SEGMENT INFORMATION (Details) - Revenue from External Customers by Products and Services - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Revenue from External Customer [Line Items]
Revenue	$ 11,672	$ 9,628	$ 38,612	$ 31,270
Satellite Revenue [Member]
Revenue from External Customer [Line Items]
Revenue	5,822	5,272	20,050	14,704
Government Non-Space Revenue [Member]
Revenue from External Customer [Line Items]
Revenue	5,469	3,165	16,324	12,680
Other Commercial & Industrial Revenue [Member]
Revenue from External Customer [Line Items]
Revenue	$ 381	$ 1,191	$ 2,238	$ 3,886