Thermal Fluids Analysis Workshop (TFAWS) 2015, Silver Spring, MD NCTS 21070-15. This paper addresses the lessons learned during the refurbishment and testing of the thermal control system for a spacecraft which was placed into long-term storage. The DSCOVR (Deep Space Climate Observatory) Observatory (formerly known as Triana) was originally scheduled to launch on the Space Shuttle in 2002. With the Triana spacecraft nearly complete, the mission was canceled and the satellite was abruptly put into storage in 2001. In 2008 the observatory was removed from storage to begin refurbishment and testing. Problems arose associated with hardware that was not currently manufactured, coatings degradation, and a significant lack of documentation. Also addressed is the conversion of the thermal and geometric math models for use with updated thermal analysis software tools

Hawk, John

Peabody, Sharon

Stavely, Richard

NASA Technical Reports Server

GSFC· 2015
Lessons Learned during 
the Refurbishment and 
Testing of an 
Observatory after Long-
term Storage
John Hawk, Sharon Peabody, and 
Richard Stavely
NASA Goddard Space Flight Center
https://ntrs.nasa.gov/search.jsp?R=20150018326 2019-08-31T06:28:38+00:00Z
Background
• The Triana mission development proceeded for 21 
months before it was abruptly postponed in 2001.
• The duration of the shut down was significantly longer 
than anticipated and the Observatory was stored for 
nearly a decade.
• The Triana observatory was stored in “stable suspension” 
in a cleanroom under nitrogen purge.
2TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Background
• After the mission was placed into storage, it was renamed 
DSCOVR (Deep Space Climate Observatory) and the 
primary science was changed from Earth science to 
space weather.
• The Deep Space Climate Observatory (DSCOVR) is now 
a joint mission between NASA, NOAA and the U.S. Air 
Force.
• After the nearly decade of “stable suspension” NASA 
refurbished the DSCOVR satellite and instruments.
3TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Background
• DSCOVR, currently stationed at the first Sun-Earth 
Lagrange point (L1), is designed to provide advanced 
warning of solar wind activity that could damage low Earth 
orbiting satellites and ground systems. DSCOVR also 
hosts two secondary instruments for Earth observations.
4TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Lessons Learned
• Documentation
• Software/modeling
• Hardware
• Propulsion
• Thermal Vacuum Testing
• Thermal Blankets
• Thermal Coatings
5TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Documentation
• Due to the abrupt shut down, data stored on various 
computers was not transferred to a central repository.
• Hard copies of documentation were often not properly 
stored. 
• When the DSCOVR mission ramped up a decade later, 
the documentation for the spacecraft was not readily 
available or no longer existed.
6TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Documentation
Lessons Learned: 
• Provide adequate time to allow for data collection and 
proper storage of data from all subsystems, including 
contractor support teams.
• Protocol should be established to govern the shutdown of 
a project / mission, with data deliverables to the project 
Configuration Management group from every discipline.
• Data stored by contractors should be listed as a 
deliverable.
7TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Software/Modeling
The thermal models were 
originally built in Thermal 
Synthesizer System (TSS) 
and SINDA/FLUINT, but were 
rebuilt in Thermal Desktop 
using the existing thermal 
models and available 
documentation for the rebuild 
process.
8TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Software/Modeling
• Certain portions of the heritage models have the 
surfaces integrated in to the Thermal Desktop model 
with the capacitance and conductance calculations 
integrated via INCLUDE files. 
• The instrument models obtained from the delivered 
TRIANA data were basic instrument models, with very 
little fidelity.
Lessons Learned:
• With discrepancies in the available documentation and 
missing information it is necessary to examine the flight 
hardware to verify the thermal model.
• Sufficient documentation and/or access to the model 
originator is needed to rebuild and update the models.
9TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Hardware Changes
• The instruments were removed from the Spacecraft for 
refurbishment.
• The bulk of the avionics had to be de-integrated from the 
Spacecraft for refurbishment.
• The ESA instrument was relocated from the end of the 
boom to the propulsion module.
• An extension was added to the end of the deployable 
boom to host the magnetometer.
• The reaction wheel assemblies had magnetic shields 
added to them to meet the new science requirements.
• Choke rings were added to the omni antennas.
• A new lithium ion battery was installed.
• Struts were added to strengthen the instrument deck.
10TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Hardware Changes
Lessons Learned: 
• Using existing hardware with new primary science 
objectives and requirements is likely going to drive 
multiple hardware changes that may not initially be know. 
• With numerous hardware changes and broken thermal 
interfaces thermal balance is highly recommend.
11TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
During the entirety of the thermal 
balance testing the external run 
of propulsion line zone 5 was 
running well below the minimum 
temperature requirement. During 
hot balance, this section of line 
reached a temperature of +2.3°C. 
Propulsion - Module Hardware
12TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
( )
Dual 
Thruster 
Modules 4
Liquid Fill and Drain 
Valve
Gas Fill and Drain 
Valve
Tank
Axial thrusters
Axial thrusters
External Section of Prop 
Zone 5 Line Heater
Propulsion
External Run of Propulsion Line Zone 5 
13TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Propulsion Line Heater Zone 5 Heater Control located inside the prop module
Med Control Thermistor  On @ 24°C Off @ 26°C
Low Control Thermistor   On @ 18°C Off @ 20°C 
Propulsion
• Further examination of the thermal balance test data from 
TRIANA testing revealed the same propulsion line 5 
behavior.
• On the external run, an auxiliary dual element heater with 
a pair of series redundant thermostats had to be installed 
over the existing line 5 heater.
• The added thermostats were chosen with control points 
lower than the existing electronic controller set-points so 
that the auxiliary heater wouldn't impact the function of the 
existing heater.
• Structural analysis had to be performed to assure that 
