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The concept of a Solar System, a fundamental Copernican construct, started to gain a footing in the seventeenth century. Although the cosmological debates around the Copernican system are the subject of a vast literature, the role of images in firming the concept of the Copernican Solar System has received scant attention. This paper addresses the emergence and early development of Solar System maps and diagrams, focusing on images produced by Andreas Cellarius, Christiaan Huygens (especially), William Whiston, and James Ferguson between the mid-seventeenth century and the mid-eighteenth century that ultimately turned the Solar System into a cartographic object depicted to scale, in a manner akin to that of terrestrial maps. This paper also shows that while these images were originally produced with the aim of sustaining particular claims and arguments about Copernicanism, the plurality of inhabited worlds, and Newtonianism, they gained a life of their own, codifying a set of visual conventions that have been used to this day to represent the Solar System and its scale. [ABSTRACT FROM AUTHOR]

In the later stages of his life, Christiaan Huygens semi-empirically derived a set of relations between the objective focus and diameter, the eyepiece focus, and the magnification that resulted from combining the two lenses. These relations were used by him and his brother to build what he believed were optimized telescopes. When comparing these equations to the ones derived from modern optical principles, Huygens' telescopes were in fact far from optimal. While there are several potential reasons for this discrepancy, one possible reason, explored in this work, is that Huygens might have suffered from a mild case of myopia (or near-sightedness) and that he compensated this condition by building telescopes that overmagnified by a factor of 3.5. Based on this hypothesis, Huygens' visual acuity is estimated to be around 20/70, which on average corresponds to an optical prescription of −1.5 diopters. [ABSTRACT FROM AUTHOR]

O objetivo deste artigo é apresentar parte de um estudo histórico sobre a Tractriz. A metodologia utilizada foi a histórico documental. A partir da carta escrita por Huygens endereçada à Beauval, entre 1691 e 1695, apresentamos uma compreensão da curva e dos métodos utilizados por Huygens, além de uma construção deste método utilizando o software GeoGebra para uma representação matemática da curva.

This article traces the conceptual origins of Newton's draft scholia to Propositions IV through IX of Book III of the Principia to a manuscript booklet of observational data. By coordinating passages marked by dog-eared pages in Newton's books with his correspondence and working papers, it is possible to date these references to a time when he was still actively working on the Principia itself. This provides the basis for a new interpretation of Newton's uses of Egyptian and Graeco-Roman antiquity to counter rival histories of astronomy and philosophy influenced by Descartes. [ABSTRACT FROM AUTHOR]

The way Leibniz applied his philosophy to mathematics has been the subject of longstanding debates. A key piece of evidence is his letter to Masson on bodies. We offer an interpretation of this often misunderstood text, dealing with the status of infinite divisibility in nature , rather than in mathematics. In line with this distinction, we offer a reading of the fictionality of infinitesimals. The letter has been claimed to support a reading of infinitesimals according to which they are logical fictions, contradictory in their definition, and thus absolutely impossible. The advocates of such a reading have lumped infinitesimals with infinite wholes, which are rejected by Leibniz as contradicting the part–whole principle. Far from supporting this reading, the letter is arguably consistent with the view that infinitesimals, as inassignable quantities, are mentis fictiones , i.e., (well-founded) fictions usable in mathematics, but possibly contrary to the Leibnizian principle of the harmony of things and not necessarily idealizing anything in rerum natura. Unlike infinite wholes, infinitesimals—as well as imaginary roots and other well-founded fictions—may involve accidental (as opposed to absolute) impossibilities, in accordance with the Leibnizian theories of knowledge and modality. [ABSTRACT FROM AUTHOR]

In this article, we have investigated the effect of using a real feed on the performance of one-dimensional binary Huygens metasurfaces (BHMS). The designed structure has variable periods and each unit-cell consists of two dipoles with different lengths. Floquet theory and local constant period assumption are used to design these metasurfaces. The simulation results show the high efficiency of the designed structure and its beam squint capability. The results in this article make it possible to use this type of metasurface in real applications under the illumination of real feed sources. [ABSTRACT FROM AUTHOR]

