Engineering topics

Baker, Charles

Publications and source records attributed to Baker, Charles.

15 records

NASA NTRS2020

NASA-ISRO Synthetic Aperture Radar (NISAR) Mission

NISAR is a multi-disciplinary Earth-observing radar mission that makes global measurements of land surface changes that will greatly improve Earth system models. NISAR data will clarify spatially and temporally complex phenomena, including ecosystem disturbances, ice sheet collapse, and natural hazards including earthquakes, tsunamis, volcanoes, and landslides. It provides societally relevant data that will enable better protection of life and property. The mission, a NASA-ISRO partnership, uses two fully polarimetric SARs, one at L-band (L-SAR) and one at S-band (S-SAR), in exact repeating orbits every 12 days that allows interferometric combination of data on repeated passes. NASA provides the L SAR; a shared deployable reflector; an engineering payload that supports mission-specific data handling, navigation and communication functions; science observation planning and L SAR data processing. ISRO provides the S-SAR, spacecraft, launch vehicle, satellite operations, and S-SAR data processing. The mission will be launched from the Satish Dhawan Space Centre, Sriharikota, India. Mission development has addressed many unique challenges and incorporates many “firsts” for a jointly-developed free-flyer radar science mission.

Sarma, C V H S↗

NASA NTRS2016

Design Development of a Combined Deployment and Pointing System for the International Space Station Neutron Star Interior Composition Explorer Telescope

This paper describes the design of a unique suite of mechanisms that make up the Deployment and Pointing System (DAPS) for the Neutron Star Interior Composition Explorer (NICER/SEXTANT) instrument, an X-Ray telescope, which will be mounted on the International Space Station (ISS). The DAPS system uses four stepper motor actuators to deploy the telescope box, latch it in the deployed position, and allow it to track sky targets. The DAPS gimbal architecture provides full-hemisphere coverage, and is fully re-stowable. The compact design of the mechanism allowed the majority of total instrument volume to be used for science. Override features allow DAPS to be stowed by ISS robotics.

Budinoff, Jason↗

NASA NTRS2015

Design Development of a Combined Deployment and Pointing System for the International Space Station Neutron Star Interior Composition Explorer Telescope

This paper describes the design of a unique suite of mechanisms which make up the Deployment and Pointing System (DAPS) for the Neutron Star Interior Composition Explorer (NICER/SEXTANT) instrument, an X-Ray telescope, which will be mounted on the International Space Station (ISS). The DAPS system uses 4 stepper motor actuators to deploy the telescope box, latch it in the deployed position, and allow it to track sky targets. The DAPS gimbal architecture provides full-hemisphere coverage, and is fully re-stowable. The compact design of the mechanism allowed the majority of total instrument volume to be used for science. Override features allow DAPS to be stowed by ISS robotics.

NICER Pointing↗

NASA NTRS2011

Lunar Reconnaissance Orbiter (LRO) Thermal On-Orbit Performance

The Lunar Reconnaissance Orbiter (LRO) was launched on June 18, 2009. The nominal mission ended on September 15, 2010 and LRO is now on a four-year extended mission. The LRO performances in hot and cold cases are compared to pre-launch analysis predicts, and operational lessons learned are discussed. One instrument has required tighter-than-anticipated thermal control, and two others have frequently requested unanticipated calibration maneuvers that had to be evaluated for their thermal performance. A series of off nadir thermal analyses of the entire orbiter were performed prior to launch, and these predictions are compared to actual maneuvers, with a discussion of the process by which maneuvers can be rapidly evaluated for thermal concerns. On December 21st, 2010, LRO experienced its first severe Lunar Eclipse. Operationally, this required the Spacecraft to pre-heat its main avionics panel in order to minimize control heater power during the period when the Earth blocks the sun from the moon. The operational design and in-flight performance are summarized.

Baker, Charles↗

NASA NTRS2011

Geoscience Laser Altimetry System (GLAS) Loop Heat Pipe Anomaly and On Orbit Testing

