Extended Space Sensors Architecture

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Tech Notes
Extended                            Since the first manmade satellites
                                    orbited the earth in the 1950s, space
                                                                                        Extended Space Sensors Architecture
                                                                                        (ESSA) project is an Advanced Concept

Space Sensors                       assets have become essential to national
                                    security. Satellites provide communica-
                                                                                        Technology Demonstration to explore
                                                                                        the issues, highlight the benefits, and
Architecture                        tions and navigation for military per-
                                    sonnel. Naval strategists use satellite
                                                                                        demonstrate the use of a service-
                                                                                        oriented architecture (SOA) in support
                                    surveillance data to monitor ship move-
                                    ments, while meteorologists gather
                                                                                         In an SOA, data and service
Lincoln Laboratory is               information relayed from space to track
                                                                                         providers “register” their offerings
                                    weather patterns. Both manned and
demonstrating a service-            unmanned exploration flights contrib-
                                                                                         in common online registries. Users
                                                                                         in need of data or processing
oriented network architecture       ute to military scientists’ understanding            can perform a web search to find
                                    of space. To protect these assets from
that enables the space              both natural and manmade harm, the
                                                                                         appropriate data and services.

community to share                  United States first has to have an accu-
information and services            rate picture of everything in space and             of space missions. In an SOA, data
                                    what it is doing—i.e., space situational            and service providers “register” their
from the varied systems of the      awareness.                                          offerings in common online registries.
Space Surveillance Network.             MIT Lincoln Laboratory is working               Users in need of data or processing can
                                    to provide an information technol-                  perform a web search to find appropri-
                                    ogy structure to enable access to and               ate data and services. By visiting the
                                    distribution of space situational aware-            referenced website, users obtain full
                                    ness data to the space community. Its               instructions for how to automatically

                                                                                Register data
                                                                                and services

                                              Data and Service
                                                 Registries                                                    Data and Service
                                               Search and                                                Deploy data and
                                              discover data                                            processing services
                                              and services

                                                                                Access data
For further information, contact:                                               and services
                                          Data and Service                                                             Servers
Communications Office
MIT Lincoln Laboratory
244 Wood Street                           Service-oriented architectures make data and services readily available to both antici-
Lexington, MA 02420-9108                  pated and unanticipated users by allowing providers (1) to register and post information
781-981-4204                              and services that consumers (2) can search for and then access.
request information or processing and            outside the conventional space com-                 In the ESSA SOA, Lincoln Labora-
a description of what exactly will be            munity, as well as among the various            tory has attached auxiliary comput-
returned. Users can then configure their         mission areas within the space com-             ers (referred to as sidecars) to three
systems to access and use this informa-          munity, resulting in the underutiliza-          operational Space Surveillance Net-
tion or processing. The loose coupling           tion of data. Furthermore, this network         work radars in the continental United
between providers and users, and the             infrastructure can prevent utilization          States and the Marshall Islands, and
use of registries to advertise and dis-          of space information in other mission           has deployed three more sidecars—
cover capabilities, greatly facilitates          areas. The existing architecture also           one to an operational optical site in
integration of new value-added pro-              impedes development and deployment              New Mexico, another to a space assets
cessing and services to the SOA.                 of new capabilities by making it dif-           ground station in Colorado, and a third
    The need for a structure such as             ficult not only to access and distribute        to a DoD radar in Hawaii. The system
ESSA is driven by the fact that the              information, but also to integrate data         in Hawaii is included to demonstrate
information technology infrastructure            and processing into the current, some-          cross-mission asset interoperability.
for the United States’ array of sensors          times proprietary, system.                          New data from any of these sys-
                                                                                                 tems are published to one of the NCES
                                                                                                 messaging channels. Data are also
Since users do not necessarily know when data will be available, and hence                       archived by these sidecars and are
when to request it, a “pub-sub” (publish and subscribe) messaging service
                                                                                                 searchable and retrievable by users
that publishes all new information to one of many “channels” to which users
                                                                                                 after the fact. The Laboratory has simi-
can subscribe is highly valuable.
                                                                                                 larly tapped two processing facilities:
                                                                                                 the Space Defense Operations Center,
                                                                                                 which publishes high-level space situ-
is still largely based in early 1980s tech-           The ESSA concept makes all                 ational awareness information such
nology. This infrastructure adequately           domain-specific services available, but         as satellite launch, decay, maneuver,
accommodated space surveillance                  several common “core” services are              and orbital element sets information;
when it was simply concerned with                also needed by all to make an SOA               and the Lexington Space Situational
tracking and cataloguing a small popu-           interoperable. In particular, since users       Awareness Center (LSSAC) in Mas-
lation of satellites. During the 1950s           do not necessarily know when data will          sachusetts. The LSSAC hosts a number
and 1960s, satellites were launched              be available, and hence when to request         of services that can be used by clients
infrequently and had limited capabili-           it, a “pub-sub” (publish and subscribe)         in the SOA, including satellite status,
ties. However, over the years, as many           messaging service that publishes all            satellite viewing, threat assessment,
countries established their presence in          new information to one of many “chan-           and conjunction predictions (satellite
space, the space population grew to              nels” to which users can subscribe is           close approaches), and change detec-
tens of thousands of objects, ranging            highly valuable. All of these interac-          tion information. All channels and ser-
from large payloads to microsatellites           tions must also be secure to protect            vices are protected via NCES security.
to debris. In response, the United States        Department of Defense (DoD) informa-                The ESSA effort is demonstrating
developed and deployed an array of               tion. To enable network interoperability,       the ability to deliver space situational
sensors—radar and optical—to find,               a common security service is essential          awareness information and capabili-
track, categorize, catalogue, and assess         for avoiding the problem of different           ties that were not previously available
the status of satellites; yet, the technol-      usernames, passwords, and policies for          to the space community or to other
ogy used to distribute and integrate             different websites/services.                    DoD users. It is likewise illuminating
these sensors’ data lagged behind.                    The Defense Information Security           networking infrastructure, core service,
    Currently, the data produced by the          Agency has initiated the Net-Centric            and policy and procedure issues that
Space Surveillance Network are largely           Enterprise Services (NCES) program to           will need to be addressed in the future
routed point-to-point, hub and spoke,            provide the DoD with pub-sub, secu-             to support operational SOAs. 
with bandwidths less than those of               rity, and other common services, as well
today’s home Internet dial-up services.          as data, service, and user registries with
This structure limits access by users            which to instantiate SOAs.

Opinions, interpretations, and recommendations herein are not necessarily endorsed by Lincoln
Laboratory’s government sponsors. Work described in this document is performed under the prime
contract with the U.S. Air Force, FA8721-05-C-0002.