In recent years there has been a shift of interest in the Nanophotonics community moving from using metallic/plasmonic materials to using high‐index dielectric materials for the construction of metasurfaces. Although high‐index dielectrics hold many advantages over their plasmonic counterparts, the selection of materials that exhibit high‐index properties, have low loss, and are complemetary metal‐oxide‐semiconductor (CMOS) compatible that also operate in the visible regime is extremely challenging. In this work, a high‐index dielectric material using silicon rich nitride (SRN) is proposed and experimentally demonstrated as a platform for solving this problem. While SRN has been used before for diffractive lenses and structural colors, here its applicability for Huygens‐type metasurfaces is focused upon. Specifically, a Huygens metasurface that operates in the visible range around a wavelength of 575 nm is theoretically and experimentally demonstrated, and the capabilities of spatially controlling the phase of this metasurface are further demonstrated by designing and fabricating a Huygens meta hologram. The study also shows that the refractive index can be controlled by the interplay between SiH4 and NH3 during the plasma‐enhanced chemical vapor deposition (PECVD) process. [ABSTRACT FROM AUTHOR]

In 1682, Leibniz published an essay containing his solution to the classic problem of squaring the circle: the alternating converging series that now bears his name. Yet his attempts to disseminate his quadrature results began seven years earlier and included four distinct approaches: the conventional (journal article), the grand (treatise), the impostrous (pseudepigraphia), and the extravagant (medals). This paper examines Leibniz's various attempts to disseminate his series formula. By examining oft-ignored writings, as well as unpublished manuscripts, this paper answers the question of how one of the greatest mathematicians sought to introduce his first great geometrical discovery to the world. [ABSTRACT FROM AUTHOR]

Christiaan Huygens spent five years (between 1663 and 1668) deeply involved in carriage design and manufacturing. This method of transportation, essential to living a honest bourgeois life in European cities, especially in Paris, where the streets’ muck was glorious, took many forms and concerned more than specialized artisans. Several members of Huygens’s family took an interest in improving this technology. The article, in detailing Huygens’s commitment to a distinct type of urban commodity, seeks to exemplify the savant’s early method of creating new technical knowledge. Questions were raised from theoretical and craft perspectives; securing patents and authorship became a crucial feature of knowledge making. From such concerns regarding a fast-evolving and transformative urban commodity, the article argues that Huygens’s approach to carriage design is another instance that conditioned him to respond effectively to the several priority disputes he would face during his lifetime regarding other technological devices, especially his balance-spring watch. [ABSTRACT FROM AUTHOR]

In this article, a new transmitarray (TA) antenna is designed and fabricated based on Huygens metasurfaces (HMSs). An analytical method has been used to achieve the distribution of surface parameters equivalent to HMS. In this method, the required equations for computing the surface parameters are derived using ray tracing, generalized sheet transition conditions, and two conditions of local power consumption and local impedance equalization. In order to implement these surface parameters, wire and loop unit cells are utilized, which are exposed to the radiation transversely. The array of these unit cells offers high aperture efficiency broadband TA antennas in low aperture profile. The fabricated TA antenna with a low aperture thickness of $0.2\lambda $ exhibits the bandwidth, sidelobe level (SLL), and cross-polarization level of 14%, −19 dB, and −19 dB, respectively. In addition, the high aperture efficiency of 65% is reached with this TA, which shows great improvement in comparison to previous works. [ABSTRACT FROM AUTHOR]

In this letter, a new technique based on passive two-dimensional (2-D) Huygens metasurface (HMS) is investigated to control the beam of a linear polarized horn antenna. In this proposed method, the spherical electromagnetic waves inside the horn are expanded to plane wave terms in spectral-domain for dominant mode. Then, using these plane waves, enforcing two conditions of local power conservation and local impedance equalization, the required surface electrical and magnetic impedance equivalent to HMS are calculated. Using this method, two different structures are designed and simulated for the deviation of the main beam on the H-plane and creating an orbital angular momentum wave at 10 GHz. Then, one sample is fabricated and measured. The results show improvement in aperture efficiency in comparison to similar works. [ABSTRACT FROM AUTHOR]

