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Tempe, AZ, United States

Farquhar I.,Farquhar Consultants System Analysis and Design | Dunham D.,KinetX, Inc
Proceedings of the International Astronautical Congress, IAC

We developed and demonstrated the feasibility of an autonomous architecture-ARCTIC-that will deploy the capabilities of continuous reliable communications, e-navigation and vessel tracking, accurate geodetic framework, dynamic support of operations and logistics, and in-situ ice-sea and Marginal Ice Zone research in the Arctic. ARCTIC is a distributed, dynamic network of autonomous platforms combining sonar, RF, active RFID, laser communication, and power technologies and microsatellite relay. It enables the real-time acoustic and non-acoustic signal processing (image, optic, water properties) and functions from the bottom floor, through the entire water column, on water surface, ground level, and into the atmosphere and beyond. For the global coverage, a constellation of 30-72 microsatellites will support real-time RF communication with intended ground-level assets. The basic system consists of a minimum of 30 microsatellites, in three 530 km, circular, polar orbits whose orbital planes are separated by 120 degrees. With 10 satellites evenly spaced, in each of 3 polar orbits, it is highly likely that at least 2 satellites will be above 5 degrees elevation at any given time. With the basic 30 satellite system, the maximum slant range to any Ground Asset will be 2140 km. The LORAN-type (eLoran) triangulation model is used for determining and dynamic maintenance of the positioning coordinates of the entire architecture and its individual components. The architecture can associate GPS geospatial coordinates with its own organic geospatial reference system. A relay of 3-5 microsatellites will enable the real-time communication over any localized region. The relay of microsatellites (iteratively expandable and reconfigurable) in the calculated polar orbits will remain operational for over hundred years. ARCTIC and most of its platforms will continuously transfer data at 200 Kb/s-to-700Kb/s and, discretely, 10GB every 10 minutes using Earth-to-Space Forward Link (Ground Asset) transmit power of 20 Watts at the RF transmit frequency of 9750 MHz and Space-to-Earth Return Link (Microsatellite) transmit power of 25 Watts at the RF transmit frequency of 8600 MHz. In the short run, the proposed architecture will sustain continuous reliable communications in the region, e-navigation, and VHF data exchange system. In the long-run, the iteratively déployable dynamic network of autonomous platforms will serve multifunctional and multinational purposes of cost-effective maritime safety, Aid(s)-to-Navigation (AtoN), search and rescue, hazardous material spill response, MIZ research, and security of Arctic stakeholders and activities. ARCTIC meets requirements of providing AtoN services in Polar Regions specified by the International Association of Maritime Aids to Navigation and Lighthouse Authorities [1] and Maritime Transportation Safety information infrastructure laid out in the U.S. Committee on the Marine Transportation System document [2]. Whereas, this paper focuses on the feasibility of operational and technical requirements and the feasibility of ARCTIC to deploy the required capabilities, its companion paper-IAC-14 B5.2.5 Multi-Sensor Architecture for Dynamic Signal Processing and Global Communication-discusses the limitless scope of operational requirements that the real-time information and communication architecture will enable, work breakdown structure (WBS) of the architecture prototype, and proof-of-concept, integrated end-to-end solution for real-time acoustic signatures differentiation and mapping. Source

Hodgson M.E.,University of South Carolina | Davis B.A.,Washington Technology | Cheng Y.,Jet Propulsion Laboratory | Miller J.,KinetX, Inc
Cartography and Geographic Information Science

