Unfortunately Chinmokunouta is correct. Thanks to the way the rules are now written, the destruction of the sun station part of that quest line is nothing more then a suicide attack at best. Killfast used 22 Space Warders and lost them all in the blast.
At the beginning it was probably possible to destroy a Sun Station for human quest line 4, with just a Death Star or Supernova Star that had gravitation weapons, giving how the wording of the quest is, but that is no longer possible. Because of so many nerfs and updates over the last few years, that quest, as well as others are for all intent and purposes broken and/or are almost impossible to complete or not worth the time, resources or forces to complete and from what i heard the reward(s) to do so does not even come close to compensating you. Its kind of messed up with the rule wording, your supposed to get 60x debris on any station you destroy but because of the gravity wave sun stations produce, it wipes out everything, fleets, debris, the works. That my friends is called a 'Catch 22' and what makes this quest a suicide run and broken.
Unfortunately, that is not the only suicide quest, there is another one for humans in quest line 6 were you have to destroy the pirate leader Montana, who appears at coordinates
[100:666:6] and stays there for 1 hour each day, but at a random time. Again, like quest line 4, you don't get battle experience or debris from his destruction. The problem with this quest is three fold: 1) He appears in a Juann...which pretty much says it all for the amount of forces you need to take THAT puppy out. 2) Location location location. Depending on were you are, this quest could take hours or days to travel to from your point of origin and he only sticks around for 1 hour each day, giving you a small window of time to do the quest in. If your more then a hour distant flight time with your forces, your going to have to colonize a planet within 30 mins attack distance of the location in question, then relay forces to that planet and wait wait wait hopeing while your waiting someone does hit your relay planet and your attack fleet, knocking you back to square one again. 3) The location is usually swarming with high level players on the look out for anyone showing up to take him out. With the warm up timer now in effect, if he does not destroy your forces, other players parked in the area might, though most decent players and alliances follow the unspoken long standing gamer rule of not hitting a player doing a quest. Unfortunately, as we all know, there are some out there that are total a-holes who do not follow that rule (there are some in every game), and even if they do not hit you, your a long way from home and all that debris you left behind is free and clear to be scooped. Since there is no xp or debris from Montana, they are more then happy to scoop up yours. As for quest completion reward...i have not done it yet so i can only guess a ship(s), badge or resources of some kind.
Then there is Toss quest 8 line, were you have to send a Gigalord to colonize any planet in galaxy arm number 11081985, in 806-989 solar systems. No matter where you are, a straight flight takes months and Billions (yes i said Billions) in gas just to get there, as your looking at 10 Billion+ ckm distance for a one way colony trip. If you try to use tramps, you would need so many to make the trip, (for those who love math, going by 10 tramps sends you a distance of 635,463 ckm, you would need approx 15,750 tramps to pull this stunt off and good luck with THAT one!!) that it is not even worth trying, not to mention that if anyone sees that many tramps they will try to destroy them, unless you have a major armada guarding them. And i seriously doubt if you did complete the quest some how, it definitely will not be worth it in regards to reward for completion. The only other way i can think of to make this work is to planet hop, sending a colony ship out as far as you can, colonize then move the gigalord, rinse and repeat, requiring the use of two planet slots. But again this will take a long time too. Imho this quest is bloody insane by any measure and why a quest was made like this is totally beyond my ken of understanding.
And those are only the toss and human ones im aware of so far, i can only imagine what craziness the toss ones have.
Sadly the devs have not bothered to update any of the quests at all, they just keep updating and nerfing the game. As Chin mentioned, your only viable options at this time, if you do not want to throw away tons of vessels to take out the Sun Station without getting anything for it, are to try to make a Space Station with a Gravity Gun (Moon Weapon), use a Nuclear Missile, or move to a different planet. That is until they nerf the game again and make moon based gravity gun and nuke attacks useless too.