Space Internet Technologies at Glenn Research Center
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Space Internet Technologies at Glenn Research Center Abstract NASA and the Department of Defense (DOD) are currently involved in defining the next-generation network architecture for space. This new architecture will utilize Internet Protocols to ensure interoperability between terrestrial (land, sea, and air) and satellite- based systems. NASA’s Glenn Research Center (GRC), located in Cleveland, Ohio, has been heavily involved in the development of Internet technologies for space applications since the mid-1990’s. Through consortium-based research utilizing the Advanced Communication Technology Satellite (ACTS), GRC has validated the use of Internet Protocols through space at geostationary distances. Today, GRC is conducting research that concentrates on the development of secure, mobile network hardware, software, protocols, and operations applications for eventual use in space platforms. The current development activities are all cooperative in nature and utilize, to the greatest extent possible, commercial-off-the-shelf (COTS) network equipment that has been designed to open standards, helping to reduce costs and ensure compatibility with future commercial systems. GRC’s secure, mobile network research has been conducted using bent-pipe satellite links over government satellite systems (ACTS and NASA’s Tracking and Data Relay Satellite System [TDRSS]), commercial satellites (Iridium and Globalstar), and other moving communications platforms (cars, trucks, military vehicles, and ships). Future demonstrations will include a Mobile IP demonstration on board shuttle and an interoperability experiment using a commercial miniature router on a microsatellite. Additional research will also be needed to define and test the security and interoperability features envisioned for NASA’s new integrated architecture. Index 1. Background. a. About GRC b. Why IP in Space? i. TCP/IP at Geostationary Distances. ii. Normalization of Space. 1. Design, Build, Test, and Validation. 2. Integrated Operations. c. NASA/DOD Future TCA Architecture. d. Issues with IP in Space. 2. Current GRC Research. a. Hardware Development. i. Cisco’s Mobile Router. ii. Western DataCom’s NSA Approvable, HAIPE-Compliant, Mobile, Type 1 / Type 2 Encryption Devices. iii. Spectrum Astro’s Space Network Devices (SND). b. Software Development. i. Embedded Web Technology (EWT). c. Operations Application Development. i. Veridian Information Solution’s Virtual Mission Operations Control Consol (VMOCC). d. End-to-End IP-Compliant Mission Development. i. New Mexico State University e. Terrestrial Experiments. i. JSC’s Inspection 1999 / 2000. ii. Neah Bay Secure, Mobile Networking Experiment. f. Flight Experiments. i. CANDOS. ii. MANTIS. 3. Future GRC Research. 4. Contact Information. Background About GRC The Glenn Research Center (GRC) is the third oldest NASA Center. Built in 1944 to perform propeller research in support of the WWII effort, GRC (then the Lewis Research Center) predates the creation of NASA in the 1960’s. Today, GRC performs far more than propeller research. GRC is internationally recognized for its pioneering work in cryogenic propulsion, computational fluid dynamics, turbomachinery, space power, and space communications research. GRC’s Space Communications Office managed the design, build, test, validation, and operation of the Advanced Communication Technology Satellite (ACTS). A geostationary communications test platform, ACTS provided for the development and flight test of high-risk, advanced communications satellite technology. Using multiple spot beam antennas and advanced on-board switching and processing systems, ACTS has pioneered the use of the Ka Band for communications satellite technology. Why IP in Space? TCP/IP at Geostationary Distances Early in 1995, a Satellite Industry Task Force (SITF) was initiated by executives of the satellite industry to define the role for communications satellites in the National and Global Information Infrastructures (NII/GII). Satellites were considered to be essential to the NII/GII since they offer ubiquitous coverage. The SITF was chaired by Dr. Thomas Brackey of the Hughes Space and Communications Division and grew out of a series of workshops held during the summer of 1994 by the communications industry, NASA, and the Defense Information Systems Agency (DISA). Experts were convened from twenty companies representing satellite and terrestrial network builders, operators, and users. For eight months the SITF worked to identify opportunities to exploit and challenges to overcome for the satellite industry to play a key role in the NII/GII. NASA personnel participated in the SITF's meetings to contribute on technical and policy