#23 – Helen Fricker

#23 – Helen Fricker

August 15th, 2025

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Announcer: Welcome to the LIDAR Magazine Podcast, bringing measurement, positioning and imaging technologies to light. This event was made possible thanks to the generous support of rapidlasso, producer of the LAStools software suite.

Austin Madson
Welcome, everyone, to the LIDAR Magazine podcast series. My name is Austin Madson and I’m an associate editor at LIDAR Magazine. Thanks for tuning in as we continue our journey exploring the many different applications of lidar remote sensing. Today we’re really happy to have the opportunity to chat with Dr. Helen Fricker, the science team lead for NASA’s Ice, Cloud and Land Elevation Satellite 2 or ICESat-2, a spaceborne photon-counting laser altimeter.

Dr. Helen Amanda Fricker is a professor of geophysics in the Cecil H. and Ida Green Institute of Geophysics and Planetary Physics at Scripps Institution of Oceanography at UC San Diego, where she also co-leads the Scripps Polar Center. Dr. Fricker is from the UK and went to the University College London, where she studied math and physics. She then went on to Australia for a PhD in Antarctic Glaciology at the University of Tasmania.

Helen has been involved in NASA’s laser altimetry missions since she came to the US in 1999. She’s been a science team leader for both ICESat and ICESat-2 and was able to attend both satellite launches at Vandenberg Air Force Base. Beyond her NASA contributions, Dr. Fricker served on the 2016 and 2017 Earth Science and Applications from Space Decadal Survey Steering Committee. That was for ice sheets and she was an author on the Rising Seas California Report as well.

Dr. Fricker has shown a really strong commitment to mentorship, this is evidenced by advising numerous graduate students, nurturing the development of more than 14 postdoctoral research scholars, and is active in training the next generation of scientists. Dr. Fricker was awarded the 2010 Martha T. Mews Prize for Science and Policy in Antarctica, became an American Geophysical Union, or AGU, fellow in 2017, and gave the AGU cryosphere section 9 lecture in 2019.

Austin Madson (02:15.338)
What I think is really rad too, not that all those other things aren’t rad, but the Fricker Ice Piedmont was named after her by the British Antarctic Place Names Committee in 2020, which is really amazing. She was awarded the University of Tasmania International Alumni Award in 2023. And I really could go on and on for five more minutes talking about Dr. Fricker’s awards and her experience using spaceborne light, products and glaciology and research in the cryosphere. Why don’t we jump in and pick Dr. Fricker’s brain about spaceborne lidar. So thanks for joining us today, Dr. Fricker.

Helen Fricker
Thanks, Austin. Thanks for that great introduction. It’s kind of funny hearing people talking about, well, your accolades speak for themselves. What’s he going to say next though?

Austin Madson (03:02.158)
Of course, yeah, so welcome. So why don’t we start by having you talk a bit about your background and how you came to be involved in the remote sensing and lidar communities. and I really enjoy hearing these, you know, how did I get here stories? So what is yours?

Helen Fricker
Yeah, no, this is great. It’s nice to think about it, the whole sort of path. So as you mentioned, I did my undergrad at University College London, and I was actually doing maths and physics, so more, you disciplinary and not applied and not, you know, earth physics or anything like that. In my third year there, I met Professor Chris Rapley, who at the time, because we’re talking about, it’s probably 1990 at this point. And he was teaching a very, very well attended class called Physics of the Earth that was open to final year students in physics.

I actually had to petition to take that class because it was seen as a soft option at UCL for physics students, especially double majors. Anyway, I took the class and then I also got along with Chris a lot. I really, really loved his class. It was actually one of the most illuminating classes I’ve ever taken and I ended up appealing and winning an appeal to do a project with him for my final term at UCL, which involved going down to the Mallard Space Science Laboratory once a week, driving down there from the middle of London. used to get the tube to Putney and meet Seymour Laxon, was my advisor.

