It seems like you want to call an existing function, satelliteScenarioViewer, using Simulink. We can utilize the MATLAB function block for this purpose. In the code section of the MATLAB Function block, we can make a call to the required MATLAB function.
You can do something like this inside the MATLAB Function block:
function y = fcn(u)
viewer1 = satelliteScenarioViewer(scenario);
y = u;
Moreover, ensure that the MATLAB Function block can access the called function. If the .m file (containing the called function) is not in the current MATLAB path, you'll need to add its location to the path. This can be done by using the addpath function in MATLAB before running the Simulink model.
addpath('path_to_your_function');
You can refer to the following MathWorks documentation for more information on the MATLAB Function block:
