X-Sat

X-Sat is a microsatellite developed and built by the Nanyang Technological University (NTU) in collaboration with Defence Science Organisation (DSO) Singapore. The satellite was launched by ISRO's PSLV-C16 on 20 April 2011 from Satish Dhawan Space Centre FLP in Sriharikota, India. The satellite was launched along with Indian ResourceSat-2 and Indo-Russian YouthSat.

The objective of the X-SAT mission is to demonstrate technology in support of high-resolution imaging capabilities and to analyse and implement onboard parallel-processing algorithms, thereby demonstrating improved mission achievements for generally downlink-limited small satellite imaging missions.

The satellite carries three payloads, namely the imaging system IRIS, the communication platform ADAM, and the Parallel Processing Unit (PPU) for image processing. Further research experiments using the communication and navigation instruments on-board will be conducted to investigate atmospheric question and communication related issues.

The camera is built by SatReCi and designed as a push-broom scanner with three individual scan lines in the green (520 nm – 600 nm), red (630 nm – 690 nm), and near-infrared (760 nm – 890 nm) wavelength range. The three linear detectors consist of 5000 active elements each, which were all manufactured on the same wafer and subsequently coated with different interference filters to select the appropriate spectral characteristic. The design provides a high degree of band-to-band alignment, i.e. 0.1 pixels. The provided spatial resolution will be 10 m for the nominal altitude of 685 km, thus enabling a swath width of 50 km. The optics were designed as a variant of the Mangin telescope with a primary and secondary mirror as well as two correction lenses and has an aperture diameter of 120 mm. Internally the IRIS is equipped with a redundant signal processingand control module, which pre-processes the image data for the storage in the 8 Gbit large memory module. This bulk storage module is entirely under the control of the IRIS.

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