He was a postdoc at the time, and drive with him very fast down the A3 to Surrey to Holmbury St. Mary where this incredible building is where they have or had the Mullard Space Science Laboratory. Although I think it’s still there, but the remote sensing group is no longer there. So this was the early days of radar altimetry and actually ERS-1 was launched in 1991. So at this time, unbeknownst to me really, I guess it was the beginning of it all. So here I was an undergraduate student working with Chris Reckley and his group.

Austin Madson (04:55.829)
I see.

Helen Fricker (05:14.432)
There’s other people there who people listening to this probably will know. So Seymour Laxton, obviously, Jonathan Bamber, Sharon Burkett, like lots of people that started their MSSL in the early days of all this work they were doing for the European Space Agency. And the satellite ERS-1 was launched, which carried a radar altimeter. And this was the first radar altimeter that actually had what we call an ice mode because CSAT had been launched in the 70s and then we had GeoSAT and they were in an orbit that didn’t go as far as the ice sheets. It was in a lower latitude orbit. But some of the data kind of clipped the edges of the ice sheets and so it was determined that the data could be useful over the flatter parts of the ice sheets. So, AirS1 was launched with a more higher latitude turning latitude. So it went down to the ice sheets and had an ice mode as well.

So I remember the excitement of this launch of this instrument, but it wasn’t just radar altimetry. ERS-1, you it was the size of a school bus and it carried also a SAR and multiple other instruments, a scatterometer, lots of different instruments on board. But the radar altimeter was the one that I worked on. Subsequently, I did my PhD using ERS-1 and ERS-2.

Austin Madson
Wow. Yeah. And so you went over to Tasmania to do your PhD, right?

Helen Fricker
Exactly. Yes. It’s quite common in the UK and also in Australia to take what they now call a gap year. We didn’t call it that then, just a year off. And so I had a year off in Australia and I really liked it there and wanted to go and spend more time there. And so when I finished my project at UCL, when I graduated with my undergrad, I asked Chris Verappley if he knew anything about working in Australia and staying in this field…

Helen Fricker (07:08.032)
…and incredibly serendipitously, he said, actually, I’ve just done a tour of Australia last year and visited all the remote sensing groups and I have a list of 30 names that you can write to. snail mail, I wrote them all out and printed them out and put them in these little folders and took them to the post office in the middle of London. And one by one, all these letters came back and it was like, sorry, sorry, like forever. And I was getting really despondent. And then one of the last letters that came back was actually from Professor Bill Kersley at the University of New South Wales. And he was like, yes, actually, I do have a project. And it would be great if you came over. And so I went over there and started a research position, which was kind of funny because I wasn’t, you know, I hadn’t done a PhD yet. And it was kind of a very entry level below being a PhD student.

But it was very good because that gave me some skills that I could then go on and apply to do a PhD application and I was able to get a fellowship from the Britain Australia Society to do a PhD in Australia because I was an overseas student. That was fantastic. Ultimately, I ended up going to the University of Tasmania to do my PhD because Tasmania is further south in Australia and it’s closer to Antarctica and that is where the Australian Antarctic Division is and where the University of Tasmania.

There was a group there that was based at consortium of Australian Antarctic Division, CSIRO, University of Tasmania. It was a big cooperative research center and there was a department at the university called the Institute of Antarctic and Southern Ocean Studies. In Sydney, had met Richard Coleman, Professor Richard Coleman, who encouraged me to take my scholarship to Tasmania and be mentored by him. He was my supervisor and how it all happened.

And then you came to the US in 1999 and landed at, in my opinion, one of the most amazing institutes in the country. Not to mention your department, I think is right on the water.

Right. Yeah. And it’s kind of funny. It’s about as close to Antarctica as you can get in the US. Because, all the ships leave from if they do like Port Honimi is just up the coast and you know, it’s most people fly from LAX. So people say, how can you study Antarctica in in San Diego? Well, you said I sort of say, well, we’re closer than you.

Austin Madson
That’s right. That’s pretty good.

Helen Fricker (09:38.734)
But for me, so I did my PhD using this radar altimetry, ERS-1, ERS-2, but the next thing that was on the horizon for altimetry was this NASA laser altimeter mission which was coming called ICESat, which carried the GLAS instrument. that was coming in the 2000s. And in the mid-90s, that was a really big deal. And I remember just it was like the next, you know, the bee’s knees.

