EPFL - LMTS N. Scheidegger

1. EPFL - LMTSN. Scheidegger Science Payload

2. Science Objectives Measure the airglow emission in the upper atmosphere at 100 km altitude to : • Demonstrate the feasibility of using airglow as a basis for a low-cost Earth Sensor • Validate the established airglow model or bring additional information about airglow dependence on → latitude→ altitude→ local solar time Nightglow and aurora borealis

3. Earth Appearance at 762 nm for different Solar Local Times

4. Expected airglow at 700 km altitude Airglow [photons/pixel/s] * *for an aperture of Ø4 mm and a FOV of 0.16°/pixel = minimum photon flux

5. Driving Requirements • Payload may be a technology demonstrator of the Earth Sensor based on airglow • Observes the emission at 762 nm with a bandwidth of at least [10] nm • Has a spatial resolution of at least [0.3]° and a FOV of at least [20]° • Observes the airglow with a CMOS SPAD array if possible • Survives having its boresight directly sun pointing for a period of at least 10 hours • Can perform science mission with the sun no closer than [30]° from its boresight. • Physical constraints • Volume: [30 x 30 x 70] mm3 for optics and detector [70 x 30 x 20] mm3 for mainboard • Mass: [60] g • Power: [450] mW, during [10]s for each image

6. Science Payload Instrument Design headboard mainboard baffle filter detector optical system

7. Design Description • Detector and control electronics • Detect photons and generate digital output which is proportional to local light intensity • Provides required power and control signal for the detector • Interfaces with CDMS and ground station • Optical system • Magnifies the image • Filters the selected airglow line • Protects detector from sun • Links the detector mechanically to the satellite bus

8. Detector * for an aperture of Ø4 mm and a total FOV of 25° for a SPAD array = current baseline design † including a Binning of 4 x 4 pixels

9. Optical System: Design Parameters

10. Optical System: Baseline Design

11. Diploma project: Design of a Telescope for the SwissCube Picosatellite • Understanding of the science and project requirements on the payload • Optical design for the payload • Opto-mechanical design for the payload, including selection of material for lens and support structure • Assembly of the overall payload subsystem based on the CMOS detector • Testing and verification of the optical properties of the payload • Documentation, preparation of end-of-phase review. • (Electrical design for the CMOS detector control) • (Establishment of hardware, data flow and cabling block diagrams for the payload subsystem, including connection with the other subsystems) • (Testing and verification of the electrical, power and sensitivity performance of the detector)

12. My inputs: • Filter design (1.5.07) • Determination of the interface with the CDMS sub-system (1.4.07) • (Electrical design for the CMOS detector control) (1.5.07) • (Establishment of data flow and cabling block diagrams for the payload subsystem, including connection with the other subsystems) (1.5.07)

13. Planned meetings and reports: • 1 x per month with the whole payload subsystem team • Every week: each student reports briefly his/her last analyses and results (1 A4 page)

14. Questions ?

15. CDMS – Payload Interface • PL microcontroller: • Guarantees a standard interface between the detector and the CDMS subsystem or commands coming from the ground station • CDMS subsystem: • Controls activation of the payload subsystem • Provides the parameters for the detector initialization (integration time, binning factor, DCR suppression factor,…) • Reads the science data directly form the detector • Does image compression if necessary • Formats science data according to the science data product • Stores the science data until transfer to the ground station