NASA's Lunar Laser
Communication Demonstration
(LLCD) has made history using a
pulsed laser beam to transmit
data over the 239,000 milesbetween the moon and Earth at a
record-breaking download rate
of 622 megabits per second
(Mbps).
LLCD is NASA's first system for
two-way communication using a
laser instead of radio waves. It
also has demonstrated an error-
free data upload rate of 20 Mbps
transmitted from the primary
ground station in New Mexico to
the spacecraft currently orbiting
the moon.
"LLCD is the first step on our
roadmap toward building the
next generation of space
communication capability," said
Badri Younes, NASA's deputy
associate administrator for space
communications and navigation
(SCaN) in Washington. "We are
encouraged by the results of the
demonstration to this point, and
we are confident we are on the
right path to introduce this new
capability into operational
service soon."
Since NASA first ventured into
space, it has relied on radio
frequency (RF) communication.
However, RF is reaching its limit
as demand for more data
capacity continues to increase.
The development and
deployment of laser
communications will enable
NASA to extend communication
capabilities such as increased
image resolution and 3-D video
transmission from deep space.
"The goal of LLCD is to validate
and build confidence in this
technology so that future
missions will consider using it,"
said Don Cornwell, LLCD
manager at NASA's Goddard
Space Flight Center in Greenbelt,
Md.
"This unique ability
developed by the Massachusetts
Institute of Technology's Lincoln
Laboratory has incredible
application possibilities."
LLCD is a short-duration
experiment and the precursor to
NASA's long-duration
demonstration, the Laser
Communications Relay
Demonstration (LCRD). LCRD is
a part of the agency's
Technology Demonstration
Missions Program, which is
working to develop crosscutting
technology capable of operating
in the rigors of space. It is
scheduled to launch in 2017.
LLCD is hosted aboard NASA's
Lunar Atmosphere and Dust
Environment Explorer (LADEE),
launched in September from
NASA's Wallops Flight Facility on
Wallops Island, Va. LADEE is a
100-day robotic mission operated
by the agency's Ames Research
Center at Moffett Field, Calif.
LADEE's mission is to provide
data that will help NASA
determine whether dust caused
the mysterious glow astronauts
observed on the lunar horizon
during several Apollo missions.
It also will explore the moon's
atmosphere. Ames designed,
developed, built, integrated and
tested LADEE, and manages
overall operations of the
spacecraft. NASA's Science
Mission Directorate in
Washington funds the LADEE
mission.
The Lunar Laser
Communications Demonstration
(LLCD) relies on the Lunar
Atmosphere and Dust
Environment Explorer (LADEE)
spacecraft for sending data
between Earth and the Moon.
The 622 Mbps is a maximum
speed for the downlink from
lunar orbit, which is achievable
only when the Moon is high in
the sky on Earth. When the
Moon is low, atmospheric effects
like scattering and absorption
reduce the rate to half that. The
uplink, from a ground station at
White Sands, New Mexico, was a
mere 20 Mbps.
On the other hand, there are
the extremely optimistic
luminaries like Craig Venter,
sequencer of the first human
genome (his own). Venter notes
in his new book, “Life at the
speed of Light,” that right now
his sequence is streaming out
from our planet as a radio
transmission with an expanding
front that will eventually
encompass the far reaches of
the galaxy. Furthermore, he
envisions the most important
data that the interplanetary
network might send are
commands for robots capable of
sequencing and synthesizing, to
print new life — and beam back
the sequences of any they might
find.
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