Space Internet Technologies at Glenn Research Center
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. NASAs Glenn Research Center (GRC), located in Cleveland, Ohio, has
been heavily involved in the development of Internet technologies for space applications
since the mid-1990s. 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. GRCs secure, mobile network research has been conducted using bent-pipe
satellite links over government satellite systems (ACTS and NASAs 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 NASAs 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. Ciscos Mobile Router.
ii. Western DataComs NSA Approvable, HAIPE-Compliant, Mobile,
Type 1 / Type 2 Encryption Devices.
iii. Spectrum Astros Space Network Devices (SND).
b. Software Development.
i. Embedded Web Technology (EWT).
c. Operations Application Development.
i. Veridian Information Solutions Virtual Mission Operations
Control Consol (VMOCC).
d. End-to-End IP-Compliant Mission Development.
i. New Mexico State University
e. Terrestrial Experiments.
i. JSCs 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 1960s. 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. GRCs 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 fai