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NASA NTRS1993

The atmospheres of Uranus and Neptune

The atmospheres of Uranus and Neptune are discussed in the light of the Voyager 2 flybys of these planets. A basic overview of their atmospheres is presented, with emphasis on thermal structure, composition, energy and opacity sources, cloud structure, and the horizontal structure of the atmospheres. The nature and implications of the different internal heat flows on the two planets, and the implications of the deuterium and helium abundances for the origin and evolution of these ice giants, as distinct from Jupiter and Saturn, are discussed. Selected chemical and physical processes in the atmospheres of Uranus and Neptune are illustrated.

Lunine, Jonathan I.↗

NASA NTRS2005

The Space Infrared Interferometric Telescope (SPIRIT)

SPIRIT, a candidate NASA "Origins Probe," is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets form, and why some planets are ice giants and others are rocky; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with the space-based SPIRIT will be complementary to those of ground-based submillimeter and millimeter arrays and to JWST. We report results of a recently-completed pre-Phase A mission study.

Leisawitz, David↗

NASA NTRS2007

The Space Infrared Interferometric Telescope (SPIRIT): High-resolution Imaging and Spectroscopy in the Far-infrared

We report results of a recently-completed study of SPIRIT, a candidate NASA Origins Probe. SPIRIT is a spatial and spectral interferometer with an operating wavelength range 25 - 400 microns. SPIRIT will provide sub-arcsecond resolution images and spectra with resolution R = 3000 in a 1 arcmin field of view to accomplish three primary scientific objectives: (1) Learn how planetary systems form from protostellar disks, and how they acquire their chemical organization; (2) Characterize the family of extrasolar planetary systems by imaging the structure in debris disks to understand how and where planets form, and why some planets are ice giants and others are rocky; and (3) Learn how high-redshift galaxies formed and merged to form the present-day population of galaxies. Observations with SPIRIT will be complementary to those of the James Webb Space Telescope and the ground-based Atacama Large Millimeter Array. All three observatories could be operational contemporaneously. SPIRIT will pave the way to the 1 km maximum baseline interferometer known as the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS). In addition to the SPIRIT mission concept, this talk will emphasize the importance of dense u-v plane coverage and describe some of the practical considerations associated with alternative interferometric baseline sampling schemes.

Leisawitz, D,↗

NASA NTRS2008

The Space Infrared Interferometric Telescope (SPIRIT): The Mission Design Solution Space and the Art of the Possible

Although the Space Infrared Interferometric Telescope (SPIRIT) was studied as a candidate NASA Origins Probe mission, the real world presents a broader set of options, pressures, and constraints. Fundamentally, SPIRIT is a far-IR observatory for high-resolution imaging and spectroscopy designed to address a variety of compelling scientific questions. How do planetary systems form from protostellar disks, dousing some planets in water while leaving others dry? Where do planets form, and why are some ice giants while others are rocky? How did high-redshift galaxies form and merge to form the present-day population of galaxies? This paper takes a pragmatic look at the mission design solution space for SPIRIT, presents Probe-class and facility-class mission scenarios, and describes optional design changes. The costs and benefits of various mission design alternatives are roughly evaluated, giving a basis for further study and to serve as guidance to policy makers.

Leisawitz, David↗

NASA NTRS2017

Progress Towards providing Heat-Shield for Extreme Entry Environment Technology (HEEET) for Venus and other New Frontiers Missions

Heat-shield for Extreme Entry Environment Technology (HEEET) has been in development since 2014 with the goal of enabling missions to Venus, Saturn and other high-speed sample return missions. It is offered as a new technology and incentivized for mission use in the New Frontiers 4 AO by NASA. The current plans are to mature the technology to TRL 6 by FY18. The HEEET Team has been working closely with multiple NF-4 proposals to Venus, Saturn and has been supporting recent Ice-Giants mission studies. This presentation will provide progress made to date and the plans for development in FY18.

