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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3

A TPS Design Analysis of Entry Probe Delivery from Orbit for Ice Giant Missions

Previous investigation of direct delivery of a probe into Neptune’s atmosphere showed said approach to be challenging due to high stagnation pressures and heat loads. Entering at a high entry flight path angle (EFPA) results in stagnation pressure beyond current Heatshield for Extreme Entry Environment Technology (HEEET) qualification, while entering at a lower EFPA results in higher heat loads, leading to required HEEET thicknesses beyond manufacturing capabilities. Aerocapture is an enticing alternative entry scenario because it enables a fast trip and the placement of a payload in orbit around Neptune that can also reach Triton. Here, we investigate entry conditions associated with delivering a probe from orbit to assess feasibility. We consider whether 1) this entry scenario results in reasonable conditions, and 2) HEEET single insulating layer (mid-density carbon phenolic, 3MDCP) can be used to decrease mass, risk, and cost.

H. S. Alpert↗

A TPS Design Analysis of Entry Probe Delivery from Orbit for Ice Giant Missions

Previous investigation of direct delivery of a probe into Neptune’s atmosphere showed said approach to be challenging due to high stagnation pressures and heat loads. Entering at a high entry flight path angle (EFPA) results in stagnation pressure beyond current Heatshield for Extreme Entry Environment Technology (HEEET) qualification, while entering at a lower EFPA results in higher heat loads, leading to required HEEET thicknesses beyond manufacturing capabilities. Aerocapture is an enticing alternative entry scenario because it enables a fast trip and the placement of a payload in orbit around Neptune that can also reach Triton. Here, we investigate entry conditions associated with delivering a probe from orbit to assess feasibility. We consider whether 1) this entry scenario results in reasonable conditions, and 2) HEEET single insulating layer (mid-density carbon phenolic, 3MDCP) can be used to decrease mass, risk, and cost.

Hannah S. Alpert↗

The Science Case for Spacecraft Exploration of the Uranian Satellites: Candidate Ocean Worlds in an Ice Giant System

The 27 satellites of Uranus are enigmatic, with dark surfaces coated by material that could be rich in organics. Voyager 2 imaged the southern hemispheres of Uranus’s five largest “classical” moons—Miranda, Ariel, Umbriel, Titania, and Oberon, as well as the largest ring moon, Puck—but their northern hemispheres were largely unobservable at the time of the flyby and were not imaged. Additionally, no spatially resolved data sets exist for the other 21 known moons, and their surface properties are essentially unknown. Because Voyager 2 was not equipped with a near-infrared mapping spectrometer, our knowledge of the Uranian moons’ surface compositions, and the processes that modify them, is limited to disk-integrated data sets collected by ground- and space-based telescopes. Nevertheless, images collected by the Imaging Science System on Voyager 2 and reflectance spectra collected by telescope facilities indicate that the five classical moons are candidate ocean worlds that might currently have, or had, liquid subsurface layers beneath their icy surfaces. To determine whether these moons are ocean worlds, and to investigate Uranus’s ring moons and irregular satellites, close-up observations and measurements made by instruments on board a Uranus orbiter are needed.

Richard J. Cartwright↗

The Habitable Exoplanet (HabEx) imaging mission concept: preliminary science drivers and technical requirements

HabEx is one of 4 possible NASA flagship mission concepts studied for a possible launch in the 2030s. It will be optimized for direct imaging and spectroscopy of habitable exoplanets, and will also enable a wide range of general astrophysics observations. HabEx shall characterize full planetary systems around nearby solar-type stars for the first time, including rocky planets, possible water worlds, gas giants, ice giants, and faint circumstellar debris disks. It will in particular explore our nearest neighbor planetary systems and search for signs of habitability and bio-signatures in the atmospheres of rocky planets. Such high spatial resolution high contrast observations require a large (~3.5 to 8m) stable diffraction- limited optical space telescope, which also opens new unique capabilities for studying the formation and evolution of stars and galaxies. We present here some preliminary science objectives identified for HabEx by our Science and Technology Definition Team (STDT), together with a first look at the key challenges and design trades ahead.

Mennesson, Bertrand↗

Oceanus: A High Science Return Uranus Orbiter with a Low-Cost Instrument Suite

Ice-giant-sized planets are the most common type of observed exoplanet, yet the two ice giants in our own solar system (Uranus and Neptune) are the least explored class of planet, having only been observed through ground-based observations and a single flyby each by Voyager 2 approximately 30 years ago. These single flybys were unable to characterize the spatial and temporal variability in ice giant magnetospheres, some of the most odd and intriguing magnetospheres in the solar system. They also offered only limited constraints on the internal structure of ice giants; understanding the internal structure of a planet is important for understanding its formation and evolution. The most recent planetary science Decadal Survey by the U.S. National Academy of Sciences, ''Vision and Voyages for Planetary Science in the Decade 2013-2022,'' identified the ice giant Uranus as the third highest priority for a Flagship mission in the decade 2013-2022. However, in the event that NASA or another space agency is unable to fly a Flagship-class mission to an ice giant in the next decade, this paper presents a mission concept for a focused, lower cost Uranus orbiter called OCEANUS (Origins and Composition of the Exoplanet Analog Uranus System). OCEANUS would increase our understanding of the interior structure of Uranus, its magnetosphere, and how its magnetic field is generated. These goals could be achieved with just a magnetometer and the spacecraft's radio system. This study shows that several of the objectives outlined by the Decadal Survey, including one of the two identified as highest priority, are within reach for a New-Frontiers-class mission.

Elder, C. M.↗