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In the first section (1-139) of his Minne-vlam (1642) the Leyden student François le Bleu (ab.1620 - post 1655) tells the love story of Phillis and Amaril in various poetic forms. Probably the 'Julia Monobiblos' of Janus Secundus was his inspiration, as he also included ten 'Kusjes' (Basia) in the story. A second section (140-237) contains a number of poems and some 'Thoughts' in prose on Amarillis' death, curiously dedicated to Cassandra, the poet's new love. His enduring love for Amaril should prove to Cassandra that he will be faithful to her as well. The article discusses both the traditionality of the book as a kind of show case of erotic poetry as well as the surprising presentation of the love affair, and its autobiographical background. In that connection attention is given to Le Bleus literary friends, and especially his efforts to make the acquaintance of the poet Constantijn Huygens, secretary of the stadtholder Frederik Hendrik. One of Le Bleus friends, prof. Zuerius van Boxhorn wrote an introductory letter to Huygens, praising Le Bleu's poetry. Huygens donates the usual amount of money for a laudatory poem on the prince. So encouraged, Le Bleu dedicates his Minne-vlam to both Huygens and another highly placed poet Jacob Cats, curator of the university. Both poets are well known for their Calvinism and in their poetry there is rarely, if ever, place for pagan mythology. Probably they were not happy with a book of poems by a young student, full of classical mythology and without any Christian background, even in the poems on Amaril's death and the funerary poetry as found in the second, more general part of the book (239-415). Maybe Le Bleu was disappointed about the lack of recognition from the dedicatees. In any case, he never published any other poetry. [ABSTRACT FROM AUTHOR]

This letter presents a simple, yet effective method for dynamic beamforming that can be readily realized by integrating a tunable binary Huygens’ metasurface with a leaky-waveguide antenna. Heretofore, dynamic beamforming has been difficult to achieve owing to the challenges in attaining full 360 $^\circ$ of dynamic phase tunability, while also independently controlling the local aperture amplitudes from zero to unity. In contrast, the hereby proposed method only requires $\pm 90^\circ$ of dynamic phase tunability (with arbitrary transmission amplitudes), thereby significantly alleviating the stringent tuning requirements. In particular, the proposed method is obtained by leveraging the antenna-array and holography theories, and utilizing the idea of “virtual” electric line sources. Based on full-wave simulations, we demonstrate the versatility of the proposed method through the designs of a Huygens’-metasurface-assisted leaky-waveguide antenna that generates various complex far-field patterns such as sector beams and Dolph–Chebyshev patterns. [ABSTRACT FROM AUTHOR]

Copyright of XVIIe Siècle is the property of Presses Universitaires de France and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract River valleys have been observed on Titan at all latitudes by the Cassini‐Huygens mission. Just like water on Earth, liquid methane carves into the substrate to form a complex network of rivers, particularly stunning in the images acquired near the equator by the Huygens probe. To better understand the processes at work that form these landscapes, one needs an accurate digital terrain model (DTM) of this region. The first and to date the only existing DTM of the Huygens landing site was produced by the U.S. Geological Survey (USGS) from high‐resolution images acquired by the DISR (Descent Imager/Spectral Radiometer) cameras on board the Huygens probe and using the SOCET SET photogrammetric software. However, this DTM displays inconsistencies, primarily due to nonoptimal viewing geometries and to the poor quality of the original data, unsuitable for photogrammetric reconstruction. We investigate a new approach, benefiting from a recent reprocessing of the DISR images correcting both the radiometric and geometric distortions. For the DTM reconstruction, we use MicMac, a photogrammetry software based on automatic open‐source shape‐from‐motion algorithms. To overcome challenges such as data quality and image complexity (unusual geometric configuration), we developed a specific pipeline that we detailed and documented in this article. In particular, we take advantage of geomorphic considerations to assess ambiguity on the internal calibration and the global orientation of the stereo model. Besides the novelty in this approach, the resulting DTM obtained offers the best spatial sampling of Titan's surface available and a significant improvement over the previous results.

The consensus today is that both Newton and Leibniz created calculus independently. Yet, this was not so clear at the beginning of the eighteenth century. A bitter controversy took place at that time, which came to be known as the 'calculus war', probably the greatest clash in the history of science. While it is accepted that the debate started when Fatio de Duillier publicly accused Leibniz of plagiarism in 1699, earlier evidence of its origins can be found in an exchange of letters between Leibniz and Huygens. [ABSTRACT FROM AUTHOR]

