The space jump gate is used to instantly transport ships between your planets. You must have at least two gates, one to send and one to receive. You can not move resources throught jump gates. Also there is no gas savings by using a jump gate. They require the same amount of gas as a conventional transport between planets. Level 1 gates require 24 hours to cool down before they can be used again and each increase in level decreases cool down time by 2 hours.