NARRATOR

On Tuesday, December 7, 2021, NASA launched the Laser Communications Relay Demonstration, or LCRD, NASA’s latest demonstration of high data rate optical communications technologies. LCRD is demonstrating NASA’s first two-way laser relay communications system, sending and receiving data using invisible infrared lasers. Over five episodes of this podcast, we encountered the dream, design, and future of LCRD and laser communications at NASA. If you haven’t yet given them a listen, they’re episodes 18 through 22.

During the season, we solicited your questions about the mission with the hashtag #AskSCaN on social media. We really appreciate all the great input we received! In this bonus episode of the podcast, we’re going to answer four fun questions from our listeners, pairing each with a subject matter expert who can provide the context we need to better understand the LCRD mission.

I’m Danny Baird, this is “The Invisible Network.”

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NARRATOR

For our first question, we turn to Richard Tseng, Deputy Spectrum Manager at NASA’s Goddard Space Flight Center in Greenbelt. He works closely with missions seeking services from NASA’s Near Space Network, which provides communications and navigation solutions to missions from the launch pad to a million miles away.

RICHARD TSENG

My name is Richard Tseng. I’m the Deputy Spectrum Manager at NASA’s Goddard Space Flight Center. I’ve been with NASA for about two years. Previously, I’ve worked at various government agencies with communication equipment and issues for the last 18 years. So I’ve been with the government for about 20…

A spectrum manager is basically someone who manages how radio transmissions interact with each other and also how to avoid interfering with the transmissions from all the different systems using the spectrum.

NARRATOR

Our listener’s question for Richard is, “How does laser communications avoid interference with other satellites?”

RICHARD TSENG

Laser communications avoids interference with other satellites by using a very directional emitter to aim the communication to very specific locations on Earth. In other words, the areas covered by laser is extremely small compared with the area covered by typical satellite [radio] systems. So by avoiding the coverage overlap, the interference from laser into traditional satellite ground stations can be avoided at the same time.

NARRATOR

So: infrared lasers spread out less than radio waves, which makes it easier to avoid the transmissions of other spacecraft. And that’s not the only way laser communications avoid interference:

RICHARD TSENG

Right now, the radio frequency is very crowded… moving into higher frequencies, there’s definitely less users involved. And you can avoid a lot of interference by using infrared frequencies.

NARRATOR

Most spacecraft currently use radio frequency when communicating with Earth. The portions of the spectrum available for use by missions are a finite resource. With the growing number of missions in space, moving to infrared lasers opens up new swaths of the spectrum for missions to use.

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NARRATOR

Our second question is, “Can we retrofit satellites with laser transceivers so they can take advantage of laser communications’ benefits?”

For an answer, we turn to Chetan Sayal, project manager for NASA’s Integrated LCRD Low-Earth Orbit User Modem and Amplifier Terminal, or ILLUMA-T. The ILLUMA-T project will furnish the International Space Station with a laser communications terminal capable of relaying data through LCRD to ground stations.

CHETAN SAYAL

What you would have to do is convert that [RF] signal into optical signal, which generally requires additional hardware. Right? So, you can’t just… attach an optical uplink or downlink receiver. You have to be able to design that interface so that you can go from that [RF] signal to that optical signal… You can’t go do that conversion haphazardly.

NARRATOR

In low-Earth orbit, the space station’s robotic arm will hook up ILLUMA-T with relative ease, providing astronauts aboard the orbiting laboratory with laser links through LCRD. Unfortunately, distant satellites at places like Mars or the LaGrange points are just too far away for a crewed team to service and retrofit.

Currently, the most effective way to transition to laser communications is to encourage new missions to embrace the technology when they’re being formulated.

But who knows? NASA advances in robotic servicing may one day offer new capabilities for retrofitting missions with optical capabilities. You can check out some of the amazing robotics work done at NASA’s Goddard Space Flight Center at nexis.gsfc.nasa.gov.

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NARRATOR

Our third listener question is about space junk!

For an answer, we turn to Jason Mitchell, Director of Advanced Communications and Navigation Technology within NASA’s Space Communications and Navigation program at NASA Headquarters. He’s also the program executive for LCRD.

JASON MITCHELL

[The] program executive is responsible for the overall execution of the of the project as it relates to the broader program. As director, I have a portfolio of projects, other optical projects as well, in addition to sort of traditional navigation projects, timing projects… advanced technologies that will support NASA missions.

NARRATOR

Our question for Jason: “Will space junk occasionally block LCRD’s laser links?”

JASON MITCHELL

Absolutely. I mean, anything that comes between you and the other end of your link is something that can that can block that signal. Now… we spend a lot of effort… in tracking space junk… Active missions — even aircraft — could potentially block the laser beams from reaching a ground station, which is why we coordinate with the standards groups… like the laser clearing house to make sure that when we’re planning on operating, that we have clearance that there won’t be any aircraft in the area and that we’ve done our planning to make sure that there’s… no active spacecraft… or… space junk in the way.

NARRATOR

Thorough planning helps NASA avoid sending LCRD’s lasers toward space junk, active missions, and aircraft. However, if a laser did intersect a crewed mission or an aircraft, no one would be harmed.

JASON MITCHELL

Fortunately for us… we picked a laser frequency that’s eye safe. So, there’s no human danger for that… unless you’re up really close… But… out of an abundance of caution, we want to make sure that we’re not we’re not inadvertently intersecting anyone with laser beam.

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NARRATOR

The last question today is a two-parter. For answers, we turn to LCRD Principal Investigator Dave Israel.

The first part: “Can optical terminals on the East Coast communicate with LCRD?”

DAVID ISRAEL

So yes, from some places in the East Coast, we can see LCRD. We don’t currently have any terminals on the East Coast, but we are looking into the potential to do some experiments with it with a terminal on the East Coast.

NARRATOR

The second part: “Are there existing airborne terminals that could send data through the mission?”

DAVID ISRAEL

So, there are not any existing airborne terminals that can communicate through LCRD, though we would be interested in doing experiments if there were any available that people would like to propose for us to try. Certainly, an airborne system could be designed that would work through LCRD, we just don’t have any that we’re doing in our program. But we would be very happy to support them.

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NARRATOR

Thanks so much for listening! We hope this answered some questions you might have about LCRD.

If you’re interested in learning more about NASA laser communications capabilities, visit nasa.gov/lasercomms and stay tuned for exciting news about the first experiments to run through the mission. These experiments are designed to test the efficacy of laser communications. For one of our first transmissions through the system, we’ll be sending 2022 New Year’s Resolutions submitted on social media through space!

LCRD is funded through NASA’s Technology Demonstration Missions program, part of the Space Technology Mission Directorate, and the Space Communications and Navigation (or SCaN) program, part of the Space Operations Mission Directorate. To learn more about NASA’s Space Communications and Navigation program, visit NASA.gov/SCaN. Finally, for a transcript of this episode and more podcast content, visit NASA.gov/invisible.