Ablative thermal protection system↗

NASA NTRS2019

Challenges in Qualification of Thermal Protection Systems for Extreme Entry Environments

Planetary entry vehicles employ ablative TPS materials to shield the aeroshell from entry aeroheating environments. To ensure mission success, it must be demonstrated that the heatshield system, including local features such as seams, does not fail at conditions that are suitably margined beyond those expected in flight. Furthermore, its thermal response must be predictable, with acceptable fidelity, by computational tools used in heatshield design. Mission assurance is accomplished through a combination of ground testing and material response modelling. A material's robustness to failure is verified through arcjet testing while its thermal response is predicted by analytical tools that are verified against experimental data. Due to limitations in flight-like ground testing capability and lack of validated high-fidelity computational models, qualification of heatshield materials is often achieved by piecing together evidence from multiple ground tests and analytical simulations, none of which fully bound the flight conditions and vehicle configuration. Extreme heating environments (>2000 W/cm2 heat flux and >2 atm pressure), experienced during entries at Venus, Saturn and Ice Giants, further stretch the current testing and modelling capabilities for applicable TPS materials. Fully-dense Carbon Phenolic was the material of choice for these applications; however, since heritage raw materials are no longer available, future uses of re-created Carbon Phenolic will require re-qualification. To address this sustainability challenge, NASA is developing a new dual-layer material based on 3D weaving technology called Heatshield for Extreme Entry Environments (HEEET) [1]. Regardless of TPS material, extreme environments pose additional certification challenges beyond what has been typical in recent NASA missions.Scope of this presentation: This presentation will give an overview of challenges faced in verifying TPS performance at extreme heating conditions.

Mahzari, Milad↗

NASA NTRS2019

Thermal Protection System Technology Maturation and Sustainment in Support of In-situ Science Missions: HEEET and PICA

Among the challenges faced by the Entry Descent and Landing (EDL) community have been: the lack of a matured forebody heatshield thermal protection system (TPS) capable of meeting the demanding entry environments for the high priority in-situ science missions identified in the decadal survey at Venus, Saturn and the Ice Giants, and the continued sustainment of thermal protection systems/materials. In response to the identified shortfall in TPS technologies capable of extreme entry environments NASA's Space Technology Mission Directorate (STMD) and Science Mission Directorate (SMD) initiated the Heatshield for Extreme Entry Environment Technology (HEEET) project which has matured a 3D-Woven TPS to Technology Readiness Level 6 and which is ready for infusion into these high priority missions. During the development of HEEET long term sustainability was a key consideration. However existing TPS also continue to face sustainability issues. Phenolic Impregnated Carbon Ablator (PICA) has been/is being utilized by many SMD Missions (Stardust, Mars Science Laboratory, OSIRIS-Rex, Mars 2020, Dragonfly) and is under consideration for others including Mars Sample Return, so maintaining PICA for the long term is a priority for NASA. This presentation will discuss raw material sustainability challenges faced by PICA and the efforts by NASA to work with Fiber Materials Inc (FMI) to resolve these challenges with a more sustainable supply chain. In addition, NASA is working with FMI to increase the manufacturing scale for single piece PICA heatshields and to expand the aerothermal performance envelop maturing PICA for larger sized heatshield and more aggressive entry environments. This presentation will also identify challenges and limitations with these systems, particularly around understanding failure modes in these materials and systems and how understanding these may allow use of these systems in environments that are difficult to achieve in ground based testing.

Heatshield for Extreme Entry Environment Technolog↗

NASA NTRS2019

Thermal Protection System Technology Maturation and Sustainment in Support of In Situ Science Missions: HEEET and PICA

Challenges faced by the Entry Descent and Landing (EDL) community include the lack of a matured forebody heatshield thermal protection system (TPS) capable of meeting the demanding entry environments for the high priority in-situ science missions identified in the decadal survey at Venus, Saturn and the Ice Giants, and the continued sustainment of thermal protection systems/materials. In response to the identified shortfall in TPS technologies capable of extreme entry environments NASA's Space Technology Mission Directorate (STMD) and Science Mission Directorate (SMD) initiated the Heatshield for Extreme Entry Environment Technology (HEEET) project which has matured a 3D-Woven TPS to Technology Readiness Level 6 and which is ready for infusion into these high priority missions. During the development of HEEET long term sustainability was a key consideration. However existing TPS also continue to face sustainability issues. Phenolic Impregnated Carbon Ablator (PICA) has been/is being utilized by many SMD Missions (Stardust, Mars Science Laboratory, OSIRIS-Rex, Mars 2020, Dragonfly) and is under consideration for others including Mars Sample Return, so maintaining PICA for the long term is a priority for NASA. This presentation will discuss raw material sustainability challenges faced by PICA and the efforts by NASA to work with Fiber Materials Inc (FMI) to resolve these challenges with a more sustainable supply chain. In addition, NASA is working with FMI to increase the manufacturing scale for single piece PICA heatshields and to expand the aerothermal performance envelop maturing PICA for larger sized heatshield and more aggressive entry environments. This presentation will also identify challenges and limitations with these systems, particularly around understanding failure modes in these materials and systems and how understanding these may allow use of these systems in environments that are difficult to achieve in ground based testing

