September 8, 2014
Israel has a first-rate air force and a strong capability to perform precision strike. Why then, in this most recent conflict with Hamas in Gaza, did it deal with rockets and tunnels through a costly, destructive, and unpopular ground incursion? One factor may be the hard technical limitations of Israel’s aerial Intelligence, Surveillance, and Reconnaissance (ISR) assets. Like all military capabilities, Israel’s ISR assets must obey the laws of physics and geometry. Reliably detecting targets from the air is hard. Detection is even harder when the targets are either fleeting or well camouflaged, like Hamas’s rockets and tunnel entrances. Contrary to media narratives, there is no such thing as an aerial “unblinking eye” for this mission. These problems are difficult enough that they will probably not be solved any time soon; the laws of physics place harsh limitations on what intelligence can collect. In the future, Israeli decision makers should consider these facts and implications if and when they decide to fight. Other policymakers who plan to rely on ISR operating in cluttered environments might also benefit from understanding these limitations.
When Israel decided to expand Operation Protective Edge (OPE) to include a ground incursion into Gaza, it significantly increased its exposure to Hamas’s combat power. Israel knew from experience that incursions into Gaza are risky: 19 IDF soldiers died during its last two raids into the territory. Hamas, unable to inflict damage to Israel’s military for weeks prior to the assault, was able to kill dozens of soldiers once OPE ground operations began. Hamas’s tunnel network and rocket capabilities were both major targets of the incursion. The tunnels were a massive undertaking for Gaza’s small economy. By one estimate each one required ten truckloads of building material to complete. By another reckoning these projects required 800 tons of concrete. These tunnels served multiple purposes; they were conduits for the movement of weapons into Gaza, provided protection for fighters and equipment, and some tunnels dug under the border gave Hamas the ability to send ground forces into Israel. The rocket threat is linked to the tunnel threat. The former are smuggled into Gaza through the latter. Rockets are then often cached in tunnels and sometimes fired remotely from underground launch sites.
Every successful rocket attack against Israel demonstrates that its highly capable security and intelligence apparatus cannot completely seal off the country. Israel is vulnerable to rocket fire despite its effective intelligence collection and analysis, and its complete access to and dominance of Gazan airspace. Israel’s use of rocket (and tactical missile) defenses such as the Iron Dome surface-to-air missile system and civil defense measures like bunkers mitigate the rocket threat. Mitigation, though, is not invulnerability. There is evidence that Iron Dome is not performing as well as hoped. Rockets get through, and they have an effect.
The Threat Detailed
Hamas’s rockets are terror weapons – smaller in scale but identical in mission to the German V-1 and V-2 rockets of World War II. The V-2s lacked the accuracy of manned bombers of the era, which could usually hit individual ports or airfields. But the rockets could and did kill British citizens in droves, and they did so in a way that was more chilling than the manned bombing raids of the London Blitz. The V-2, traveling at supersonic speed, provided no warning and no chance to reach a bomb shelter. The weapons created a terrifying psychological effect; at any time, anybody could become victim. Because of this, their destruction was an allied priority, absorbing significant ISR and strike assets as allied Bomber Command attacked V weapon Research and Development, and manufacturing facilities. In a similar manner, detection of Hamas’s rockets can occupy Israeli ISR and strike assets that could otherwise be tasked with searching for command and control capabilities and ground forces, or be redirected to other missions entirely, such as providing surveillance along Israel’s borders or in connection with the ongoing conflict in Syria.
Hamas has several types of rockets at its disposal. The indigenously-produced Qassam rocket has a range (depending on model) of 4-12 kilometers. The grad, a Soviet-style rocket produced in Iran, has a range of 20 kilometers. Its longest range rocket, the M302, has a range of 150 kilometers and can reach Tel Aviv.
The longer-range rockets carry larger warheads, but that is not a factor for the ISR mission. All of the rockets carry enough explosive and potential fragmentation to kill, destroy light-skinned vehicles, and inflict property damage, which makes detecting all of them with ISR assets a critical objective. However, rocket range is the key for two connected reasons. First, increased range means that a weapon system can be placed further away from the Gazan border and still hit its target in Israel. All things being equal, if I double the range of a weapon system, I have quadrupled its possible hiding area. Second, conversely, as I add range I increase potential targets. This increases burdens for on-call first responders, bomb shelter construction, and air defenses.
Historically, Hamas has deployed some types of rockets, like the Fajr-5, principally in the agricultural areas by the border. But given the multitude of rocket types with varying range capabilities, all of the Gaza strip’s 360 square kilometers are potential launch zones. So, for counter-rocket operations, the entire strip is within the IDF’s “area of interest.”
The ISR Response
This large hiding area is a problem for Israel’s ISR assets. The country has a strong intelligence service and good technical reconnaissance assets. Many of its fighter planes have targeting pods that can pick out a rocket launcher from high altitudes. But better suited to the task are Unmanned Aerial Systems (UASs). The IISS Military Balance credits the Israeli Air Force with 48 UASs, ranging from older RQ-5B Hunters to the newer and very capable Hermes 450. The Hermes, manufactured domestically by Elbit Systems, is a first-rate ISR platform. It has FMV sensors as well as Synthetic Aperture Radar, and can stay aloft for 17 hours, giving it a long time to potentially loiter over a target.
