Calibration of Capella

Doesn’t SNAP provide a calibration function for Capella images yet?
When I tried it, I got the following error message:
“Error: Mission Capella is currently not supported for calibration.”

I want to get the normalized backscattering value from SAR images to generate input data for deep-learning models.
Corresponding comparisons between different satellites and images must be possible to train some models such as detection, classification, or segmentation.
So, I’m trying many other satellite images to convert to gamma0 value for deep-learning models.

Then, is it impossible for Capella data?
If so, do you have any recommendations for getting normalized backscattering values?

Thanks in advance for your answer.