Indian Nano Satellite-1C (INS-1C) is an experimental satellite launched by PSLV-C40 on Jan 12, 2018 as a co-passenger payload. It is the third satellite in the Indian Nano Satellite (INS) series. The first two satellites (INS-1A and INS-1B) of this series were carried as co-passenger payloads by PSLV-C37 in February 2017. INS-1C carries Miniature Multi-spectral Technology Demonstration (MMX-TD) Payload from Space Applications Centre (SAC), ISRO Ahmedabad.

Compact imaging systems with reduced weight and size offer tremendous opportunities for their use in space borne micro/nano satellites and planetary missions where size and weight are at a premium. Although miniature cameras such as those found in cell-phones are now available commonly, their resolution and light collection are poor with respect to their full size counterparts. Robust Technology Development Programme of SAC/ISRO developed an innovative satellite payload using the concept of Origami - the art of folding paper. ISRO Nano Satellite (INS-1C) payload team has used the concept of multi-fold reflective optics to design imagers of significantly reduced thickness compared with conventional refractive cameras.

This multi-fold optical configuration is known as Origami optics. It is important to note that the reflective optics is based on metal mirrors, rather than the usual glass based Origami lens. The use of metal reflectors makes the camera potentially much more versatile in terms of spectral coverage. The mirrors and the optical assembly were developed indigenously. The optics is fabricated using single-point diamond turning machine with a fast-tool servo. Ray diagram of the Origami optics, Individual mirrors and Comparison with a conventional lens system are shown in the figures below:

Optical Ray Diagram

Mirror-1 Mirror-2

Indigenously developed Metal Origami Optics

Comparison between Origami Optics and Conventional Lens

Utilising the capability of the optics, a compact Miniature Multi-spectral Technology Demonstration (MMX-TD) payload was configured for INS-1C nanosatellite. The camera provides RGB snaps of 29 km x 29 km area with 23 m ground sampling from polar sun-synchronous orbit of 505 km altitude.

The first payload operation was carried out successfully on January 16, 2018 and since then, the payload is providing excellent images. Data sent by this camera is useful for topographical mapping, vegetation monitoring, aerosol scattering studies and cloud studies etc.,.

INS-1C MMX-TD Payload Mounted on Spacecraft

Images acquired by MMX-TD Payload

Himalyan Region seen from INS -1C

Nagqu, Tibet