River valleys have been observed on Titan at all latitudes by the Cassini‐Huygens mission. Just like water on Earth, liquid methane carves into the substrate to form a complex network of rivers, particularly stunning in the images acquired near the equator by the Huygens probe. To better understand the processes at work that form these landscapes, one needs an accurate digital terrain model (DTM) of this region. The first and to date the only existing DTM of the Huygens landing site was produced by the U.S. Geological Survey (USGS) from high‐resolution images acquired by the DISR (Descent Imager/Spectral Radiometer) cameras on board the Huygens probe and using the SOCET SET photogrammetric software. However, this DTM displays inconsistencies, primarily due to nonoptimal viewing geometries and to the poor quality of the original data, unsuitable for photogrammetric reconstruction. We investigate a new approach, benefiting from a recent reprocessing of the DISR images correcting both the radiometric and geometric distortions. For the DTM reconstruction, we use MicMac, a photogrammetry software based on automatic open‐source shape‐from‐motion algorithms. To overcome challenges such as data quality and image complexity (unusual geometric configuration), we developed a specific pipeline that we detailed and documented in this article. In particular, we take advantage of geomorphic considerations to assess ambiguity on the internal calibration and the global orientation of the stereo model. Besides the novelty in this approach, the resulting DTM obtained offers the best spatial sampling of Titan's surface available and a significant improvement over the previous results. Key Points: We create a new digital terrain model (DTM) of the Huygens landing site that offers the best available resolution of river valleys on TitanThe complexity of the data set requires a tailor‐made reconstruction procedure that is detailedThe workflow uses reprocessed Huygens/DISR images and an automated shape‐from‐motion algorithm to improve an earlier DTM [ABSTRACT FROM AUTHOR]

The elastodynamic geometrical theory of diffraction (GTD) has proved to be useful in ultrasonic nondestructive testing (NDT) and utilizes the so-called diffraction coefficients obtained by solving canonical problems, such as diffraction from a half-plane or an infinite wedge. Consequently, applying GTD as a ray method leads to several limitations notably when the scatterer contour cannot be locally approximated by a straight infinite line: when the contour has a singularity (for instance, at a corner of a rectangular scatterer), the GTD field is, therefore, spatially nonuniform. In particular, defects encountered in ultrasonic NDT have contours of complex shape and finite length. Incremental models represent an alternative to standard GTD in the view of overcoming its limitations. Two elastodynamic incremental models have been developed to better take into consideration the finite length and shape of the defect contour and provide a more physical representation of the edge diffracted field: the first one is an extension to elastodynamics of the incremental theory of diffraction (ITD) previously developed in electromagnetism, while the second one relies on the Huygens principle. These two methods have been tested numerically, showing that they predict a spatially continuous scattered field and their experimental validation is presented in a 3-D configuration. [ABSTRACT FROM AUTHOR]

Este artigo apresenta uma análise crítica da possível disputa entre as teorias sobre luz e cores elaboradas por Newton e Huygens que teria ocorrido entre os séculos XVII e XIX. Com base em diversos estudos historiográficos já realizados sobre o tema, será mostrado que na Historiografia da Ciência a ideia de uma disputa entre as ópticas de Newton e Huygens é considerada ultrapassada. O artigo fornece um apanhado histórico da Óptica no período, oferecendo subsídios para que essa questão seja também problematizada no Ensino, assim como foi na Historiografia da Ciência atual.

Deconvolution is typically used to sharpen fluorescence images, but when the signal-to-noise ratio is low, the primary benefit is reduced noise and a smoother appearance of the fluorescent structures. 3D time-lapse (4D) confocal image sets can be improved by deconvolution. However, when the confocal signals are very weak, the popular Huygens deconvolution software erases fluorescent structures that are clearly visible in the raw data. We find that this problem can be avoided by prefiltering the optical sections with a Gaussian blur. Analysis of real and simulated data indicates that the Gaussian blur prefilter preserves meaningful signals while enabling removal of background noise. This approach is very simple, and it allows Huygens to be used with 4D imaging conditions that minimize photodamage.

Deconvolution is typically used to sharpen fluorescence images, but when the signal-to-noise ratio is low, the primary benefit is reduced noise and a smoother appearance of the fluorescent structures. 3D time-lapse (4D) confocal image sets can be improved by deconvolution. However, when the confocal signals are very weak, the popular Huygens deconvolution software erases fluorescent structures that are clearly visible in the raw data. We find that this problem can be avoided by prefiltering the optical sections with a Gaussian blur. Analysis of real and simulated data indicates that the Gaussian blur prefilter preserves meaningful signals while enabling removal of background noise. This approach is very simple, and it allows Huygens to be used with 4D imaging conditions that minimize photodamage .

