With a diameter of approximately 10 kilometers , Amundsenia is one of the largest mid-sized Mars-crossing asteroid s such as 1139 Atami ( 9.35 km ) , 1474 Beira ( 14.9 km ) , 1011 Laodamia ( 7.39 km ) , 1727 Mette ( est 9 km ) , 1131 Porzia ( 7.13 km ) , 1235 Schorria ( est .