{"id":31230,"date":"2017-04-06T06:00:47","date_gmt":"2017-04-05T20:00:47","guid":{"rendered":"https:\/\/www.aspistrategist.ru\/?p=31230"},"modified":"2017-04-05T18:14:30","modified_gmt":"2017-04-05T08:14:30","slug":"antpy-2-radar-second-strike-guarantees","status":"publish","type":"post","link":"https:\/\/www.aspistrategist.ru\/antpy-2-radar-second-strike-guarantees\/","title":{"rendered":"The AN\/TPY-2 radar and second-strike guarantees"},"content":{"rendered":"
<\/p>\n
International relations sometimes turn on points of deep uncertainty. One of the hottest current debates concerns the capabilities of the AN\/TPY-2 radar associated with the THAAD system being deployed in South Korea. The question of how far the radar can see into China ranks up there with great mysteries, such as the fate of the crew of the Mary Celeste<\/em> and the air-speed of an unladen swallow. The headline of a Reuters<\/em> column<\/a> captured the dilemma neatly: \u2018China wary about US missile system because capabilities unknown\u2019.<\/p>\n Estimates of the radar\u2019s range vary widely\u2014blurred in part by the fact that it can be used in two modes. In its forward-based mode, the radar is deployed in reasonable proximity to the probable launch point. It detects and tracks all classes of missiles in their launch\/boost phase, and subsequently hands off its data to the wider Ballistic Missile Defence System. In its terminal mode, itmonitors incoming missiles and warheads to enable interception by its THAAD battery.<\/p>\n Many of the arguments about the radar in South Korea assume it\u2019ll be used in its forward-based mode. Chinese commentators, in particular, are concerned about its ability to degrade the effectiveness of China\u2019s strategic missile arsenal, either by providing more granular data on Chinese missile testing, or by contributing early trajectory data to the broader US Ballistic Missile Defense System<\/a>. But in South Korea, the principal mission will be to guide terminal interceptions by THAAD. It\u2019s primarily going to be used in the terminal mode. True, the hardware\u2019s the same for both modes and swapping the software seems to take only a matter of hours.<\/p>\n Still, with the radar configured to its forward-based mode, the THAAD interceptors in South Korea would be largely useless. An AN\/TPY-2 operating in forward-based mode can support cueing for another AN\/TPY-2 operating in terminal mode, but it can\u2019t replace it.<\/p>\n With that caveat, let\u2019s have a closer look at range estimates. Back in September 2012, US scientists George Lewis and Theodore Postol calculated<\/a> the radar\u2019s range as 870 km for simple detection, and 580 km for discrimination. Lewis and Postol spell out in detail the assumptions upon which their calculation is based. One of those assumptions, for example, is that the target is \u2018a conical warhead with a radar cross-section at X-band of 0.01m2<\/sup>.\u2019<\/p>\n The Lewis and Postol estimate coincides broadly with the figure used later by Jaganath Sankaran and Bryan Fearey, who argue<\/a> that \u2018a THAAD radar would have a maximum range of approximately 800 kilometers under even highly optimistic conditions\u2019. Sankaran and Fearey use that estimate to point out that the radar would have almost no capability to detect and track Chinese ICBMs.<\/p>\n In July 2016, a commentator<\/a> on a missile defence blog separated out a range of different estimates\u2014from about 480 km to 3,000 km\u2014and explored the reasoning behind them. The range is \u00a0shortest when the radar is in terminal guidance mode, and at its (uncertain) longest when in the forward-based mode. That makes sense. The range of the THAAD interceptor is about 200 km. There\u2019s little point in having a radar with an excessively long range if its primary function is to guide interceptors to targets in the demanding terminal phase.<\/p>\n So let\u2019s assume 800 km is approximately right for the radar in its forward-based mode. Yes, the range would be longer if the target were bigger\u2014if the radar were looking at a warhead from side-on, for example, rather than front-on. And, yes, the radar will get better over time. It\u2019s currently being upgraded<\/a> from gallium-arsenide to gallium-nitride components: the benefits, apparently, include enhanced range, and increased detection and discrimination performance. The software\u2019s getting better too.<\/p>\n But I think the Reuters<\/em> headline is wrong on one important point: Chinese analysts are concerned about the radar not simply on the basis of what they don\u2019t know, but on the basis of what they do. They only have to look at the record of testing by the US Missile Defense Agency (MDA) to know that the AN\/TPY-2 radar, operating in its forward-based mode, is frequently a featured sensor, even in relation to intercepts of longer-range missiles. See, for example, this brief video<\/a> of FTG-05, a test conducted in December 2008. The AN\/TPY-2, deployed in Juneau, Alaska, acted as the forward radar in relation to the tracking and interception of a missile launched from Kodiak, Alaska.<\/p>\n