This is what you just go and work on, you know, graduating from Tasmania using radar altimetry. Well, let’s go and look at the next big thing, laser altimetry. So I came to the US in 99 before, so ICET was not launched until 2003. So that was great. I got the last four years of mission development under the mentorship of Professor Bernard Minster at IGPP Scripps, UC San Diego.

Austin Madson
It’s an amazing entry into this world that you didn’t know existed until you took that one class and petitioned to do that thesis. It’s really an amazing story.

Helen Fricker
Yeah, and there’s a couple of other things there actually. also was quite good, well, I was good friends with a lot of people who did geography. And so I was quite aware of the kinds of things that they were doing, and they were more likely to do remote sensing type things. And there was one person I remember in particular who was looking at remote sensing. And I remember thinking, wow, satellites, that’s incredible. You know, it was just this thing and then, and then meeting Chris, it all kind of fell into place. It was sort of serendipitous.

Austin Madson (11:16.95)
Right, yes, it’s amazing how that works and here you are now. And so I want to, you kind of segued into this talking about ICESat and GLAS. So you were part of the science team for the first ICESat platform launched in 2003 that you just said, right? It flew the Geoscience Laser Altimeter System or GLAS. Can you talk a little bit about the GLAS instrument and then some of the science that you participated in using that data?

Helen Fricker (11:45.198)
Yes. So ISA is now what I would call a, it was a pathfinder mission. basically it was demonstrating laser altimetry on a free-flying spacecraft. We had had the shuttle laser altimeter before. So this was very, very new territory, actually mapping the ice sheets going all the way to 86 degrees north and south. It was just single profile. So it was red laser, infrared, 1064 nanometers…

Austin Madson
Right.

Helen Fricker (12:14.28)
…waveform recording though, so very good for many, many applications across the land, the ice, sea ice, land ice, glaciers, even the oceans as well. And so the data when they came back, they were fantastic, you know, really transformed the way that we could see some processes. Radar altimetry was great, but the problem with radar altimetry is the resolution on the ground, so the spatial

Austin Madson
Right.

Helen Fricker (12:43.34)
The size of the footprint on the ground is much, much larger with radar altimetry. So the features that you look at in a radar altimeter profile kind of appear a bit blurry or smoothed out, very sort of broad. So it’s kind of like zooming in and getting into focus when you move to a laser. So everything along track is really, really high-resolution spatially. So it meant that we could do things that we couldn’t do before, such as on ice shelves, we’re really interested in mass loss processes like iceberg carving, for example. And you could actually use ICESat to get the rifts all the way up to the rift.

So where the ice is broken apart, being severed in two, and it’s now got this sort of fall off into the ocean and there’s little bits of ice in between it called melange, infilling. You could actually get all of that in one profile. You get the rift, the shape of the rift, go drop down into the intervening space in between, get the melange in the middle, and then come back up the other side. And that was all captured because we’re talking about tens of meters footprints as opposed to several kilometers with radar altimetry. Radar altimetry wasn’t able to capture anything like that. You couldn’t get that detail. just, you know, glossed over it. And then for the radar altimeters too, wasn’t there some re-tracking algorithm that had to apply to the…

Yes. that’s because, well, back in the 90s, one of the limiting factors, of course, with remote sensing was storage space and how big the data sets and data streams were. And so they limited how much of the return pulse they recorded. And so that means you have a finite range window that you had to place where you thought the echo was going to come from on the ground. So you had to have an apiary knowledge of what the surface was to know where to put your range window to capture it. Like, try to catch a butterfly as it’s flying, or I don’t even know what the analogy would be. But, you know, so if you miss it, you miss it, and you just don’t capture it. It’s gone. And so you had to make sure that you captured this signal. But because of that, it didn’t always capture it in exactly the right place. So the range that’s reported by radar altimetry is to the middle of that range window.

Austin Madson (14:49.559)
Right.

