February 13, 2012: Israel has decided to replace its four decade old M109 155mm self-propelled armored artillery vehicles with guided rockets. This comes a year after deciding that the M109s could not be refurbished and upgraded anymore and would have to be replaced. At first, other artillery systems were examined. But then it was remembered that two years ago Israel had accepted that the U.S. use of GPS guidance in rockets, while more expensive, was more effective than the cheaper (but less accurate) Israeli developed rocket guidance system and even cheaper unguided artillery shells. So now the M109s are being replaced with guided rockets.
This radical shift in artillery weapons has been coming since the 2006 war with Hezbollah, when the Israelis found that they did little damage to Hezbollah bunkers, even though over 120,000 unguided 155mm shells were fired (mostly by M109 guns) at them. Meanwhile, they noted that the U.S. 227mm MLRS rockets with GPS guidance was excellent at taking out similar targets in Iraq and Afghanistan. So Israel equipped its 160mm Accular rockets with GPS. These 110 kg (242 pound) rockets have a range of 40 kilometers and enable one bunker to be destroyed with one rocket.
This was a big change. Up until Israel adopted GPS guidance for rockets they had used cheaper, but less accurate, systems for their rockets. The main effort here was the Trajectory Correction System (TCS), which was installed in U.S. 227mm MLRS unguided rockets as well as Israeli 160mm rockets. TCS used rockets equipped with a guidance system and radio. The ground portion of TCS consists of a control unit that tracks the position of the rockets in flight, calculates where they will land, and sends orders to the guidance system (small vanes) in the rocket. This makes the rockets as accurate as unguided artillery shells. TCS is cheaper than GPS guided rockets. Israel bought 48 MLRS launchers in the 1990s, but has mostly used them to fire unguided rockets.
Israel always recognized the superiority of GPS in some situations. For example, Israel developed LORA (Long Range Artillery Rocket) which is similar to the U.S. ATACMS. Each LORA missile weighs 1.23 tons and carries a half ton warhead. With a range of 300 kilometers, GPS guidance is used to land the warhead within 10 meters (31 feet) of the aim point. These missiles are expensive. The similar U.S. ATACMS, which is fired from a MLRS container that normally carries six of the standard MLRS rockets, cost a million dollars each. It's often a lot cheaper if you can use smart bombs (which cost less than $50,000). But if you don't have aircraft up there, or control of the air is contested, you can get a LORA missile on a target within ten minutes of the order being given.
Israel expects to replace a lot of artillery shells, air delivered missiles, and bombs with its GPS guided rockets and take out more targets with far fewer rockets and artillery shells.