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NASA NTRS2003

Citizen Explorer: An Earth Observer With New Small Satellite Technology - 1

Citizen Explorer-I (CX-I), designed and built by students at Colorado Space Grant Consortium in Boulder to provide global ozone monitoring, employs a unique mission architecture and several innovative technologies during its mission. The mission design allows K-12 schools around the world to be involved as ground stations available to receive science data and telemetry from CX-I. Another important technology allows the spacecraft to be less reliant on ground operators. Spacecraft Command Language (SCL) allows mission designers to set constraints on the satellite operations. The satellite then automatically adheres to the constraints when the satellite is out of contact with Mission Operations. In addition to SCL, a low level of artificial intelligence will be supplied to the spacecraft through the use of the Automated Scheduling and Planning ENvironment (ASPEN). ASPEN is used to maintain a spacecraft schedule in order to achieve the objectives a mission operator would normally have to complete. Within the communications system of CX-I, internet of CX-I, internet protocols are the main method for communicating with the satellite. As internet protocols have not been widely used in satellite communication, CX-I provides an opportunity to study the effectiveness of using internet protocols over radio links. The Attitude Determination and Control System (ADCS) on CX-I uses a gravity gradient boom as a means of orienting the satellite's science instruments toward nadir. The boom design is unique because it is constructed of tape measure material. These new technologies' effectiveness will be tested for use on future small satellite projects within the space satellite industry.

Allen, Zachary↗

NASA NTRS2009

Use of the Delay-Tolerant Networking Bundle Protocol from Space

The Disaster Monitoring Constellation (DMC), constructed by Survey Satellite Technology Ltd (SSTL), is a multisatellite Earth-imaging low-Earth-orbit sensor network where captured image swaths are stored onboard each satellite and later downloaded from the satellite payloads to a ground station. Store-and-forward of images with capture and later download gives each satellite the characteristics of a node in a Delay/Disruption Tolerant Network (DTN). Originally developed for the Interplanetary Internet, DTNs are now under investigation in an Internet Research Task Force (IRTF) DTN research group (RG), which has developed a bundle architecture and protocol. The DMC is currently unique in its adoption of the Internet Protocol (IP) for its imaging payloads and for satellite command and control, based around reuse of commercial networking and link protocols. These satellites use of IP has enabled earlier experiments with the Cisco router in Low Earth Orbit (CLEO) onboard the constellation's UK-DMC satellite. Earth images are downloaded from the satellites using a custom IPbased high-speed transfer protocol developed by SSTL, Saratoga, which tolerates unusual link environments. Saratoga has been documented in the Internet Engineering Task Force (IETF) for wider adoption. We experiment with use of DTNRG bundle concepts onboard the UKDMC satellite, by examining how Saratoga can be used as a DTN convergence layer to carry the DTNRG Bundle Protocol, so that sensor images can be delivered to ground stations and beyond as bundles. This is the first successful use of the DTNRG Bundle Protocol in a space environment. We use our practical experience to examine the strengths and weaknesses of the Bundle Protocol for DTN use, paying attention to fragmentation, custody transfer, and reliability issues.

Wood, Lloyd↗

NASA NTRS2004

Protocol for a Delay-Tolerant Data-Communication Network

As its name partly indicates, the Delay-Tolerant Networking (DTN) Bundle Protocol is a protocol for delay-tolerant transmission of data via communication networks. This protocol was conceived as a result of studies of how to adapt Internet protocols so that Internet-like services could be provided across interplanetary distances in support of deep-space exploration. The protocol, and software to implement the protocol, is being developed in collaboration among experts at NASA's Jet Propulsion Laboratory and other institutions. No current Internet protocols can accommodate long transmission delay times or intermittent link connectivity. The DTN Bundle Protocol represents a departure from the standard Internet assumption that a continuous path is available from a host computer to a client computer: It provides for routing of data through networks that may be disjointed and may be characterized by long transmission delays. In addition to networks that include deepspace communication links, examples of such networks include terrestrial ones within which branches are temporarily disconnected. The protocol is based partly on the definition of a message-based overlay above the transport layers of the networks on which it is hosted.

Torgerson, Jordan↗

NASA NTRS2013

ISS Live!