Helen Fricker (15:04.226)
But sometimes the echo is a little bit before and sometimes it’s a little bit after. So that leads to a few meters of offset that you have to correct for. That’s what we call re-tracking.

Austin Madson
Right.

Helen Fricker
Then so with the geoscience laser altimeter system, right, all of that was out the window. You all are using totally different instruments to derive the trajectories and everything even so the return waveform when it came in, more of it was recorded, it was shorter anyway, then you just used actually the – basically it’s like a Gaussian shape and you used that, the centroid of that Gaussian return and look at the time delay from the centroid of the Gaussian from the outgoing pulse and get the range that way.

Now if the surface is a bit complicated, you end up with sort of multiple Gaussians, so it’s a bit of a more complex return waveform, but the team came up with algorithms to sort that out as well.

Austin Madson
You talked a little bit about the orbital inclination and we can get the coverage from that. What about some sort of accuracy and uncertainty metrics that you saw when you are working with this data?

Helen Fricker (16:11.074)
Yeah. So for ICESat, we actually went to the Salar de la Uni in Bolivia because it’s the flattest, largest, sort of most stable surface to calibration on earth. And we did some GPS surveys. We actually did one right before launch in 2002. So it’s actually similar to what I had done as a student on a Marie I shelf, driving around in some sort of vehicle. In Antarctica, it was a Ski-Doo on the Slardia Uni, was a Jeep that we washed very well afterwards because it got lots of salt under it. You put an antenna somewhere on the vehicle, mount it really, really stably, and then drive around in a grid. We did that. Using those data, we were able to determine the precision and accuracy of ICESat over a surface like that.

Austin Madson
Right.

Helen Fricker (17:10.541)
It was on the order of centimeters. think two to three centimeters was the number that we got from those experiments is just incredible. A couple of centimeters from what is the orbit? Several hundred kilometers. I don’t remember what it was for ICESat, but it’s so I sat was sort of five, it’s something like 590 kilometers.

And that’s a great paper too, the paper you were just talking about. So if you can do a quick Google query or Google scholars, and then go check out that uncertainty and accuracy work that they did on the uni, U-Y-U-N-I.

Austin Madson (17:45.356)
Well, as good as the ICESat data was, and it was good, especially coming from the ERS data, what things weren’t possible with the GLAS data? What left you itching for more?

Helen Fricker
Yeah, so that’s the thing. So I kind of think of it, I’ve actually started using the analogy of, it’s a bit like cell phones, where when we first had cell phones, you we had the flip top phone. And so you kind of, you you’re connected and you get an idea of what you can do when you can walk around and be contactable with your flip top phone, but you’re only getting part of the capability with ICESat. The big thing about ICESat was because it was a single profiling instrument, the tracks couldn’t completely be repeated.

When the repeat tracks came back around, the cycle came back around to repeat the ground track, it only did it to plus or minus 100 meters or so on the ground. You ended up with offsets. You’re trying to look for repeat tracks, changes, sometimes what you’re seeing is cross track slope because the tracks were not laid down in the exact same geographic location. With ICESat-2, and that’s a problem for steeper glaciers and places that we’re actually looking for large changes, or actually small changes was the worst thing. So if you’re looking for very small signals of change compared to the topography that you’re trying to detect the change in, then it’s really hard to unravel.

Austin Madson (19:19.564)
Right.

Helen Fricker
I mean, obviously people came up with algorithms to do that, but if you’ve got a changing surface, it’s very difficult because the slope is changing in the background as well. So what we did was with ICESat-2, the team came up with a design that was basically splitting the beam so that you ended up with, we call it, it’s a multi-beam basically. And on the space station, which was launched at the same time actually had a similar approach, multi-beam approach. It was done differently. with ICESat-2, first of all, went to photon counting, as you mentioned, and that’s green laser, 532 nanometers.

And the beam was split into six beams. So the outgoing beam was split into six, and they were arranged in a very specific way, chosen for various different reasons to satisfy the needs of the different scientists on the science team, which range from ice to different types of ice, land ice, sea ice, then to vegetation and inland water people. The design that came up with was basically three pairs of beams. Within the beam pairs, the two beams were 90 meters apart.

