Fig. 1. Structure of the polar orbit constellation

Fig. 2. Two-dimensional topology of polar orbiting satellite networks

Fig. 3. Source-destination node data propagation direction diagram

Fig. 4. Single-node element

Fig. 5. Flowchart of the DE-LS algorithm

Fig. 6. 48/6/30 Constellation model structure

Fig. 7. Trajectories of the satellites of the polar orbiting satellite network

Fig. 8. The state of motion of a fragment at a moment

Fig. 9. Visibility of 95 links in the network at a given moment（inter-satellite visibility）

Fig. 10. Cost of satellite 21 with four neighbouring satellites under Dijkstra's algorithm

Fig. 11. Cost of satellite 21 to four adjacent satellites under DE-LS algorithm

Fig. 12. Satellite 21 and Satellite 25 routing hops

Fig. 13. Satellite 21 and Satellite 55 routing hops

Fig. 14. Satellite 21 and Satellite 25 transmission time delay

Fig. 15. Satellite 21 and Satellite 55 transmission time delay