The sensor suite and long loiter time are critical to provide access to the rockets. Access equates to a sensor’s ability to reach a target. The Israeli Air Force (IAF) needs a lot of access because the rocket’s signature is comparatively small. Qassam rockets can be set up in a matter of minutes and fired by remote control. A Fajr-5 takes longer to set up, but the time when the rocket is visible, as opposed to being stored in a tunnel or a truck, is still measured in minutes, not hours. To support precision strike, FMV needs to be looking at the right place at the right time, analyze what it sees, and inform a strike asset. If an FMV operator looks away for too long, it may miss its chance to close the kill chain.
UASs are usually deployed in groups of 4-6 air frames and a control element. This collection makes up one complete system, sometimes called an orbit or “cap” in the vernacular. One orbit can guarantee 24-hour coverage of one target set, as one aircraft is aloft, one is on deck to fly and relieve it on station, one is recovering from a flight, and one is in back-up or longer-term maintenance.
IISS does not specify if it is counting individual air frames or systems. If we assume the latter, that gives us 48 potential sensors flying over the Gaza strip (in reality, some would be held in reserve, used for training, or deployed near the Syrian or Lebanese borders). Flying at 3000 meters above ground level, the Hermes would be out of small arms range, not too noisy, and get a good view of the strip.
The Hermes can be equipped with the Compass FMV sensor pod (sometimes called a “ball”). Also built by Elbit, the Compass has both CCD TV and Forward Looking Infrared imaging capability. Any sensor’s ability to see anything is driven by several factors including lens quality, the number of pixels in a display, the distance from the target (the slant range) and the sensor’s field of view. In narrow angle mode, necessary to provide good magnification and give good resolution of a target, a Compass’s field of view covers just .7 degree by .52 degree. To get a sense of what is visible through a UAS sensor ball, one should imagine looking through a telescope. They aid in distance but limit a user’s field of view.
The sensor ball’s footprint varies widely depending on altitude, the angle of the sensor to the ground, and a variety of other factors. Given some realistic operating parameters for the Hermes, the Compass FMV ball could have a footprint of roughly 1500 square meters. This is a good field of view for picking out a Hamas crew assembling a rocket launcher and preparing to fire, but it is a soda straw compared to the entire Gaza strip. Multiply 1500 by all 48 UASs in the IAF inventory, and total coverage is still only about 20% of the Gaza strip. This is the potential coverage area, I’d like to emphasize, which would require completely stripping UAS assets away from every other conceivable mission, including the overwatch of ground forces. This is not a winning proposition when one rocket can shut down your country’s only international airport for 24 hours.
Such hard realities of aerial surveillance are driving engineers to design wide area motion imaging sensors. One of them, BAE Systems’ ARGUS-IS, combines 368 Focal Plane Arrays, or mini cameras, to provide a wider battlefield view. Even if such systems mature and are fielded, they will not change the problems of FMV employment because cameras – even huge 1,000 lens arrays of cameras – are still “line of site” sensors. In a cluttered, urban environment, buildings will cut off line of sight, create what the infantry calls “dead space” and prevent wide area sensors from reliably viewing spaces such as structural overhangs and areas next to tall buildings.
Lasting Lessons
There simply is no good fix to the FMV coverage problem. Engineers and sensor operators can argue that certain flight profiles and altitudes will eke out larger footprints from sensor balls, but the bottom line is that the only place the unblinking eye exists is in the marketing slick sheets of defense contractors. This trope is then perpetuated by general interest news media and defense analysts who do not put sufficient effort into their work. In the real world ISR utility is limited and this fact very likely drove the IDF in its decision to invade Gaza and cut off its tunnels and rockets by fire and maneuver instead of precision strike.
TR Fehrenbach’s trenchant observation about ground combat applies here. Speaking of the Korean War, he observed: “You may fly over a land forever; you may bomb it, atomize it, pulverize it and wipe it clean of life – but if you desire to defend it, protect it, and keep it for civilization, you must do this on the ground, the way the Roman legions did, by putting your young men into the mud.” Hamas is determined to keep Gaza as a staging area from which it can bludgeon Israel with rockets. Because of the difficulties of detecting rockets from the air, Israel is obliged to seek them on the ground. If, after this punitive expedition, Hamas rebuilds and re-arms, it may be obliged to do so again.
Andrew Marvin is a managing consultant with IBM’s public sector Advanced Analytics and Optimization service area where he supports clients with data analytics and process improvement. He has supported the Department of Defense as both a consultant for ISR assessment, and as an intelligence analyst team lead. He served eight years as an Army officer fulfilling command and staff positions in both Field Artillery and Military Intelligence. During that time he deployed to Bosnia and Iraq.. He is on Twitter as @armarvin. His views are his own.
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