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August
10, 2004 - Release 04-042
NASA MIT LINCOLN LABORATORY TEAM TO TEST FIRST INTERPLANETARY
LASER COMMUNICATION LINK
A NASA MIT Lincoln Laboratory team has decided to forge the first
laser communication link between Mars and Earth. This unique experiment
is part of the new Vision for Space Exploration, and will also greatly
benefit the transmission of data from robotic spacecraft.
In 2010, the Mars Laser Communication Demonstration (MLCD) will test the
first deep-space laser communication link, which promises to transmit
data at a rate nearly ten times higher than any existing interplanetary
radio communication link. MLCD will fly on the Mars Telecommunications
Orbiter spacecraft, which is planned for launch in 2009. The experiment
is a partnership among NASA's Goddard Space Flight Center in Greenbelt,
Md., NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., and the
Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL), Lexington,
Mass.
"If we are planning to put people on Mars, we'll need highly reliable
communication links with high data rates, and our team wants to show how
this can be done with lasers," said Rick Fitzgerald, Project Manager
at NASA Goddard.
"Lincoln
Lab is very excited about this program because it challenges us, and provides
an opportunity for the country to field, in-space, a very advanced system
far earlier than might otherwise be possible," said Dr. Roy Bondurant,
leader of the MIT/LL team.
The NASA-funded project is managed by Goddard, which also provides systems
engineering management and mission assurance functions. JPL provides the
Principal Investigator and the ground network development, with MIT/LL
responsible for the flight laser communication terminal development and
systems engineering. Goddard and MIT/LL each will have a Co-Investigator
on the team.
The
expected data rate varies depending on Mars's position in its orbit, the
weather and atmospheric conditions on Earth, and whether reception is
occurring in daytime or nighttime. When Mars is at its farthest point
from Earth and the reception is occurring during daytime, the team expects
to receive data at a rate of a million bits per second, but when Mars
is at its closest approach and reception is at night, the rate could be
thirty times higher. Today, the maximum data rate transmitted to Earth
by spacecraft at Mars is about 128,000 bits per second (for NASA's Mars
Odyssey spacecraft).
Lasers have not been used for deep-space communications until now because
they first had to be made reliable and efficient enough for use in spacecraft
millions of miles (km) from Earth. Additionally, the radio frequencies
traditionally used for deep space can pass through clouds, while laser
(optical frequencies) can be partially to completely blocked by them.
The project hopes to overcome this limitation by employing two separate
ground terminals, on the chance that if one terminal is clouded over,
the other might be clear.
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