NARRATOR
In this third episode of a five-part series about NASA’s Laser Communications Relay Demonstration, we’ll look at the LCRD flight payload, which launched on the U.S. Space Force’s Space Test Program Satellite-6 earlier this month, December of 2021.
I’m Danny Baird. This is “The Invisible Network.”
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GLENN JACKSON
My name is Glenn Jackson and I’m the project manager for the Laser Communications Relay Demo.
NARRATOR
Glenn leads a team of scientists, engineers, and technicians who worked diligently over many years to assure the success of LCRD’s path to launch and continue to work towards on-orbit testing of the payload. Previously, he’s worked on missions like NASA’s Lunar Reconnaissance Orbiter’s Lunar Orbiter Laser Altimeter, which provides precise topographic models of the lunar surface.
GLENN JACKSON
This is unique. In my previous missions, they were NASA space vehicles that I was working on. In this activity we’re a hosted payload on a U.S. Space Force spacecraft, so we coordinate with the Space Force. The Space Force is building the space vehicle itself, and we deliver the payload to the Space Force, and we’re testing with them.
NARRATOR
So, what does the LCRD payload actually do? I know we’ve covered it in the previous two episodes, but I’ll let Glenn give us a little refresher:
GLENN JACKSON
So what we’re going to do with LCRD is we’re going to use laser light to move information from space down to two ground stations. One ground station is in Hawaii on a mountain top, and the other is in California on a mountain top.
So you can imagine the laser is like a flashlight. The light shines back to Earth and it makes a light spot on Earth. We’ll use a telescope to look at that light spot, and inside that light we’re communicating information…
Using laser comm, we will have the opportunity to get high-definition video back from the space station, and we’ll be able to have the opportunity to move high amounts of high-definition data back from deep space… So as you compare that to like cable TV or the internet, it provides a very high bandwidth so that you have very clear pictures and high data information transferring.
NARRATOR
We’ll cover the ground stations in Hawaii and California during next week’s episode. Today, we’re focused just on the LCRD flight payload. A great question to start with is a simple, “Where is it?”
GLENN JACKSON
So, we’ll be in one position relative to Earth in our orbit. It’s a geosynchronous orbit — it’s about 30,000 kilometers off the surface of the planet. And unlike the previous optical communication experiments… we will be doing a relay.
So, we actually have two telescopes on the spacecraft. Each telescope can look at different ground stations. And from those different ground stations, we can communicate up to the spacecraft and relay down to the other ground station.
Now, this is unique. It hasn’t been done before and allows us to practice the laser communication through the atmosphere and transferring between two ground stations very high definition, high bandwidth information.
NARRATOR
A listener across the Atlantic might wonder, “Don’t we already have a system like this?” While it is true that the European Space Agency’s European Data Relay System uses optical communications to relay data down to Earth, there’s a key difference:
GLENN JACKSON
So this system is light from ground to space. So, other systems also utilize light in communication. But generally it’s satellite to satellite in space. When you’re in space, there’s no atmosphere. Part of the challenge we’re going to solve is shining the laser light through the atmosphere and how we operate when a cloud comes across and the laser light may be obstructed.
NARRATOR
That’s a pretty good explanation of the “where,” “what,” and “why” of LCRD:
Where is it? Geosynchronous orbit, steady in the sky. What is it? A laser communications payload on a Space Force satellite. Why did NASA build it? To test and refine optical communications through the atmosphere, which is a bit more challenging than optical communications between two spacecraft.
So, now we move to the “how” of LCRD. How does it accomplish its mission? That’s where the engineering comes in.
The payload is comprised of two primary pieces: the optical modules and the modems.
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NARRATOR
Russ Roder serves as the product design lead for LCRD’s optical module.
RUSS RODER
I need to make sure that every member of the team has what they need to do their job. I also interface with the project, and the main goal is to deliver a piece of hardware on time, on budget, and make sure that it meets all of its performance requirements.
NARRATOR
The optical module is the telescope that sends and receives the laser communications. The module was design by the Massachusetts Institute of Technology Lincoln Laboratory and built at Goddard Space Flight Center in Greenbelt, Maryland, with components sourced from companies like L3Harris Technologies and the Sierra Nevada Corporation.
Overall, the optical modules look like the fancy moving lights you might see at a Broadway theatre, but they’re a good deal more complex.
RUSS RODER
So, it’s about the size of a microwave and on the bottom there is a rectangular honeycomb panel. That’s the part that actually bolts to the spacecraft. And on top of that is a two axis gimbal. One gimbal axis controls side to side motion, so that would be east/west pointing. And the other axis is for north and south.
On top of the gimbal is basically a tube with a window on the end. The window looks like a mirror because it reflects almost all light, but it does let through the range of wavelengths that we use for optical communications.
And the most interesting stuff is actually inside the tube. There’s a small telescope and an optical bench that are mounted on an inertially stable platform. Basically, it cancels out any mechanical noise coming up through the honeycomb panel into the optical module so that telescope can be pointed in a very steady way. The beam coming out of the optical module is very narrow, so if you don’t do a good job pointing it, you’re going to miss your ground station or miss whatever you’re trying to talk to.