Electrically thin and effectively 2-D material composites, metasurfaces, have been widely exploited for the manipulation of electromagnetic waves. For many applications, it is desired to transform incident waves of a specific frequency range keeping the metasurface invisible at other frequencies. Such a frequency-selective response can be achieved based on subwavelength Huygens’ inclusions. However, their fabrication requires sophisticated processes due to the 3-D geometry. Here, we propose a planar Huygens’ meta-atom with the goal to open a way to realize broadband invisible metasurfaces with topologies suitable for the conventional printed circuit board fabrication technology. We synthesize and analyze, both numerically and experimentally, three different metasurfaces capable of polarization and amplitude transformations of incident waves. [ABSTRACT FROM AUTHOR]

Light sheet fluorescence microscopy (LSFM) allows for high-resolution three-dimensional imaging with minimal photo-damage. By viewing the sample from different directions, different regions of large specimens can be imaged optimally. Moreover, owing to their good spatial resolution and high signal-to-noise ratio, LSFM data are well suited for image deconvolution. Here we present the Huygens Fusion and Deconvolution Wizard, a unique integrated solution for restoring LSFM images, and show that improvements in signal and resolution of 1.5 times and higher are feasible. [ABSTRACT FROM AUTHOR]

Translated from the French by Glenn Shafer, the French text will appear as Chapter 1 of Volume 2 of Les jeux de I'infini et du hasard, by Marie-France and Bernard Bru, to be published by the Presses universitaires de Franche-Comte. The translation is published here with the permission of the publisher and the surviving author. The text has been edited to omit most references to other parts of the book. The authors extensive notes, which provide many additional references and historical details, have also been omitted. [ABSTRACT FROM AUTHOR]

In this study, the high-efficiency phase control Si metasurfaces are investigated based on aperiodic nanoarrays unlike widely-used period structures, the aperiodicity of which providing additional freedom to improve metasurfaces’ performance. Firstly, the phase control mechanism of Huygens nanoblocks is demonstrated, particularly the internal electromagnetic resonances and the manipulation of effective electrical/magnetic polarizabilities. Then, a group of high-transmission Si nanoblocks with 2π phase control is sought by sweeping the geometrical parameters. Finally, several metasurfaces, such as grating and parabolic lens, are numerically realized by the nanostructures with high efficiency. The conversion efficiency of the grating reaches 80%, and the focusing conversion efficiency of the metalens is 99.3%. The results show that the high-efficiency phase control metasurfaces can be realized based on aperiodic nanoarrays, i.e., additional design freedom.

The article deals with selected aspects of two well-known publications on the multiplicity of worlds and extraterrestrial life that emerged at the end of the 17th century. These are Entretiens sur la pluralité des mondes (1686) by Bernard de Fontenelle and Cosmotheoros (1698) by Christiaan Huygens. In the first part, the article focuses primarily on how both authors understand the position of man in an inhabited and unbounded universe. Fontenelle and Huygens provide in their texts a convincing refutation of the often repeated notion that the idea of the infinite universe awakened terror and fears in early modern intellectuals. Actually, for them, the unbounded universe meant a celebration of reason that is able to emancipate itself from a geocentric superstition and anthropocentrism. At the same time, in the spirit of the early Enlightenment, it was also a celebration of the cosmic universality of reason. In its second part, the article deals with so-called cognitive passions: especially with fear, amazement and curiosity. The analysis of Huygens' and Fontenelles' works confirms and deepens some points of Lorraine Daston's research. It turns out that at the end of the 17th century, fear and admiration were clearly understood as manifestations of ignorance and backwardness, although in the previous philosophical tradition they were associated with piety and the beginning of philosophy. Compared to it, traditionally condemned curiosity has become a legitimate, even desirable, characteristics of a true scientist. [ABSTRACT FROM AUTHOR]

Huygens é conhecido no ensino introdutório de Física por dar conta da refração segundo um modelo ondulatório. Livros didáticos lhe rendem homenagens atribuindo seu nome a um princípio, mas em sua obra máxima, Tratado sobre a luz, é possível se ver muito mais: sua inventividade na defesa de um modelo ondulatório para a luz como alternativo ao modelo corpuscular. Neste trabalho, tenta-se evidenciar o raciocínio de Huygens, mostrando que, apesar de ter sido publicada há mais de trezentos anos, a obra está escrita numa linguagem relativamente acessível.