State and local agencies involved in emergency response to natural disasters such as hurricanes have explicidy indicated they need imagery covering the disaster area within diree days of the event; and more desirably within 24 hours of the event. Airborne image collections have often been used but suffer from several problems, most noticeably the collection time (days or week) required for larger areas. The use of remote sensing satellites carrying high spatial resolution sensors has often been touted as the logical response for rapidly collecting post-disaster event imagery for emergency response. Unfortunately, satellites are maintained on fixed orbits. The repeat interval for remote sensing satellites carrying high spatial resolution sensors, even with pointable sensors, is on the order of several days, depending on the latitude for the disaster event. Fortunately, more than one satellite carries high spatial resolution imagery. This combination of requirements and restrictions may result in either a relatively high (or low) likelihood of collecting imagery within the three-day window of opportunity. This research investigated the likelihood of collecting imagery over a hurricane disaster area based on the orbital cycles of diree high spatial resolution imaging satellites. Using the spatial-temporal distribution of historic hurricane landfall locations as a proxy for the probability distribution of future hurricanes by latitude, the "visibility" of each landfall location to future satellite imaging opportunities was determined. The results indicate that the likelihood of collecting imagery within one day of the event varied between 17 and 39 percent by relying on one satellite image provider. However, if either of diree satellite imagery sources (i.e., Ikonos-2, Quickbird-2, and Orbview-3) could be used, then the likelihood increased to 61 percent. By relying on diree satellite imagery providers there is a likelihood of between 94 and 100 percent of collecting imagery within two or diree days, respectively, after the event. Source

Shaklan S.B.,Jet Propulsion Laboratory | Marchen L.,Jet Propulsion Laboratory | Lisman P.D.,Jet Propulsion Laboratory | Cady E.,Jet Propulsion Laboratory | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering

We present a starshade error budget with engineering requirements that are well within the current manufacturing and metrology capabilities. The error budget is based on an observational scenario in which the starshade spins about its axis on timescales short relative to the zodi-limited integration time, typically several hours. The scatter from localized petal errors is smoothed into annuli around the center of the image plane, resulting in a large reduction in the background flux variation while reducing thermal gradients caused by structural shadowing. Having identified the performance sensitivity to petal shape errors with spatial periods of 3-4 cycles/petal as the most challenging aspect of the design, we have adopted and modeled a manufacturing approach that mitigates these perturbations with 1-m long precision edge segments positioned using commercial metrology that readily meets assembly requirements. We have performed detailed thermal modeling and show that the expected thermal deformations are well within the requirements as well. We compare the requirements for four cases: a 32 m diameter starshade with a 1.5 m telescope, analyzed at 75 and 90 mas, and a 40 m diameter starshade with a 4 m telescope, analyzed at 60 and 75 mas. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). Source

Kidd J.N.,Jr. | Furfaro R.,127 E. James E. Rogers Way | Dunham D.,KinetX, Inc
Advances in the Astronautical Sciences

This paper will concentrate on one mission profile of particular interest, a manned mission to Mars. Specifically, the study will explore the use of HEOs whose line of apsides can be rotated using lunar swingbys to approximate the V vector necessary for such a mission, reducing the required energy cost of such a mission. The HEO also provides a convenient and relatively fast location for rendezvous with crew, or to add propulsion or cargo modules, a technique that we call "Phasing Orbit Rendezvous." From a HEO, a propulsive maneuver, considerably smaller than that needed from a circular low-Earth orbit, can be applied at the right perigee to send the spacecraft on the appropriate departure asymptote. A propulsive maneuver at perigee can be used to re-capture the spacecraft into a loosely-bound orbit at the return, perhaps assisted by a lunar swingby. Earth-Moon (and possibly Sun-Earth) libration point orbits and double-lunar swingby orbits will be used, along with time to change the orbital orientation between missions. There might be wait times of several months to years between missions, when the interplanetary spacecraft could be "parked" in a small-amplitude Lissajous orbit about a libration point, similar to that flown by the WMAP mission. Source

Durech J.,Charles University | Kaasalainen M.,Tampere University of Technology | Herald D.,International Occultation Timing Association IOTA | Dunham D.,KinetX, Inc | And 8 more authors.

Asteroid sizes can be directly measured by observing occultations of stars by asteroids. When there are enough observations across the path of the shadow, the asteroid's projected silhouette can be reconstructed. Asteroid shape models derived from photometry by the lightcurve inversion method enable us to predict the orientation of an asteroid for the time of occultation. By scaling the shape model to fit the occultation chords, we can determine the asteroid size with a relative accuracy of typically ∼10%. We combine shape and spin state models of 44 asteroids (14 of them are new or updated models) with the available occultation data to derive asteroid effective diameters. In many cases, occultations allow us to reject one of two possible pole solutions that were derived from photometry. We show that by combining results obtained from lightcurve inversion with occultation timings, we can obtain unique physical models of asteroids. © 2011 Elsevier Inc. Source

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