International Space Station Live! (ISSLive!) is a Web application that uses a proprietary commercial technology called Lightstreamer to push data across the Internet using the standard http port (port 80). ISSLive! uses the push technology to display real-time telemetry and mission timeline data from the space station in any common Web browser or Internet- enabled mobile device. ISSLive! is designed to fill a unique niche in the education and outreach areas by providing access to real-time space station data without a physical presence in the mission control center. The technology conforms to Internet standards, supports the throughput needed for real-time space station data, and is flexible enough to work on a large number of Internet-enabled devices. ISSLive! consists of two custom components: (1) a series of data adapters that resides server-side in the mission control center at Johnson Space Center, and (2) a set of public html that renders the data pushed from the data adapters. A third component, the Lightstreamer server, is commercially available from a third party and acts as an intermediary between custom components (1) and (2). Lightstreamer also provides proprietary software libraries that are required to use the custom components. At the time of this reporting, this is the first usage of Web-based, push streaming technology in the aerospace industry.

Price, Jennifer↗

NASA NTRSDate not supplied

LunaNet Governance: Organizing and Planning for LunaNet Operations

LunaNet is proposed to be the lunar internet, providing services for communications, networking, position, navigation, and timing for missions in transit to and from the moon, in orbit around the moon, in transit to and from the surface, and on the surface. It is envisioned to be an open, international architecture with contributions from multiple organizations including international civil space agencies, commercial service providers, academic institutions, and other organizations. Using a combination of conventional and emerging technologies, LunaNet will create a lunar-centric network-of-networks that inherits some features of the terrestrial internet but has unique characteristics that will drive substantially different operations. Government acquisition efforts have already begun to procure commercial lunar communications and navigation services. A multi-stakeholder approach to developing the community-wide concepts of operation has been initiated by the Interagency Operations Advisory Group (IOAG), which is formed of international government space agencies, that includes other international organizations such as the Internet Society, Internet Engineering Task Force, International Committee on Global Navigation Satellite Systems, and Space Frequency Coordination Group as well as industry and academic participants. Products of the Interim Committee on LunaNet Governance will include the recommendation and definition of an initial international organizational governance structure; associated roles, responsibilities, and processes; and recommended steps to implement the governance approach. This paper will describe the progress made in developing these concepts and coordinating them among the participating organizations.

LunaNet↗

NASA NTRS1994

A land-surface Testbed for EOSDIS

The main objective of the Testbed project was to deliver satellite images via the Internet to scientific and educational users free of charge. The main method of operations was to store satellite images on a low cost tape library system, visually browse the raw satellite data, access the raw data filed, navigate the imagery through 'C' programming and X-Windows interface software, and deliver the finished image to the end user over the Internet by means of file transfer protocol methods. The conclusion is that the distribution of satellite imagery by means of the Internet is feasible, and the archiving of large data sets can be accomplished with low cost storage systems allowing multiple users.

Emery, William↗

NASA NTRS1995

Home Page: The Mode of Transport through the Information Superhighway

The purpose of the project with the Aeroacoustics Branch was to create and submit a home page for the internet about branch information. In order to do this, one must also become familiar with the way that the internet operates. Learning HyperText Markup Language (HTML), and the ability to create a document using this language was the final objective in order to place a home page on the internet (World Wide Web). A manual of instructions regarding maintenance of the home page, and how to keep it up to date was also necessary in order to provide branch members with the opportunity to make any pertinent changes.

Lujan, Michelle R.↗

NASA NTRS1996

Integration of the White Sands Complex into a Wide Area Network

The NASA White Sands Complex (WSC) satellite communications facility consists of two main ground stations, an auxiliary ground station, a technical support facility, and a power plant building located on White Sands Missile Range. When constructed, terrestrial communication access to these facilities was limited to copper telephone circuits. There was no local or wide area communications network capability. This project incorporated a baseband local area network (LAN) topology at WSC and connected it to NASA's wide area network using the Program Support Communications Network-Internet (PSCN-I). A campus-style LAN is configured in conformance with the International Standards Organization (ISO) Open Systems Interconnect (ISO) model. Ethernet provides the physical and data link layers. Transmission Control Protocol and Internet Protocol (TCP/IP) are used for the network and transport layers. The session, presentation, and application layers employ commercial software packages. Copper-based Ethernet collision domains are constructed in each of the primary facilities and these are interconnected by routers over optical fiber links. The network and each of its collision domains are shown to meet IEEE technical configuration guidelines. The optical fiber links are analyzed for the optical power budget and bandwidth allocation and are found to provide sufficient margin for this application. Personal computers and work stations attached to the LAN communicate with and apply a wide variety of local and remote administrative software tools. The Internet connection provides wide area network (WAN) electronic access to other NASA centers and the world wide web (WWW). The WSC network reduces and simplifies the administrative workload while providing enhanced and advanced inter-communications capabilities among White Sands Complex departments and with other NASA centers.

