LPD-28, the 12th ship in the San Antonio class line, may serve as somewhat of a bridge to the upcoming class of amphibious transport docks, currently dubbed the LX(R). As part of this transitional vessel, Lockheed wants to install its vaunted Aegis Combat System aboard it, giving the ship a much higher level of defensive capabilities, independence and situational awareness.
Structural analysis of lunar subsurface with Chang׳E-3 lunar penetrating radar
Authors:
Lai et al
Abstract:
Geological structure of the subsurface of the Moon provides valuable information on lunar evolution. Recently, Chang׳E-3 has utilized lunar penetrating radar (LPR), which is equipped on the lunar rover named as Yutu, to detect the lunar geological structure in Northern Imbrium (44.1260N, 19.5014W) for the first time. As an in situ detector, Chang׳E-3 LPR has relative higher horizontal and vertical resolution and less clutter impact compared to spaceborne radars and earth-based radars.
In this work, we analyze the LPR data at 500 MHz transmission frequency to obtain the shallow subsurface structure of the landing area of Chang׳E-3 in Mare Imbrium. Filter method and amplitude recovery algorithms are utilized to alleviate the adverse effects of environment and system noises and compensate the amplitude losses during signal propagation. Based on the processed radar image, we observe numerous diffraction hyperbolae, which may be caused by discrete reflectors beneath the lunar surface. Hyperbolae fitting method is utilized to reverse the average dielectric constant to certain depth (View the MathML sourceε¯). Overall, the estimated View the MathML sourceε¯ increases with the depth and View the MathML sourceε¯ could be classified into three categories. Average View the MathML sourceε¯ of each category is 2.47, 3.40 and 6.16, respectively. Because of the large gap between the values of View the MathML sourceε¯ of neighboring categories, we speculate a three-layered structure of the shallow surface of LPR exploration region.
One possible geological picture of the speculated three-layered structure is presented as follows. The top layer is weathered layer of ejecta blanket with its average thickness and bound on error is 0.95±0.02 m. The second layer is the ejecta blanket of the nearby impact crater, and the corresponding average thickness is about 2.30±0.07 m, which is in good agreement with the two primary models of ejecta blanket thickness as a function of distance from the crater center. The third layer is regarded as a mixture of stones and soil. The echoes below the third layer are in the same magnitude as the noises, which may indicate that the fourth layer, if it exists, is uniform (no clear reflector) and its thickness is beyond the detection limit of LPR. Hence, we infer the fourth layer is a basalt layer.
The Navy and two shipbuilders are moving forward with the Flight III upgrade to the Arleigh Burke guided missile destroyers (DDG-51), which adds an air and missile defense radar to the ship class starting this fiscal year.
General Dynamics Bath Iron Works and Ingalls Shipbuilding are collaborating on detail design of the Flight III upgrade, which should be complete by the summer of 2017, and both have responded to the Navy’s draft request for proposals (RFP) for Fiscal Year 2016 ship construction, DDG-51 program manager Capt. Mark Vandroff told USNI News in a Nov. 12 interview.
The two yards have taken the Navy’s preliminary design for Flight III, which was broken into 17 individual statements of work, and are working together to develop a 3D model of the ship that includes all equipment and distributed systems.
“We always planned to complete that some time in the late summer of 2017 because a ship that’s appropriated in FY ’16 generally spends about a year [procuring materials],” Vandroff said.
“A typical FY ‘16 ship wouldn’t start until the later part of 2017, and we would want the detail design to be done about the same time.”
Radar scattering of linear dunes and mega-yardangs: Application to Titan
Authors:
Paillou et al
Abstract:
The Ku-band (13.8 GHz - 2.2 cm) RADAR instrument onboard the Cassini-Huygens spacecraft has revealed the richness of the surface of Titan, as numerous seas, lakes, rivers, cryo-volcanic flows and vast dune fields have been discovered. Linear dunes are a major geomorphological feature present on Titan, covering up to 17% of its surface, mainly in equatorial regions. However, the resolution of the RADAR instrument is not good enough to allow a detailed study of the morphology of these features. In addition, other linear wind-related landforms, such as mega-yardangs (linear wind-abraded ridges formed in cohesive rocks), are likely to present a comparable radar signature that could be confused with the one of dunes. We conducted a comparative study of the radar radiometry of both linear dunes and mega-yardangs, based on representative terrestrial analogues: the linear dunes located in the Great Sand Sea in western Egypt and in the Namib Desert in Namibia, and the mega-yardangs observed in the Lut Desert in eastern Iran and in the Borkou Desert in northern Chad. We analysed the radar scattering of both terrestrial linear dunes and mega-yardangs, using high-resolution radar images acquired by the X-band (9.6 GHz - 3.1 cm) sensor of the TerraSAR-X satellite. Variations seen in the radar response of dunes are the result of a contrast between the dune and interdune scattering, while for mega-yardangs these variations are the result of a contrast between ridges and erosion valleys. We tested a simple surface scattering model, with parameters derived from the local topography and surface roughness estimates, to accurately reproduce the radar signal variations for both landforms. It appears that we can discriminate between two types of dunes - bare interdunes as in Egypt and sand-covered interdunes as in Namibia, and between two types of mega-yardangs - young yardangs...
