The Third mission for Captains is Journey and Exploration of New Distant Asteroids.
These asteroids have lots of GRVX, however, long flights require much fuel that takes up most of the cargo bay area.
Only rank III Captains can go on this mission. This mission grants Captains rank IV and teaches Captains to send ships to long distances and get them back with GRVX reward.
Certain Captains could fly on this mission only on certain ship types.
Types of ship
Long distance mission GRVX mining boost
Keelback, Harvester, Mining Barge
General Miura Kentaro
Mining Barge, Flying Refinery, Star Fort
Star Fort, Leviathan
After a Captain gets rank IV, his ability to mine will increase according to his rarity.