[DaveyJ576]

When the USS Nautilus (SSN-571) first went to sea for exercises with the fleet in 1955-56 the incredible performance advantage she enjoyed over a conventional diesel-electric GUPPY boat shocked many naval strategists. The sudden realization that she nearly rendered all existing anti-submarine warfare (ASW) techniques obsolete hit the establishment like a ton of bricks. A conference was called together in the late summer of 1956 at Nobska, Massachusetts to study the problem. One of the main issues the attendees tackled was how to hunt and destroy a high speed, high endurance, deep diving nuclear submarine.

One of the solutions they came up with was (predictably for the 1950's) to nuke it. A developmental outgrowth of the Nobska study was the Mk 45 ASTOR (anti-submarine torpedo). With an 11 kiloton yield W34 fission warhead, the Mk 45 would overcome the limitations of the existing sonar and tracking systems and largely negate the speed and depth advantages of a nuclear submarine through good old fashioned brute force.

The Mk 45 was a 19 inch diameter swim out weapon that was 19 feet long and weighed in at a 2300 lbs. It was an electric torpedo of a relatively simple design. It had a range of approximately 7 nautical miles (14000 yards) and ran at a speed of 40 knots. It had no internal guidance or sonar systems other than a gyro. It was guided to the target via a control wire back to the firing sub. U.S. nuclear weapons doctrine of the day dictated that the weapon could not be allowed to auto-burst via it's own systems. It had to be detonated by the firing sub's crew at the appropriate moment (hence the control wire). The 11 kT warhead had a hard kill radius of 8000 yards. In other words, if your target was within that radius when the weapon detonated, it was dead, no joke. At 12000 yards the weapon could still be lethal, although the probability of a kill dropped quite a bit. At 16000 yards the target stood a reasonably good chance of surviving. It entered service in 1963 and was finally retired for good in the 1979 as the highly capable Mk 48 came on line.

There was a bit of gallows humor amongst the submarine crews that carried this weapon to sea. It was said you were assured of two kills anytime you used a Mk 45, your target and yourself. Remember that in the early 1960's the vast majority of the USN submarine force was still made up of diesel-electric GUPPIES and the new Tang, Darter, and Barbel class diesel "fast" attack boats. The maximum speed of these boats varied between 15 and 18 knots. At those speeds the battery would be completely dead in about a half hour. The concern was that if you fired a Mk 45 at an enemy it would be virtually a suicide shot. You wouldn't be able to get away from it fast enough to survive the detonation of your own weapon.

The hard kill radius of the weapon was 8000 yards, with a good probability of a kill out to 12000 yards. Let's assume best case scenario and say you obtain a firing solution on your target at 14000 yards. You fire your Mk 45 and she is running to your target at 40 knots. It will take about 10 1/2 minutes for the weapon to run that far. You can't maneuver and run away to increase the range. Remember the weapon has no internal sonars or guidance, you have to guide it to the target with your boat's own sonars, meaning you have to keep pointed at the target and stay slow and quiet. You send the command for the weapon to burst when it hits the calcuated range of 14000 yards and you wait for the shock wave to hit, fingers crossed.

Accurately tracking a submerged target at 14000 yards was problematic at best in those days. You wanted to rely on passive sonar so that you wouldn't give away your presence with active sonar pings. This made accurate ranging very difficult. Tracking ranges of 9 to 11000 yards were more realistic, and often it was less than that. This gave you precious little room for error when using this weapon. Later advances in sonar increased detection and tracking ranges and made the use of the Mk 45 a bit safer, but the submarine crews never really liked it and always viewed it with a great deal of justified trepidation. No one was sad to see it go when it was finally pulled from service.

If you want to see a Mk 45 torpedo, the USS Torsk (SS-423) museum has one on display on board the boat in Baltimore, Maryland, minus the warhead of course! The Torsk herself never carried the Mk 45 while in service as she did not have the proper sonars or fire control systems.