how would i retrieve a spacecraft that is orbiting the sun?

[onionsiegward]

i put like 30 pollux boosters on a little craft with like 50 science experiments on it, and I didn't think it would orbit the sun(i was mistaken). 

i want to retrieve it instead of transmitting the science, because there's like 400 science stored on it and i don't want to sacrifice it.

heres a screenshot: https://gyazo.com/c3713b8a285c5734254401da52364161 (yellow line is spacecraft, blue is kerbin)

what science tree things would i need and how would i do it?

 

please help i dont want to lose 400 science and jebadiah

[king of nowhere]

do the ship has still fuel? assuming it has, you are still close enough to kerbin that you can just set kerbin as target, point towards it, and burn.

else, if you have little fuel, your orbit is very similar to kerbin, you should be able to return there in the next orbit. set kerbin as target, you should see a close approach marker. if kerbin is in front of your ship during the close approach, then burn retrograde - while your orbit is still touching kerbin's orbit! important - and watch the marker get closer until you get an encounter. if kerbin is behind, then burn progade instead. this is actually not difficult, but I have no idea how much experience you have in interplanetary traveling.

if the ship has no fuel, you need to send a rescue mission. send another ship in solar orbit, and do a rendez-vous just like you would do around kerbin. only, it's going to be a lot slower.

Regarding needs, if you can strap 30 pollux boosters on a ship, you can go everywhere. I suspect your ship and flight was very inefficient, else you wouldn't just be in solar orbit, you could go all the way to eeloo and back.

[Vanamonde]

The orbit is crossing that of Kerbin and will likely get an intercept over time even if you don't do anything. Once you do, a burn while still very high with Kerbin's SOI will likely be enough to put into an aerobraking descent. If the craft has a heat shield and parachutes, your problem is then solved. If not, put it into orbit (aerobraking can help with that) and then meet it with another ship. Have a kerbal go it, collect the science, and then ride his/her own ship home.