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Otting W.,Aerojet Rocketdyne | Gard L.,Aerojet Rocketdyne | Hammel T.E.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc.
10th Annual International Energy Conversion Engineering Conference, IECEC 2012 | Year: 2012

The multi-mission Radioisotope Thermoelectric Generator (RTG), or MMRTG, was developed to be a workhorse unit for a variety of potential future missions. The MMRTG is capable of operating over a range of environments, from planetary atmosphere to the vacuum of space. The operating envelope spans a wide range of thermal environments providing the necessary flexibility to address a broad range of potential future missions. The high grade waste heat from MMRTG is ideal for thermal integration with the spacecraft, with the MMRTG providing both heat and electrical power to the spacecraft. The system is robust and will withstand very high launch and landing loads. The thermoelectric system is inherently radiation tolerant, making it ideal for the harshest space environments. The nuclear heat generator coupled with the solid state power conversion provides a simple, highly reliable, long life power system with no moving parts. The first use of the MMRTG is the Mars Science Laboratory (MSL) mission. The MMRTG is providing both heat and electrical power to the MSL rover, named Curiosity. The MMRTG went through a litany of tests and checkouts in preparation for the MSL mission. Initially, the MMRTG was tested as an ETG (Electrically Heated Thermoelectric Generator) to characterize the performance envelope and to ensure that the unit was acceptable to commit to fueling. Once fueled, the MMRTG went through a proto-flight acceptance test series including vibration, magnetic, thermal vacuum, and mass properties testing. These tests confirmed that the unit was acceptable for the MSL mission prior to shipping the unit to Kennedy Space Center (KSC). Once at KSC, the MMRTG underwent fit checks and final performance measurements prior to final integration with the spacecraft at the Vertical Integration Facility located at Launch Complex 41. The system was successfully launched on November 26th, 2011 and is currently in transit to Mars. © 2012 by Pratt & Whitney Rocketdyne.


Hammel T.E.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Keyser S.,Teledyne Energy Systems, Inc. | Sievers R.,Teledyne Energy Systems, Inc. | Otting W.,Aerojet Rocketdyne
10th Annual International Energy Conversion Engineering Conference, IECEC 2012 | Year: 2012

The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) was developed to serve as a power source for a variety of space missions, from planetary surface to deep space interplanetary missions. Its special capability to handle the harsh surface environment of Mars makes it unique among recent RTGs, which could not survive on the surface of Mars. The special design characteristic of an isolated and hermetically sealed thermoelectric converter compartment enables long term performance in a multitude of environments. The heat source compartment is separated from the thermoelectric converter compartment by means of a metallic liner. The heat source generated helium gas is slowly vented to the exterior through a gasket which is designed to maintain a nominal 1 atmosphere pressure inside the heat source compartment. The heart of the MMRTG, its thermoelectric couple, is based on the proven design heritage of the Pioneer and Viking RTGs. The Pioneer RTGs provided power for more than 30 years, long beyond their design life of only three years. The Viking RTGs for the Mars landers had a design life of only 90 days but they were operating when the landers were shut down after four years and they continued to operate for at least another 14 years after that. All crucial design aspects developed over the decades that are key to the rugged, reliable and long life of the Pioneer/Viking family of RTGs have been carried into the MMRTG design. Notable among these is the thermoelectric module cold end hardware thermal management system. This applies a constant spring force on each individual thermoelectric leg while providing a minimal temperature drop from the thermoelectric cold junction to the external radiator, which maximizes thermoelectric and system efficiency. This paper will expand on these design features and present test results which demonstrate the MMRTG's capability to reliably provide power for all types of deep space and planetary surface missions. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.


Holgate T.C.,Teledyne Energy Systems, Inc. | Song Y.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Keyser S.,Teledyne Energy Systems, Inc. | And 4 more authors.
14th International Energy Conversion Engineering Conference, 2016 | Year: 2016

The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) developed for NASA by Aerojet Rocketdyne and Teledyne Energy Systems, Inc. (TESI) has been providing reliable power to the Mars Curiosity Rover since its launch in 2011 (Mission on Mars began in August 2012). An improvement of the performance of the MMRTG is underway at TESI through a technology maturation program where higher efficiency skutterudite materials developed on the laboratory scale at NASA’s Jet Propulsion Laboratory (JPL) are being further developed at the production level into “flight-ready” materials and components. The success of this project will result in an enhanced MMRTG (eMMRTG) with an anticipated improvement of 25-30% in the beginning-of-life power and even greater improvement by end-of-life due to improved thermoelectric life properties. The status of the program, including engineering challenges, successes and current production capabilities will be presented. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.


