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About These Blogs: The JPL Science & Technology Blogs are a way for our researchers and technical staff to give first-hand accounts of the activities that are going on at the Jet Propulsion Laboratory. A cross-section of our staff contribute posts about the tasks they are currently involved in for NASA and JPL. These blog posts are meant to discuss technical topics. Selected comments that are on-topic are published and are moderated.

<< Return to Latest Entries

Topic: Exploration & Observational Systems: Detectors and Instrument Systems
09.24.2009 9:41 AM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

As a follow-up to my previous entry regarding the bonding issues of the thermal spreader, I was able to complete a Thermal Math Model (TMM) to verify my hand calculations. The TMM results confirmed that even with a “dry” mount, meaning there was no bond material and only conductance due to the mechanical fasteners were used, there was sufficient thermal margin that the electronics boxes would not violate their AFT requirements. However, by having a good “wet” interface, meaning a uniformly filled ...Read More on 'Spacecraft Thermal Engineering'

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07.22.2009 8:11 AM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

Often times in addition to regular project work, surprises emerge that require immediate attention. Recently, a sudden issue came up with one of my tasks regarding a bonding issue. Essentially, the bond between a thermal spreader plate and a panel did not cure to specifications. The original bond was supposed to be a uniformly distributed 15 mil layer between the plates. However, upon inspection post curing, there were sections of the thermal spreader that could be depressed (essentially bubbling ...Read More on 'Spacecraft Thermal Engineering'

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07.14.2009 11:00 AM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

The Cassini spacecraft operates on sequences of commands that control every function the spacecraft executes. These commands are a combination of science and engineering requests designed to follow through on the mission. The engineering commands are in support of the science commands and they ensure the spacecraft operates correctly, stays on orbit, and is protected from any hazard.

One set of commands that I am in charge of as a member of the Thermal/Devices team are the Main Engine Assembly ...Read More on 'Spacecraft Thermal Engineering'

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07.07.2009 1:05 PM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

One of the issues that came up recently for the Juno task is the installation of a Waveguide Load (WGL). The primary purpose of this component is to dissipate energy in the event of a fault. The excess power is transferred to the WGL which is converted into thermal energy and this thermal energy has to be dissipated. The concern is that the WGL may heat up beyond its AFT due to a limited thermal path to the telecom panel, which is serving as the heat sink.

A simple hand calculation was conducted ...Read More on 'Spacecraft Thermal Engineering'

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06.23.2009 2:54 PM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

For the Juno Telecom panel, I am currently focused on creating my thermal math model (TMM). This model will be used to predict the thermal performance of the hardware under various operating conditions. Initially, these predictions will help to plan the combined thermal balance and qualification test that is scheduled for the telecom panel in early 2010. We can use the model to determine whether our test setup is adequate and to help define what typical temperatures to expect during testing. ...Read More on 'Spacecraft Thermal Engineering'

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06.16.2009 9:32 AM
Ruwan Somawardhana

By Ruwan Somawardhana
Spacecraft Thermal Engineering

NASA flight projects are broken up into 5 phases, A-E. Phase A is Concept Development, Phase B is Preliminary Design, Phase C is Detailed Design, Phase D is Fabrication, Assembly, Test & Launch Operations, and Phase E is Operations & Sustainment.

My Cassini work that I mentioned in my previous entry falls under Phase E. I have recently been assigned to do some work on Juno which is in Phase D. The telecom panel is set for testing in early 2010, but before that can happen, a lot of preparation ...Read More on 'Spacecraft Thermal Engineering'

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Author Bios

Erik Bailey
Guidance and Control Systems Engineering
Julie Castillo
Planetary Ices
Parker Fagrelius
Astronomy and Physics Missions Concepts
Chuck Manning
Microdevices Laboratory
Jeff Norris
Supervisor, Planning Software Systems Group
Tom Roberts
Optical Communications
Ruwan Somawardhana
Spacecraft Thermal Engineering


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