scholarly journals New Thermal Design Strategy to Achieve an 80-kg-Class Lightweight X-Band Active SAR Small Satellite S-STEP

Aerospace ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 278
Author(s):  
Tae-Yong Park ◽  
Bong-Geon Chae ◽  
Hongrae Kim ◽  
Kyung-Rae Koo ◽  
Sung-Chan Song ◽  
...  
Keyword(s):  
Design Strategy ◽  
Heat Fluxes ◽  
Thermal Design ◽  
Module Structure ◽  
Small Satellite ◽  
Graphite Sheet ◽  
Heater Power ◽  
X Band ◽  
Experimental Project ◽  
Flexible Graphite

The main objective of the S-STEP (the Small Synthetic Aperture Radar (SAR) Technology Experimental Project (S-STEP)) mission is developing an 80-kg-class active X-band SAR observation small satellite. For lighter, smaller, better, and cheaper development of the S-STEP system, a new thermal design strategy is essential. Therefore, we proposed a new thermal design strategy in this study. The main features of the proposed thermal design involve the minimization of heater power consumption by optimizing environmental heat fluxes on the satellite, the provision of long-term SAR imaging duration in both right- and left-looking modes, and the use of a lightweight flexible graphite sheet as a thermal interface for some high-power instruments. These features contribute to minimizing the satellite’s mass budget through heater power minimization and achieving on-orbit system performance of S-STEP. The effectiveness of the proposed thermal design was numerically verified by on-orbit thermal analysis of the S-STEP system. In addition, the thermal design on a key payload component and the multifunctional transmit/receive module structure were verified through a space-simulated thermal vacuum test.

scholarly journals Innovative Mechanical Design Strategy for Actualizing 80 kg-Class X-Band Active SAR Small Satellite of S-STEP

Aerospace ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 149
Author(s):  
Seong-Cheol Kwon ◽  
Ji-Hae Son ◽  
Sung-Chan Song ◽  
Jin-Han Park ◽  
Kyung-Rae Koo ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
Mechanical Design ◽  
Test Results ◽  
Small Satellite ◽  
Satellite Systems ◽  
X Band ◽  
Experimental Project ◽  
Imaging Mode ◽  
New Space ◽  
Plate Type

The Small SAR Technology Experimental Project (S-STEP) mission aims to develop a new (space-based 80 kg-class active X-band synthetic aperture radar (SAR)) satellite with a main imaging mode of 1 m resolution stripmap. In the S-STEP mission, to achieve the design goal of developing faster, cheaper, better, and lighter small SAR satellite systems, innovative thermo-mechanical design approaches have been proposed and investigated. The major design approaches are the bus-payload integrated flat plate-type structure, multifunctional transmit/receive (TR) module, and dedicated vibration-free orbit deployer (VFOD) with the function of whole spacecraft vibration isolation. To validate the feasibility of the innovative mechanical design of S-STEP, a structural analysis considering launch and on-orbit environments is performed. In addition, development test results are presented to confirm the effectiveness of the proposed design approach for VFOD.

Development and flight qualification of a small satellite X-band spherical membrane antenna

2021 ◽  
Author(s):  
Aman Chandra ◽  
Terrance Pat ◽  
Juan Carlos Lopez Tonazzi ◽  
Christopher K. Walker
Keyword(s):  
Small Satellite ◽  
X Band

High speed downlink system for small satellite and high-efficiency x-band GaN SSPA

2014 ◽  
Author(s):  
Hiromi Watanabe ◽  
Tomoya Fukami ◽  
Hirobumi Saito ◽  
Atsushi Tomiki ◽  
Osman Ceylan ◽  
...  
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Small Satellite ◽  
X Band ◽  
Downlink System

PEM Fuel Cell Stack Development: Grafoil Bipolar Materials — A Feasibility Study

2004 ◽  
Author(s):  
N. Rajalakshmi ◽  
V. Vijay ◽  
S. Pandian ◽  
K. S. Dhathathreyan
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Driving Forces ◽  
Applied Pressure ◽  
Pem Fuel Cell ◽  
Flow Fields ◽  
Proton Exchange ◽  
Graphite Sheet ◽  
Fuel Cell Stack ◽  
Flexible Graphite

