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High resolution directional of arrival (DOA) estimation technology play an important role in passive RF signal source localization, enhancing the performance of MIMO and beamforming arrays for mobile wireless communication. This paper presents the performance analysis and comparison for MUltiple SIgnal Classification (MUSIC) DOA estimation algorithm with uniform circular arrays (UCA). It has been...
Dust poses significant challenges to future exploration missions on asteroids. From the Apollo era, we know that highly abrasive regolith particles have a potential to coat instruments and astronauts as well as cause clogging and excess wear in mechanical devices. In the reduced gravity environment of asteroids, dust will be easily released from the surface due to vehicle activities and may stably...
The goal of this project is to produce an inexpensive yet highly reliable system for detecting wind shear at small and improvised airfields. While the largest commercial airports do have wind shear detection systems and they have proven to be life savers, the overwhelming majority of places where aircraft land have no such protection. The system described here is self-organizing, redundant and highly...
In satellite missions, there are many complex factors requiring complex software or hardware design; for example: orbital calculation, Doppler shift correction. In optimization and computer aided design, the use of surrogate models has been increasing lately. These models replace a complex calculation or simulation by a simpler one, with good approximation. Neural Networks, Support Vector Machines...
In a strength based learning classifier systems (LCS), auctioning among classifiers that match to an environmental message has been used as a way of identifying winner classifiers. All classifiers participating in an auction issue a bid proportional to their strength and a winner classifier is allowed to fire and receive a reward or punishment from its environment as a consequence of its action. In...
In this paper, we investigate cloud platform support that provides distributed applications with automatic service placement across different cloud computing systems (hybrid clouds), and that enables application developers to investigate the impact of using different cloud-based data consistency models with their applications. By pursuing its implementation at the cloud runtime layer (platform), we...
Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency...
This paper describes the design and testing of two cold-capable SiGe BiCMOS wireline transceivers targeted for applications in distributed electronics systems in space-based vehicles. Space-based electronic systems face extremely wide temperature ranges and hazardous radiation that can cause unpredicted behavior in sensitive circuitry. The most common mitigation procedure involves extensive shielding...
Reliability of electronic circuits over an extended temperature range is a critical consideration in demanding applications such as aerospace and the military. Achieving this reliability on modern deep submicron process nodes is a significant challenge especially for analogue circuits due to the high level of device variability. A novel approach is proposed in this paper that employs online adjustment...
The Starshade is an external occulter being developed for a future exoplanet imaging and characterization mission. The large, petal-shaped screen efficiently blocks starlight (to better than 1 part in 1010) by using precisely-controlled edges to suppress diffraction and prevent the formation of Arago's spot. A conventional telescope, operating in the shadow of the starshade, then has an unobstructed...
Real-time digital beamforming, combined with lightweight, large aperture reflectors, enable a new architecture, which is the baseline for the proposed DESDynI [Deformation, Ecosystem Structure, and Dynamics of Ice] SAR [Synthetic Aperture Radar] Instrument (or DSI). This new instrument concept requires new methods for calibrating multiple simultaneous channels. The calibration of current state-of-the-art...
Although there are excellent estimates of ages of terrains on Mars from crater counting, even a few absolute ages would serve to validate the calibration. Results with uncertainties, although much larger than those that could be achieved in labs on Earth, would be extremely valuable. While there are other possibilities for in situ geochronology instruments, we describe here two alternative technologies,...
The first mission in the Mars Sample Return campaign is the 2018 Mars Astrobiology Explorer-Cacher (MAX-C) rover. Its goal is to acquire rock cores and regolith samples, hermetically seal them inside a cache, and leave the cache to be collected at a later stage. To help analyzing of rock samples in-situ before returning them to earth, we have developed five bits: a combined Brushing and Abrading Tool...
The need for launch opportunities for nanosatellite missions is ever increasing as the number of nanosatellites in development increases. Nanosatellites are typically launched as secondary, also known as auxiliary payloads, on missions to minimize launch costs. This creates managerial and technical challenges for integrating multiple nanosatellite programs as auxiliary payloads with primary missions...
The performance of wheels operating in loose granular material for the application of planetary vehicles is well researched but little effort has been made to study the soil shearing which governs traction. Net traction measurements and application of energy metrics have been solely relied upon to investigate performance but lack the ability to evaluate or describe soil-wheel interaction leading to...
Solar sails have long been known to be an attractive method of propulsion in the inner solar system if the areal density of the overall spacecraft (S/C) could be reduced to ∼10 g/m2. It has also long been recognized that the figure (precise shape) of useful solar sails needs to be reasonably good, so that the reflected light goes mostly in the desired direction. If one could make large reflective...
This paper analyzes a Mixed Ornstein-Uhlenbeck (MOU) process that has a number of appealing properties as a target motion model. Relevant earlier models that have been proposed include the standard nearly constant velocity motion model (unbounded long-term position and velocity), the Ornstein-Uhlenbeck process (bounded position, but no defined velocity), and the Integrated Ornstein-Uhlenbeck process...
Planetary and sample return missions require surface cleaning procedures using biocides. However, a deep understanding of how microorganisms respond to biocides is needed. The response of different Salmonella serovars to defined concentrations of chlorine, chlorine dioxide, and cetylpyridinium chloride (CPC) was studied. Microbial responses in terms of culturability, and virulence gene expression...
In the earliest phases of space mission conceptual design it is important for engineers to work collaboratively and arrive at multiple decisions concurrently as a team due to the interdependent nature of every mission aspect. JHU/APL has implemented the APL Concurrent Engineering (ACE) Lab to support collaborative design. With its wide array of analysis techniques and tools and an extensive library...
Hopping vehicles provide advantages over traditional surface exploration vehicles, such as wheeled rovers, by enabling in-situ measurements in otherwise inaccessible terrain. However, significant development over previously demonstrated vehicle navigation technologies is required to overcome the inherent challenges involved in navigating a hopping vehicle, especially in adverse terrain. This paper...
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