Search NASA⌕ Search

SEARCH · Search NASA

Results for “starshade”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Fabrication and Design Testing of 4 Petals for Deployable Starshade Prototype : JPL Summer Internship Program : Final Report

One of the next steps in the exoplanet search is the development of occulter technology. Starlight suppression for a telescope would provide the ability to more accurately find and characterize potential true-Earth analogs. Coronagraphs have been the subject of much research in recent years but have yet to prove themselves a feasible approach. Attention has now turned to external occulters or starshades. A large occulting mask in front of a telescope should provide a comparable optical resolution to a coronagraph. Under a TDEM grant, a proposed starshade design was demonstrated to exceed coronagraph resolution by at least an order of magnitude. The current project is to demonstrate that the current design can be manufactured and then properly deployed. 4 sample starshade petals were constructed, ready to be attached to a pre-existing deployment truss. Time was spent detailing and modifying the petal construction process, so that future petals could be constructed at a more accurate and faster pace.

Starshade petals↗
NASA NTRS2013

Using a Starshade with WFIRST

A starshade operating with WFIRST at Earth-Sun L2 can characterize Earthlike exoplanets. A starshade can launch together with WFIRST via EELV with standard 5m launch fairings. A starshade experiment requires no telescope modification and limited instrumentation. Implementation requirements are all realistically achievable. Key performance parameters are being verified via NASA TDEMs (ROSES NRA)

exoplanet↗
NASA NTRS2016

Precision Optical Edges for a Starshade External Occulter

The use of a starshade is one technique to perform high contrast imaging with space-based telescopes. The primary function of a starshade is to suppress light from a target star in order to image its orbiting planets. In order to provide the proper apodization function the edges of the starshade must follow a precise in-plane profile. However of equal importance is the issue of light from our own sun scattering off of the edges and entering the telescope. A method to alleviate this problem is to make the edges extremely sharp (< 1 µmterminal radius) such that the area available for scattering is minimized. The combination of these two requirements, along with the need to integrate the edges into a 30-40 m dia. deployable structure, present a number of significant engineering challenges. Substrate etching techniques are used to obtain both the intended profile as well as the edge sharpness. Current efforts implement an isotropic etching process on thin metal substrates. This paper discusses the progress towards producing a sharp optical edge at the coupon level. Samples have been characterized using scanning electron microscopy as well as a custom testbed to assess their scattered-light performance.

starshade↗
NASA NTRS2012

The Search for Habitable Worlds. 1. The Viability of a Starshade Mission

As part of NASA's mission to explore habitable planets orbiting nearby stars, this article explores the detection and characterization capabilities of a 4 m space telescope plus 50 m starshade located at the Earth-Sun L2 point, known as the New Worlds Observer (NWO). Our calculations include the true spectral types and distribution of stars on the sky, an iterative target selection protocol designed to maximize efficiency based on prior detections, and realistic mission constraints. We conduct simulated observing runs for a wide range in exozodiacal background levels (epsilon = 1-100 times the local zodi brightness) and overall prevalence of Earth-like terrestrial planets (eta(sub solar halo))0.1-1). We find that even without any return visits, the NWO baseline architecture (IWA = 65 mas, limiting FPB = 4 x 10(exp -11) can achieve a 95% probability of detecting and spectrally characterizing at least one habitable Earth-like planet and an expectation value of approximately 3 planets found, within the mission lifetime and delta V budgets, even in the worst-case scenario (eta(sub solar halo) = 0.1 and = epsilon = 100 zodis for every target). This achievement requires about 1 yr of integration time spread over the 5 yr mission, leaving the remainder of the telescope time for UV-NIR general astrophysics. Cost and technical feasibility considerations point to a "sweet spot" in starshade design near a 50 m starshade effective diameter. with 12 or 16 petals, at a distance of 70,000-100,000 km from the telescope.

