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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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NASA NTRSDate not supplied

The TESS Mission Target Selection Procedure

We describe the target selection procedure by which stars are selected for 2 minute and 20 s observations by TESS. We first list the technical requirements of the TESS instrument and ground systems processing that limit the total number of target slots. We then describe algorithms used by the TESS Payload Operation Center (POC) to merge candidate targets requested by the various TESS mission elements (the Target Selection Working Group, TESS Asteroseismic Science Consortium, and Guest Investigator office). Lastly, we summarize the properties of the observed TESS targets over the two-year primary TESS mission. We find that the POC target selection algorithm results in 2.1–3.4 times as many observed targets as target slots allocated for each mission element. We also find that the sky distribution of observed targets is different from the sky distributions of candidate targets due to technical constraints that require a relatively even distribution of targets across the TESS fields of view. We caution researchers exploring statistical analyses of TESS planet-host stars that the population of observed targets cannot be characterized by any simple set of criteria applied to the properties of the input Candidate Target Lists.

Michael Fausnaugh↗
NASA NTRS2011

Warm Debris Disk Candidates from WISE

The Wide Field Infrared Survey Explorer (WISE) has just completed a sensitive all-sky survey in photometric bands at 3.4, 4.6, 12, and 22 microns. We report on a preliminary investigation of main sequence Hipparcos and Tycho catalog stars with 22 micron emission in excess of photospheric levels. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets and is preferentially found in young systems with ages < 1 Gyr. Nearly a hundred new warm debris disk candidates are detected among FGK stars and 150 A stars within 120 pc. We are in the process of obtaining spectra to determine spectral types and activity level of these stars and are using HST, Herschel and Keck to characterize the dust, multiplicity, and substellar companions of these systems. In this contribution, we will discuss source selection methods and individual examples from among the WISE debris disk candidates.

Padgett, Deborah↗
DOE OSTI2020

TESS Reveals a Short-period Sub-Neptune Sibling (HD 86226c) to a Known Long-period Giant Planet

The Transiting Exoplanet Survey Satellite mission was designed to find transiting planets around bright, nearby stars. Here, we present the detection and mass measurement of a small, short-period (≈4 days) transiting planet around the bright (V = 7.9), solar-type star HD 86226 (TOI-652, TIC 22221375), previously known to host a long-period (∼1600 days) giant planet. HD 86226c (TOI-652.01) has a radius of 2.16 ± 0.08 R {sub ⊕} and a mass of 7.25{sub −1.12}{sup +1.19} M {sub ⊕}, based on archival and new radial velocity data. We also update the parameters of the longer-period, not-known-to-transit planet, and find it to be less eccentric and less massive than previously reported. The density of the transiting planet is 3.97 g cm{sup −3}, which is low enough to suggest that the planet has at least a small volatile envelope, but the mass fractions of rock, iron, and water are not well-constrained. Given the host star brightness, planet period, and location of the planet near both the “radius gap” and the “hot Neptune desert,” HD 86226c is an interesting candidate for transmission spectroscopy to further refine its composition.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1971

Mission operations for unmanned nuclear electric propulsion outer planet exploration with a thermionic reactor spacecraft.

Mission operations are presented for comet rendezvous and outer planet exploration NEP spacecraft employing in-core thermionic reactors for electric power generation. The selected reference missions are the Comet Halley rendezvous and a Jupiter orbiter at 5.9 planet radii, the orbit of the moon Io. The characteristics of the baseline multi-mission NEP spacecraft are presented and its performance in other outer planet missions, such as Saturn and Uranus orbiters and a Neptune flyby, are discussed. Candidate mission operations are defined from spacecraft assembly to mission completion. Pre-launch operations are identified. Shuttle launch and subsequent injection to earth escape by the Centaur D-1T are discussed, as well as power plant startup and the heliocentric mission phases. The sequence and type of operations are basically identical for all missions investigated.