Boucher, Phillip Larry↗

NASA NTRS1997

Enhancing End-to-End Performance of Information Services Over Ka-Band Global Satellite Networks

The Internet has been growing at a rapid rate as the key medium to provide information services such as e-mail, WWW and multimedia etc., however its global reach is limited. Ka-band communication satellite networks are being developed to increase the accessibility of information services via the Internet at global scale. There is need to assess satellite networks in their ability to provide these services and interconnect seamlessly with existing and proposed terrestrial telecommunication networks. In this paper the significant issues and requirements in providing end-to-end high performance for the delivery of information services over satellite networks based on various layers in the OSI reference model are identified. Key experiments have been performed to evaluate the performance of digital video and Internet over satellite-like testbeds. The results of the early developments in ATM and TCP protocols over satellite networks are summarized.

Bhasin, Kul B.↗

NASA NTRS1997

Study and Simulation of Enhancements for TCP (Transmission Control Protocol) Performance Over Noisy, High-Latency Links

The designers of the TCP/IP protocol suite explicitly included support of satellites in their design goals. The goal of the Internet Project was to design a protocol which could be layered over different networking technologies to allow them to be concatenated into an internet. The results of this project included two protocols, IP and TCP. IP is the protocol used by all elements in the network and it defines the standard packet format for IP datagrams. TCP is the end-to-end transport protocol commonly used between end systems on the Internet to derive a reliable bi-directional byte-pipe service from the underlying unreliable IP datagram service. Satellite links are explicitly mentioned in Vint Cerf's 2-page article which appeared in 1980 in CCR [2] to introduce the specifications for IP and TCP. In the past fifteen years, TCP has been demonstrated to work over many differing networking technologies, including over paths including satellites links. So if satellite links were in the minds of the designers from the beginning, what is the problem? The problem is that the performance of TCP has in some cases been disappointing. A goal of the authors of the original specification of TCP was to specify only enough behavior to ensure interoperability. The specification left a number of important decisions, in particular how much data is to be sent when, to the implementor. This was deliberately' done. By leaving performance-related decisions to the implementor, this would allow the protocol TCP to be tuned and adapted to different networks and situations in the future without the need to revise the specification of the protocol, or break interoperability. Interoperability would continue while future implementations would be allowed flexibility to adapt to needs which could not be anticipated at the time of the original protocol design.

Shepard, Timothy J.↗

NASA NTRS1999

ACTS 118x Final Report High-Speed TCP Interoperability Testing

With the recent explosion of the Internet and the enormous business opportunities available to communication system providers, great interest has developed in improving the efficiency of data transfer using the Transmission Control Protocol (TCP) of the Internet Protocol (IP) suite. The satellite system providers are interested in solving TCP efficiency problems associated with long delays and error-prone links. Similarly, the terrestrial community is interested in solving TCP problems over high-bandwidth links. Whereas the wireless community is interested in improving TCP performance over bandwidth constrained, error-prone links. NASA realized that solutions had already been proposed for most of the problems associated with efficient data transfer over large bandwidth-delay links (which include satellite links). The solutions are detailed in various Internet Engineering Task Force (IETF) Request for Comments (RFCs). Unfortunately, most of these solutions had not been tested at high-speed (155+ Mbps). Therefore, the NASA's ACTS experiments program initiated a series of TCP experiments to demonstrate scalability of TCP/IP and determine how far the protocol can be optimized over a 622 Mbps satellite link. These experiments were known as the 118i and 118j experiments. During the 118i and 118j experiments, NASA worked closely with SUN Microsystems and FORE Systems to improve the operating system, TCP stacks. and network interface cards and drivers. We were able to obtain instantaneous data throughput rates of greater than 520 Mbps and average throughput rates of 470 Mbps using TCP over Asynchronous Transfer Mode (ATM) over a 622 Mbps Synchronous Optical Network (SONET) OC12 link. Following the success of these experiments and the successful government/industry collaboration, a new series of experiments. the 118x experiments. were developed.