The Geoscience Laser Altimetry System (GLAS) is the sole instrument on the ICESat Satellite. On day 230 of 2003, the GLAS Component Loop Heat Pipe (CLHP) entered a slow circulation mode that resulted in the main electronics box reaching its hot safing temperature, after which the entire instrument was turned off. The CLHP had a propylene working fluid and was actively temperature controlled via a heater on the compensation chamber. The slow circulation mode happened right after a planned propulsive yaw maneuver with the spacecraft. It took several days to recover the CLHP and ensure that it was still operational. The recovery occurred after the entire instrument was cooled to survival temperatures and the CLHP compensation chamber cycled on a survival heater. There are several theories as to why this slow circulation mode exhibited itself, including: accumulation of Non-Condensible Gas (NCG), the secondary wick being under designed or improperly implemented, or an expanded (post-launch) leak across the primary wick. Each of these is discussed in turn, and the secondary wick performance is identified as the most likely source of the anomalous behavior. After the anomaly, the CLHP was controlled to colder temperatures to improve its performance (as the surface tension increases with lower temperature, as does the volume of liquid in the compensation chamber) and only precursor pulses occurred later in the mission. After GLAS s last laser failed, in late 2009, a decision was made to conduct engineering tests of both LHPs to try and duplicate this flight anomaly. The engineering tests consisted of control setpoint changes, sink changes, and one similar propulsive Yaw maneuver. The only test that showed any similar anomaly precursors on the CLHP was the propulsive maneuver followed by a setpoint increase. The ICESat Satellite was placed in a decaying orbit and ended its mission on August 30, 2010 in Barents Sea.

Baker, Charles↗

NASA NTRS2010

Application of a Physics-Based Stabilization Criterion to Flight System Thermal Testing

The theory shown here can provide thermal stability criteria based on physics and a goal steady state error rather than on an arbitrary "X% Q/mC(sub P)" method. The ability to accurately predict steady-state temperatures well before thermal balance is reached could be very useful during testing. This holds true for systems where components are changing temperature at different rates, although it works better for the components closest to the sink. However, the application to these test cases shows some significant limitations: This theory quickly falls apart if the thermal control system in question is tightly coupled to a large mass not accounted for in the calculations, so it is more useful in subsystem-level testing than full orbiter tests. Tight couplings to a fluctuating sink causes noise in the steady state temperature predictions.

Baker, Charles↗

NASA NTRS2009

Lunar Reconnaissance Orbiter (LRO) Rapid Thermal Design Development

The Lunar Reconnaissance Orbiter (LRO) project had a rapid development schedule starting with project conception in spring of 2004, instrument and launch vehicle selection late in 2005 and then launch in early 2009. The lunar thermal environment is one of the harshest in our solar system with the heavy infrared loading of the moon due to low albedo, lack of lunar atmosphere, and low effective regolith conduction. This set of constraints required a thermal design which maximized performance (minimized radiator area and cold control heater power) and minimized thermal hardware build at the orbiter level (blanketing, and heater service). The orbiter design located most of the avionics on an isothermalized heat pipe panel called the IsoThermal Panel (ITP). The ITP was coupled by dual bore heat pipes to an Optical Solar Reflector (OSR) covered heat pipe radiator. By coupling all of the avionics to one system, the hardware was simplified. The seven instruments were mainly heritage instruments which resulted in their desired radiators being located by their heritage design. This minimized instrument redesigns and therefore allowed them to be delivered earlier, though it resulted in a more complex orbiter level blanket and heater service design. Three of the instruments were mounted on a tight pointing M55J optical bench that needed to be covered in heaters to maintain pointing. Two were mounted to spacecraft controlled radiators. One was mounted to the ITP Dual Bores. The last was mounted directly to the bus structure on the moon facing panel. The propulsion system utilized four-20 pound insertion thrusters and eight-5 pound attitude control thrusters (ACS) in addition to 1000 kg of fuel in two large tanks. The propulsion system had a heater cylinder and a heated mounting deck for the insertion thrusters which coupled most of the propulsion design together simplifying the heater design. The High Gain Antenna System (HGAS) and Solar Array System (SAS) used dual axis actuator gimbal systems. HGAS required additional boom heaters to cool the approximately 10 W of RF losses thru the rotary joints and wave guides from the 40 W Ka system. By design this module needed a fair amount of heater, blanketing, and radiator complexity. The SAS system required a separate cable wrap radiator to help cool the Solar Array harness which dissipated 30 W thru the actuators and cable wraps. This module also was complex.

Baker, Charles↗

NASA NTRS2004

Community Plan for Far-Infrared/Submillimeter Space Astronomy

This paper represents the consensus view of the 124 participants in the Second Workshop on New Concepts for Far-Infrared/Submillimeter Space Astronomy.We recommend that NASA pursue the vision for far-IR astronomy outlined in the NAS Decadal Survey, which said: A rational coordinated program for space optical and infrared astronomy would build on the experience gained with NGST1 to construct [a JWST-scale filled-aperture far-IR telescope SAFIR, and then ultimately, in the decade 2010 to 2020, build on the SAFIR, TPF, and SIM experience to assemble a space-based, far-infrared interferometer. SAFIR will study star formation in the young universe, the buildup of elements heavier than hydrogen over cosmic history, the process of galaxy formation, and the early phases of star formation, which occur behind a veil of dust that precludes detection at mid IR and shorter wavelengths. The far-infrared interferometer will resolve distant galaxies to study protogalaxy interactions and mergers and the processes that led to enhanced star formation activity and the formation of Active Galactic Nuclei, and will resolve protostars and debris disks in our Galaxy to study how stars and planetary systems form.