Phenolic Impregnated Carbon Ablator (PICA)↗

NASA NTRS2017

Progress Towards Providing Heat-Shield for Extreme Entry Environment Technology (HEEET) for Venus and Other New Frontiers Missions

Heat-shield for Extreme Entry Environment Technology (HEEET) has been in development since 2014 with the goal of enabling missions to Venus, Saturn and other high-speed sample return missions. It is offered as a new technology and incentivized for mission use in the New Frontiers 4 AO by NASA. The current plans are to mature the technology to TRL 6 by FY’18. The HEEET Team has been working closely with multiple NF-4 proposals to Venus, Saturn and has been supporting recent Ice-Giants mission studies. This presentation will provide progress made to date and the plans for development in FY’18.

Ablative thermal protection system↗

NASA NTRS2019

NASA's Space Launch System: Payload Opportunities for Lunar Exploration, Science Missions

Nearing its first launch, the Space Launch System (SLS), NASA’s new super heavy-lift launch vehicle, offers highly energetic launches that deliver more mass and provide more volume in 8.4 m-diameter and potentially larger fairings to make a new generation of deep space missions possible. An evolvable launcher available in crew, crew with a co-manifested payload (CPL) and cargo-only configurations, SLS is a crucial capability to enable astronauts to return to the Moon, but it also offers key benefits for science missions. NASA’s 21st-century return to the Moon recently received a formal name: the Artemis program. In addition to the core enabling capabilities of SLS and the Orion crew spacecraft, NASA will also enlist international and commercial partnerships for Artemis. The Agency intends to build a scientific outpost in lunar orbit, the Gateway, from which human and robotic missions to and from the surface can rendezvous. SLS will launch Orion on a series of missions leading to landing the first woman and the next man on the Moon as part of Artemis. SLS uses proven propulsion systems: two solid rocket boosters and four RS-25s engines that have been upgraded to provide more thrust and operate in the SLS environment. SLS Block 1 uses a modified Delta IV Heavy upper stage, called the Interim Cryogenic Propulsion Stage (ICPS) and lifts at least 26 metric tons (t) to trans-lunar injection (TLI). The Block 1 vehicle can also be outfitted with a 5 m-diameter fairing. Block 1B, the next major variant, also uses solid rocket boosters and RS-25 engines to achieve Earth escape velocity, but replaces the single-engine liquid hydrogen (LH2)/liquid oxygen (LOX) ICPS with a four-engine LH2/LOX Exploration Upper Stage (EUS) to increase mass to TLI to 34-37 t, depending on crew or cargo configuration. In the Block 1B crew configuration, a 10 m-tall Universal Stage Adapter (USA) connects the vehicle to Orion and can carry a CPL up to 10 t. The USA provides 286 m3 of unpressurized volume for payloads. For large payloads, 8.4 m- and 10 m-diameter cargo fairings in 19.1 m and 27.4 m lengths are possible. The ultimate SLS vehicle, Block 2, incorporates evolved boosters to reach a lift capacity of more than 45 t to TLI. The capabilities of SLS not only make new missions to the Moon possible, but also game-changing science missions, such as deployment of large-aperture space telescopes, spacecraft to the ice giants or even probes to the interstellar medium. This paper will discuss the capabilities of SLS, the vehicle’s planned evolution, missions that can effectively utilize the vehicle and manufacturing status of the vehicle.

Creech, Stephen D.↗

NASA NTRS2019

NASA's Space Launch System: Payload Opportunities for Lunar Exploration, Science Missions

Creech, Steve↗

NASA NTRS2019

Voyager 2 Constraints on Plasmoid‐based Transport at Uranus

A magnetosphere controls a planet's evolution by suppressing or enhancing atmospheric loss to space. In situ measurements of Uranus' magnetosphere from the Voyager 2 flyby in 1986 provide the only direct evidence of magnetospheric transport processes responsible for this atmospheric escape at Uranus. Analysis of high‐resolution Voyager 2 magnetic field data in Uranus' magnetotail reveals the presence of a loop‐like plasmoid filled with planetary plasma traveling away from the planet. This first plasmoid observation in an Ice Giant magnetosphere elucidates that (1) both internal and external forces play a role in Uranus' magnetospheric dynamics, (2) magnetic reconnection contributes to the circulation of plasma and magnetic flux at Uranus, and (3) plasmoids may be a dominant transport mechanism for mass loss through Uranus' magnetotail.

