At 17.00 hours on 1 December, U-575 (Heydemann) spotted the unescorted and unarmed tanker and tracked her until 20.57 hours. Then Heydemann noticed the painted American flag on the side and let her go. Also about 17.00 hours, U-43 spotted the tanker, followed her and missed with a first torpedo shot at 24.00 hours. The torpedo must have been seen by someone on the Astral, because she immediately began steaming a zigzag course at full speed to escape. The U-boat followed throughout the full moon night. At 09.24 hours on 2 December, the tanker was hit by two torpedoes, one in the stern and one amidships. The Astral exploded into flames and sank within minutes. The flaming cargo in the water burned for an hour longer. No survivors among the eight officers and 29 men on board.

This was the third of the four American merchant ships sunk by U-boats prior to America´s entry to the war. The others were Robin Moor, Lehigh and Sagadahoc.