On October 7, 2023, Israel’s Iron Dome defense system, known for its advanced missile interception capabilities, faced unexpected challenges. Although the system has historically been 90% effective, it has been vulnerable to massive missile attacks from the Palestinian group Hamas in Gaza.
Faced with unique national security challenges, Israel has long been committed to developing efficient, advanced defense technologies and capabilities. The Iron Dome air defense system is the best example of Israel's military strength. It is widely regarded as the best system in the world for defense against missiles and rockets.
However, on October 7, 2023, Hamas, the Palestinian militant organization headquartered in Gaza, launched a large-scale rocket attack, catching Israel by surprise. The group reportedly fired thousands of rockets at multiple targets in Israel. Although there are no precise details, what is certain is that a large number of Hamas rockets penetrated the Israeli defense system, causing huge damage and casualties.
I'm an aerospace engineer who studies space and defense systems. Israel’s defense strategy has not been entirely effective against Hamas attacks, and the reason for this is simple. To understand why, you first need to understand the basics of air defense systems.
Air Defense: Detect, Determine, Destroy
The air defense system consists of three key components. The first is radar, used to detect, identify and track incoming missiles. The detection ranges of these radars vary. According to manufacturer Raytheon, the Iron Dome radar has an effective detection range of 2.5 to 43.5 miles (4 to 70 kilometers). After an object is detected by radar, it must be evaluated to determine whether it poses a threat. Information such as direction and speed are used to make judgments.
If an object is confirmed as a threat, Iron Dome operators will continue to track the object via radar. Rocket speeds vary widely, but assuming a velocity of 3,280 feet per second (1 kilometer per second), defense systems would have up to a minute to respond to the attack.
The second major element of the air defense system is the combat control center. The center is responsible for determining the appropriate means of engaging identified threats. It uses constantly updated radar information to determine where and how many interceptor missiles to launch against incoming rockets to best respond.
The third major component is the interceptor missile itself. In the case of Iron Dome, it is a supersonic missile with a thermal sensor. These sensors provide the interceptor missile with up-to-date information in flight, allowing it to steer toward and close to the threat. The interceptor uses a short-range fuse activated by a small radar that explodes when close to an incoming rocket, eliminating the need for a direct hit to disable the rocket.
Challenges facing systems such as Iron Dome
Israel has at least 10 "Iron Dome" systems in operation, each containing 60 to 80 interceptor missiles. Each missile costs approximately $60,000. In previous attacks involving smaller numbers of missiles and rockets, Iron Dome was 90 percent effective against a range of threats.
So why was the system less effective against Hamas’ recent attacks?
It's a simple matter of numbers. Hamas fired thousands of rockets, while Israel had fewer than a thousand interceptors on the battlefield ready to counterattack. Even if Iron Dome is 100% effective against incoming threats, the sheer volume of rockets fired by Hamas means there will always be some that penetrate the defense network.
The Hamas attack illustrates very clearly that even the best air defense systems can be overwhelmed if the number of threats they have to deal with becomes too great.
Israel's missile defense system has been built for many years and has invested a lot of money. How can Hamas be vulnerable? It still comes down to numbers. The rockets launched by Hamas cost about $600 each, about 100 times cheaper than the Iron Dome interceptor. The total cost for Israel to launch all interceptors is approximately $48 million. If Hamas fired 5,000 rockets, the cost would be only $3 million.
Thus, in a carefully planned and executed strategy, Hamas gradually accumulated a large number of relatively cheap rockets that it knew would make the Iron Dome defenses vulnerable to attack. Unfortunately for Israel, the Hamas attack is a very clear example of military asymmetry: low-cost, low-capability methods are able to defeat high-cost, high-tech systems.
Looking ahead: The future of air defense
Hamas's attack will have an impact on the world's major military powers. It clearly shows that air defense systems need to be more effective in two important ways. First, a more powerful defensive arsenal is needed to deal with a large number of missile threats. Second, the cost of each defensive weapon needs to be significantly reduced.
This incident may accelerate the development and deployment of directed energy air defense systems based on high-energy lasers and high-power microwaves. These devices are sometimes called "infinite magazines" because they cost relatively little per shot and can continue firing as long as power is available.
Author: Iain Boyd, Director of the National Security Initiative Center and Professor of Aerospace Engineering Sciences at the University of Colorado, Boulder.
Adapted from an article originally published in The Conversation.