DiBraccio, Gina A.↗

NASA NTRSDate not supplied

NASA’s Space Launch System: High C3 Launch Capability for Science Missions

As NASA’s initial Space Launch System (SLS) Block 1 vehicle enters integration and stacking operations at Kennedy Space Center (KSC) this year in preparation for a 2021 launch, work is in progress on future more powerful variants of the vehicle. Available in the mid 2020s and 2030s, Block 1B and Block 2 will feature increased performance and unparalleled volume for payloads, providing an enabling launch option for science mission planners. The baseline SLS architecture consists of two five-segment solid rocket boosters and four RS-25 LH2/LOX engines. The evolved Block 1B and Block 2 vehicles use a four-engine LH2/LOX upper stage and can be outfitted with an 8.4 m-diameter pay-load fairing. Additional upper stages can be packaged in the 8.4 m fairing to enable high C3 (in the range of 300 km2/sec2) missions to Mercury, the Jovian system, the ice giants, the Kuiper Belt and beyond.

Stephen D Creech↗

NASA NTRSDate not supplied

NASA’s Space Launch System: New Launch Capability for Artemis Lunar and Deep Space Science Missions

With stacking and integration of the initial Block 1 Space Launch System (SLS) expected to begin in 2020, NASA’s powerful new launch vehicle is ready to take center stage in the agency’s Artemis program to return astronauts to the Moon. Combining the highest launch thrust and largest payload capacity ever developed, SLS also enables a new generation of high-C3 science missions to destinations such as the gas and ice giants, the Kuiper Belt, and even beyond the solar system. Block 1 is only the beginning, as the vehicle has a planned evolution path to progressively more powerful variants. In addition to these block upgrades providing increased lift capability, the vehicle can be configured to fly in crew configuration with the Orion spacecraft or in cargo configuration with payload fairings for launching science mission or large infrastructure, providing a flexible launch option. For Artemis I, the first SLS flight, the Block 1 vehicle in the crew configuration will send an uncrewed Orion spacecraft to lunar orbit for a thorough systems checkout before the crewed Artemis II flight. The Block 1 vehicle uses a proven propulsion system consisting of solid rocket boosters and RS-25 engines to lift more than 27 metric tons [t] to trans-lunar injection (TLI). In its cargo configuration, Block 1 can be fitted with a 5 m payload fairing. The second variant, Block 1B, uses a more powerful upper stage to increase payload mass to TLI to 38-42 t, depending on crew or cargo configuration. In the crew configuration, a co-manifested payload of up to 10 t can ride along in the Universal Stage Adapter (USA), which has as much volume for payloads as a 5 m-class payload fairing. The Block 2 evolved variant will lift 43-46 t to TLI, depending on crew or cargo configuration. The Block 1B and Block 2 vehicles can be outfitted with an 8.4 m-diameter payload fairing, available in 19.1 m and 27.4 m lengths, providing unprecedented volume for payloads. Larger-diameter 10 m fairings may also be an option in the future on the Block 2 vehicle. The unrivalled mass, volume and high-energy launches of SLS can provide significant mission flexibility for payloads and/or additional upper stages to open trade space for a new generation of exploration missions. SLS was designed to meet requirements for launching large-volume infrastructure as outlined in numerous studies of missions to cislunar space or Mars. Mission concept studies from the science community also point toward new possibilities enabled by SLS. Probes with more robust science packages can be sent to the gas giants. Dual spacecraft can be manifested for missions to Uranus and Neptune. Additional third or fourth payload stages can be encapsulated in the payload fairings to achieve missions to the Kuiper Belt or beyond. In addition, the large volume can be used to design and deploy wide-aperture mirrors on future space telescopes and to enable nuclear-thermal propulsion missions. At AIAA Ascend, the SLS Program will provide technical information on vehicle capabilities as well as descriptions of ongoing discussions with mission planners for utilizing the vehicle for an array of deep space missions.

