While many people with the joint program between the U.S. Geological Survey and NASA are busy working to prepare for the building and launching of Landsat Next, others are also preparing for the large amount of data that will be coming and working to ensure its consistency and accuracy.

Sources/Usage: Public Domain. View Media Details

We talked with a variety of these people recently for two new Eyes on Earth podcast episodes focused on Landsat Next preparations. In Part 1, we learn about how the Landsat Next mission will be different from previous Landsat missions and its benefits to science and society. Part 2 contains more technical information about the ground system and plans for processing and validating the data. 

Landsat data is all processed, archived and distributed at the USGS Earth Resources Observation and Science (EROS) Center. Guests for Part 2 were USGS Landsat Next Project Manager Brian Sauer at EROS, USGS Acting Ground System Manager for Landsat Next Chris Engebretson at EROS, and Cody Anderson, Project Manager of the EROS Calibration and Validation Center of Excellence (ECCOE).

In this Q&A based on edited Eyes on Earth episode comments, Sauer, Engebretson and Anderson describe more about what the Landsat Next mission involves.

Landsat Next roles for USGS, NASA and EROS

QUESTION: How do the Landsat Next partnership roles between the USGS and NASA break down?

SAUER: The Landsat project is a joint one between NASA and the USGS. Think of us as one project team. We work very closely together. And similar to Landsat 9, during development, NASA is responsible for the space segment. That includes the instrument, the spacecraft and the launch vehicle. USGS is responsible for the development of the ground system. During development, while NASA leads the mission, the joint agency partners in areas such as science, calibration and validation, and mission engineering also work closely together. NASA leads the mission readiness campaign and launch, early orbit and commissioning, and then upon success, they hand over the mission to the USGS. After handover, the responsibilities sort of flip. USGS takes primary responsibility for the mission and operates it, and NASA turns into more of a support role. 

Q: What is EROS’s role for Landsat Next as the satellites head to orbit?

SAUER: The Landsat Next and Landsat Operations project offices are located here at EROS. We work closely together throughout the development and operations cycles. EROS will provide the flight operations team, the ground system and engineering support during launch, early orbit and commissioning. NASA is leading and responsible for the on-orbit validation and acceptance periods right after launch, when we test out the system. NASA is responsible for making sure that the system meets the requirements and is verified and validated. After we get through that period, the USGS then takes ownership of it. And our flight operations team being involved in the deployment phase and testing phase and especially when we’re on orbit really provides a seamless transition for when we get into operations.

Sources/Usage: Public Domain. View Media Details

Q: What are the differences in duties between EROS Center staff in South Dakota and EROS staff at NASA Goddard Space Flight Center?

SAUER: Staff at the EROS Center take care of all the ground systems, testing, integration, development of the ground system and so forth. But we also have a flight operations team and a flight operations contract in our Mission Operations Center, and for Landsat 8 and 9, that is located at Goddard Space Flight Center. For Landsat 8 and 9, our operations for monitoring the system, performing commanding to the satellite, health and safety of the satellite—the Mission Operations Center capabilities—are performed at Goddard. We haven’t figured out where Landsat Next is going to be operated yet at this stage when we’re formulating the mission, so we’re going through those processes to determine that, and we’re performing studies and other activities.

Differences on the Ground

Q: How will the current ground system have to change to support this new mission?

SAUER: We have to make sure the ground system is efficient and cost effective for long-term operations. The most significant changes of the ground system include handling the three satellites efficiently with much greater automation, modifying the system to be able to acquire and downlink the increased volume of the science data, and getting that data to the ground and then modifying the data processing and archive system to handle that data. The EROS team has been soliciting industry on several fronts to help us formulate the ground system architecture, the OPS con and the requirements. The team solicited industry requests for information to understand the capabilities of the ground system and the Mission Operations Center. The responses were outstanding and are helping the team here at EROS formulate the strategy.

On the ground network side, the antennas needed for Landsat Next to bring the data down to the ground use a different frequency than existing antennas. This will require either acquiring services, maybe modifying existing systems, or potential build-outs. So the request for information we used helped us solicit industry to understand what capabilities and what services are out there so we can architect the ground network system appropriately. I should note that EROS has also recently issued an industry request for information for upgrading or replacing an existing antenna here at EROS. That antenna would support the existing missions, Landsat 8 and 9, and potentially would be used for Landsat Next. The results of that are still being analyzed. 

