SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 13 - JULY 05, 2006

88 SPACE SCIENCES (GENERAL)
Includes general research topics related to the natural space sciences.

For specific topics in space sciences see categories 89 through 93.

20060016959 Maryland Univ., College Park, MD USA

Eulerian Many-Body Problems

Krishnaprasad, P S; Jan 1989; 24 pp.; In English Contract(s)/Grant(s): AFOSR-87-0073; NSFD-CDR-8803012 Report No.(s): AD-A444546; TR-89-15; No Copyright; Avail.: CASI: A03, Hardcopy

The hamiltonian dynamics of coupled structures is discussed. There are geometric parallels in earlier work on the Newtonian (gravitational) many- body problem. In the study of relative equilibria, a theorem due to Smale has a useful role. Relative stability module a group of symmetries can be determined using the energy-Casimir (or energy - momentum) method. For nongeneric values of momenta, the Poisson structure can affect stability. DTIC

Celestial Mechanics; Construction; Gravitational Fields; Hamiltonian Functions; Many Body Problem

20060019176 Government Accountability Office, Washington, DC, USA

NASA's Deep Space Network: Current Management Structure is not Conducive to Effectively Matching Resources with Future Requirements

April 2006; 29 pp.; In English; Original contains black and white illustrations Report No.(s): GAO-06-445; No Copyright; Avail.: CASI: A03, Hardcopy

NASA s Deep Space Network (DSN) is able to meet most of the requirements of its current workload, but serious questions exist as to whether it will be able to keep up with both near-term and future demands. In the near term, DSN faces a deteriorating infrastructure and a limited capacity to serve additional missions.

System infrastructure, which has been marked by extensive deferred maintenance, is aging and is likely to become increasingly fragile and subject to breakdown at a time when demand is anticipated to increase. The potential exists for the loss of scientific data that would be difficult, if not impossible, to replace. In addition, new users will find that, aside from competing for network capacity with each other, they must also compete with legacy programs that have been extended far beyond their intended lifetimes, but still return science data and thus take up considerable network time. For example, the Voyager mission launched in 1977 still requires DSN support and is envisioned to rely on DSN for the foreseeable future.

Capacity limits constrain the amount of science data that can be returned from deep space by new missions that are added to DSN s set of users. DSN s future utility is also in question because NASA currently has no mechanism in place to match funding for space communications capabilities with agency-wide space communications requirements.

The agency s Space Communication Coordination and Integration Board is responsible for reviewing the technical requirements of space communications programs to determine whether they fit into an agency wide architecture. However, according to agency officials, the Board is only advisory in nature and does not review all program requirements, such as infrastructure needs. As a result, such program requirements are often not raised at the agency level.

Furthermore, funding for space communications capabilities is controlled by the individual communications programs and their associated mission directorates, who may not necessarily consider agency wide goals when making investments. This disconnect between establishment of requirements and control of resources creates the potential for programs to make investments in capabilities that may undercut agency wide goals for space communications. For example, agency officials noted both the Deep Space Network and the Ground Network programs recently were on a path to develop separate array technologies to support overlapping requirements for the same lunar missions. These efforts would have undercut the agency s goals of a seamless, integrated architecture for space communications and would have represented unnecessary duplication of effort and added costs.

After our review was initiated, NASA created a task group to study how to better manage this gap between agency-level requirements and program-level funding, but it has not yet made any recommendations for action to address the situation. We are making recommendations to NASA that the DSN program identify its current and future requirements in more comprehensive terms and how those requirements might be supported as well as items that NASA s task group on space communications should consider to better align program requirements with agency space communications goals. In written comments on a draft of this report, NASA concurred with our recommendations. Derived from text

Deep Space Network; Space Communication; Support Systems; Space Missions; Workloads (Psychophysiology); Spacecraft Structures

Source: NASA