Probabilistic Constraints from Existing and Future Radar Imaging on Volcanic Activity on Venus
Author:
Lorenz
Abstract:
We explore the quantitative limits that may be placed on Venus' present-day volcanic activity by radar imaging of surface landforms. The apparent nondetection of new lava flows in the areas observed twice by Magellan suggests that there is a ~60% chance that the eruption rate is ~1 km3/yr or less, using the eruption history and area/volume flow geometry of terrestrial volcanos (Etna, Mauna Loa and Merapi) as a guide. However, if the detection probability of an individual flow is low (e.g. ~10%) due to poor resolution or quality and unmodeled viewing gemetry effects, the constraint (less than 10 km3/yr) is not useful. Imaging at Magellan resolution or better of only ~10% of the surface area of Venus on a new mission (30 years after Magellan) would yield a better than 99% chance of detecting a new lava flow, even if volcanic activity is at the low end of predictions (~0.01 km3/yr) and is expressed through a single volcano with a stochastic eruption history. Closer re-examination of Magellan data may be worthwhile, both to search for new features, but also to establish formal (location-dependent) limits on activity against which data from future missions can be tested. While Magellan-future and future-future comparisons should offer much lower detection thresholds for erupted volumes, a probabilistic approach will be required to properly understand the implications.
The U.S. Navy and Raytheon Company (NYSE: RTN) have completed the AN/SPY-6(V) Air and Missile Defense Radar (AMDR) critical design review. The outcome confirms Raytheon's design and technologies as mature, producible and low risk; on track to meet all radar performance requirements, on schedule and within cost.
The CDR assessed all technical aspects of the program, from hardware specifications, software development, risk mitigation and producibility analysis, to program management, test and evaluation schedules, and cost assessments. The review concluded with Navy stakeholders impressed with the radar's progress to date and confident in the program's path forward to on-time delivery.
"This successful milestone is the culmination of our team's unwavering focus on continuous technology maturity, risk mitigation and cost reduction throughout all phases of development," said Raytheon's Kevin Peppe, vice president of Integrated Defense Systems' Seapower Capability Systems business area. "With customer validation in hand, we will now advance production, driving toward the ultimate – and timely – delivery of this highly capable and much-needed integrated air and missile defense radar capability to the DDG 51 Flight III destroyer."
A prototype quantum radar that has the potential to detect objects which are invisible to conventional systems has been developed by an international research team led by a quantum information scientist at the University of York.
The new breed of radar is a hybrid system that uses quantum correlation between microwave and optical beams to detect objects of low reflectivity such as cancer cells or aircraft with a stealth capability. Because the quantum radar operates at much lower energies than conventional systems, it has the long-term potential for a range of applications in biomedicine including non-invasive NMR scans.
The research team led by Dr Stefano Pirandola, of the University's Department of Computer Science and the York Centre for Quantum Technologies, found that a special converter - a double-cavity device that couples the microwave beam to an optical beam using a nano-mechanical oscillator - was the key to the new system.
The device can either generate microwave-optical entanglement (during the signal emission) or convert a microwave into an optical beam (during the collection of the reflection beams from the object). The research is published in Physical Review Letters.
Chinese spies stole key design information about Australia's new Joint Strike Fighter, according to top secret documents disclosed by former US intelligence contractor Edward Snowden.
German magazine Der Spiegel has published new disclosures of signals intelligence collected by the United States National Security Agency (NSA) and its "Five Eyes" partners, including the Australian Signals Directorate. The intelligence reveals new details of the directorate's efforts to track and combat Chinese cyber-espionage.
According to a top secret NSA presentation, Chinese cyber spies have stolen huge volumes of sensitive military information, including "many terabytes of data" relating to the Joint Strike Fighter (JSF) - also known as the Lockheed Martin F-35 Lightning II.
The leaked document shows that stolen design information included details of the JSF's radar systems which are used to identify and track targets; detailed engine schematics; methods for cooling exhaust gases; and "aft deck heating contour maps".
China has unveiled a new counter stealth radar that can detect and track stealth aircraft like America's famed F-22 Raptor fighter jet.
The new phased array named JY-26 was showcased at the 10th China International Aviation and Aerospace Exhibition in Zhuhai that concluded Sunday, along with four other Chinese radar systems: the YLC-20, the YLC-2V, the YLC-8B and the JY-27A.
Designed to detect fifth-generation stealth fighters, the JY-26 phased array radar is capable of high accuracy, target tracking, and separation, and can operate up to a range of 500 kilometers, according to the manufacturer.
Chinese media reported recently that the JY-26 radar had spotted an F-22 Raptor stealth fighter -- the United States' most advanced stealth fighter -- when it flew over South Korea during a recent military exercise.
Increasingly sophisticated radar in China and Russia may soon be able to pierce the stealth armor on F-22 and F-35 fighter jets, according to a news report.
The stealth coating on the U.S.-made fifth-generation fighters shields the aircraft from high-frequency radars operating in the Ku, X and C bands and some of the S band, but not from low-frequency systems utilizing L, UHF and VHF wavelengths, according to an article by Dave Majumdar at USNI News.
China and Russia are now developing low-frequency radars with more computing power designed to track stealth aircraft with more precision — enough to target with a missile, according to the report, citing an unnamed former senior U.S. Navy official.
“Acquisition and fire control radars are starting to creep down the frequency spectrum,” the official told USNI News. “I don’t see how you long survive in the world of 2020 or 2030 when dealing with these systems if you don’t have the lower frequency coverage.”
To be sure, the Defense Department is aware of the increasing sophistication of enemy air defenses, known in military parlance as anti-access, area-denial, or A2-AD, environments.
