craters on fire                         
                                            ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯                         
                                                   ^                                
                                                   |                                
                                                   |                                
                                                   |                                
                                                   |                                
                                                   |             ---------          
                                                   |            |         |         
                                                   |            |         |         
                                                   |            |         |         
                                                   |            |         |         
                                                   |            |         v         
                                                   |            |                   
                                                   |            |   friction center 
                                                   |            |   ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ 
                                                   |            |                   
                                                   |            |                   
                                                   |            |                   
                                                   |            |                   
                           ------------------------              -------------------