thermal design and modeling for infra red spectroscopic imaging survey payload (irsis) s. l....

Thermal Design and Modeling

for

Infra Red Spectroscopic Imaging Survey Payload (IRSIS)

S. L. D’Costa

Goals to be achieved

1. Detector temperature to be at 77 K

2. Filter and grating temperature to be at 77 K

3. Optic fibre coupling at 100 K

4. Primary and Secondary mirrors to be at 100 K

5. Electronics temperature ~ 290 K

Parameters involved in Thermal Modeling

1. Orbital Parameters

2. Payload geometry

3. Total allowed size and weight of the Payload

4. Configuration of optics

5. Placement of Electronics

6. Total power dissipation in the entire electronics

7. Materials to be used in construction

Orbital Parameters

Orbit : Sun synchronous Polar orbit of ~800 km.

Source : Cooling Technology for Large Space Telescopes – Keith Walyus (NASA Science Technology Conference 2007)

Preferred Orbit : Dawn / Dusk Sun Synchronous~ 800 km., ~ 96 min/orbit~ 98 degrees inclination

Environmental Heat Loads

Source : Thermal Performance of the CrIS passive cryocooler – B. Ghaffarian et al – Cryogenics 46 (2006) 158-163

Sun Albedo Earth Total

Noon orbit 3.143 Watts 0.628 Watts 4.290 Watts 7.961 Watts

13:30 orbit 0.128 Watts 0.553 Watts 4.290 Watts 5.001 Watts



Heat loads for different Sun Synchronous orbits in Watts

ISRO Launch Capability

In 2001, ISRO launched PSLV-C3 with the followingSatellites put into orbit

1. TES (Technology Experiment Satellite) 1108 kg. 568 km. Sun Synchronous Polar Orbit

2. PROBA (PRoject for On Board Autonomy) of Belgium, 94 kg., Elliptical orbit 568 x 638 km.

3. BIRD (Bispectral and Infrared Remote Detector of Germany, 92 kg., 568 km. SSO

1. Telescope optics always pointing in the Anti – Sun direction

2. Sun Shield with multiple layers to be deployed after reaching orbit 3. Separate enclosure for Spectrometer with radiation shields and one side facing deep space

4. Detector and spectrometer components cooled by Stirling Cooler

5. Low thermal conductivity struts for mounting telescope and spectrometer on satellite deck

Payload Geometry

Telescope Optics

1. Cassegrain configuration for telescope

2. High conductivity, high strength (Beryllium?) mount for secondary mirror

3. Open configuration for telescope

4. Type of baffling to be used

5. Fibre coupling to spectrometer enclosure

Strategy for Thermal design

1. Firming up basic satellite, telescope and orbit parameters

2. Interacting with ISRO engineers for inputs on thermal insulation and shield design

3. In-house thermal modeling using software like Radtherm

4. Final thermal modeling to be outsourced with inputs from ISRO

5. Testing strategy and facilities

thermal design and modeling for infra red spectroscopic imaging survey payload (irsis) s. l....

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