Spera, R. J.↗
NASA NTRS1989

Building a pathway to the planets - Expanding the frontiers of human exploration

The basic mission options, transportation, robotic precursors, technology, and human factors involved in the advance into interplanetary exploration and establishment of bases on the moon, planets, and planetary satellites are discussed. Case studies that have been undertaken for four candidate missions are briefly addressed. The role of international cooperation and the selection criteria pertaining to such missions are addressed.

O'Handley, Douglas A.↗
NASA NTRS1979

Minor planets and related objects. XXVII - Lightcurves of 887 Alinda

Eleven light curves and UBV photometry of the Amor asteroid Alinda, a candidate for having a cometary origin, are analyzed. A probable rotation period of 73 h 58 m + or - 3 m (p.e.) is derived on the assumption of two maxima and two minima per cycle in a composite light curve. An absolute V magnitude of 14.10 + or - 0.08 and a phase coefficient of 0.042 + or - 0.003 mag/deg in V are obtained, along with a B-V color of 0.86 + or - 0.02 and a U-B color of 0.50 + or - 0.05, both extrapolated to zero phase. The rotation period is shown to be the longest yet observed for an asteroid. It is concluded that the colors of Alinda are not unusual for an asteroid, that Alinda is probably not an extinct cometary nucleus, that the slow rotation may be a consequence of one or more collisions, and that the pole of Alinda may be nearly perpendicular to the ecliptic.

Dunlap, J. L.↗
NASA NTRS1977

Jupiter Probe Heatshield design

A heatshield performance assessment is made for extraterrestrial entry into the atmosphere of the planet Jupiter. A rigorous determination of the potential ablation and thermostructural failure mechanisms for a candidate carbon-phenolic heatshield is made. The thermostructural integrity of the char layer is addressed in detail with the total response phenomenology involving char layer formation, stress under aerodynamic and thermodynamic loads, and points of stress concentration under the high radiative heat rates and severe temperature gradients encountered in the Jovian atmosphere. An alternate material concept in the carbon-carbon generic material class is examined to assess the viability of this material class for application to the Jupiter Probe Heatshield.

Kratsch, K. M.↗
NASA NTRS1998

Exploring Aristarchus Plateau as a Potential Lunar Base Site

As part the exploration strategy, NASA has been studying the feasibility of a low cost human return to the Moon. The currently planned mission has a dual focus on the advancement of lunar science and the use of in situ resources. Thus far, our space exploration plans have relied almost exclusively on equipment and supplies transported from Earth. This may be appropriate for operations in Earth orbit, or for short duration stays on the lunar surface. However, the ability to "live off the land," will prove vital for long term habitation of the Moon and planets. This study takes a close look at the Aristarchus Plateau, one of the primary candidate sites for human lunar exploration. Based on this synthesis study, we recommend two sites on the Aristarchus Plateau that will maximize science return and provide a convincing demonstration of the use of in situ resources and which may be a viable future lunar base site.

Coombs, Cassandra R.↗
NASA NTRS1991

Solar System Exploration Division Strategic Plan, volume 1. Executive summary and overview

This first document is the first of a six-volume series presenting the Solar System Exploration Division's Strategic Plan for the 10-year period FY 1994 to FY 2003. The overall strategy is characterized by five fundamental precepts: (1) execute the current program; (2) improve the vitality of the program and the planetary science community; (3) initiate innovative, small, low-cost planetary missions; (4) initiate new major and moderate missions; and (5) prepare for the next generation of missions. This Strategic Plan describes in detail our proposed approach to accomplish these goals. Volume 1 provides first an Executive Summary of highlights of each of the six volumes, and then goes on to present an overview of the plan, including a discussion of the planning context and strategic approach. Volumes 2, 3, 4, and 5 describe in detail the initiatives proposed. An integral part of each of these volumes is a set of responses to the mission selection criteria questions developed by the Space and Earth Science Advisory Committee. Volume 2, Mission From Planet Earth, describes a strategy for exploring the Moon and Mars and sets forth proposed moderate missions--Lunar Observer and a Mars lander network. Volume 3, Pluto Flyby/Neptune Orbiter, discusses our proposed major new start candidate for the FY 1994 to FY 1998 time frame. Volume 4, Discovery, describes the Near-Earth Asteroid Rendezvous, as well as other candidates for this program of low-cost planetary missions. Volume 5, Toward Other Planetary Systems, describes a major research and analysis augmentation that focuses on extrasolar planet detection and the study of planetary system processes. Finally, Volume 6 summarizes the technology program that the division has structured around these four initiatives.

