I found this achievement easy to do after the final battle and you are able to return to the open world. Once you visit a planet, you will be able to fast travel just by aiming towards it in spaceflight mode and pressing and holding the
button. So, if it is a new planet that you haven't been to, go to a nearby one and you can then jump to hyper speed after that aiming at the 'unknown' planet. It doesn't take very long to get from planet to planet, just look out for traps.
There are only seven planets and three you had to get to 50% to build the tower to fight Grax, (one in each sector) so you only have 4 left:
Dark Sector (Easy)
Ashar
Necrom
Frontier Sector (Medium)
Vylus
Tundria
Trade Sector (Hard)
Kirite
Sonatus
Haven
If this helped you, please give me a positive vote. If giving a negative, please let me know what I can do to fix this guide. Thanks for reading, and best of luck.