Turnbull, Margaret C.↗
NASA NTRS2014

Successful Starshade Petal Deployment Tolerance Verification in Support of NASA's Technology Development for Exoplanet Missions

A Starshade is a sunflower-shaped satellite with a large inner disk structure surrounded by petals that flies in formation with a space-borne telescope, creating a deep shadow around the telescope over a broad spectral band to permit nearby exoplanets to be viewed. Removing extraneous starlight before it enters the observatory optics greatly loosens the tolerances on the telescope and instrument that comprise the optical system, but the nature of the Starshade dictates a large deployable structure capable of deploying to a very precise shape. These shape requirements break down into key mechanical requirements, which include the rigid-body position and orientation of each of the petals that ring the periphery of the Starshade. To verify our capability to meet these requirements, we modified an existing flight-like Astromesh reflector, provided by Northrup Grumman, as the base ring to which the petals attach. The integrated system, including 4 of the 30 flight-like subscale petals, truss, connecting spokes and central hub, was deployed tens of times in a flight-like manner using a gravity compensation system. After each deployment, discrete points in prescribed locations covering the petals and truss were measured using a highly-accurate laser tracker system. These measurements were then compared against the mechanical requirements, and the as-measured data shows deployment accuracy well within our milestone requirements and resulting in a contrast ratio consistent with exoplanet detection and characterization.

External occulters↗
NASA NTRS2015

Error Budgets for the Exoplanet Starshade (exo-s) Probe-Class Mission Study

Exo-S is a probe-class mission study that includes the Dedicated mission, a 30 millimeters starshade co-launched with a 1.1 millimeter commercial telescope in an Earth-leading deep-space orbit, and the Rendezvous mission, a 34 millimeter starshade intended to work with a 2.4 millimeters telescope in an Earth-Sun L2 orbit. A third design, referred to as the Rendezvous Earth Finder mission, is based on a 40 millimeter starshade and is currently under study. This paper presents error budgets for the detection of Earth-like planets with each of these missions. The budgets include manufacture and deployment tolerances, the allowed thermal fluctuations and dynamic motions, formation flying alignment requirements, surface and edge reflectivity requirements, and the allowed transmission due to micrometeoroid damage.

high-contrast imaging↗
NASA NTRS2019

Habitable Exoplanet Observatory (HabEx) starshade-only architectures

The HabEx mission concept is intended to directly image planetary systems around nearby stars, and to perform a wide range of general astrophysics and solar system observations. The baseline HabEx design would use both a coronagraph and a starshade for exoplanet discovery and characterization. We describe a lower-cost alternative HabEx mission design, which would only use a starshade for exoplanet science. The starshade would provide excellent exoplanet science performance, but for a smaller number of detected exoplanets of all types, including exoEarth candidates, and a smaller fraction of exoplanets with measured orbits. The full suite of HabEx general astrophysics and solar-system science would be supported.

Benson, Jonathan↗
NASA NTRS2021

Starshade Rendezvous: Exoplanet Sensitivity and Observing Strategy

Launching a starshade to rendezvous with the Nancy Grace Roman Space Telescope (Roman) would provide the first opportunity to directly image the habitable zones (HZs) of nearby sunlike stars in the coming decade. A report on the science and feasibility of such a mission was recently submitted to NASA as a probe study concept. The driving objective of the concept is to determine whether Earth-like exoplanets exist in the HZs of the nearest sunlike stars and have biosignature gases in their atmospheres. With the sensitivity provided by this telescope, it is possible to measure the brightness of zodiacal dust disks around the nearest sunlike stars and establish how their population compares with our own. In addition, known gas-giant exoplanets can be targeted to measure their atmospheric metallicity and thereby determine if the correlation with planet mass follows the trend observed in the Solar System and hinted at by exoplanet transit spectroscopy data. We provide the details of the calculations used to estimate the sensitivity of Roman with a starshade and describe the publicly available Python-based source code used to make these calculations. Given the fixed capability of Roman and the constrained observing windows inherent for the starshade, we calculate the sensitivity of the combined observatory to detect these three types of targets, and we present an overall observing strategy that enables us to achieve these objectives.

