We compare the performance of two segmentation algorithms, previously proven on high resolution airborne synthetic aperture radar (SAR) data, on lower resolution spaceborne SAR data. The algorithms are: RWSEG - iterative multiscale edge detection/segment growing; and ANNEAL - maximum a posteriori radar cross-section reconstruction via simulated annealing. To test the utility and robustness of the algorithms they are applied to ERS-1 PRI images of an agricultural area in the UK and salt playa in Tunisia. These scenes are chosen for the differences between what we would define as useful segmentations of them. A number of tests are applied to segmentation output to measure the homogeneity of segments and the complexity of segment boundaries. The segmentations produced by ANNEAL are generally more detailed than those produced by RWSEG, but take much longer to produce. We also investigate how RWSEG can be used to detect structural change in multitemperal sequences of images. It is found that it is not possible to clearly identify structural similiarites and differences when images are segmented separately and segment boundaries are then overlaid. Much better results occur when a multitemporal sequence is segmented as a single entity.