Stephen Creech↗

NASA NTRSDate not supplied

Applications of Nuclear Thermal Propulsion Systems for Deep Space Science Missions

Nuclear thermal propulsion (NTP) systems occupy a unique area in the space propulsion technology landscape, due to their ability to combine moderate-to-high thrust systems normally seen in chemical propulsion systems with specific impulses that are higher than those of more traditional chemical propulsion systems. Thus, NTP systems have the potential to greatly expand our access to deep space and can enable or enhance capabilities for a variety of missions that achieve science goals as outlined in NASA’s decadal surveys. This paper leverages previous work performed on applying NTP systems for multiple science missions. It also expands the mission portfolio to additional NTP-powered science mission profiles, evaluating the system performance benefits delivered by this propulsion option. This paper will also outline efforts to improve the fidelity of the existing NTP design concepts and vehicles that are utilized, leveraging previous work on nuclear propulsion systems for human-Mars missions to enhance the fidelity of results obtained from previous science mission concept studies – specifically Triton lander, solar polar orbiter, and the interstellar medium probe missions. The work outlined in this paper will also examine additional missions that have been highlighted in the recent decadal surveys, which may include robotic missions to the ice giant Uranus, robotic missions to Venus, and missions to various Kuiper belt objects (KBOs).

K A Polzin↗

NASA NTRS2019

Voyager 2 Constraints on Plasmoid-Based Transport at Uranus

Gina A Dibraccio↗

NASA NTRSDate not supplied

Outer Planet Global Reference Atmospheric Model (GRAM) Upgrades

Introduction: The Global Reference Atmospheric Model (GRAM) is one of the most widely used engineering models of planetary atmospheres. The GRAM upgrades are being developed by NASA Marshall Space Flight Center and NASA Langley Research Center. This presentation will provide details regarding the upgrades to the existing GRAMs, the development of new GRAMs, and the ongoing objectives, tasks, and milestones related to the GRAM upgrades funded by the NASA Science Mission Directorate (SMD). GRAM: The GRAMs are engineering-oriented atmospheric models that estimate mean values and statistical variations of the atmospheric properties for numerous planetary destinations. They provide mean values and variability for any point in the atmosphere as well as seasonal, geographic, and altitude variations. GRAM outputs include atmospheric density, temperature, pressure, winds, and chemical composition along a user-defined path. They are extensively used by the engineering community because of their ability to create realistic dispersions. GRAMs have been integrated into high fidelity flight dynamic simulations of launch, entry, descent and landing (EDL), aerobraking and aerocapture. GRAMs are currently available for Earth, Mars, Venus, Neptune, Titan, and Uranus. Outer Planet GRAM Upgrade Status: Code Modernization. The outer planet GRAMs have been rearchitected from Fortran to a common object-oriented C++ framework called the GRAM Suite. This new architecture creates a common GRAM library of data models and utilities. The first C++ releases of the rearchitected legacy outer planet GRAMs (Neptune and Titan-GRAM) are straight conversions from the latest Fortran version. Model Upgrades. The focus of the model upgrade task is to improve the atmosphere models in the existing GRAMs and to establish a foundation for developing GRAMs for additional destinations. The GRAM ephemeris has been upgraded to the NASA Navigation and Ancillary Information Facility (NAIF) SPICE toolkit (version N0066). The calculation of the speed of sound has also been improved in the GRAMs. In FY20, the GRAM project established a contract with Hampton University to develop empirical global models for Jupiter, Saturn, Uranus, Neptune, and Titan. Upgraded Outer Planet GRAM Releases. GRAM Suite Version 1.0 was released in May 2020 and contains the rearchitected Neptune-GRAM, including the common GRAM framework and planet–specific code. GRAM Suite Version 1.1 was released in September 2020 and added the rearchitected Titan-GRAM to the GRAM Suite. A User Guide and Programmer’s Manual are released with all GRAMs. New Outer Planet GRAM Releases. New GRAMs have been developed for Uranus and Jupiter. Uranus-GRAM is based on the NASA Ames Research Center (ARC) Uranus Atmospheric Model [1,2] and was released in GRAM Suite Version 1.2 in July 2021. Jupiter-GRAM is based on Galileo probe Atmospheric Structure Instrument (ASI) data from Seiff et al. [3] Saturn-GRAM is also under development. Both Jupiter and Saturn-GRAM will be released in future versions of the GRAM Suite. Conclusions: GRAMs are vital and frequently used toolsets. Releases of the GRAM Suite, upgrades of the existing planetary GRAMs, and development of new planetary GRAMs are ongoing. Titan-GRAM atmosphere model upgrades will be included in the next phase of GRAM tasks. References: [1] Allen Jr., G.A. et al. (2014) 11th International Planetary Probe Workshop, Abstract #8023. [2] Allen Jr., G.A. et al. (2014) Workshop on the Study of the Ice Giant Planets, Abstract #2001. [3] Seiff, A. et al. (1998) JGR, 103, 22,857 -22,889. Acknowledgments: The authors gratefully acknowledge support from the NASA SMD.

