Here's What You Need to Know: Countries are weighing whether to purchase the Aster or the Patriot.

Ballistic missiles are making a comeback in the twenty-first century because they give countries like China, Iran, North Korea and Russia the ability to strike targets hundreds or thousands of miles away without having to expose vulnerable warplanes to interception. The precision allowed by modern guidance systems allows even non-nuclear missiles to deliver highly-deadly attacks against airbases, fuel and ammunition depots, and even moving aircraft carriers. 

Therefore, the ability to intercept ballistic missiles is also growing in importance. But surface-to-air missiles (SAMs) designed to shoot-down aircraft struggle to hit missiles flying many times faster and higher. And the further a ballistic missile can go, the faster and higher it must fly, and the harder it becomes to intercept. 

The United States has developed a spectrum Anti-Ballistic Missiles (ABMs)s, from the Patriot PAC-3 MSE which can intercept tactical ballistic missiles, the high-flying THAADS and naval SM-3 Block II missiles which can counter short to intermediate-range systems, and GMD interceptors in Alaska that can tackle intercontinental-range missiles.

Several European countries have caught up with lower-tier ABMs by developing a versatile SAM of which arguably exceeds the Patriot missile in capability—and may evolve a similar capability to THAADs.

The Aster missile—named after the Greek word for “Star”—was conceived in the 1990s by Eurosam, a consortium of MBDA and Thales, to defend warships from enemy aircraft and sea-skimming cruise missiles at short range. Today, Aster missiles can be found in the launch cells of warships including the Royal Navy’s Type 45 destroyers and France’s Horizon-class frigates.

In the 2000s, Eurosam began developing an enlarged Aster missile with four times the range to provide area air defense. This new Aster 30 not only supplements the short-range Aster 15 variant at sea, but is also deployed on a land-based launcher, the SAMP/T (French: “Surface-to-Air Medium-Range/Land-based”), replacing dated I-Hawk and Crotale SAMs

The latest Aster-30 Block 1NT model can intercept aircraft up to seventy-five miles away, and can fly fast and high enough (maximum 65,000 feet) to intercept tactical and short-range ballistic missiles, as well as low-flying drones, cruise missiles and aircraft.

How SAMP/T Works

A SAMP/T battery has three truck-mounted elements: an Arabel multi-function radar, a command-and-control vehicle, and four or six launch vehicles each carrying eight boxy vertical launch canisters with a missile inside ready for launch. The road-mobile battery takes forty-five minutes to set up on average, with launchers often dispersed a few miles away from the radar. A single battery can be manned by as few as fourteen personnel.

The three-dimensional X-band Arabel radar completes one rotation per second and is frequency-agile, allowing it to resist jamming and other electronic countermeasures. It boasts 360-degree coverage, meaning it can defend against attacks from any angle, can track up to one hundred targets and direct up to sixteen missiles simultaneously to engage them.

Though Arabel’s basic search radius of thirty-seven miles is unimpressive, it can use a Link-16 datalink to connect to another radar—say, a longer-range ground-based radar, or an orbiting AWACS aircraft—to “focus” its scan, allowing it to double its range to seventy-five miles versus high-flying targets. However, due to the constraints imposed by intervening terrain, the maximum engagement range for low-flying targets remains thirty-one miles for aircraft and twenty-one miles for missiles.

The SAMP/T battery’s command unit transmits coordinates from the radar transmit to the missile launchers. Each truck can launch all eight of its 4.9-meter-long Aster-30 missiles in just ten seconds. Within four more seconds, the missiles’ solid-fuel rocket boosters accelerate the half-ton missile to Mach 4.5—nearly a mile per second—before being jettisoned as a second-stage booster activates.

Initially, the Aster is guided by an internal inertial guidance system, but the command vehicle transmits updates on the target’s position via an uplink, allowing the supersonic weapon to adjust its trajectory should the target change course.

