Laser-powered farewell to Moon mission

NASA's LADEE mission sends laser data to ESA's Optical Ground Station, testing future deep-space communication technologies

Laser from the Moon

25 April 2014

Just before NASA’s latest Moon mission ended last week, an ESA telescope received laser signals from the spacecraft, achieving data speeds like those used by many to watch movies at home via fibre-optic Internet.

During an intense, three-day effort starting on 1 April, ESA’s Optical Ground Station in Spain received data signals via laser from the Moon at the stunning speed of 80 megabits per second.

The signals were transmitted from NASA’s Lunar Atmosphere and Dust Environment Explorer, or LADEE, from a distance of 400 000 km. LADEE completed its seven-month exploration and technology mission on 17 April in a planned impact on the Moon.

The speed is high enough to transmit an entire movie DVD in about eight minutes and is many times faster than provided by traditional radio links used by today’s spacecraft.

Faster than traditional radio

“We had already achieved 40 Mbit/s in our first round of laser communication with LADEE in October, so we’re pretty happy that the final test transmissions were able to double that,” says Klaus-Juergen Schulz, responsible for tracking station engineering at ESA’s ESOC operations centre.

“We also demonstrated that we could transmit laser signals to LADEE and even obtain highly accurate range data, just like our traditional but much larger radio tracking stations can. Overall, the test series has been a big success.”

ESA’s station in Spain’s Canary Islands was equipped with advanced technology developed in Switzerland, France and Denmark that could communicate with LADEE using infrared laser beams.

ESA to catch laser beam from Moon mission

ESA to catch laser beam from NASA Moon mission Ladee
 
Laser lights up Moon in previous optical experiments
 
 

19 June 2012
 
In 2013, a NASA satellite will beam digital signals to an ESA receiving station fast enough to stream dozens of movies at once. The test will help to demonstrate the readiness of next-generation optical links for future data-intensive deep-space missions.
 
Even today’s highest-tech satellites still employ radio waves for communication back to ground stations on Earth, meaning that satellites require large and bulky antenna dishes.

But if all goes as planned next year, ESA will help to demonstrate that communication at optical wavelengths from ground to space and back is a mature – and very fast – technology and ready to be used in upcoming missions around Earth and in the Solar System.

The joint ESA/NASA activity is part of NASA’s Lunar Laser Communication Demonstration (LLCD) project, which will use a new optical terminal flying on NASA’s Lunar Atmosphere and Dust Environment Explorer – LADEE – spacecraft to communicate with a trio of stations on Earth.

 
 
ESA: world-first in space laser communication
 
“In 2001, the world’s first spacecraft-to-spacecraft laser communication demonstration was performed by ESA, and a second-generation laser communication system will be deployed in 2013 on Alphasat and, starting from 2015, on the European Data Relay Satellite system,” says Zoran Sodnik, manager for ESA’s Lunar Optical Communication Link project.

“Now, we want to confirm the effectiveness of laser communication from the Moon through Earth’s atmosphere to ground and back.

 
 
Optical communication ready for ground-to-space data
 
“This will show that optical communication technology is ready for future science and exploration missions that need improved capacity to transmit valuable scientific data, while reducing onboard resources.”
 
 

ESA to catch laser beam from NASA Moon mission
   
Computer-generated model of the LADEE spacecraft
 

Communication by optical laser promises to reduce the mass and volume needed for onboard receiving/transmitting equipment, and can provide data rates many times faster than possible with traditional radio frequencies.

NASA’s LADEE spacecraft, to be launched to the Moon in 2013, will transmit laser signals to two NASA stations, one in California and one in New Mexico, and to ESA’s Optical Ground Station (OGS), in Tenerife, Spain.

 
 
“The LLCD mission, using both NASA and ESA optical ground stations, is also a demonstration of the value of cross-agency support for optical communications as recommended by the Optical Link Study Group,” says John Rush, at NASA’s Office of Space Communication & Navigation.

The OLSG, a subcommittee of the Interagency Operations Advisory Group (see link at right), is co-chaired by ESA and NASA and is developing guidance for the standardisation of optical communication that will enable future cross-support services among international space agencies.

 
 

ESA to catch laser beam from NASA Moon mission Ladee
   
Telescope at ESA’s Optical Ground Station, Tenerife
 

The group has found that in order to reach high levels of optical data transfer reliability, multiple ground stations with diverse geographic locations will be necessary in order to deal with cloud obscuration (when one station is clouded over, another can take over).

“Due to the high cost of multiple ground stations, sharing among space agencies will speed the introduction of optical communication technology in our space missions,” says Mr Rush.

In autumn 2013, test data will be transmitted through the atmosphere to the receiver on LADEE and back by a beam of infrared light at 1550 nm wavelength using new modulation and coding techniques.

 
 
Optical communication technology provides very high data rates
 
ESA’s Tenerife station will be equipped with upgraded pointing, acquisition and tracking equipment, since laser signals travel along a very narrow beam path and must be pointed very accurately, and with a novel optical receiver developed for the Agency by Switzerland’s RUAG Space.
 
 
The new optical receiver will be tested at a RUAG facility in January 2013 and installed at Tenerife next March. LADEE launch is planned for mid-2013, and the first laser link tests are scheduled about four weeks after lunar orbit entry.
 
 

“Optical data communication working from ground through the atmosphere to space and back is ready to support future missions.”

“With our partners, we are developing optical space communication technology providing very high data rates using lasers weighing just a few kilograms and needing just a few watts of power,” says ESA’s Klaus-Juergen Schulz, Head of the Ground Station Systems Division.

“We aim to show that optical data communication working from ground through the atmosphere to space and back is ready to support future missions.”