©Mark Ollig
An exciting plan is in the works at NASA for speeding
up radio reception from distant satellites, future space missions to Mars, and
beyond.
For more than 50 years, NASA has been using traditional
radio-frequency (RF) wave spectrum for communicating with spacecraft and
satellites.
RF waves are used because of their ability to be
transmitted over long distances in space.
Besides, what else would we use?
How about light amplification by stimulated emission of
radiation, more commonly called a laser?
A laser beam travels at the speed of light.
So does a radio signal; however, the big difference is
the radio signal is transmitted within a much lower frequency range than a
laser.
According to NASA, using laser optical communications
in space will significantly increase the transfer-rate speed of information
broadcasted to Earth from satellites, and other spacecraft.
Using a laser beam for the communications medium is
analogous to the “pipe” through which the radio information is carried and
transported back to Earth in.
Use of lasers as a deep-space communications medium
will allow scientists and researchers on Earth to more quickly obtain data;
especially video, from spacecraft landings or satellites traversing out-worldly
celestial bodies.
According to NASA, the “pinpoint precision of laser
communications” is well suited to the goals of NASA mission planners.
“Laser technology is ideal for boosting downlink
communications from deep space,” said Abi Biswas, the supervisor of the Optical
Communications Systems group at NASA’s Jet Propulsion Laboratory, in Pasadena,
CA.
Other advantages of using laser communications include
receiving much higher-resolution images from satellite or spacecraft missions
to other planets.
Astronauts performing an extravehicular activity will
be able to select and view laser-carried video feeds to quickly aid in whatever
task they are performing.
NASA’s Mars Reconnaissance Orbiter is currently 185 million
miles from Earth.
It transmits data at a minimum of 500 kbps (kilo or
thousand bits per second) from its furthest distance away from Earth; about 250
million miles.
From about 60 million miles, its closest distance from
Earth, it can send data at 3 to 4 Mbps (mega or million bits per second).
If it was using laser communication technology, the
Mars Reconnaissance Orbiter’s maximum data rate could be a speedy 250 Mbps.
NASA’s Deep Space Network antennas are located in
Australia, Spain, and California. These are primarily used for X-band (8 to 12
GHz) radio frequency range communications with the Mars Reconnaissance Orbiter
via its ultra-high frequency antennas.
We know some of the advantages of using laser
communications technology in space, when will NASA begin using it?
First, they needed to demonstrate the communications
laser overall effectiveness, reliability, and long life operation in space by
making an experimental launch of a laser- equipped, communications relay
satellite.
NASA did this in 2013, with the Lunar Laser
Communications Demonstration (LLCD) mission.
The mission’s Lunar Atmosphere and Dust Environmental
Explorer (LADEE) satellite launched Sept. 6, 2013, and aligned itself in the
proper orbit over the moon.
Its onboard communications laser system was prepared
for the test.
Oct. 18, 2013, NASA’s ground station located in White
Sands Complex in Las Cruces, NM, activated its communications laser beam, which
traveled 239,000 miles to the LADEE spacecraft in lunar orbit.
The LADEE satellite used a communications laser beam
focused on a special ground transmitting/receiving station on Earth.
The download data speed of the satellite information
sent to the Earth from the moon reached an amazing maximum rate of 622 Mbps.
Worth mentioning; an error-free upload rate of 20 Mbps
was also accomplished during the LLCD mission.
The LLCD mission proved laser communications could be
successfully transmitted to Earth from a satellite in space with greater speed
and efficiency than current RF signaling methods.
Unfortunately, the LADEE ended up crashing onto the
moon’s surface a couple months later; however, it did answer the important
question about successfully using long-range laser communications in space.
The next high-profile NASA laser test is the LCRD
(Laser Communications Relay Demonstration) mission slated to launch in 2019.
This mission will last for two years, and will test
long-term, regularly used laser communications from the Earth-orbiting
International Space Station, and ground stations located in Hawaii and
California.
NASA hopes this mission will be the prelude to the
launching of future laser-communications equipped satellite missions to Mars,
the other planets, moons, and spacecraft traveling beyond our solar system.
Perhaps, future laser communications technology will be
used to obtain more information (or even communicate?) with NASA’s recently
announced TRAPPIST-1 solar system containing exoplanets or earth-like planets,
where life may have evolved.
Stay tuned.
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@bitsandbytes.