Then the separation between the beams was 3.3 kilometers. The full sort of swath, if you like, but it wasn’t really a swath, was 6.6 kilometers. Each of those pairs had a weak beam and a strong beam. There’s a lot going on in that description and it’s better seen with the diagram really, but that’s how I set to describe the surface profiles of the Earth.

Helen Fricker (21:03.978)
Every single time you could get a cross-track slope estimate because it’s all done at the same time. It’s a snapshot, think too there was some off-nadir pointing of the Atlas instrument on ICESat too that, well, both instruments could off point to… I couldn’t remember if it was just the most recent.

Yeah, no, ICESat and ICESat-2 had a targeting capability where you could actually submit targets of opportunity in terms of latitude, longitude on the ground that you want to be sampled by the laser. We did that for a uni. We did it for different places for calibration and other things like some targets of interest that people were looking at. But you’re robbing Peter to pay Paul sometimes where you end up them with no… Some people want the track off-pointed, but then other people didn’t want it off-pointed. there was some, yeah, there was definitely a little bit of like an approval process for how to do the off-pointing.

Austin Madson
Right, and you were the science team lead, is that right for the ICESat-2 mission?

Helen Fricker
I only recently became the science team lead. Before that, up until launch and then after launch, there were various different science team leads. Lori Magruder at the University of Texas, she was the science team lead for 10 years before me. She saw the whole mission through development and then into on orbit. Then the new science team that was competed in (not initially), I think it was 2022. That’s when I became the science team lead for the last three years.

Austin Madson
Yeah. And then for reference for our listeners, the launch of ICESat-2 was in 2018, and Dr. Fricker, it’s still collecting science-proven data to this day, right?

Helen Fricker
Yes, it is still working really well. It’s still collecting amazing data. And yeah, it’s been on orbit for six, coming up for seven years. It’s incredible.

Austin Madson
Yeah, it’s really incredible. And I just want to pause really quickly for a word from our sponsor, LAStools.

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Austin Madson (23:48.494)
Well, so we’ve got this follow-on mission, ICESat-2, that flies the Advanced Topographic Laser Altimeter System, or Atlas. And so we’ve made some improvements, right, since the first ICESat platform. What kind of science did you participate in, Dr. Fricker, that ICESat-2 really helped drive?

Yeah, so back to ICESat a little bit too. One of the things that we did with ICESat was use this repeat track sampling to look at different places on the ice sheet that were changing rapidly, such as the grounding lines of ice shelves. So the tidal action of the ocean tide going up and down, the ice shelves are floating and they respond to that, but the grounded ice of the ice sheet does not.

Austin Madson
Right.

Helen Fricker (24:35.106)
So it’s really nice because you can pick out the flexure zone around the edges of the eye sheets with ICESat and ICESat-2. So that’s some work that we did. ICESat sort of showed the capability and was able to pull out quite a lot of grounding lines using the technique, but then ICESat-2 extended it further because of the better coverage and going further south, so we could actually capture more. And yeah, very, very nice work that’s been done now looking at changes because ICESat in the end was only a five, six year mission. If you want to look at height changes with time over ice sheets, you need longer time period to really drive at those sort of decadal changes. First of all, we could look at changes in things like the grounding line and also subglacial lakes.

Austin Madson (25:27.438)
Right. Tell us about this, there’s a fun story, right? Tell us about how y’all came about this, I love it.

Helen Fricker
Yeah, yes, it is a fun story. It was actually a totally, I think I’ve already used the word serendipitous. I’ll use it again, because this was serendipitous. So we were actually mapping the grounding line of Ross’ ice shelf using ICET. And it was a bit of a laborious process at the very beginning. But one of the very first tracks that I looked at went across this feature, which subsequently, after quite a bit of digging, we found out was a subglacial lake…

Austin Madson
That’s it.

