[Laser] MIT-NASA team to test first interplanetary laser comms

[ed]

http://physlink.com/News/081704EarthMarsLaserLink.cfm

http://science.slashdot.org/science/04/11/16/0248259.shtml?tid=215&tid=160&tid=14

A NASA–MIT Lincoln Laboratory team will forge the first laser communication 
link between Mars and Earth. This unique experiment, part of NASA's Vision 
for Space Exploration, will 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, NASA's Jet Propulsion 
Laboratory (JPL), and MIT’s Lincoln Laboratory (MIT/LL).

"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 it 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 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.