The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
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of natural disasters has shown rapid increase. Examples of this 
trend are related to floods, earthquakes, tsunamis, hurricanes 
and forest fires (Tralli, et al., 2005). Methods and strategies 
have to be developed to predict as well as to tackle the natural 
disasters. It is shown that near-space does indeed offers a 
significant opportunity for homeland security applications, and 
no other way existed can provide similar effects. Issues have 
been highlighted, but there are clear paths of future work such 
as synchronization, signal detection, imaging algorithms and 
motion compensation to overcome them. The concepts and 
techniques investigated in this paper may be regarded as the 
Phase I work towards promising near-space passive remote 
sensing for homeland security applications. Although exploring 
the potential of near-space passive remote sensing missions 
requires significant work on many fronts, we are indeed 
convinced the effort will be worth it. 
ACKNOWLEDGEMENTS 
This work was supported in part by the Open Fund of the Key 
Laboratory of Ocean Circulation and Waves, Chinese Academy 
of Sciences under Contract number KLOCAW0809; and 
supported in part by the Open Fund of the Beijing Key Lab of 
Spatial Information Integration and 3S Application, Peking 
University under Contract number SIIBKL08-1-04. 
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