In the production of Proton Exchange Membrane Fuel Cell (PEMFC) stacks with multiple cell units, graphite has been widely used as a bipolar material. Graphite has excellent electrical conductivity, high electrochemical stability, and good machining characteristics, enabling fine and complex fuel/oxidant flow fields to be used. In spite of the above advantages, search for alternate materials is counting owing mainly to the present requirement of reduced cell volume and weight per power yield (kW) in many applications. Cost reduction for this component and volume production are other driving forces for the continuous thrust in this subject. Flexible (exfoliated) graphite is an alternate material that could meet many of the above requirements. We have made use of flexible graphite to fabricate a PEM fuel cell stack. The flow fields were introduced by stamping. An optimization study has been carried out for the width and depth of the flow field designs in terms of applied pressure to accommodate the resilience of the flexible graphite sheet. The performance of the 500 watts stack fabricated using this material compares well with that fabricated using the conventional graphite plates. However there are some technical issues still to be sorted out which will be discussed.

A Review of Two-Phase Forced Cooling in Three-Dimensional Stacked Electronics: Technology Integration

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Craig Green ◽  
Peter Kottke ◽  
Xuefei Han ◽  
Casey Woodrum ◽  
Thomas Sarvey ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Three Dimensional ◽  
High Heat ◽  
Heat Fluxes ◽  
Thermal Design ◽  
High Heat Flux ◽  
Two Phase ◽  
Forced Cooling ◽  
Fluidic Routing

Three-dimensional (3D) stacked electronics present significant advantages from an electrical design perspective, ranging from shorter interconnect lengths to enabling heterogeneous integration. However, multitier stacking exacerbates an already difficult thermal problem. Localized hotspots within individual tiers can provide an additional challenge when the high heat flux region is buried within the stack. Numerous investigations have been launched in the previous decade seeking to develop cooling solutions that can be integrated within the 3D stack, allowing the cooling to scale with the number of tiers in the system. Two-phase cooling is of particular interest, because the associated reduced flow rates may allow reduction in pumping power, and the saturated temperature condition of the coolant may offer enhanced device temperature uniformity. This paper presents a review of the advances in two-phase forced cooling in the past decade, with a focus on the challenges of integrating the technology in high heat flux 3D systems. A holistic approach is applied, considering not only the thermal performance of standalone cooling strategies but also coolant selection, fluidic routing, packaging, and system reliability. Finally, a cohesive approach to thermal design of an evaporative cooling based heat sink developed by the authors is presented, taking into account all of the integration considerations discussed previously. The thermal design seeks to achieve the dissipation of very large (in excess of 500 W/cm2) background heat fluxes over a large 1 cm × 1 cm chip area, as well as extreme (in excess of 2 kW/cm2) hotspot heat fluxes over small 200 μm × 200 μm areas, employing a hybrid design strategy that combines a micropin–fin heat sink for background cooling as well as localized, ultrathin microgaps for hotspot cooling.

Thermal Design and Analysis of Spacecraft During Flight Missions

2013 ◽  
Author(s):  
Ahmed M. Farag ◽  
Essam E. Khalil
Keyword(s):  
Heat Dissipation ◽  
Thermal Conditions ◽  
Thermal Control ◽  
Cooling Capacity ◽  
Low Earth Orbit ◽  
External Heat ◽  
Heat Fluxes ◽  
Thermal Design ◽  
Surface Areas ◽  
Variable Space

Thermal control system (TCS) is one of the main systems in spacecraft, which guarantees the assigned thermal conditions of all subsystems and equipment during spacecraft (SC) lifetime, and partially participation in ground thermo-stating during testing. TCS is designed according to the calculation of SC thermal budget to estimate device panels’ ability for dissipation excess heat, which is emitted by SC equipment in process of nominal operation during maximum external heat flux. Calculating radiation surface areas of equipment panels is performed to reject heat dissipation. Estimating of SC panels cooling capacity during minimum external heat fluxes is required to calculate power of heaters. SC model in Low Earth Orbit (LEO) is created by thermal desktop program, in order to launch a parametric study of the variable space parameters which would effect on SC at the LEO.

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