In this paper, we propose a low-frequent feedback adaptive transmission strategy in low-earth-orbit (LEO) satellite adaptive transmission system based on that the satellite trajectory can be predicted. In this adaptive transmission system, we adopt rateless Spinal Codes as physical layer coding and modulation method. We use finite sets of feedback data to predict and revise the signal-to-noise ratio (SNR) in real time to adjust the number of transmitted symbols of Spinal Codes during a communication window. The feedback times can be reduced to almost 1/300 of the Digital Video Broadcasting (DVB-S2) which sends the feedback information every 2 seconds. Our simulation results show the maximum reduction of throughput doesn't exceed 0.4% while more feedback resources are reserved.