Source record↗
NASA NTRS1998

From GTO to the Planets

This paper discusses the Ariane 5 configuration, mission analyses, and launch scheduling issues associated with these opportunities and describes some applicable candidate mission concepts.

Ariane↗
DOE OSTI2021

A Tidal Origin for a Three-body Resonance in Kepler-221

Over the course of the last two decades, traditional models of planet formation have been repeatedly challenged by the emerging census of extrasolar planets. Key among them is the orbital architecture problem: while standard models of orbital migration predict resonant orbits for short-period objects, most planets do not appear to lie in orbital resonances. Here, we show that the four-planet system Kepler-221, not previously recognized to have active orbital resonances, has a three-body commensurability relation unique within the Kepler sample. Using a suite of numerical experiments as well as a perturbative analysis, we demonstrate that this system likely began as a resonant chain and proceeded to undergo large-scale divergence away from resonance, under the action of tidal dissipation. Our results further indicate that obliquity tides, driven by a secular spin–orbit resonance and mutual inclination, are an excellent candidate for driving this orbital divergence, and that the high tidal luminosity may also explain the anomalous size of planet b, which lies within the Fulton radius gap.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2015

Lower Limits on Aperture Size for an ExoEarth Detecting Coronagraphic Mission

The yield of Earth-like planets will likely be a primary science metric for future space-based missions that will drive telescope aperture size. Maximizing the exoEarth candidate yield is therefore critical to minimizing the required aperture. Here we describe a method for exoEarth candidate yield maximization that simultaneously optimizes, for the first time, the targets chosen for observation, the number of visits to each target, the delay time between visits, and the exposure time of every observation. This code calculates both the detection time and multiwavelength spectral characterization time required for planets. We also refine the astrophysical assumptions used as inputs to these calculations, relying on published estimates of planetary occurrence rates as well as theoretical and observational constraints on terrestrial planet sizes and classical habitable zones. Given these astrophysical assumptions, optimistic telescope and instrument assumptions, and our new completeness code that produces the highest yields to date, we suggest lower limits on the aperture size required to detect and characterize a statistically motivated sample of exoEarths.

Earth-like planets↗
NASA NTRS2023

A High-Eccentricity Warm Jupiter Orbiting TOI-4127

We report the discovery of TOI-4127 b, which is a transiting, Jupiter-sized exoplanet on a long period (P=56.39879 +0.00010 -0.00010 days) and a high-eccentricity orbit around a late F-type dwarf star. This warm Jupiter was first detected and identified as a promising candidate from a search for single-transit signals in TESS Sector 20 data and was later characterized as a planet following two subsequent transits (TESS Sectors 26 and 53) and follow-up ground-based RV observations with the NEID and SOPHIE spectrographs. We jointly fit the transit and RV data to constrain the physical (R p =1.096 +0.039 -0.032 R J , M p =2.30 +0.11 -0.11 M J ) and orbital parameters of the exoplanet. Given its high orbital eccentricity (𝓮=0.7471 +0.0078 -0.0086 ), TOI-4127 b is a compelling candidate for studies of warm Jupiter populations and of hot Jupiter formation pathways. We show that the present periastron separation of TOI-4127 b is too large for high-eccentricity tidal migration to circularize its orbit, and that TOI-4127 b is unlikely to be a hot Jupiter progenitor unless it is undergoing angular momentum exchange with an undetected outer companion. Although we find no evidence for an external companion, the available observational data are insufficient to rule out the presence of a perturber that can excite eccentricity oscillations and facilitate tidal migration.