Ade, Peter↗

NASA NTRS2003

In-Flight Thermal Performance of the Geoscience Laser Altimeter System (GLAS) Instrument

The Geoscience Laser Altimeter System (GLAS) instrument is NASA Goddard Space Flight Center's first application of Loop Heat Pipe technology that provides selectable/stable temperature levels for the lasers and other electronics over a widely varying mission environment. GLAS was successfully launched as the sole science instrument aboard the Ice, Clouds, and Land Elevation Satellite (ICESat) from Vandenberg AFB at 4:45pm PST on January 12, 2003. After SC commissioning, the LHPs started easily and have provided selectable and stable temperatures for the lasers and other electronics. This paper discusses the thermal development background and testing, along with details of early flight thermal performance data.

Grob, Eric↗

NASA NTRS2001

Evaluation of GLAS Demonstration Model Loop Heat Pipe Thermal Vacuum Performance with Various Fluid Charges

Two loop heat pipes (LHPs) are to be used for tight thermal control of the Geoscience Laser Altimeter System (GLAS) instrument, planned for flight in late 2001. The LHPs are charged with Propylene as a working fluid. One LHP will be used to transport 110 W from a laser a radiator, the other will transport 190 W from electronic boxes to a separate radiator. The application includes a large amount of thermal mass in each LHP system and low initial startup powers. This along with some non-ideal flight design compromises, such as a less than ideal charge level for this design concept with a symmetrical secondary wick, lead to inadequate performance of the flight LHPs during the flight thermal vacuum test in October of 2000. This presentation focuses on identifying; the sources of the flight test difficulties by modifying the charge and test setup of the successfully tested Development Model Loop Heat Pipe (DM LHP). While very similar to the flight design, the DM L14P did have several significant difference in design and method of testing. These differences were evaluated for affect on performance by conforming the DM LHP to look more like the flight units. The major difference that was evaluated was the relative fill level of the working fluid within the concentrically design LHP compensation chamber. Other differences were also assessed through performance testing including starter heater size and "hot biasing" of major interior components. Performance was assessed with respect to startup, low power operation, conductance, and control heater power. The results of the testing showed that performance improves as initial charge increases, and when the starter heater is made smaller. The "hot biasing" of the major components did not appear to have a detrimental effect. As a result of test results of the DM LHP, modifications are being made to the flight units to increase the fluid charge and increase the watt-density of the starter heater.

Baker, Charles↗

NASA NTRS2001

Geoscience Laser Altimeter System (GLAS) Instrument: Flight Loop Heat Pipe (LHP) Acceptance Thermal Vacuum Test

Two loop heat pipes (LHPs) are to be used for tight thermal control of the Geoscience Laser Altimeter System (GLAS) instrument, planned for flight in late 2001. The LHPs are charged with Propylene as a working fluid. One LHP will be used to transport 110 W from a laser to a radiator, the other will transport 160 W from electronic boxes to a separate radiator. The application includes a large amount of thermal mass in each LHP system and low initial startup powers. The initial design had some non-ideal flight design compromises, resulted in a less than ideal charge level for this design concept with a symmetrical secondary wick. This less than ideal charge was identified as the source of inadequate performance of the flight LHPs during the flight thermal vacuum test in October of 2000. We modified the compensation chamber design, re-built and charged the LHPs for a final LHP acceptance thermal vacuum test. This test performed March of 2001 was 100% successful. This is the last testing to be performed on the LHPs prior to instrument thermal vacuum test. This sensitivity to charge level was shown through varying the charge on a Development Model Loop Heat Pipe (DM LHP) and evaluating performance at various fill levels. At lower fills similar to the original charge in the flight units, the same poor performance was observed. When the flight units were re-designed and filled to the levels similar to the initial successful DM LHP test, the flight units also successfully fulfilled all requirements. This final flight Acceptance test assessed performance with respect to startup, low power operation, conductance, and control heater power, and steady state control. The results of the testing showed that both LHPs operated within specification. Startup on one of the LHPs was better than the other LHP because of the starter heater placement and a difference in evaporator design. These differences resulted in a variation in the achieved superheat prior to startup. The LHP with the lower superheat was sensitive to the thermal environment around the compensation chamber, while the LHP with the higher superheat (similar in design to DM LHP) was not. In response to the test results the placement of the starter heater will be optimized for the flight instrument testing for higher achieved superheat. This presentation discusses startup behavior, overall conductance of a radiator system, low power operation, high power operation, temperature control stability, and control heater power requirements as measured during this acceptance thermal vacuum test. A brief summary of 'lessons learned' will be included.

