An artist's concept of LADEE in orbit via
On Friday, NASA is sending a spacecraft to the Moon to investigate an Apollo-era mystery. Moon-walking astronauts reported seeing a glow on the lunar horizon, and this mission, the Lunar Atmosphere and Dust Environment Explorer (LADEE), is going to see if the glow is actually dust floating in an exotic and tenuous lunar atmosphere. But that’s not all LADEE is going to do. On board is a Lunar Laser Communication Demonstration (LLCD), technology that will prove two-way laser communications through space is possible, which promises to open up a world of possibilities on future missions.
Every mission NASA has ever launched – from the first satellites, to Apollo, to the shuttle program – has relied on radio frequency communication (RF). But this decades-old technology is starting to reach its limits. A spacecraft can only send so much data to tracking stations on the ground via radio frequencies, but missions are starting to demand more data-transfer capacity.
That’s where laser communications comes in. Laser communications, which use shorter wavelengths, can not only transmit data at a higher rate using less power, it’s a more secure method, less susceptible to issues like interference and jammed signals. LADEE will rely on tried-and-true radio communications, but the LLCD experiment will be the first demonstration of this faster transfer of higher amounts of data between two bodies in space.
Having a new flight-worthy communications system is an exciting prospect, and not just for NASA. This technology could change the way the public interacts with space missions. Down the line, laser communications could open the door for extended communication applications, like increased image resolution and 3-D video transmission from deep space. The flip side of that, of course, is that the more public interest in space arroused by the videos, the more money NASA will get for missions. It’s basically win-win.
The LADEE spacecraft via
After launching atop a US Air Force Minotaur V rocket from NASA's Wallops Flight Facility on Wallops Island, Virginia, it will take 30 days for LADEE to get to the Moon. The LLCD package will come online shortly thereafter and run for about 30 days. During its demonstration, LLCD will transmit hundreds of millions of bits of data per second from the Moon to Earth, a transfer rate equivalent to streaming more than 100 HD television channels at the same time. LLCD’s receiving capability will also be tested: tens of millions of bits per second of data will be sent from the Earth to the Moon for the spacecraft to receive.
LLCD’s primary Earth-bound component is at NASA’s White Sands proving ground in New Mexico. There are also two backup sites should something happen to the primary station—one at NASA’s JPL in California, which can only receive signals from LLCD, and one run by the European Space Agency on the Spanish island of Tenerife that can both send and receive signals.
If the LLCD demonstrations work, it will prove that the technology exists to send increased bandwidth on future missions. And things will only get better from there. LLCD is a precursor to NASA's next phase, a long duration demonstration called the Laser Communications Relay Demonstration (LCRD) scheduled to launch in 2017. There’s also the OPALS proof of concept optical laser communications mission launching to the International Space Station in December.
Once the LLCD demonstration ends, LADEE will switch to radio communications and begin its 100-day primary mission. When that’s over, the spacecraft will crash into the Moon.
Laser communications could drastically change the way we explore space. With enough bandwidth, missions could transmit 3-D, high definition video signals that could make human telepresence on distant asteroids and moons a reality. And that would bring a whole new dimension to the human-machine relationship in space.