SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 13 - JULY 5, 2006

17 SPACE COMMUNICATIONS, SPACECRAFT COMMUNICATIONS, COMMAND AND TRACKING
Includes space systems telemetry; space communications networks; astronavigation and guidance; and spacecraft radio blackout.

For related information see also 04 Aircraft Communications and Navigation; and 32 Communications and Radar.

20060017049 NASA Glenn Research Center, Cleveland, OH, USA

Dilution of Precision-Based Lunar Navigation Assessment for Dynamic Position Fixing

Sands, Obed S.; Connolly, JosephW.; Welch, BryanW.; Carpenter, James R.; Ely, Todd A.; Berry, Kevin; April 2006; 16 pp.; In English; National Technical Meeting 2006, 18-20 Jan. 2006, Monterey, CA, USA; Original contains color illustrations Contract(s)/Grant(s): 432-07-02-03-03 Report No.(s): NASA/TM-2006-214247; E-15492; No Copyright; Avail.: CASI: A03, Hardcopy

The NASA Vision for Space Exploration is focused on the return of astronauts to the Moon. While navigation systems have already been proven in the Apollo missions to the moon, the current exploration campaign will involve more extensive and extended missions requiring new concepts for lunar navigation. In contrast to Apollo missions, which were limited to the near-side equatorial region of the moon, missions under the Exploration Systems Initiative will require navigation on the moon's limb and far-side. As these regions have poor Earth visibility, a navigation system comprised solely of Earth-basedtracking stations will not provide adequate navigation solutions in these areas. In this paper, a Dilution of Precision (DoP) based analysis of the performance of a network of Moon orbiting satellites is provided. The analysis extends previous analysis of a Lunar Network (LN) of navigation satellites by providing an assessment of the capability associated with a variety of assumptions. These assumptions are with regard to the navigation receiver and satellite visibility. The assessment is accomplished by making appropriately formed estimates of DoP. Different adaptations of DoP (i.e., GDoP, PDoP, etc.) are associated with a different set of assumptions regarding augmentations to the navigation receiver or transceiver. Author

Geometric Dilution of Precision; Navigation Satellites; Space Exploration; Astronauts

20060017055 Defense Science Board, Washington, DC USA

Defense Science Board Task Force on The Future of the Global Positioning System

Oct 2005; 110 pp.; In English; Original contains color illustrations Report No.(s): AD-A443573; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA443573; Avail.: CASI: A06, Hardcopy

On April 9, 2004, the acting USD (AT&L) and the ASD (NII) jointly requested that the Defense Science Board undertake a Task Force on the future of the Global Positioning System (GPS). The request focused on the implications for GPS from a civil-commercial Galileo, the European Union's proposed Global Navigation Satellite System (GNSS). The Terms of Reference also requested assessment of several other aspects of GPS military and commercial competitiveness and of upgrade strategies and technical alternatives.

The DSB empanelled a Task Force comprised of GPS experts with extensive public and private sector experience. Deliberations on relevant GPS topics were conducted primarily among the Task Force members without side briefings limited to current activities affecting the program itself and other directly relevant topics. During the course of the year several outside events significantly modified the issues of uncertainty that had existed when the Task Force was formed. Those events included the signing of a cooperative agreement on GPS and Galileo between the USA and the European Union in June 2004, a major study on GPS commercial viability as approved by the Deputy Secretary of Defense in October 2004 and signature by the President of an updated national policy on GPS and related systems in December 2004.

While each of these events moderated specific areas of uncertainty that had been complicating GPS planning, each is still a work in progress that will require monitoring as leadership moves to address the still substantive issues facing GPS operation and evolution. DTIC

Global Positioning System; Galileo Spacecraft; Navigation Satellites

20060017331 Ohio State Univ., Columbus, OH USA

Tracking Control for an Overactuated Hypersonic Air-Breathing Vehicle with Steady State Constraints (PREPRINT)

Dec 2005; 20 pp.; In English Contract(s)/Grant(s): F33615-01-C-3154; Proj-A02D Report No.(s): AD-A444875; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA444875; Avail.: CASI: A03, Hardcopy

No abstract available

Hypersonic Vehicles; Steady State

20060019188 NASA Ames Research Center, Moffett Field, CA, USA

Spacecraft guidance, navigation, and control requirements for an intelligent plug-n-play avionics (PAPA) architecture

Kulkarni, Nilesh; Krishnakumar, Kalmaje; [2005]; 23 pp.; In English; AIAA Infotech\@Aerospace, 26-29 Sep. 2005, Washington, DC, USA; Original contains black and white illustrations; Copyright; Avail.: CASI: A03, Hardcopy

The objective of this research is to design an intelligent plug-n-play avionics system that provides a reconfigurable platform for supporting the guidance, navigation and control (GN&C) requirements for different elements of the space exploration mission.

The focus of this study is to look at the specific requirements for a spacecraft that needs to go from earth to moon and back. In this regard we will identify the different GN&C problems in various phases of flight that need to be addressed for designing such a plug-n-play avionics system.

The Apollo and the Space Shuttle programs provide rich literature in terms of understanding some of the general GN&C requirements for a space vehicle. The relevant literature is reviewed which helps in narrowing down the different GN&C algorithms that need to be supported along with their individual requirements. Author

Avionics; Spacecraft Guidance; Navigation; Space Shuttles; Algorithms

Source: NASA