Exoplanet astronomy↗
DOE OSTI2022

A search for transit timing variations in the HATS-18 planetary system

ABSTRACT HATS-18 b is a transiting planet with a large mass and a short orbital period, and is one of the best candidates for the detection of orbital decay induced by tidal effects. We present extensive photometry of HATS-18 from which we measure 27 times of mid-transit. Two further transit times were measured from data from the Transiting Exoplanet Survey Satellite (TESS) and three more taken from the literature. The transit timings were fitted with linear and quadratic ephemerides and an upper limit on orbital decay was determined. This corresponds to a lower limit on the modified stellar tidal quality factor of $Q_\star ^{\, \prime } \gt 10^{5.11 \pm 0.04}$. This is at the cusp of constraining the presence of enhanced tidal dissipation due to internal gravity waves. We also refine the measured physical properties of the HATS-18 system, place upper limits on the masses of third bodies, and compare the relative performance of TESS and the 1.54 m Danish Telescope in measuring transit times for this system.

Southworth, John (ORCID:0000000238073198)↗
NASA NTRS1974

Upper atmospheres and diagnostic measurements

Candidate space missions to study the temperature profiles, and ratios of hydrogen to helium in outer planet atmospheres are discussed in terms of scientific payloads for optical occultation, radio occultation, and thermometer measurements.

Hunten, D.↗
NASA NTRS2002

Candidate Coatings and Dry Traction Drives for Planetary Vehicles

Robert Fusaro and Fred Oswald of the Mechanical Components Branch discussed 'Candidate Coatings and Dry Traction Drives for Planetary Vehicles'. Vehicles to be designed for exploration of planets and moons of the solar system will require reliable mechanical drives to operate efficiently. Long-term operation of these drives will be challenging because of extreme operating conditions. These extreme conditions include: very high and/or very cold temperatures, wide temperature ranges, dust, vacuum or low-pressure atmospheres, and corrosive environments. Most drives used on Earth involve oil-lubricated gears. However, due to the extreme conditions on planetary surfaces, it may not be advisable or even possible to use oil lubrication. Unfortunately, solid lubricants do not work well when applied to gears because of the high contact stress conditions and large sliding motion between the teeth, which cause wear and limit life. We believe traction drives will provide an attractive alternative to gear drives. Traction drives are composed of rollers that provide geometry more conducive to solid lubrication. Minimal slip occurs in this contact geometry and thus there is very low wear to the solid lubricant. The challenge for these solid-lubricated drives is finding materials or coatings that provide the required long-life while also providing high traction. We seek materials that provide low wear with high friction.

Fusaro, Robert↗
NASA NTRS2012

Ground Demonstration of Planetary Gas Lidar Based on Optical Parametric Amplifier

We report on the development effort of a nanosecond-pulsed optical parametric amplifier (OPA) for remote trace gas measurements for Mars and Earth. The OPA output has high spectral purity and is widely tunable both at near-infrared and mid-infrared wavelengths, with an optical-optica1 conversion efficiency of up to approx 39 %. Using this laser source, we demonstrated open-path measurements of CH4 (3291 nm and 1651 nm), CO2 (1573 nm), H2O (1652 nm), and CO (4764 nm) on the ground. The simplicity, tunability. and power scalability of the OPA make it a strong candidate for general planetary lidar instruments, which will offer important information on the origins of the planet's geology, atmosphere, and potential for biology,

Numata, Kenji↗
NASA NTRS2019

Power Systems for Miniature Interstellar Flyby Probe

In the last few years, the concept that an ultra-lightweight probe could be sent to one of the nearby stars pushed by a laser beam reflecting from a lightweight sail has moved from science fiction into conceptual design. A candidate interstellar sail envisions a two- to three-gram "starchip" micro probe, flying past a planet of Proxima Centauri after a 20 year voyage. With the probe moving at 60,000 km/sec, the flyby encounter at the target planet is within 1 AU of the target planet at most a few hours, and in the case of an encounter with a planet of Proxima Centauri, is close to the star for only a few minutes. With current technology, no power system exists that can produce the required power with a mass of less than one gram.

Landis, Geoffrey A.↗