atmospheric models↗

NASA NTRSDate not supplied

Robust and Mass Efficient Thermal Protection Systems for Future Venus Missions

Several international Venus missions, both orbiter, and in-situ probe are in the works after a prolonged absence. Future missions are expected to be long-duration lander missions and balloon missions to investigate the cloud layer. The entry mass for these in-situ missions will be significantly higher, and the aeroshell will be larger, than previous missions. Two cardinal requirements govern the selection and use of thermal protection systems (TPS), namely, robustness to assure mission safety during entry and mass efficiency so that the useful mass for science is maximized. One cannot trade mission safety for mass when it comes to TPS. The robustness of the TPS is a paramount requirement as it is a single point of system failure. At the same time, TPS mass is carried for the entire mission duration prior to entry, and any excess TPS mass is at the cost of science payload. Future missions will benefit enormously from TPS options with mass and performance benefits far beyond advanced carbon-carbon (ACC) that is currently proposed for the DAVINCI mission. NASA STMD, and SMD jointly invested in the development of 3-D woven thermal protection systems in the last decade, and as a result, the Heat-shield for Extreme Entry Environment Technology (HEEET) TPS has been matured to TRL 6. It is ready for future mission use including Venus. The HEEET project focused on developing a broad technology base, applicable for missions not only to Venus, but also to Saturn, the Ice Giants, and higher speed sample return missions such as Mars Sample Return requiring extreme robustness due to bio-hazards. The dual-layer HEEET (DL-HEEET) is proven to be extremely robust. DL-HEEET performed well in arc jet and laser testing conditions where heritage carbon-phenolic failed. HEEET also proved to be more mass efficient compared to Carbon-Phenolic. Recently, the principal author was invited to present his perspectives to the 2023-2032 Planetary Sciences Decadal Venus subcommittee on the current state of TPS for future Venus missions [1]. In addition to pointing out successful TPS and other developments in the last decade in support of entry systems, the principal author made two findings: 1) importance of and need to sustain TPS capabilities that took nearly a decade to develop and 2) the opportunity to further optimize TPS mass without sacrificing robustness to further enable future in-situ missions. This talk will focus on the above two recommendations and provide the rationale for them. The intent of the talk is to seek advocacy from the VEXAG community for the criticality of TPS sustainment and the benefits of 3D woven TPS optimization. TPS Capability Sustainment: HEEET development was necessitated by the atrophy of heritage carbon-phenolic. Atrophy has impacted other TPS materials as well. Avcoat, the TPS that successfully allowed astronauts to explore the Moon in the 1960s and 70s, took nearly a decade and $10’sM to recover in support of Orion/Artemis. One of the most used TPS materials, SLA 561V, had to be recovered prior to its use on Mars Pathfinder. Phenolic Impregnated Carbon Ablator (PICA), the TPS that replaced SLA 561V on MSL, has undergone multiple replacements and recovery due to constituent rayon changes. Recently, NASA invested in a domestic rayon replacement program and also invested in FMI to consolidate PICA capability for NASA missions, as a result of FMI’s decision to discontinue commercial FiberForm, which is needed for PICA. TPS used for planetary missions are unique and have no other commercial or defense use. In addition, low mission cadence is also a driver for TPS atrophy. Hence, NASA, as the steward, must take steps to ensure and sustain TPS capabilities. In this talk, we outline steps NASA can take to keep abreast of emerging risks and target risk mitigation steps to ensure TPS capability sustainment for Venus and other extreme environment missions. Next Generation of Mass efficient and Robust TPS: NASA invested in an alternate TPS to PICA based on felt-technology called Conformal-PICA which has the potential to save 30% - 50% mass over PICA. The development was discontinued at a Technology Readiness Level (TRL) of ~ 5. 3D Mid-Density Carbon Phenolic (3MDCP) is a single layer variant of HEEET, based on the insulating layer only (SL-HEEET) and currently baselined for the Mars Sample Return Mission Earth Entry System due to its mass efficiency (30% more mass efficient than DL- HEEET). Currently, SL-HEEET is limited to aeroshell diameters of < 1.3m. The SL-HEEET was compared to DL-HEEET in the recent ADVENT flag-ship class mission study in support of the Planetary Science Decadal. SL HEEET was the recommended TPS based on 30% mass savings for both the balloon and lander missions. Given C-PICA and SL-HEEET have superior reliability and mass efficiency, advocacy from VEXAG is sought for completing their further development to TRL 5/6 in this decade so as to enable TPS readiness for future missions.

Thermal Protection Systems↗