The light going out of the telescope — the transmit light — goes out at the same time that light comes into the telescope because it’s bi-directional. And in that small optics bench, you have these little, dime-sized optics, which… have special coatings on them to separate the different wavelengths that we use…
So the transmit signal comes from the modem through a fiber that goes into the optical module, and it gets launched from the fiber into free space, bounces off couple optics, and goes out the telescope. And while that’s happening, the receive light and the acquisition light is coming in the telescope. And those two signals also bounce off some small coated optics to get where they need to go. The receive light goes into a fiber that goes into the modem.
And there’s also a signal called acquisition, which goes through a small acquisition sensor. And we use that… when we establish an optical link. If you just tried to use the regular transmit beam, it would be very hard because the beam is so narrow. So we have to use a wider beam and a sensor with a wider field of view. So the two ends of the link — the two terminals — can find each other and lock onto each other before they start to communicate.
NARRATOR
Putting all that into the simplest possible terms, the optical module is a telescope with mirrors and specially coated surfaces that channels three different types of transmissions. First, there’s wide beam transmissions used to make sure the module is pointed at a ground station or space user. The wide beam transmission assures LCRD can establish the much narrower laser communications with precision.
The other two types of transmissions are the laser communications links sent and received by LCRD. These happen at two distinct frequencies, with the optical module funneling these transmissions into and out of LCRD’s modems.
RICK BUTLER
My name is Rick Butler, and I’m the product design lead for the LCRD modems…
The modem converts optical light signals into electrical — digital — data, and vice versa: it converts — on the transmit side — digital data into optical light.
So, there are two modems on the spacecraft. Each modem consists of two separate boxes… Each box is about the size of a four-slice toaster… They’re gold in color and connected to each other with a bunch of black harnesses, electrical cables, and connecting to the other subsystems with several separate cables.
NARRATOR
The modems might look a little less flashy than the optical module, but there’s a ton of important hardware packed inside them. If you opened them up?
RICK BUTLER
On the first tower, you would actually see the power supplies… They take the spacecraft power and they condition it into the lower voltages needed for the modem to run. That’s on one of the towers.
And on the other tower, you would actually see a bunch of fiber optic cable, which looks like very thin fishing line, essentially. And it’s that cable — that fiber optic cable — that the light actually flows through.
NARRATOR
These fiber optic cables are very similar to the ones that might carry internet to your home. In fact, much of the modem is commercially available technology.
RICK BUTLER
The thing about LCRD is: it leverages the work done in the telecommunications industry for the past several decades. We’re taking the components that they’ve developed, and we’re applying it to the space regime.
The trick about that is that we have to make sure the components work in space. And so, we have to do things like: we have to do radiation testing on the components, we have to put them under vacuum to make sure they still operate the same, and we have to operate them over the extended temperature ranges that the LCRD modem will see.
And the one big one: they have to survive launch. And so we had to vibrate them and simulate the launch environment. But, you know, once we did that, it was just all about getting the modem built and tested.
NARRATOR
The tests that Rick mentioned are part of larger effort called integration and testing. Integration ensures that all the components of LCRD play well with each other and the other systems on the host spacecraft. Testing places integrated components in simulated launch and operational environments to make sure they work as expected.
DAVE ROBINSON
My name is David Robinson. I’m the branch head of… the environmental test engineering and integration branch… What we do is: we do… the testing of flight hardware and satellites that go through the Goddard Space Flight Center… As part of that, we also do the integration of the flight hardware and we run things like the cleanrooms…
So, integration is the process of building and putting together either a flight instrument — like a telescope — or the entire satellite… Imagine buying a Lego kit — a real complicated one — and you have to put it all together. And so, that’s what integration is all about.
It’s often done in the cleanrooms because we have to keep the all the hardware super clean, and make sure there’s no… dust that can get on the lenses of the telescopes. And it’s a very controlled process where we have procedures for everything that’s done for integration.
And we also need to keep good records so that a year or two down the line — if something has a problem, if there’s a question — we can go back to the records and see how we built it. There’s a lot of photography that goes on. It’s a very step by step process…
The process of testing is to subject the flight hardware to what it would see when it’s going on the rocket, when it’s flying on the rocket, and when it is in orbit. So if you think about what a satellite sees, on the rocket, you know: when the rocket lifts off, there’s a tremendous amount of noise and that’s acoustic energy, which can damage the satellite. And then there’s the g-forces that build up from acceleration… And then there’s a lot of vibration, shaking, rattling and rolling it around.
If you can imagine taking your computer and picking it up and shaking it as hard as you can, and maybe slinging it around, and then seeing if the computer would work afterwards: that’s a little bit what our testing is designed to do.