With our acquisition cycle in the federal service, we need to make sure that we involve industry so we understand our requirements more properly and the capabilities out there in the marketplace. We use those then in driving out our requirements. We wouldn’t be near as far along as we are if we didn’t involve industry very early. 

Sources/Usage: Public Domain. View Media Details

Planning for a Lot More Data

Q: How many scenes and how much data will Landsat Next acquire?

ENGEBRETSON: Landsat Next is expected to send about 2,500 scenes per day, and that’s across all three satellites in the constellation. We’re looking at generating upwards of 15 terabits of data per satellite per day. If you compare our expected science volume output from Landsat Next to Landsat 9, we’re expecting Landsat Next to generate about 15 times the volume of the data currently being generated by Landsat 9. A lot of that is brought on by the increased spatial resolution and the new bands that we’re adding. It certainly increases the size of the data volume coming down from the spacecraft and then the size of the resulting science products.

Q: Is EROS ready to handle more data from the higher resolution and additional spectral bands when it comes?

ENGEBRETSON: The big thing that we’re doing to get ready for Landsat Next is we’re right in the middle of an activity to take all the historical Landsat processing systems running today at EROS in Sioux Falls and migrate them to the cloud. And that gives us an opportunity to revisit some of the architecture and design of those systems. At this point, some of them are fairly old. They served us very well, but it is an opportunity for us to go back and look at those systems. The other thing that moving to the cloud is going to give us is a lot of flexibility in terms of our scalability and elasticity. So if we need to scale up our processing resources to handle, whether it’s the increased load from Landsat Next or whether we want to take the entire archive and process a new Landsat collection, being in the cloud gives us the flexibility to scale up and scale down to handle those loads as appropriate. This is an activity we’ve been working on for a couple of years now; we expect to have it finished in 2026. 

Q: Why do we have to plan this far ahead for data processing?

ENGEBRETSON: Because that is how long it takes. When you read news articles or see other things about Landsat, it may be referred to as a picture-taking mission or a photo-snapping mission. That gives the impression that we have the equivalent of a cell phone camera in orbit, and we’re just taking pictures and sending them down to the ground and then making them available for people to download. The actual process that’s involved with taking raw data from a precision science instrument on orbit and generating the pretty pictures that people are used to seeing with our Level 1 and higher products is very complicated. The complexity of the algorithms and the amount of number crunching that’s required to take that raw data and turn it into a well-calibrated, useful science product is quite an undertaking, so it’s never too early to start that process. For Landsat Next, later this year, we will have an instrument vendor on board, and that’s when the work really begins between the vendor and those of us on the ground to be involved with the design of that instrument and the development of all the algorithms that are needed to take that raw data and turn it into usable science data. The design of those algorithms, the development, the validation, the integration and testing—that is a process that literally takes years. 

Getting Creative with Test Processing

Q: How is test processing possible with no Landsat Next data?

ENGEBRETSON: Going all the way back to Landsat 7, this has been a perennial challenge for us to deal with because it is your classic chicken-or-the-egg problem. When we start getting science data down from Landsat Next, we want to be able to process that data right away, but we don’t get real data from Landsat Next until we’re on orbit. So that’s always the question: How do we develop and test software to process that data and generate those products if we haven’t seen any of that actual data yet? 

We’ve developed a three-pronged approach that we’re going to be using to essentially generate simulated or proxy data for Landsat Next. First, we’re looking at existing sources of multispectral data. Landsat 9 is one of those sources, but we’re also looking at sources like Sentinel-2, which already has 20- and 10-m pixels. It also has a lot of the additional spectral bands—not all of them, but some of the additional spectral bands that we’re adding for Landsat Next. We’ve developed an algorithm where we can take that multispectral data and combine it with a land characterization database and then a spectral library. And we have an algorithm where we can use all those things and then use the spectral responses of the bands that we have to simulate the spectral responses of the bands that we don’t. That process isn’t perfect, but the resulting data should certainly be good enough for us to simulate a lot of our processing algorithms and do some of our software testing and things like that.

