Special Delivery: NASA's MESSENGER Sends
Flyby Data to Earth Using CCSDS File Delivery Protocol Developed for
Deep Space by International Team
NASA's MESSENGER team is using the CCSDS File Delivery
Protocol (CFDP), a highly specialized protocol designed to overcome
space operations communications challenges, to download data
captured during a successful flyby of Earth last week. A team of
international space data communications experts collaborating
through the Consultative Committee for Space Data Systems (CCSDS)
developed CFDP to reliably and efficiently downlink files from a
spacecraft even in the strenuous environment of deep space.
Washington, D.C. (PRWEB) August 10, 2005 -- NASA's MESSENGER team
is using the CCSDS File Delivery Protocol (CFDP), a highly
specialized protocol designed to overcome space operations
communications challenges, to download data captured during a
successful flyby of Earth last week.
A team of international
space data communications experts collaborating through the
Consultative Committee for Space Data Systems (CCSDS) developed CFDP
to reliably and efficiently downlink files from a spacecraft even in
the strenuous environment of deep space. Since the MESSENGER
spacecraft's launch a year ago, it has successfully used CFDP to
enable mission communications and will use it throughout its
7.9-billion kilometer journey to Mercury.
In using CFDP,
MESSENGER communications represents a change in the standard method
of storing science and housekeeping data on spacecraft built by the
Johns Hopkins University Applied Physics Laboratory (JHU/APL).
MESSENGER is also the first U.S. space flight mission to use CFDP in
mission operations.
Prior to MESSENGER, JHU/APL missions used
a raw storage model of storing data, but new mission and operational
requirements meant that MESSENGER would have to incorporate a file
system of data storage into its spacecraft software architecture. A
reliable method of downlinking files to the ground had to be found
and CFDP was chosen by mission planners to get the job
done.
CFDP is included in the MESSENGER software architecture
through a reuse of a NASA Jet Propulsion Lab (NASA JPL)
implementation on the ground and a JHU/APL “CFDP-lite”
implementation on the flight side. The NASA JPL implementation is
also used on NASA's highly successful Deep Impact
mission.
“JHU/APL engineers integrated CFDP software
developed by NASA JPL into the MESSENGER mission's ground system,
which communicates with a CFDP flight software implementation
developed by JHU/APL on the spacecraft,” said Christopher Krupiarz,
senior professional staff member, JHU/APL Space Department Embedded
Systems Group in Laurel, Maryland (USA). “Being able to use an
international standard like CFDP was a key factor in getting two
systems developed by two different organizations to work for one
Mercury bound spacecraft.”
CFDP is designed to function
reliably despite the long data propagation delays and frequent,
lengthy interruptions in connectivity found in deep space. It uses
powerful forward error correction coding that minimizes data loss in
communication across deep space, and also supports optional
“acknowledged” modes of operation in which data loss is
automatically detected and a retransmission of the lost data is
automatically requested.
Some of the world's leading space
communications experts working within CCSDS collaborated at
bi-annual working group sessions (similar to those scheduled to take
place next month in Atlanta, Georgia) to first standardize CFDP.
They defined the protocol according to space file transfer
requirements articulated by CCSDS participating space agencies,
including NASA, the European Space Agency (ESA), the British
National Space Centre (BNSC), the Centre National d'Etudes Spatiales
(CNES) and the Japan Aerospace Exploration Agency (JAXA). The
protocol's ability to maintain a high level of data transfer
reliability even across interplanetary distances makes it critical
to successful communications on deep space missions like the
MESSENGER mission to Mercury and is expected to have a high level of
applicability to future Lunar exploration missions.
CFDP also
benefits space flight missions in another important way: cost
savings.
CFDP allows an instrument to record an observation
in a file and transmit the file to Earth without having to consider
whether or not physical transmission is possible at that time.
Sequestering outbound data management and transmission planning
functions within CFDP can simplify flight and ground software, which
reduces mission costs - an important benefit to lower cost missions
like MESSENGER.
CCSDS will continue to foster global scale
technical cooperation to develop recommendations for space
communication like CFDP that increase interoperability, as well as
reduce risk and mission operation costs. Currently, the organization
is investigating extending the use of CFDP in emerging
delay-tolerant networking technology to Interplanetary Internet
operations, and specifically to the use of CFDP in complex mission
configurations, which should further enhance the usefulness and
value of CFDP to space exploration missions in the
future.
Scott Burleigh, CCSDS working group chair and lead
CFDP system engineer at NASA JPL in Pasadena, Calif. commented, “The
successes of CFDP on MESSENGER and the Deep Impact mission bring us
closer to having an automatic interplanetary communication fabric
that can support deep space science and exploration the way the
Internet supports science on Earth."
About CCSDS (http://www.CCSDS.org)
Established in 1982 by
the world's most influential space agencies, the Consultative
Committee for Space Data Systems (CCSDS) provides well-engineered
international space data handling standards that enhance government
and commercial interoperability and cross-support, while also
reducing risk, project cost and development
time.
A pioneer in international
cooperation in space, the CCSDS is made up of leading space
communications experts representing 28 countries, its founding
member space agencies, 22 observer space agencies and over 100
private companies. CCSDS national member space agencies include
Japan, the United Kingdom, France, Germany, Italy, Brazil, Russia,
Canada and the United States, as well as the multi-national European
Space Agency.
To date, more than
300 missions to space have chosen to fly with CCSDS protocols and
the number continues to grow. For more information on participation
or to access CCSDS standards and protocols free of charge, please
visit http://www.CCSDS.org.
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