by step:
I pick up the mission, nowhere at all does it say an SRV is needed or recommended in the mission text.
I go to the planetary hub, get a trespassing fine for flying too close, having to wrestle with infinitely spawning drones while I frantically look up what I'm even supposed to do here.
Turns out I had to scan an antenna that is labelled something different than an uplink terminal; I at first tried this and thought it just wasn't working, but it turned out I wasn't close enough(unfortunately, flying a cutter made scanning it awkward, but I eventually got it.)
Okay, next step is to go to a nearby system. Already frustrated with the confusion during the prior step, I get a mission critical message that says the target is somewhere in this system.
First thing I do, the same thing I do for any other mission, is go to the nav beacon. Wait for nav beacon data, go back to supercruise...no target on the left panel.
Okay, no biggie I figure, I'll just honk and look for it manually. Should be easy to find right? Just look for the orange circle. Well...I scan every signal source in the system, and still nothing.
I check and double check the mission description, and the message, look up what I'm supposed to do on the internet, and I'm doing everything correctly, but there is ZERO indication of where the target is or should be. Not a planet name, not a "between this planet and that planet", nothing.
I assumed it was an on-foot mission because of the little planet icon when I picked up the mission, and the fact it involved going to the surface. All I know for certain is that is this, and the fact it was an "Assassinate <some dude>" mission.
Nothing in the game has been difficult to figure out with the abundance of resources out there, so I'm not asking for help, and this would hardly be the first time a mission has asked me to do or find something that just doesn't spawn in for some reason. It's not terrifically common, but it happens every now and then, but this one in particular infuriated me because it was more vague than previous missions I've done, and the whole "scan the hub, but you're actually scanning something not named anything similar, and here's a guaranteed trespass bounty and infinitely spawning drones." This is also because I was really getting tired of anything involving missions on the ground=bounty, even when they don't say "illegal mission."