As the Aster closes in on its target, it begins using an active Ka-band AD4A doppler radar seeker in its nose for guidance. Four side-facing gas thrusters perform ultra-rapid “side-strafing” corrections to ensure a near-perfect intercept. Though Aster missiles have directly impacted their targets in tests, they also carry a small thirty-three-pound proximity-fused warhead for added punch. 

You can see the engagement process visualized in this video.

In around a half-dozen tests, Asters have shot down a diverse spectrum of targets including supersonic sea-skimming cruise missiles, jet-powered drones, and high-flying Israeli Black Sparrow ballistic target missiles designed to emulate a Scud-B.

Aster versus Patriot

The Italian Air Force currently deploys three SAMP/T regiments with two batteries of six launchers each, mounted on Atra 8x8 trucks. In 2016, Rome deployed two units to Turkey to provide air defense coverage of its border with Syria.

The French Air Force has seven squadrons of “Mambas,” each including two batteries with four launchers each. Five batteries are deployed to defend key French air bases from attack—notably including Saint-Dizier-Robinson, which hosts France’s Rafale nuclear strike squadrons. The remaining two batteries are reserved to support French ground forces deployed abroad.

The Aster 30 seems to straddle the capabilities of both the Patriot anti-aircraft PAC-2 and shorter-range missile-defense oriented PAC-3 missiles in one package. According to one survey of contemporary air defense missiles, the SAMP/T is less expensive at $500 million for a battery and $2 million per Aster-30 missile. By comparison, a PAC-2 and PAC-3 reportedly costs around $800 million to $1 billion per battery, and $2 or $3 million per missile.

On the downside, the SAMP/T seems more dependent on external radars to allow it to “see” far enough to exploit its maximum range, and it has a slightly shorter maximum engagement range than the PAC-2.

Already Romania, Poland and Sweden have considered the SAMP/T—and chosen to buy Patriot systems instead. One factor may be that the latter is combat-tested and the Aster is not. But more importantly, these buyers may feel that Patriot missiles come with the added value of currying favor with Washington, thereby “buying” a security guarantee from the United States.

So far, the SAMP/T’s sole export order has come from Singapore, which reportedly received three batteries and 300 Aster missiles in 2018 and 2019. Motivated by the use of Aster missiles by the Singapore Navy, the Singapore Air Force has networked its SAMP/Ts with longer-range American AN/FPS-117 and Swedish Giraffe radars, demonstrating how the Aster can be mated with more powerful sensors.

Currently, Canada and Switzerland are weighing purchasing the Aster versus the Patriot. Azerbaijan is also rumored to have purchased land-based Asters, and Turkey has reached a preliminary deal to study license-building the Aster missile, but whether the financing and political goodwill to make it happen is difficult to foresee following Ankara’s purchase of Russian S-400 air defense systems.

Eurosam is working on an Aster Block 2 missile designed to fly nearly four times as high at over 230,000 feet. This new hit-to-kill exo-atmospheric interceptor would be capable of smacking down hypersonic missiles and ballistic missiles traveling at seven times the speed of sound. 

The Block 2 would amount to a European version of THAAD, except with 360 degree instead of 120 degrees coverage. Notably, Block 2 is described as capable of intercepting “3000-kilometer range missiles,” which lies at the definitional intersection of a “medium-range” and “intermediate-range” ballistic missile. Notably, the collapse of the INF treaty has lifted the ban on Russian deployment of such weapons.

Thus, a European counterpart to THAAD would be useful and desirable in many quarters, particularly to counter new threats from Russia and Iran. But once again, Eurosam will have to contend with the more established THAAD system and the temptation to buy American to score points with Washington.

Sébastien Roblin writes on the technical, historical and political aspects of international security and conflict for publications including The National Interest, NBC News, Forbes.com and War is Boring. He holds a Master’s degree from Georgetown University and served with the Peace Corps in China. You can follow his articles on Twitter.

This article first appeared in 2019.

Image: UK Ministry of Defence