[Laser] NASA launches first satellite with LASER communications repeater node

[bernieS]

http://www.csmonitor.com/Technology/2016/0130/Why-lasers-are-better-for-satellie-communication-in-space

Why lasers are better for satellie communication in space

The European Space Agency is moving to improve its communications 
system in space using lasers, which have the potential to transmit 
information more effectively.

By Lucy Schouten, Staff January 30, 2016

Europe began building Phase One of a data highway in space by 
launching a laser-equipped satellite into space on Friday.

The newly launched satellite is the 
<http://www.bbc.com/news/science-environment-35446894>first node of a 
relay system designed to gather images from surrounding satellites by 
laser and return them to Earth in a concentrated laser beam, Jonathan 
Amos reported for the BBC. The completed system could transmit images 
of Earth from satellite to desktop in minutes, according to estimates 
by Airbus Defense and Space, which partnered with the European Space 
Agency (ESA). The current system, using radio waves, takes hours to 
transmit images back to Earth.

The laser system can speed up transmission rates because it enables 
spacecraft circling the Earth to transmit upward to the newly 
launched node, which is easier to reach because it orbits at a higher 
altitude than other satellites. Because it is further from the ground 
station back on Earth, however, the satellite employs laser 
communication, which transmits a stronger, less degradable beam.

The ESA says that the laser communication system will 
<http://www.csmonitor.com/Technology/2016/0129/Europe-wants-to-monitor-natural-disasters-using-an-space-data-highway>benefit 
disaster relief efforts, as the new laser system is also expected to 
return images of earth quickly enough to assist disaster relief work, 
according to Reuters. The more far-reaching implication, however, 
will be in space.

Any communication degrades as it moves through matter, and the signal 
grows weaker the further it travels due to noise, disruption, or the 
sheer volume of space. Radio waves have long been the method of 
choice for space communication, but they can degrade quickly and rely 
on extensive relay systems even when operating on Earth.

Scientists say that radio waves will eventually prove inadequate when 
confronted with the vastness of space, so they are increasingly 
experimenting with laser systems, which can transmit encoded data via 
a concentrated, and therefore less degradable, beam.

NASA has been developing laser communications for years. The 
technology is one of many expected to benefit a mission to Mars, 
because 
<http://www.csmonitor.com/Science/2014/1220/Mars-tech-from-ion-thrusters-to-laser-communications>radio 
communication requires too much power to be practical for the lengthy 
mission to Mars, Pete Spotts reported for The Christian Science Monitor.

Laser communication can potentially transmit a much higher volume of 
data than radio. The market for data communication is 
ever-increasing, and 
<https://www.nasa.gov/sites/default/files/llcdfactsheet.final_.web_.pdf>radio 
wavelengths are becoming "crowded," according to a NASA report on the 
Lunar Laser Communication Demonstration. Laser communication is still 
in the exploratory stages, but would open up a new, less busy, 
portion of the electromagnetic spectrum for use.

Laser communication could ultimately be cheaper because the tighter, 
narrower waves require smaller antennas. Engineers with NASA also 
hope it will be faster. NASA estimates that experimental spacecraft 
could download an average movie in 639 hours using the current S-band 
communication model, laser technology could cut the download time to 
eight minutes.

A test in January 2013 showed the possibilities, as NASA 
<http://www.csmonitor.com/Technology/2013/0118/Mona-Lisa-rides-laser-beams-all-the-way-to-the-moon-NASA>transmitted 
an image of the "Mona Lisa" to the moon's Lunar Reconnaissance 
Orbiter. NASA plans to expand such tests to satellites in 
geostationary orbit around the Earth by 2019 and transmit to a 
Discovery mission in deep space around 2022.