Hammel T.E.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Keyser S.,Teledyne Energy Systems, Inc. | Sievers R.,Teledyne Energy Systems, Inc.
Nuclear and Emerging Technologies for Space, NETS 2013 | Year: 2013

The November 2011 launch of the MSL mission and subsequent landing of the Curiosity Rover on Mars on August 6, 2012 began a new era for Radioisotope Power Systems (RPS) used in space exploration. Curiosity is powered by the Pu238 fueled Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). This generator represents the latest generation of RPS and is based on a heritage that dates to the highly successful Pioneer/Viking missions of the 1970's. It has no moving parts and its performance is very stable under all loads. It is capable of meeting mission requirements from planetary surface operation with high temperatures and a variety of atmospheres, to deep space and orbital missions with high radiation fields or a need to detect weak electromagnetic fields. It is also mechanically robust for a range of launch vehicles, orientations and mission maneuvers. The MMRTG design can be used for many years into the future; in fact, two additional flight units are already in production. While the next steps are not defined at this time, the MMRTG design could be used as a backbone for the next generation of advanced generators with higher power and efficiency. The spring loaded modules are ideal to accommodate new couple materials in the same physical form factor as the baseline MMRTG couple and accommodate the structural capabilities/differences of these new materials nearly seamlessly. The most significant improvements will be in the TE conversion efficiency where advanced TE materials currently under test offer the promise of efficiency gains in the range of 20 to 50%. Increases in operating temperatures as well as the number of heat sources could increase the power by almost a factor of 2. Several design options have been evaluated with the benefits and risks identified, from very low risk modest improvements (up to 20%) to higher risk improvements that could deliver a 100% improvement in power. This paper does not contain ITAR technical data.


Holgate T.C.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Hammel T.,Teledyne Energy Systems, Inc. | Caillat T.,Jet Propulsion Laboratory | And 2 more authors.
Journal of Electronic Materials | Year: 2015

The National Aeronautics and Space Administration’s Mars Science Laboratory terrestrial rover, Curiosity, has recently completed its first Martian year (687 Earth days) during which it has provided a wealth of information and insight into the red planet’s atmosphere and geology. The success of this mission was made possible in part by the reliable electrical power provided by its onboard thermoelectric power source—the multi-mission radioisotope thermoelectric generator (MMRTG). In an effort to increase the output power and efficiency of these generators, a newly designed enhanced MMRTG (eMMRTG) that will utilize the more efficient skutterudite-based thermoelectric materials has been conceptualized and modeled, and is now being developed. A discussion of the motivations, modeling results and key design factors are presented and discussed. © 2014, The Minerals, Metals & Materials Society.


Hammel T.E.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Otting W.,Aerojet Rocketdyne | Gard L.,Aerojet Rocketdyne
Nuclear and Emerging Technologies for Space 2011, NETS-2011 | Year: 2011

Long-term reliable performance is the key attribute of Radioisotope Thermoelectric Generators (RTGs). The multi-mission RTG (MMRTG) is the most robust, mission flexible RTG yet developed, capable of operating in both planetary surface environments and deep space vacuum. The first MMRTG flight unit (F1) will be on the Mars Science Laboratory (MSL) when it launches in late 2011. The Engineering Unit (EU) was the first in this line of multi-mission generators. It has provided a wealth of data to verify generator capability and to assist in predicting the long-term performance of the newly developed MMRTG. This generator has gone through shock and vibration testing, thermal vacuum testing, and an array of performance tests to verify the MMRTG design basis. After successfully completing this extensive battery of tests, the EU was placed on life test where it is providing the first generator life performance data. The unit has been on life test for more than three years.


