Development of Indigenous Metal-based Origami Payload for INS-1C Compact imaging systems with reduced weight and size offer tremendous opportunities for their use in spaceborne micro/nano satellite and planetary missions where size and weight are at a premium. Although miniature cameras such as those found in cell-phones are now commonplace, their resolution and light collection compare poorly with their full size counterparts. Origami is the art of folding paper, utilising this concept for satellite payload was truly novel approach cameout from SAC/ISRO’s robust Technology Development Programme. 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. What is significant is that the reflective optics is based on metal mirrors, rather than the usual glass based origami lens – first time in ISRO. The use of metal reflectors makes the camera potentially much more versatile in terms of spectral coverage. What is further remarkable is that the development of mirrors and the optical assembly is fully indigenous. Ray diagram of the Origami optics is shown below. The optics is fabricated using single-point diamond turning machine with a fast-tool servo. The developed optics is shown below and is compared with a conventional lens system. Utilizing the capability of the optics, a compact Miniature Multispectral 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-

Optical ray diagram

Mirror-1 Mirror-2

Indigenously developed metal Origami optics

Comparison between Origami optics and

conventional lens

Conventional lens

Origami optics

synchronous orbit of 505 km altitude. Main system parameters of the payload are tabulated below.

MMX-TD payload parameters Sr. No. Parameter Value

1 Focal length (mm) 130

2 Spectral bands Red-Green-Blue

3 Ground sampling distance (m) 23

4 Pixel format 1400 x 1400 pixels

5 Format on ground (km) 29 x 29

6 Digitization (bit) 8

7 Payload power (W) 2.6

8 Payload weight (kg) 1.6

9 Payload size (mm3) Electro-optical module: 110 x 120 x 150 Electronics: 80 x 130 x 120

The developed payload is shown below. INS-1C was launched on 12th January 2018 onboard PSLV-C40. The first payload operation was carried out successfully on 16th January 2018. Since then, the payload is providing excellent imageries. Some of the images are shown below. Possible data utilization of this payload are topographical mapping, vegetation monitoring, aerosol scattering studies, cloud studies etc.

INS-1C MMX-TD payload Mounted on spacecraft

Images acquired by MMX-TD payload

Himalyan Region seen from INS -1C

Camera

Soundur Dam, Orissa

Nagqu, Tibet