China’s Earth-Monitoring Satellites

November 9, 2011
Laura Grego
Senior Scientist

The article “Space, China’s Tactical Frontier” by Eric Hagt and Matthew Durnin  has just been published in the Journal of Strategic Studies (JSS) October 2011 issue. The piece focuses on the increase in China’s earth-observing satellite capabilities in recent years. Along with this article is commentary on the article  written by David Wright here at UCS, as well as the authors’ response to the commentary.

The Hagt-Durnin (HD) paper does not just discuss general trends, but starts with a quantitative assessment of China’s satellite reconnaissance capability and its growth over the past decade. The point of doing a quantitative analysis of this kind is to get the numbers right. Doing so requires understanding the details of the satellites included in their calculation, making sure the calculations are based on reasonable assumptions, and making sure the calculations themselves are correct. It is also important to provide references to sources that justify and substantiate the key technical inputs to the calculation.

Unfortunately, the HD paper fails to do these things rigorously. What this means is that many of the key results of their calculations are incorrect or misleading.

While the final version of the HD paper still suffers from this, it was even a bigger problem with an earlier version of the manuscript. That version was released to some reporters and bloggers in July and attracted attention because of claims about a significant acceleration in the growth of China’s satellite-based reconnaissance capabilities in recent years, and that these capabilities are comparable with those of the United States.

For example, on July 11, 2011, Financial Times’ Simon Rabinovitch wrote in “China’s ‘eye-in-the-sky’ nears par with US”:

Chinese reconnaissance satellites can now monitor targets for up to six hours a day, the World Security Institute, a Washington think-tank, has concluded in a new report. The People’s Liberation Army, which could only manage three hours of daily coverage just 18 months ago, is now nearly on a par with the US military in its ability to monitor fixed targets, according to the findings.

Starting from almost no live surveillance capability 10 years ago, today the PLA has likely equalled the US’s ability to observe targets from space for some real-time operations,” two of the institute’s China researchers, Eric Hagt and Matthew Durnin, write in the Journal of Strategic Studies.

Similar reports appeared in Reuters and For claims so extraordinary, a rock-solid case needs to be made.

The published version of the HD paper has addressed some of the problems in the analysis contained in the briefed version. Their estimate of daily monitoring time has dropped from the 6 hours reported above in the July manuscript to 4.3 hours in the optimistic case and under 2 hours in the “conservative” estimate in the October manuscript. However, other problems remain and these daily monitoring times are still too long.

In particular, Wright shows that in their “optimistic case” the average monitoring time should actually be less than 3 hours. This takes into account correcting the calculation for one satellite and removing two satellites that should not be included in their calculation.

This reduction in average monitoring time by Chinese satellites also significantly changes the growth rate of Chinese monitoring capability that they give in their paper. Instead of showing a dramatic increase in capability over the past 2 years, the revised result shows a relatively constant, but more gradual, growth over the past decade.

The HD paper contains some useful discussion of Chinese satellites and the increasing monitoring capability they provide. But readers should not rely on the quantitative analysis it gives.