And later on, when the satellite achieves orbit, then it sees these wild temperature extremes… When it’s facing the sun, parts of the satellite can easily get over — let’s say — 150 degrees Fahrenheit. And then, when it’s on the dark side — when it’s in the shadow of the Earth, and it’s all dark — the temperatures can rapidly drop to like -100 degrees Fahrenheit…
If you can imagine taking your computer and putting it in the oven, and then the freezer, and then the oven, and then the freezer, like every hour… You might expect that your computer would die unless it was designed in a certain way.
So that’s what we do for testing. We make sure that the flight hardware can survive the environments that it will see, because… if it’s going to break, we want it to break on the ground during testing so that we can fix it. If it breaks in orbit: it’s a much more difficult proposition. Sometimes it’s unfixable.
NARRATOR
Before launch, LCRD and its host spacecraft underwent many integration and test campaigns at various levels of completion. Some happened just a few buildings away from my desk at Goddard. NASA engineer Javier Ocasio-Perez managed the integration and test campaign for NASA.
JAVIER OCASIO-PEREZ
I’m responsible to make sure that LCRD launches successfully to space. And before we get there, we have to go through an integration and test campaign. So, I’m responsible for the planning and execution of that campaign, which — it’s a lot of work.
NARRATOR
Javier works with team leads from all the various LCRD subsystems, ground system managers, the design team at MIT Lincoln Lab, and stakeholders within the Department of Defense to make sure all the pieces of LCRD work together. He also coordinates with Northrop Grumman, who have been tasked with integrating the entire Space Test Program Satellite-6, LCRD’s host spacecraft.
JAVIER OCASIO-PEREZ
In a sense, it’s almost like two jobs because you have the actual integration and test campaign, but then there’s sort of like another job, which is like managing all the other folks’ expectations and making sure that we’re all on the same page. So, it can be hectic at times, but it’s also very rewarding.
NARRATOR
LCRD’s integration and testing took place in phases, with campaigns beginning as early as four or five years before launch. Each of these phases integrates more subsystems and components onto the payload.
I asked Javier how often challenges come up in the integration and testing process and…
JAVIER OCASIO-PEREZ
On a daily basis, pretty much. Actually, as we speak, I’m getting text messages and calls, but we’re good, don’t worry about it.
NARRATOR
It’s critical that Javier and his team addressed all of these issues before launch, because as Dave Robinson said, “If it breaks in orbit… sometimes it’s unfixable.” Executing some of these phases during the pandemic — where most of the LCRD staff needed to work remotely — meant embracing new and innovative ways of communicating test results and conducting spacecraft readiness reviews.
JAVIER OCASIO PEREZ
In this situation, we got to be creative and I’m happy to report that essentially, we’ve been able to execute all of our testing with the spacecraft with no interruption, really.
NARRATOR
Despite the pandemic, the team saw the spacecraft through integration and, ultimately, to launch. It was a labor of love that closed out many years of hard work.
JAVIER OCASIO PEREZ
I’ve been lucky enough that I’ve been able to work on LCRD… pretty much from like the very beginning. And I’ve been able to see LCRD go from like — I don’t want to say nothing, because it’s not nothing — but like, from just like a concept, basically, all the way to like step-by-step being built.
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NARRATOR
As we speak, the LCRD payload is on orbit as engineers preparing for what we call “first light,” the moment we begin to communicate data through LCRD’s optical telescopes. Next episode, we’ll look at the ground systems that will establish laser links with the payload. To do so, we’ll need to travel across the United States to Hawaii, California, and New Mexico. I hope we’ll see you there!
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NARRATOR
Thank you for listening. Do you want to connect with us? The Invisible Network team is collecting questions about laser communications from listeners like you! We’re putting together a panel of NASA experts from across the Space Communications and Navigation community to answer your questions.
If you would like to participate, navigate over to NASA SCaN on Twitter or Facebook and ask your question using the hashtag AskSCaN. That’s @ NASA SCaN, N-A-S-A-S-C-A-N, on social media, with the hashtag AskSCaN, A-S-K-S-C-A-N.
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This LCRD-focused season of “The Invisible Network” debuted after the launch of the U.S. Space Force’s Space Test Program Satellite-6 on Dec. 7, 2021. LCRD is led by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in partnership with NASA’s Jet Propulsion Laboratory in Southern California and the MIT Lincoln Laboratory. LCRD is funded through NASA’s Technology Demonstration Missions program, part of the Space Technology Mission Directorate, and the Space Communications and Navigation (SCaN) program at NASA Headquarters in Washington, D.C.
The podcast is produced by SCaN at Goddard with episodes written and recorded by me, Danny Baird. Editorial support provided by Katherine Schauer. Our public affairs officers are Lora Bleacher, Kathryn Hambleton, and Clare Skelly of the Space Technology Mission Directorate.
Special thanks to Barbara Adde, SCaN Policy and Strategic Communications director, and all those who have lent their time, talent and expertise to making “The Invisible Network” a reality. Be sure to rate, review, and follow the show wherever you get your podcasts. For transcripts of the episodes, visit NASA.gov/invisible. To learn more about the vital role that space communications plays in NASA’s mission, visit NASA.gov/SCaN. And for more NASA podcast offerings, visit NASA.gov/podcasts.