Helen Fricker (26:00.462)
…and what we saw was this ribbon of colors that just kind of every single time the ICESat came back to repeat the same track, the surface was going down. For three, three and a half years, it kept going down, down, down, down, down for like 10 meters. And it was this crazy thing where we just hadn’t seen anything like that before on that scale. this must be an anomaly. There’s something wrong. There’s a tide correction. There’s something you’re applying wrong, doing something wrong. It was, okay, well, let’s look at the tracks that cross it and see if the signal still there. It turns out, looking at all the tracks back and forth across that lake, it was there in every single cycle. It kept showing up every single track. Then looking over the whole ice stream that this was found on, which was the Willans Ice Stream in, well, it’s actually the southern part of Ross Ice Shelf, the Gould Coast near the Cycle Coast.

And we’ve actually uncovered a whole system of active subglacial lakes using that technique. And what was kind of unique about that was that we had actually known about lakes like that high up on the plateau from radar altimetry, but this was now under ice streams in places where radar altimetry couldn’t really capture them because of what I mentioned before, the footprint and the sort of smearing out. Like some of these lakes were quite small and you couldn’t see them in radar altimetry.

Austin Madson
And so you’ll use these great data sets to find all these subglacial lakes. And if I remember right, too, there was another group that went out and sampled one of these lakes. Is that right?

Helen Fricker
Yeah, that was actually part of, I was involved in that. what that did was it sort of spun off about a 10-year detour in terms of what I did in my career from going from looking at ice shelves to now looking at lakes. And keeping up with many other scientists, we put in an NSF proposal, which was led by Slavik Tulachic at University of California, Santa Cruz, and many others like Sridhar Anandakrishnan was involved and many others. It was very interdisciplinary geophysics, go in and drill through the lake. That was called Wizard. Then there was a follow-on one called Salsa, which was led by John Prisku. That was to drill into another lake. We drilled two different lakes, Lake Willans and Lake Mercer, with those two different projects, and also the Granning Line downstream.

Austin Madson (28:27.834)
I see. remind me, did they find forms of life in their sample?

Helen Fricker
There they did. So I’ll say I didn’t end up participating in any of this field work. was raising small children at that time. I’ve now grown up. But at the time, my graduate student, Matt Siegfried, who’s now an associate professor at the Colorado School of Mines, he actually led all of that field work for our group and our team for the geophysics side of things in both of those projects, actually, Wizard and Salsa. And he was responsible for the GPS and then also taking some EM equipment out there and detecting subglacial water and also groundwater underneath the lake. yeah, I ended up spearheading a whole lot of research with a lot of different people, multi-year projects that NSF funded. So it’s very exciting. A lot of discoveries that were made.

Austin Madson
Yeah, it’s amazing. All from that serendipitous examination of the data and trying to figure out what on earth was going on with this, you know, 10 meter vertical discrepancy.

Helen Fricker
Exactly. I mean, that’s the thing that’s so amazing. Had we not had the technology to pinpoint that lake, we wouldn’t have found it and we wouldn’t have gone there and all that work wouldn’t have been done. So yeah, it is really amazing when you think about it like that.

Austin Madson
Right. And I want to, there’s a lot of cool stuff you’ll have done with this data. I don’t want to go on and on about it I want to talk about some of your newer projects. But I did want to mention too that y’all’s group and a few other people too are looking at superglacial lakes. So lakes on the ice and in particular, the bathymetric surface. Can you just talk a little bit about that?

Helen Fricker
Yeah, that’s very specific to the green laser of ice-saturn. So because it’s green laser, it can penetrate through water as long as it’s not too turbid or like if it’s clear water and it’s still, then the signal is fantastic. A student in my group, Philip Arndt, he was able to develop an algorithm that picked out automatically…

Austin Madson (30:23.488)
Right.

Helen Fricker (30:32.054)
…where these lakes were in the data, basically going back to the point cloud data. It was a huge data project actually because of the size of the data sets when you go back to the photon clouds. going through and across all the data in Antarctica and Greenland and picking out all the lakes that existed and mapping where they were in their frequency and linking them to climate variables and things like that.

