Sathyabama nanosatellite - payload subsystem

In this paper, we present the objectives and features of the payload subsystem of SNSAT, the nanosatellite which is to be launched by SathyabamaUniversity in near future. The payload comprises of the spectrometer and its interface, with the prime aim to detect the concentration of five major constitutes green house gases namely, Carbon Dioxide, Water, Carbon Monoxide, Methane and Hydrogen Fluoride whose wavelength range between 900nm and 2.5μm (near infrared band). It records infrared radiation emitted from the Earth's surface. By absorption spectrometry, absorption and the column density of these gases can be obtained. Linear Indium Gallium Arsenide (InGaAs) photodiode detector array is employed. The array is hybrid InGaAs and CMOS active-pixel readout electronics. Detector has Spectral Resolution is approximately 6 nm. Optics employs 35 mm optics to collimate radiation from a 1 km tile onto a diffraction grating and then focus it onto the detector array. Data packets are processed and transmitted to the OBC subsystem using either RS232 interface or TLL logic at a period of 100ms. The payload is designed to consume less than 1 watts of power.