Meter-Scale Slopes of Candidate InSight Landing Sites from Point Photoclinometry

Photoclinometry was used to analyze the small-scale roughness of areas within the proposed Mars InSight landing ellipse. The landing ellipse presented in this study is in Elysium Planitia.This study was able to constrain surface slopes on length scales comparable to the HiRISE image resolution (0.25 meters/pixel and coarser). The InSight mission has various engineering constraints that each candidate landing ellipse must satisfy. These constraints indicate that the statistical value of the slopes at one, two, and five meter baselines are an important criterion. This technique estimates surface slopes across large swaths of each image, and builds up slope statistics for the images in the landing ellipse. The slopes I derived for the InSight landing site ellipse in this study are within the small-scale roughness constraints put forth by the InSight project. These results have provided input into the landing hazard assessment process.     

Use of reduce gravity conditions for the measurements of forces acting against the displacement of liquids inside containers

A setup called Controlled Rotation of Liquids (CROL) has been developed and used to investigate rotational behavior of liquids interacting with solids under reduced gravity conditions. The CROL setup allows us to evaluate the acceleration needed to overcome the interfacial forces that hinder liquid displacement inside different size containers. The well known Wilhelmy equation is used to explain the experimental results. Comparison between experimental results and theoretical predictions are presented and discussed.     

Gravity and the cells of gravity receptors in mammals.

Two new findings, that crystals located in the inner ear gravity receptors of mammals have the internal organization requisite for the piezoelectric property, and that sensory hair cells of these same receptors possess contractile-appearing striated organelles, have prompted the author to model mammalian gravity receptors in the ear on the principles of piezoelectricity and bioenergetics. This model is presented and a brief discussion of its implications for the possible effects of weightlessness follows.     

Modeling gas exchange in a closed plant growth chamber.

Fluid transport models for fluxes of water vapor and CO2 have been developed for one crop of wheat and three crops of soybean grown in a closed plant growth chamber. Correspondence among these fluxes is discussed. Maximum fluxes of gases are provided for engineering design requirements of fluid recycling equipment in growth chambers. Furthermore, to investigate the feasibility of generalized crop models, dimensionless representations of water vapor fluxes are presented. The feasibility of such generalized models and the need for additional data are discussed.     

Shuttle demonstration of large space structure fabrication and assembly

The purpose of this paper is to describe a program aimed at an early on orbit demonstration of a large space structure fabrication and assembly capability. Requirements for the demonstration concept have been formulated. The concept that has been selected to meet these requirements is a Large Space Structure Platform consisting of a triangular prism of 31.5 m length. Sensors can be mounted on this platform to perform Earth observation measurements from space. Structural elements of the platform are fabricated using an automated beam builder in the Shuttle Orbiter payload bay. Special fixtures are designed to assemble the structure with the aid of the Remote Manipulator System and two astroworkers in an EVA mode. Results are shown of the platform preliminary design in terms of a design layout with related structural, thermal, mass properties and control dynamics data. The assembly scenario is described. Estimates of the total construction time and Orbiter support requirements are also presented.     

Scattering-Center Theory and Radar Glint Analysis

The balance-point model for tracking radars has been extended by using the geometrical theory of diffraction to evaluate the magnitudes and phases of the fields received from the scattering centers on a target. Determinate, rather than statistically averaged, expressions for balance-point location are obtained. The glint model is illustrated for a right-circular cylinder.     

High-Sensitivity Fast-Response Laser Detection Systems

Electrooptical systems exist which can make use of the available bandwidth and directivity at optical frequencies without utilizing the coherence aspects of lasers. Development of a sensitive, very highspeed (microwave response) photoelectric detector which can function as a high-gain microwave amplifier and mixer is described. Sysyems are described for radar, communications, and reconnaissance purposes. Basic noise considerations are shown. CW and FM-CW optical range and range rate tracking systems are described in which the required detection bandwidth is not a direct function of the range resolution, allowing highly accurate range and range rate determination at low signal levels. Communication systems utilizing noncoherent carriers, microwave subcarriers, and the dynamic crossed field electron multiplier as the detector-amplifier-mixer are described.     

Missions to the asteroid anteros and the space of true anomalies

Three opportunities for missions to rendezvous ballistically with the Earth-crossing asteroid Anteros are studied to illustrate the requirements for a trip to a near-Earth minor planet. The rationale, sample payload, spacecraft requirements and trajectory characteristics of these opportunities are typical of a rendezvous mission to an accessible near-Earth object. Round trip ballistic trajectories to return small samples of the asteroid with launch dates between 1985 and 2000 are also presented. Contours of minimum total ΔV drawn in the space of launch and arrival true anomalies, given the designation Prime Rib curves, are introduced as a useful tool for mission design.