Also then using those data to train image-based algorithms. Because the truth is that ICESat-2, the sampling wasn’t really good enough to capture all the lakes, but what it does do is where it does make a measurement, it makes it very well. So you can use that to control other measurements that can then be used to extrapolate beyond the limits of ICESat-2. So you have the ICESat-2 data to constrain things, and then you can use imagery which has been validated and calibrated with ICESat-2 to come up with an algorithm. That was what we ended up doing. We used the data to come up with an algorithm that then is more faithfully reproducing the meltwater depths elsewhere where ICESat-2 didn’t sample. If you ICESat-2 everywhere, then you wouldn’t need the imagery, right? So, kind of a trade-off.

Austin Madson
Right. Well, speaking of getting more and more data, let’s switch gears and talk a little bit about EDGE. So you’re the PI for NASA’s Earth Dynamics Geodetic Explorer EDGE mission. Can you talk a little bit about where EDGE is in its mission lifecycle, what it is, and how it differs from its predecessors?

Helen Fricker
Yes, gladly. So EDGE, very exciting. The most exciting thing I’ve ever been involved in. It’s currently in phase A. So it was a two-step solicitation and we are nearing the end of step two. So that means that we were selected for the Earth System Explorer solicitation that NASA put out. We were one of several missions that went into that mission concepts.

Helen Fricker (32:42.286)
And we were selected as one of four to move forward into the final stage. So this is step two and full mission started that step two process. And so then we’re on the sort of clock to generate what was called a concept study report, CSR. And that kicked off in July last year, which is 2024. And we submitted it in June, 2025. And so we put in the thousand page concept study report, which now there’s a review panel that’s reviewing all four of these reports. And there will be a site visit in the fall, autumn, and that will be over at NASA Goddard. So this is in collaboration with NASA Goddard and the University of Maryland and then multiple institutions that the science teams come from. But I’m the PI and then my deputy PI is John Armston at the University of Maryland. And then Brian Blair, is the instrument PI at NASA Goddard. And then Scott Luthkowski, who’s the project scientist at NASA Goddard.

Austin Madson
So that’s where EDGE is in its mission lifecycle. Why are you so excited about Edge and its data? How does it differ from ICESat to JEDI? And what are some of the interesting science or research applications that this new platform will open up for you and the scientific community?

Helen Fricker
Yeah, this is the exciting part. So basically, as I mentioned with the evolution from ICESat to ICESat-2 in JEDI and then EDGE, basically what we’re doing is we’re going from ICESat with the single profile, kind of like a piece of thread going across Earth, but just one. ICESat-2, the thread got a little bit wider. Maybe it’s now wool and the six of them. With EDGE, it’s now ribbons and these are like thick ribbons going around the so very quickly you can map the full Earth. Not the full Earth, but you get a lot more of Earth than you are able to with these other techniques. And so it’s actually a swath mapping laser altimeter and it puts down five mini swaths at once. Each of these mini swaths are 120 meters wide described on the ground.

Helen Fricker (35:01.622)
At this point, you’ve gone past this of sweet spot where you don’t really need exact repeats anymore because there’s so much data that you go, you produce so many crossovers. So it’s transforming basically, it’s kind of a step change in the way that we look at Earth and it’s going to provide this incredible coverage. 10 times better coverage than previous missions. And now that means that these features that we got this glimpse of along track in ISA and ISA 2 and JEDI and now going to come boom into focus completely in 3D. It’s like a lighter, like an airborne lighter.

Austin Madson
Yeah, it’s amazing. Right. Yeah, it’s really amazing what’s going on in this space. And we’ll talk about that a little bit at the end of the episode. But what is the orbit for EDGE and how is it relative to ICESat-2 and JEDI?