Baker, Charles↗

NASA NTRS2000

Geoscience Laser Altimeter System (GLAS) Final Test Report of DM LHP TV Testing

Two loop heat pipes (LHPs) are to be used for thermal control of the Geoscience Laser Altimeter System (GLAS), planned for flight in 2001. One LHP will be used to transport 100 W from a laser to the radiator, the other will transport 210 W from electronic boxes to the radiator. In order to verify the LHP design for the GLAS application, an LHP Development Model has been fabricated, and ambient and thermal vacuum tested. Two aluminum blocks of 15 kg and 30 kg, respectively, were attached to the LHP to simulate the thermal masses connected to the heat sources. A 20 W starter heater was installed on the evaporator to aid the loop startup. A new concept to thermally couple the vapor and liquid line was also incorporated in the LHP design. Such a thermal coupling would reduce the power requirement on the compensation chamber in order to maintain the loop set point temperature. To avoid freezing of the liquid in the condenser during cold cases, propylene was selected as the working fluid. The LHP was tested under reflux mode and with adverse elevation. Tests conducted included start-up, power cycle, steady state and transient operation during hot and cold cases, and heater power requirements for the set point temperature control of the LHP. Test results showed very successful operation of the LHP under all conditions. The 20 W starter heater proved necessary in order to start the loop when a large thermal mass was attached to the evaporator. The thermal coupling between the liquid line and the vapor line significantly reduced the heater power required for loop temperature control, which was less than 5 watts in all cases, including a cold radiator. The test also demonstrated successful operation with a propylene working fluid, with successful startups with condenser temperatures as low as 100 C. Furthermore, the test demonstrated accurate control of the loop operating temperature within +/- 0.2 C, and a successful shutdown of the loop during the survival mode of operation.

Baker, Charles↗

NASA NTRS2000

Thermal Vacuum Test of GLAS Propylene Loop Heat Pipe Development Model

This paper presents viewgraphs on Thermal Vacuum Tests of the GLAS (Geoscience Laser Altimeter System) Propylene Loop Heat Pipe Development Model. The topics include: 1) Flight LHP System (Laser); 2) Test Design and Objectives; 3) DM (Development Model) LHP (Loop Heat Pipe) Test Design; 4) Starter Heater and Coupling Blocks; 5) CC Control Heaters and PRT; 6) Heater Plates (Shown in Reflux Mode); 7) Startup Tests; 8) CC Control Heater Power Tests for CC Temperature Control; and 9) Control Temperature Stability.

Baker, Charles↗

NASA NTRS2000

Geoscience Laser Altimeter System (GLAS): Final Test Report of DM LHP TV Testing

The Demonstration Model (DM) Loop Heat Pipe (LHP) was tested at Goddard Space Flight Center (GSFC) during September and October, 1999. The LHP system was placed in the Dynavac 36 in. chamber in Building 4. The test lasted for about 6 weeks. The LHP was built, designed, and manufactured at Dynatherm Corporation, Inc. In Hunt Valley, MD according to GSFC specifications. The purpose of the test was to evaluate the performance of a propylene LHP for the Geoscience Laser Altimetry System (GLAS) instrument application.

Baker, Charles↗

NASA NTRS2000

Comparison of Thermal Performance Characteristics of Ammonia and Propylene Loop Heat Pipes

In this paper, experimental work performed on a breadboard Loop Heat Pipe (LHP) is presented. The test article was built by DCI for the Geoscience Laser Altimeter System (GLAS) instrument on the ICESat spacecraft. The thermal system requirements of GLAS have shown that ammonia cannot be used as the working fluid in this LHP because GLAS radiators could cool to well below the freezing point of ammonia. As a result, propylene was proposed as an alternative LHP working fluid since it has a lower freezing point than ammonia. Both working fluids were tested in the same LHP following a similar test plan in ambient conditions. The thermal performance characteristics of ammonia and propylene LHP's were then compared. In general, the propylene LHP required slightly less startup superheat 5nd less control heater power than the ammonia LHP, The thermal conductance values for the propylene LHP were also lower than the ammonia LHP. Later, the propylene LHP was tested in a thermal vacuum chamber. These tests demonstrated that propylene could meet the GLAS thermal design requirements. Design guidelines were proposed for the next flight-like Development Model (DM) LHP for thermal control of the GLAS instrument.

Kaya, Tarik↗