Andrew Frederic Romero-wolf↗
NASA NTRS2010

Starshade Design for Occulter Based Exoplanet Missions

We present a lightweight starshade design that delivers the requisite profile figure accuracy with a compact stowed volume that permits launching both the occulter system (starshade and spacecraft) and a 1 to 2m-class telescope system on a single existing launch vehicle. Optimal figure stability is achieved with a very stiff and mass-efficient deployable structure design that has a novel configuration. The reference design is matched to a 1.1m telescope and consists of a 15m diameter inner disc and 24 flower-like petals with 7.5m length. The total tip-to-tip diameter of 30m provides an inner working angle of 75 mas. The design is scalable to accommodate larger telescopes and several options have been assessed. A proof of concept petal is now in production at JPL for deployment demonstrations and as a testbed for developing additional elements of the design. Future plans include developing breadboard and prototype hardware of increasing fidelity for use in demonstrating critical performance capabilities such as deployed optical edge profile figure tolerances and stability thereof.

Thomson, Mark W.↗
NASA NTRS2017

Understanding the Sun-Earth Libration Point Orbit Formation Flying Challenges For WFIRST and Starshade

In order to fly an occulter in formation with a telescope at the Sun-Earth L2 (SEL2) Libration Point, one must have a detailed understanding of the dy-namics that govern the restricted three body system. For initial purposes, a linear approximation is satisfactory, but operations will require a high-fidelity modeling tool along with strategic targeting methods in order to be successful. This paper focuses on the challenging dynamics of the transfer trajectories to achieve the relative positioning of two spacecraft to fly in formation at SEL2, in our case, the Wide-Field Infrared Survey Telescope (WFIRST) and a proposed Starshade. By modeling the formation transfers using a high fidelity tool, an accurate V approximation can be made to as-sist with the development of the subsystem design required for a WFIRST and Starshade formation flight mission.

Sun-Earth-Moon↗
NASA NTRS2018

Wide-Field Infrared Survey Telescope and Starshade Formation Flying Dynamics at Sun-Earth L2

The formation flying of an occulter with a telescope at the Sun-Earth L2 (SEL2) Libration Point can be a challenging problem. A good knowledge of the Restricted Three Body Problem dynamics is required to understand how these two spacecraft interact with each other in the SEL2 unstable environment, and how other perturbations such as Solar Radiation Pressure (SRP) affect their mutual trajectories. This paper focuses on the transfer trajectories to achieve specific relative positions between two spacecraft as they fly in formation at SEL2, andanalyzes the relevance of SRP in this formation, using the Wide-Field Infrared Survey Telescope (WFIRST) and the Starshade occulter as an example. Given that WFIRST and Starshade have very different area-to-mass ratios, SRP will affect their motion in different ways, and their relative position can be key to reduce the V cost. In this paper we intend on providing an explanation on how the relative position between both spacecrafts affects the transfer V from one observation to the other using dynamical system theory and Floquet modes.

Pressure↗
NASA NTRS2018

HabEx Lite: a Starshade-only Habitable Exoplanet Imager Alternative

The HabEx mission concept is intended to directly image planetary systems around nearby stars, and to perform a wide range of general astrophysics and solar system observations. Its main goal is the discovery and characterization of Earthlike exoplanets through high-contrast imaging and spectroscopy. The baseline HabEx concept would use both a coronagraph and a starshade for exoplanet science. We describe an alternative, “HabEx Lite” concept, which would use a starshade (only) for exoplanet science. The benefit is lower cost: by deleting the complex coronagraph instrument; by lowering observatory mass; by relaxing tolerances and stability requirements; by permitting use of a compact on-axis telescope design; by use of a smaller launch vehicle. The scientific penalty of this lower cost option is a smaller number of detected exoplanets of all types, including exoEarth candidates, and a smaller fraction of exoplanets with measured orbits. Our approach uses a non-deployed segmented primary mirror, whose manufacture is within current capabilities.

Stark, Chris↗
NASA NTRS2020

Demonstration of Deployment Accuracy of the Starshade Inner Disk Subsystem

We present experimental results that demonstrate the required in-plane deployment accuracy of the starshade Inner Disk Subsystem (IDS). This effort was to address Milestone 7C of the Starshade Technology Activity S5, which requires that the in-plane deployment accuracy of the petal interfaces on the IDS be within +/-300um. A full-scale 10m-diameter IDS prototype was constructed. This prototype comprised a medium-fidelity perimeter truss, medium-fidelity spokes, and a low-fidelity optical shield (OS). The testbed also included gravity compensation systems and a laser tracker metrology system. The post-processed measurement uncertainties of the laser tracker were less than 30um at the 3 sigma level. Design, engineering and fabrication of these components was done by JPL, Tendeg, and Roccor. Testing was performed at the Tendeg facility in Louisville, Colorado. The IDS prototype was deployed 22 times and the locations of petal interfaces on the IDS were measured after each deployment. Based on this data, tolerance intervals were calculated that would contain 99.73% of future deployment accuracy errors with 90% confidence. These tolerance intervals are conservative estimates for 3 sigma bounds. The tolerance intervals for the three pertinent error components were found to be within the required allocations, with at least 19% margin.