Ivancic, William D.↗

NASA NTRS2000

Endpoint Security Using Biometric Authentication for Secure Remote Mission Operations

We propose a flexible security authentication solution for the spacecraft end-user, which will allow the user to interact over Internet with the spacecraft, its instruments, or with the ground segment from anywhere, anytime based on the user's pre-defined set of privileges. This package includes biometrics authentication products, such as face, voice or fingerprint recognition, authentication services and procedures, such as: user registration and verification over the Internet and user database maintenance, with a configurable schema of spacecraft users' privileges. This fast and reliable user authentication mechanism will become an integral part of end-to-end ground-to-space secure Internet communications and migration from current practice to the future. All modules and services of the proposed package are commercially available and built to the NIST BioAPI standard, which facilitates "pluggability" and interoperability.

Donohue, John T.↗

NASA NTRS2001

Duplex Direct Data Distribution System

The NASA Glenn Research Center (GRC) is developing and demonstrating communications and network technologies that are helping to enable the near-Earth space Internet. GRC envisions several service categories. The first of these categories is direct data distribution or D3 (pronounced "D-cubed"). Commercially provided D3 will make it possible to download a data set from a spacecraft, like the International Space Station. as easily as one can extract a file from a remote server today, using a file transfer protocol. In a second category, NASA spacecraft will make use of commercial satellite communication (SATCOM) systems. Some of those services will come from purchasing time on unused transponders that cover landmasses. While it is likely there will be gaps in service coverage, Internet services should be available using these systems. This report addresses alternative methods of implementing a full duplex enhancement of the GRC developed experimental Ka-Band Direct Data Distribution (D3) space-to-ground communication link. The resulting duplex version is called the Duplex Direct Data Distribution (D4) system. The D4 system is intended to provide high-data-rate commercial direct or internet-based communications service between the NASA spacecraft in low earth orbit (LEO) and the respective principal investigators associated with these spacecraft. Candidate commercial services were assessed regarding their near-term potential to meet NASA requirements. Candidates included Ka-band and V-band geostationary orbit and non-geostationary orbit satellite relay services and direct downlink ("LEO teleport") services. End-to-end systems concepts were examined and characterized in terms of alternative link layer architectures. Alternatives included a Direct Link, a Relay Link, a Hybrid Link, and a Dual Mode Link. The direct link assessment examined sample ground terminal placements and antenna angle issues. The SATCOM-based alternatives examined existing or proposed commercial SATCOM services that could be available in the 2005 time frame. The alternatives were evaluated and compared in terms of average daily system throughput and cost per bit. Throughput was estimated based on hypothetical scenarios supporting the International Space Station and polar orbiting missions. The feasibility of using standard TCP and a modified TCP was evaluated and risks were identified. An estimate of the TCP acknowledgment data rate required to support a return channel rate of 622 Mbps was developed using OPNET.

Greenfield, Israel↗

NASA NTRS1995

Remote Visualization and Remote Collaboration On Computational Fluid Dynamics

A new technology has been developed for remote visualization that provides remote, 3D, high resolution, dynamic, interactive viewing of scientific data (such as fluid dynamics simulations or measurements). Based on this technology, some World Wide Web sites on the Internet are providing fluid dynamics data for educational or testing purposes. This technology is also being used for remote collaboration in joint university, industry, and NASA projects in computational fluid dynamics and wind tunnel testing. Previously, remote visualization of dynamic data was done using video format (transmitting pixel information) such as video conferencing or MPEG movies on the Internet. The concept for this new technology is to send the raw data (e.g., grids, vectors, and scalars) along with viewing scripts over the Internet and have the pixels generated by a visualization tool running on the viewer's local workstation. The visualization tool that is currently used is FAST (Flow Analysis Software Toolkit).