matters. After significant data collection and analysis on various issues, the SITF participants reached a consensus on five key challenges. Three of the challenges were policy-related: • Access to Spectrum • Trade and Security • Access to Market The remaining two were technical: • Seamless Interoperability • Technology Advancement In the technical arena, the SITF was gravely concerned about the proliferation of fiber- based terrestrial networks. Very low cost (once installed), ubiquitous (covering most of the Earth, excluding some remote locations in central Africa, Russia, and Asia), and capable of supporting a common world-wide communications interface (Internet Protocols or IP), fiber presented a tremendous challenge for the satellite industry. Satellites tend to be exactly the opposite of fiber-based networks (i.e. expensive and proprietary). Hoping to capture the “last mile” market, the SITF recommended that research be conducted to eliminate interoperability issues between the terrestrial Internet and geostationary platforms. Because of its expertise and access to the ACTS geostationary platform, a decision was made to conduct IP research for space at GRC. Central to this discussion are the Internet Protocols themselves. There is no single Internet Protocol (the IP family actually contains more than 50 protocols). Internet Protocols include such things as User Datagram Protocol (UDP), Transmission Control Protocol (TCP), Internet Protocol - "Next Generation" (TCP/IX), Electronic Mail Protocols: (SMTP, POP, IMAP, DNS-MX, PEM ), File Transfer Protocol (FTP), and the Hyper-Text Transfer Protocol (HTTP). Most people tend to associate one particular protocol with the Internet: TCP/IP (Transmission Control Protocol / Internet Protocol). TCP/IP provides reliable (guaranteed) delivery of data from one location to another over the Internet and is therefore a preferred protocol for the majority of terrestrial Internet users. The data delivery guarantee is the result of handshaking (feedback) from the remote computer back to the originating source (a missing handshake results in an automatic retransmission of the data). Handshakes can also be used by TCP/IP to identify and mitigate network congestion. Because terrestrial Internets use shared resources and data flows over networks tend to be “bursty” in nature, if too many network participants attempt to use the same resources at the same time data loss can occur. To minimize this problem, TCP/IP provides automatic congestion control. When a data recipient receives an individual TCP/IP data packet it automatically generates an acknowledgement for that specific packet and sends it back to the originator of the data. If these acknowledgements are not received in a timely fashion TCP/IP assumes that the network is congested and immediately backs off on data rate (by 50%) to minimize its contribution to the problem. Once congestion control has been activated TCP/IP also ramps up much more slowly than before (a linear increase in rate [one additional packet per round trip time] versus the exponential rate increase used at the start of the data transmission). The TCP/IP congestion control algorithm is commonly referred to as “Additive Increase, Multiplicative Decrease” (AIMD) and it is one of the key factors responsible for keeping the terrestrial Internet stable and “fair” to all users (equal access and bandwidth on a shared medium). Unfortunately, congestion control also erroneously assumes that the latency which results from using geostationary links is caused by congestion which can result in poor bandwidth utilization over high bandwidth, long delay links. To address the congestion control issue, GRC was tasked to explore the use of TCP/IP at geostationary distances using the ACTS satellite as a test platform. To conduct the research, GRC put together a multidisciplinary, consortium-based team. The team included: Computing Sun Microsystems Compaq Microsoft Intel IBM Hewlett-Packard Spacecraft Manufacturers Spectrum Astro Hughes Space & Communications Lockheed Martin Space Systems / Loral Boeing Ball Communications Ampex Data Systems Comsat Laboratories Cisco Systems FORE / Marconi Raytheon Telecom Cabletron Systems US Government Laboratories NASA Ames Research Center NASA Johnson Space Center NASA Goddard Space Flight Center NASA Jet Propulsion Laboratory U.S. Naval Research Laboratory U.S. Air Force Research Laboratory U.S. Army / CECOM To conduct the necessary research, each participant agreed to provide his state-of-the-art platform / operating system and engineering expertise. NASA GRC provided the overall leadership and the ACTS satellite platform (see Figure 1). Space Act Agreements (the military refers to them as Cooperative Research And Development Agreements or CRADAs) allowed the team to share both the