Hammel T.E.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Keyser S.,Teledyne Energy Systems, Inc. | Sievers R.,Teledyne Energy Systems, Inc. | And 2 more authors.
11th International Energy Conversion Engineering Conference | Year: 2013

The Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) has now fully demonstrated flight capability. The first flight unit (Fl) which was fueled in 2008, remained in storage on load until launch in late 2011, and experienced Atlas launch loads as well as the dramatic entry, descent and landing (EDL) of MSL on Mars. It is currently performing beyond target performance requirements providing power to the Curiosity rover. Two additional flight units (F2 and F3) will be delivered to the Department of Energy for future NASA missions. These missions are currently undefined, but will likely have different mission profiles and MMRTG operating conditions. Data to project the MMRTG performance on new missions are limited. Along with the data from Fl, the MMRTG program is collecting data from the Engineering Unit, which has been on life test for more than 40,000 hours, and two couple life test boxes, which have been on test for more than 30,000 hours. These tests provide confidence that the MMRTG will perform as well in the various environments of future missions as it is currently powering the Curiosity Rover on Mars. However, the broad application of the data to comprehensive performance predictions is limited by the sparse number of test articles and the limited test conditions. The data from all these sources will be presented and compared and relevancy to life modeling will be discussed.


Hammel T.,Teledyne Energy Systems, Inc. | Bennett R.,Teledyne Energy Systems, Inc. | Sievers B.,Teledyne Energy Systems, Inc.
IEEE Aerospace Conference Proceedings | Year: 2016

Advanced thermoelectric materials developed over the last 10 years have opened up a number of radioisotope generator design options for deep space and planetary exploration. Publications over the last several years have described options ranging from low risk upgrades to the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) to higher risk game changing designs with efficiency above 10% and power density above 5 W/kg. While the latter are very compelling to the mission planners, the reality is that only the former is within reach of the current NASA budget and near term missions. System design and mission studies have determined that even the former approach will provide significant power system improvements for future missions. A program is therefore in progress to evaluate evolutionary MMRTG upgrades using new skutterudite (SKD) thermoelectric materials. Modest temperature increases to produce higher beginning of life (BOL) power from the SKD materials are expected to be within the capability of the MMRTG system design. The SKD materials are also expected to provide a substantial end of life (EOL) improvement relative to MMRTG materials. This paper examines the evolutionary system design changes for this enhanced (e)MMRTG, provides a risk assessment of each and summarizes the expected performance. © 2016 IEEE.


Vander Veer J.R.,Teledyne Energy Systems, Inc. | Holgate T.C.,Teledyne Energy Systems, Inc. | Hammel T.E.,Teledyne Energy Systems, Inc.
IEEE Aerospace Conference Proceedings | Year: 2016

A systems integrated thermal model of an enhanced Multi-Mission Radioisotope Thermoelectric Generator (eMM-RTG) was performed utilizing Sinda 2014 from MSC Software. A comprehensive physics model was added to the Sinda solver which includes, among others, the Seebeck effect, Peltier effect, Thomson effect, Joule heating, and thermal radiation in all the applicable components. The added physics enables the computation of the power output of the eMMRTG. A custom tool was developed to rapidly and efficiently create the necessary Sinda input files allowing for parameterization and optimization of geometries and materials with ease. The methods and select results are presented and discussed. © 2016 IEEE.


Ferguson S.,Teledyne Energy Systems, Inc. | Miller M.,Teledyne Energy Systems, Inc. | Sievers B.,Teledyne Energy Systems, Inc. | Utz R.,Teledyne Energy Systems, Inc. | And 3 more authors.
IEEE Aerospace Conference Proceedings | Year: 2016

The upper stage of all launch vehicles are currently powered by batteries. This works well for short duration operation on the order of a couple hours, however the battery gets very heavy if the upper stage is needed for a longer mission to deploy multiple satellites into a broad range of orbits or to provide de-orbit or parking orbit operations. For upper stage vehicles with LOX and LH2, an option under investigation is to use a fuel cell, mounted in place of the battery and powered by the propulsion reactants from launch pad to end of mission. Launch weight can be reduced substantially while still meeting all the operation requirements of the vehicle and the mission. Design and development activities are in progress to evaluate the Proton Exchange Membrane (PEM) fuel cell for a number of current and future upper stage vehicles. © 2016 IEEE.

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