Sensor Architecture for Surveillance and Integrated Aerospace Defense

Over the short term, the PLA’s ability to conduct strategic and opera­tional strike missions is likely to be restricted by the limited range of its persis­tent surveillance assets. Thus, to expand its battlespace awareness, the PLA is investing in four key capabilities enabling it to monitor activities in the western Pacific, the South China Sea, and the Indian Ocean:

■ near-space flight vehicles

■ space-based orbital platforms

■ airborne platforms

■ land-based over-the-horizon (OTH) and other radar systems.

The PRC has placed a relatively high priority on developing sensors for persistent surveillance from near-space. However, coverage from platforms simi­lar to satellites in low Earth orbit could offer significant improvements in resolu­tion. Duration of flight for near-space vehicles far exceeds that of unmanned aer­ial vehicles (UAVs), and their small radar and thermal cross-sections make them difficult to track and target. Powered in part by high-efficiency solar cells, near­space vehicles are viewed by PLA advocates as a relatively inexpensive means of furnishing persistent broad-area surveillance.104 Thus, over the next decade, near­space flight vehicles may emerge as a dominant PLA platform for

a persistent region-wide surveillance capability during crisis situations.105 In sum, despite the significant technical challenges that exist, the PLA and China’s de­fense R&D community have become increasingly interested in near-space flight vehicles for reconnaissance, communications relay, and electronic countermea – sures.106 For reconnaissance missions, synthetic aperture radar surveillance and electronic intelligence appear to be priorities.107

In order to overcome technical challenges, CASIC established a new re­search institute in 2005 dedicated to the design, development, and manufac­turing of near-space, lighter-than-air flight vehicles for surveillance purposes. Known as the the “068 Base Near-space Flight Vehicle R&D Center” and locat­ed in Hunan Province, its initial projects include the JK-5, JK-12, and JKZ-20 airships. The 068 Base has a cooperative R&D program with Russian counter­parts for upper atmospheric airship control systems.108

Increasingly sophisticated, space-based surveillance systems would ex­pand PLA battlespace awareness and support strike operations farther from

Chinese shores.109 Space assets enable the monitoring of naval activities in sur­rounding waters and the tracking of potentially hostile air force deployments into the region. Space-based reconnaissance systems also provide imagery nec­essary for mission planning functions, such as navigation and terminal target­ing and guidance for land attack cruise missiles (LACMs). Satellite communi­cations also offer a survivable means of communication that will become par­ticularly important as the PLA operates farther from its territory.

The PRC has embarked on a major dual-use, civil-military space pro­gram that is predominantly driven by the desire to stand among equals in the international community.110 However, as in most space programs, there is a military stake. A number of authoritative journals have advocated accelerating and expanding China’s space-based surveillance system, including the need for a “space-based theater electronic information system” covering an area of 3,000 square kilometers.111 Unverified sources indicate that a strategic cueing network for long-range precision-strike missions relies on a dual-use satellite architecture that is being implemented ahead of schedule.112

Integrated aerospace operations assume fusion of multiple sensors, in­cluding high resolution, dual-use space-based SAR, electro-optical (EO), and possibly electronic intelligence (ELINT) satellites for surveillance and target­ing. China’s space industry is reportedly nearing completion of its second-gen­eration SAR satellite, and its EO capabilities have been steadily progressing. As Chinese engineers have noted, SAR imagery is key for automated target recog­nition of ships at sea.113

While information is sparse, indications exist pointing to at least some PLA investment into developing a space-based ELINT capability.114 Prudence would suggest at least a rudimentary space-based electronic intelligence capa­bility already exists, perhaps as a package onboard a communications satellite or other space system. At least one design under evaluation is a constellation of small electronic reconnaissance satellites which can ensure precise location data and survivability. In a crisis situation, China may have the option of aug­menting existing space-based assets with microsatellites launched on solid-fu­eled launch vehicles. A new CASIC business division dedicated to microsatel – lites—the CASIC First Academy—was established in 2002. Existing and future data relay satellites and other beyond-line-of-sight communications systems could transmit targeting data to and from the theater command elements.115

Not surprisingly, radar systems constitute the foundational underpin­ning of China’s early warning network.116 The general trend is for PLA ra­dar coverage to expand upward into space and outward not just in the region but to global coverage. Chinese R&D is particularly focused on countering stealthy flight vehicles. Senior Colonel Liu Yongjian, a key air force acquisition authority responsible for technical radar requirements development, noted five priorities for radar development:

■ expansion of the radar frequency range from “microwave” frequencies toward a broader portion of the frequency spectrum

■ integration of space-based, airborne, ground-based, and maritime sensors

■ integration of infrared and laser-related sensors with passive and ac­tive radars

■ integration of radar functions, such as linking early warning and sur­veillance with seekers on strike assets

■ fusion of sensor data into an integrated network.117

The PLAAF appears to operate high-frequency (HF) skywave-exploit – ing OTH radar systems as a central element of an extended-range air defense and maritime surveillance architecture.118 Skywave OTH radar systems emit a pulse in the lower range of the frequency spectrum (3-30 MHz), which bounc­es off the ionosphere to illuminate a target—either air or surface—from the top down.119 As a result, detection ranges for wide area surveillance can extend out to 1,000 to 4,000 kilometers (620-2,480 miles).120 Able to detect stealthy air­craft, cruise missiles, and maritime surface targets, a skywave-exploiting OTH radar system could define the effective range of China’s strategic strike capa­bilities. A PLAAF unit known as the “skywave brigade” mans a watch center south of Hubei city in Xiangfan. The brigade operates transmitter and receiver sites and ionosphere measuring stations along China’s southeast coast.121

In addition to OTH systems, the PLA acquisition and technology and defense industry authorities have been examining other means to reduce the effectiveness of stealthy, low observable aircraft and other flight vehicles for at least 20 years. Technologies being developed include ultrawideband and bi – and multistatic radar systems, as well as synthetic aperture ladar systems.122

While GAD has a well-established space-tracking and control network, the PLA appears to still be working on radar systems capable of providing target queuing quality data for ballistic missile and satellite intercepts. However, a pro­totype long-range, large, phased-array radar has been used to support missile de­fense and ASAT testing over the last several years. One space surveillance radar R&D study indicated a requirement for detecting and tracking targets as small as 10 centimeters (3.93 inches) at an altitude of 500 kilometers (310 miles).123

In sum, the PLAAF, while technologically behind the U. S. Air Force and others, is nevertheless evolving into a force capable of dominating the skies around its periphery with support from the Second Artillery and information warfare assets. An aerospace campaign intended to coerce an adversary would emphasize preemption, surprise, and concentration of its most advanced assets to achieve a measure of shock. In order to effectively guide such a campaign, command and control would be centrally planned and executed by the Joint Theater Command, and supported by other joint command systems, including a joint Firepower Command Center, as well as command centers that would oversee component operations of the PLAAF and the Second Artillery.