Turse, Dana↗
NASA NTRS2021

Origami-Inspired Optical Shield for a Starshade Inner Disk Testbed: Design, Fabrication, and Analysis

In 2019, a 10 m-diameter starshade inner disk test article was assembled; this test article demonstrated deployment accuracy sufficient for starshade mission concepts. Here, we describe the design, fabrication, and computational structural analysis of a key inner disk component realized for this effort: the origami-folded optical shield. The optical shield is a 10 m-diameter lightweight cover that makes the inner disk opaque. It stows within a 2.3 m-diameter volume by using an origami-inspired wrapping pattern, and is deployed passively by the inner disk perimeter truss. The fold pattern was generated by a custom algorithm based one existing generative design approaches. This prototype demonstrated critical functions: stowage in a compact volume, static equilibrium when stowed and deployed, and low strain when stowed. Four separate computational structural analysis models of the optical shield were de- veloped, at varying levels of fidelity and using a variety of software solutions: Abaqus, RAPID, and ADAMS. These models were intended to pathfind approaches for modeling the stowage and deployment of the inner disk, and to demonstrate that the optical shield is amenable existing structural modeling approaches. These models were found to adequately capture pertinent stowage and deployment behavior of the optical shield prototype.

Hoffman, Laura↗
NASA NTRS2020

Broadband Characterization of Anti-reflection Coated Starshade Optical Edges for Solar Glint Control

A starshade is a large flower-shaped screen designed to enable the direct imaging of exoplanets with a space telescope. The starshade perimeter is composed of sharp, precisely shaped edges to minimize the glint of sunlight into the telescope. Past work has focused on bare edges to minimize the terminal radius. This paper describes the broadband, wide-angle performance of edges coated with a thin multi-layer anti-reflection coating. This coating uses a combination of interference and absorption to reduce the surface reflectivity and to avoid the negative effects associated with a large cross-sectional area. A custom scattered light testbed has been developed to quantify the amount of light scattered from sample edges and to validate Finite-Difference Time-Domain (FDTD) models of the optical scatter. We show that optical edge samples with this coating significantly reduce the solar glint pattern compared to similar uncoated optical edges.

Sheikh, David↗
NASA NTRS2016

Advances in Starshade Technology Readiness for an Exoplanet Characterizing Science Mission in the 2020's

The discovery of thousands of exoplanets is generating increasing interest in the direct imaging and characterization of these planets. Starshade, and eternal occulter, could fly in formation between a telescope and distant star, blocking out the light from the star, and enabling us to focus on the light of any orbiting planets. Recent technology developments in coordination with system design, has added much needed detail to define the technology requirements for a science mission that could launch in the 2020's. This paper address the mechanical architecture, the successful efforts to date, the current state of design for the mechanical system, and upcoming technology efforts.

occulter↗
NASA NTRS2019

Starshade Rendezvous Probe

The Starshade Rendezvous Probe Mission (https://smd-prod.s3.amazonaws.com/science-red/s3fs-public/atoms/files/Starshade2.pdf ) [1] will be the first space-based, high-contrast imaging mission with the potential to detect and characterize Earth-like planets in the habitable zone (HZ) around sunlike stars while at the same time exploring entire planetary systems about our nearest neighbors. Over the last two decades, astronomers have discovered and cataloged thousands of planets around other stars. Nevertheless, we have yet to find a planetary system like our own or to characterize discovered small planets to determine if they are similar to Earth. The next step in exploration is to image full planetary systems, including their HZs, and to obtain planetary spectra with enough sensitivity to determine if a planet is Earth-like. A space-based direct imaging mission to ultimately find and characterize other Earth-like planets is a long-term priority for space astrophysics [2, 3].

Seager, Sara↗