there was no impact due to the added thermostat, heater, 
and aluminum tape masses.
14TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Propulsion
• Since there was no 
readily available flight 
experience with this 
layered construction, 
an Engineering 
Development Unit 
(EDU) was fabricated 
and tested.
• Ambient testing of the 
flight installed auxiliary 
heater, as well as the 
underlying existing 
heater, was performed 
to verify operation. 
15TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Propulsion
• Wires had to be run to the bottom of the propulsion 
module to power the flight auxiliary heater.
• The high gain antenna and the prop module access panel 
had to be removed to gain access to the inside of the prop 
module for wire routing.
• Several mli blankets had to be removed to install the 
auxiliary heater.
• The flight installation had to be tested. 
16TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Propulsion - Flight Installed Auxiliary Heater
17TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Blanket not installed
Propulsion - Auxiliary Heater Flight Data
18TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Auxiliary Heater Cycling on 
Orbit
Propulsion
Lessons Learned: 
• The successful test program demonstrated acceptable 
function of the additional heater and thermostats, while 
preserving the functionality of the underlying heater.
• When possible separate propulsion line heater zones 
should be installed on interior and exterior lines. 
• If a propulsion line heater zone spans the interior and 
exterior interface of a spacecraft use doublers to enhance 
longitudinal conduction and locate control sensor at the 
coldest section of line.   
19TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Vacuum Testing
• Several power inconsistencies between test data and the 
systems level power budget were identified during 
thermal vacuum testing.
• Further investigation yielded information that the current 
monitors for the reaction wheels were incorrect and 
could not be used since they were not calibrated.
• The design of the DSCOVR current monitoring system 
has multiple components on a single current monitor.
• Several monitors include both a heater service and 
multiple power dissipating components.
20TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Vacuum Testing
• During the TRIANA testing program, there were several 
thermocouples installed on various internal propulsion 
components (tanks, lines, propulsion control module). 
When the program was abruptly shut down, the ends of 
these TC wires were cut such that the TC labels 
(numbers) were not preserved.
• Due to some significant power uncertainties, the overall 
correlation posed a significant challenge, and the 
correlation was unable to provide a good match between 
test and model predictions.
21TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Vacuum Testing
Lessons Learned: 
• Always preserve thermocouple labeling until you are sure 
they will never again be used.
• All current monitors should be verified against 
independent measurements during any component level 
testing.
• Make sure that the test environments will bound the worst 
hot and cold flight environments such that the test results 
directly validate the adequacy of the thermal design.
• Add the appropriate margin to your correlated model flight 
predictions.
22TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Blankets
• Germanium missing from 
most areas of germanium 
black Kapton MLI; replaced 
outer layers.
• Several blankets totally 
missing.
• Had to figure out the original 
location of many others.
23TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Blankets
Lesson Learned: 
• MLI in long term storage should be in a humidity 
controlled environment and handling minimized.
• Thermal Project Engineer should understand and inform 
Project Management regarding the scope and complexity 
of thermal blanket fabrication and installation.
• Individual blanket designs and fabrications should be 
identified with sufficient time allocated for these activities 
in the I&T schedule. 
• Individual blanket installations should be identified in the 
I&T schedule as any other hardware installation task, 
rather than specifying a general time period for overall 
installations.
24TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Blankets - Grounding
Lesson Learned:
• The design and implementation of blanket ground wire 
attachments should be completed prior to blanket 
installation.
– Provides for blanket grounding and grounding measurements 
during the blanket installation task.  By doing so, blanket 
installation can be fully completed during the scheduled 
installation session. 
– Ungrounded blankets can possibly interfere with other 
integration activities. 
25TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Blankets - Mechanisms
Lessons Learned: 
• For blanket applications associated with moving 
mechanism parts, blanket coverage and installation 
should be adequately discussed prior to the blanket 
installation.  After installation, blankets should be 
critically inspected by all required discipline engineers so 
that any blanket modifications can be performed to 
finalize the installation.
• Up-front planning can minimize or eliminate cost and 
schedule impacts resulting from blanket modifications 
required later in the program.
• Blanket modifications at higher levels of assembly later 
in the program can prove to be challenging.
26TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Coatings
• Most thermal control surfaces 
showed damage due to mishandling, 
although the optical properties hadn’t 
changed during storage.
– NS43C white coatings touched up with 
Z93C55 white paint. 
– High temperature E-glass MLI near the 
thrusters were shedding particles; 
required stainless steel shells be 
installed to contain the particles. 
– Phosphoric-acid etched nickel inside the 
NISTAR baffles began flaking. 
Instrument was taken apart, surfaces 
stripped and recoated with Z306 black 
paint.
– Root cause of shedding not clear.
27TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Thermal Coatings
Lessons Learned: 
• Schedule and budget for increased cleanings and 
inspections of coatings throughout the I&T campaign.
• Early on in the refurbishment consider stripping and re-
applying coatings to all shedding surfaces.
28TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD
Acknowledgements
• DSCOVR mechanical team.
• DSCOVR coatings group.
• DSCOVR contamination team.
29TFAWS 2015 – August 3-7, 2015 – Silver Spring, MD


Lessons Learned During the Refurbishment and Testing of an Observatory After Long-Term Storage

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