Sources/Usage: Some content may have restrictions. View Media Details

The second approach is looking at hyperspectral data. We have a fairly large volume of hyperspectral data in the archive at EROS from missions like EO-1 and the Hyperion sensor. We’re also looking at other sources of hyperspectral data such as the EnMAP mission from our German colleagues, which is a hyperspectral mission at 653 kilometers, where Landsat Next is going to be. Having that hyperspectral data gives us the ability to simulate some of those new spectral bands that were not there before.

And then the final thing is working with our colleagues at NASA and at the Rochester Institute of Technology in New York, where they have a physics-based model where we can feed the exact characteristics of our instrument. That model does a lot of physics-based simulation of not just the ground but also various atmospheric features. So we can use that model to generate some very high-fidelity simulated images of what we would expect Landsat Next data to look like. 

Maintaining the Landsat Gold Standard

Q: One of the truly valuable things about Landsat is how consistent and accurate it is. How do we keep it that way with Landsat Next?

ANDERSON: The gold standard is something that I take very personally, and at the EROS Cal/Val Center of Excellence, or ECCOE, one of our mission statements is to maintain that gold standard. So looking forward to Landsat Next, everything that’s new on it still has to be at that absolute highest level. We’re going to have to tighten up our geometry a bit because we’re going from 30 meters to 10 meters, and we’re going to have to come up with a couple of new algorithms to calibrate the new spectral bands. We’re adding some atmospheric bands that won’t even see the surface, so we’ll have to adapt some of our traditional techniques and come up with new ones to make sure that Landsat Next is at the same class at the same reliability and the same consistency as previous missions.

Q: How does the higher resolution present accuracy challenges? 

ANDERSON: Currently we say that we’re accurate within about half a pixel for Landsat 8-9, which is half of a 30-meter pixel. We’re talking 15 meters. 15 meters is no longer good enough when your resolution is 10 meters. So we’re going to have to improve all those things, then flow all those changes that we’re making for Landsat Next back through the archive so the whole archive stays internally consistent.

Q: With a new generation of sensor, how do you make sure the Landsat Next data will be consistent with data from previous Landsats?

ANDERSON: We are adding a few new spectral bands, so we’re going into uncharted territory with those. But we are keeping all the bands we’ve had in the past: blue, green, red, near infrared channels, SWIR channels, thermal channels. The channels have to be consistent with what we’ve had in the past. That’s been the crux of Landsat and is one of the key parts of that gold standard: When it’s Landsat data, you can trust that it will fit with the data in the past. But there are some challenges going from 30 meters to 10 meters. We need to make sure those new pixel resolutions will stack, or lay on top of, the previous data. We’re coming up with new ways of maybe referencing the pixels to make sure those different pixel sizes will all lay on top of each other, so you can use older Landsat data with the new data. And for the radiometry, for those spectral channels that are the same that have existed in the past, we will come up with extensive cross-calibration techniques. We’re going to launch three satellites on Landsat Next all at the same time, so we have to make sure those three are all intercalibrated, that all three of them agree with each other. And then it’s assumed that Landsat 9 at least is still operational when we launch Landsat Next, and there will be campaigns of comparing Landsat Next with Landsat 9 and hopefully Landsat 8, and making sure that all those existing channels will be lined up and consistent across the entire archive. This is what calibration is all about. This is what we’ve been doing with the Landsat archive for 50 years to make sure that when it says Landsat, people know what they get.

Q: Will Landsat Next turn and look at the full moon like previous Landsat satellites?

ANDERSON: Yes, we’re planning that Landsat Next will continue lunar calibration. It will still perform a 180° maneuver to do all the moon calibration with all three satellites. And with those new spectral channels that we have, the Moon is one of those targets that we think will be really valuable. There’s no atmosphere on the moon, so the new channels we’re adding that look at the atmosphere, they won’t see the surface of the Earth, but they’ll still see the surface of the moon. So we’re expecting the moon to be very valuable for us. 

Find more information and updates on progress with the Landsat Next mission here.