Watson, Val↗

NASA NTRS2002

MDP: Reliable File Transfer for Space Missions

This paper presents work being done at NASA/GSFC (Goddard Space Flight Center) by the Operating Missions as Nodes on the Internet (OMNI) project to demonstrate the application of the Multicast Dissemination Protocol (MDP) to space missions to reliably transfer files. This work builds on previous work by the OMNI project to apply Internet communication technologies to space communication. The goal of this effort is to provide an inexpensive, reliable, standard, and interoperable mechanism for transferring files in the space communication environment. Limited bandwidth, noise, delay, intermittent connectivity, link asymmetry, and one-way links are all possible issues for space missions. Although these are link-layer issues, they can have a profound effect on the performance of transport and application level protocols. MDP, a UDP (User Datagram Protocol)-based reliable file transfer protocol, was designed for multicast environments which have to address these same issues, and it has done so successfully. Developed by the Naval Research Lab in the mid 1990s, MDP is now in daily use by both the US Post Office and the DoD (Department of Defense). This paper describes the use of MDP to provide automated end-to-end data flow for space missions. It examines the results of a parametric study of MDP in a simulated space link environment and discusses the results in terms of their implications for space missions. Lessons learned are addressed, which suggest minor enhancements to the MDP user interface to add specific features for space mission requirements, such as dynamic control of data rate, and a checkpoint/resume capability. These are features that are provided for in the protocol, but are not implemented in the sample MDP application that was provided. A brief look is also taken at the status of standardization. A version of MDP known as NORM (Nack Oriented Reliable Multicast) is in the process of becoming an IETF (Internet Engineering Task Force) standard.

Rash, James↗

NASA NTRS2002

Using the Web for Competitive Intelligence (CI) Gathering

Businesses use the Internet as a way to communicate company information as a way of engaging their customers. As the use of the Web for business transactions and advertising grows, so too, does the amount of useful information for practitioners of competitive intelligence (CI). CI is the legal and ethical practice of information gathering about competitors and the marketplace. Information sources like company webpages, online newspapers and news organizations, electronic journal articles and reports, and Internet search engines allow CI practitioners analyze company strengths and weaknesses for their customers. More company and marketplace information than ever is available on the Internet and a lot of it is free. Companies should view the Web not only as a business tool but also as a source of competitive intelligence. In a highly competitive marketplace can any organization afford to ignore information about the other players and customers in that same marketplace?

Rocker, JoAnne↗

NASA NTRS2003

P2P Technology for High-Performance Computing: An Overview

The transition from cluster computing to peer-to-peer (P2P) high-performance computing has recently attracted the attention of the computer science community. It has been recognized that existing local networks and dedicated clusters of headless workstations can serve as inexpensive yet powerful virtual supercomputers. It has also been recognized that the vast number of lower-end computers connected to the Internet stay idle for as long as 90% of the time. The growing speed of Internet connections and the high availability of free CPU time encourage exploration of the possibility to use the whole Internet rather than local clusters as massively parallel yet almost freely available P2P supercomputer. As a part of a larger project on P2P high-performance computing, it has been my goal to compile an overview of the 2P2 paradigm. I have studied various P2P platforms and I have compiled systematic brief descriptions of their most important characteristics. I have also experimented and obtained hands-on experience with selected P2P platforms focusing on those that seem promising with respect to P2P high-performance computing. I have also compiled relevant literature and web references. I have prepared a draft technical report and I have summarized my findings in a poster paper.

Follen, Gregory J.↗

NASA NTRS2004

IPv6 Test Bed for Testing Aeronautical Applications

Aviation industries in United States and in Europe are undergoing a major paradigm shift in the introduction of new network technologies. In the US, NASA is also actively investigating the feasibility of IPv6 based networks for the aviation needs of the United States. In Europe, the Eurocontrol lead, Internet Protocol for Aviation Exchange (iPAX) Working Group is actively investigating the various ways of migrating the aviation authorities backbone infrastructure from X.25 based networks to an IPv6 based network. For the last 15 years, the global aviation community has pursued the development and implementation of an industry-specific set of communications standards known as the Aeronautical Telecommunications Network (ATN). These standards are now beginning to affect the emerging military Global Air Traffic Management (GATM) community as well as the commercial air transport community. Efforts are continuing to gain a full understanding of the differences and similarities between ATN and Internet architectures as related to Communications, Navigation, and Surveillance (CNS) infrastructure choices. This research paper describes the implementation of the IPv6 test bed at NASA GRC, and Computer Networks & Software, Inc. and these two test beds are interface to Eurocontrol over the IPv4 Internet. This research work looks into the possibility of providing QoS performance for Aviation application in an IPv6 network as is provided in an ATN based network. The test bed consists of three autonomous systems. The autonomous system represents CNS domain, NASA domain and a EUROCONTROL domain. The primary mode of connection between CNS IPv6 testbed and NASA and EUROCONTROL IPv6 testbed is initially a set of IPv6 over IPv4 tunnels. The aviation application under test (CPDLC) consists of two processes running on different IPv6 enabled machines.

Wilkins, Ryan↗