Este artículo trata de las diversas observaciones a propósito de la música en España, que se encuentran en la correspondencia entre Sébastien Chièze (embajador del Príncipe de Orange en Madrid) y Constantijn Huygens (La Haya), entre 1672 y 1679. Huygens pidió a Chièze que le encontrara un ejemplar del De musica de Salinas (1577), así como tonadas españolas y piezas para guitarra. A Chièze le llevó dos años hallar una copia del De musica en territorio español y hacer que el libro llegara a Holanda sano y salvo. Las tonadas remitidas por Chièze (de compositores tales como Juan del Vado, José Marín, Cristóbal Galán y Juan Hidalgo), no gustaron nada a Huygens, que las halló demasiado “africanas”. Como tampoco le gustaron las tabulaturas españolas para guitarra, anotadas al revés (boca abajo) de las tabulaturas francesas a las que Huygens estaba acostumbrado. Chièze consiguió también una guitarra -hecha para Huygens- en Madrid, pero este instrumento también se topó con su desaprobación. Al final, Chièze hubo de pedir a dos conocidos suyos boloñeses, Giulio y Guido Bovio, que le buscaran en Bolonia un laúd que fuera adecuado para Huygens. Le encontraron dos, pero se desconoce si llegaron alguna vez a Holanda. Este trabajo muestra la importancia de los contactos extranjeros (diplomáticos) para la adquisición de objetos musicales, tales como libros de música, composiciones musicales, e instrumentos.

The history of the introduction of exotic therapeutic drugs in early modern Europe is usually rife with legend and obscurity and Peruvian bark is a case in point. The famous antimalarial drug entered the European medical market around 1640, yet it took decades before the bark was firmly established in pharmaceutical practice. This article argues that the history of Peruvian bark can only be understood as the interplay of its trajectories in science, commerce, and society. Modern research has mostly focused on the first of these, largely due to the abundance of medico-historical data. While appreciating these findings, this article proposes to integrate the medical trajectory in a richer narrative, by drawing particular attention to the acculturation of the bark in commerce and society. Although the evidence we have for these two trajectories is still sketchy and disproportionate, it can nevertheless help us to make sense of sources that have not yet been an obvious focus of research. Starting from an apparently isolated occurrence of the drug in a letter, this article focuses on Paris as the location where medical and public appreciation of the bark took shape, by exploring several contexts of knowledge circulation and medical practice there. These contexts provide a new window on the early circulation of knowledge of the bark, at a time when its eventual acceptance was by no means certain. [ABSTRACT FROM AUTHOR]

We compare measurements made by two impact penetrometers of different sizes and with different tip shapes to further understand penetrometer design for performing penetrometry on an asteroid. To this end we re-visit the interpretation of data from the Huygens’ penetrometer, ACC-E, that impacted Titan’s surface. In addition we investigate the potential of a spacecraft fitted with a penetrometer to bounce using a test rig, built at The Open University (UK). Analysis of ACC-E laboratory data, obtained from impacts into ∼4 mm diameter gravel, was found to produce an unusual decrease in resistance with depth (force–depth gradient) which was also seen in the Huygens’ ACC-E data from Titan and originally interpreted as a wet or moist sand. The downward trend could also be reproduced in a hybrid Discrete Element Model (DEM) if it was assumed that the near surface particles are more readily mobilised than those deeper in the target. With regard to penetrometer design penetration resistance was found to be sensitive to the ratio of particle to tip diameter. A clear trend was observed with a conical tip penetrometer, X-PEN, of decreasing force–depth gradients with increasing particle sizes most likely due to a transformation from a bulk displacement of material by the penetrating tip to more local interactions. ACC-E, which has a hemispherical tip, was found to produce a wider range of force–depth gradients than X-PEN, which had a conical tip, possibly due to difficulties dislodging jammed particles. Both penetrometers were able to determine particle diameter and mass after post-processing of the data. Laboratory simulations of landings with the test rig suggest that a large impact penetrometer under certain circumstances could absorb a significant amount of the elastic energy of the spacecraft possibly aiding landing. Alternatively a small impact penetrometer would allow the spacecraft to bounce freely off the surface to make a measurement at another location. [ABSTRACT FROM AUTHOR]