Helen Fricker
Yeah, so this is kind of interesting. So EDGE is in a sun synchronous orbit, which means it goes to 82 degrees north and south. Now, people who look at polar altimetry and work in polar altimetry for the longest time thought that the best thing for polar altimetry was that you had your turning latitude as close to the pole as you could get, which is why the ICESat was at 86 degrees and ICESat-2 was 88. And then, know, what’s coming next. But it turns out that actually, you know, the map that we got from looking at the difference in the ice sheets from ICESat-2 to ICESat, which is 16 years of change or something, showed us that most of the change was happening around the edges. Right? And so EDGE, there’s the play on words. We need to map the margins at high resolution to understand what’s happening. We need a snapshot at high resolution of these dynamic surfaces that are kind of messy and noisy and altimetry struggled in many ways to capture them. So we’ve got a situation where the signal’s really large in terms of change, but the data are actually sparse because of the track sampling that we’ve had, where the tracks sort of splay out wider as you go to the edges of the ice sheets. Well, especially in Antarctica, I’m sort of talking about. We need better coverage than that. So the sun synchronous orbit turns out, obviously you miss what’s in the pole hole.

But what’s in the pole hole is actually only a small amount of the signal. Most of the signal is well captured by the sun’s synchronous orbit. it’s another trade-off. And it turns out, in the end, very attractive for polar altimetry, especially in the Antarctic, for the whole of Greenland, and for the Antarctic sea ice, which has undergone a regime shift in the last three to five years. So the mapping is going to be fantastic.

Austin Madson
Yeah, I think we’re all looking for it and we all have our fingers crossed for the next selection phase. Well, what about your cryospheric scientists? What about some other use cases, right? This will really hit the boreal forests hard and I think there’ll be a lot of data there. Can you talk about some other methods and I guess areas that people will utilize the data?

Helen Fricker
Yes, mean, obviously, so JEDI showed the incredible capability, but it was limited to the orbit of the International Space Station. So what it did miss was the Boreal, so EDGE is going to basically extend the coverage up into the Boreal so we get the whole thing throughout the whole mission. We’re going to get all of the ecosystems at once. And the coverage will be so much better.

So yeah, I it’s going to be fantastic. And we also have chosen a frozen orbit that has the lowest altitude over the equator. And that’s because that’s where the canopies are the densest. And so that, you know, increases the signal to noise ratio in those areas. So the truth is that laser altimetry is actually, it’s the only space based technology that can penetrate these dense canopies and also deliver the high vertical accuracy. So it’s literally seeing through the trees at all latitudes and providing high vertical accuracy of the ground below, like the height of the ground below and also the canopy top and information about the canopy structure and also high vertical accuracy for changes on the ice as well.

Austin Madson
Well, speaking of accuracy, what are some of the mission standards that you’re hoping to hit?

Helen Fricker
Yeah, we’re looking at about three meters horizontal accuracy, about eight centimeters vertical on low slopes.

Austin Madson
Gotcha, yeah. And then so, well, you kind of touched on this, right? Some of the different wants and needs, right? So the orbit being lowest over the equator because of the dense canopies. As the PI for a big mission like this where you’re trying to satisfy different end users and different members of the scientific community, how do you handle all these competing desires?

Helen Fricker
Well, that’s kind of how we ended up with the sun-sync orbit. I think if we’d only had a ice-focused team thinking about the right orbit, we probably wouldn’t have come up with it. But the vegetation people suggested it. And at the beginning, you sort of go, no, you can’t do that because you’re going to have a hole at the pole. But then you start thinking about it. And in the end, I think it’s really great what we came up with. I’m really sold on the sun-sync.

Helen Fricker (40:22.988)
You know, there’s other missions that can fill in the areas that were not sampled by EDGE. EDGE is designed to get the high resolution mapping in the places where we need it.

Right, yeah. Well, so outside of the obvious, right? What do you see or hope to see for the future of spaceborne lidar? And the obvious being here is EDGE being selected.

Yes, well, because we’re also teaming up with industry partners here for this mission. we’re flying on Maxar, the Worldview Legion, Maxar 500 spacecraft. This is the same spacecraft that’s used for the Worldview satellites. This gives it agility. And this is a big thing about EDGE that we haven’t mentioned yet. We talked about targeting for ICESat and ICESat-2, but EDGE takes that a step further.

It can target very rapidly. If an event happens and you need to go and look at it, you can do that. But it can also spend longer looking at the surface in those areas to get a higher resolution mapping of an area. Just say there’s been a flood or a fire or an extreme event, you can actually program the spacecraft to look at that area for longer and dwell and get more data. This is providing this incredible capability for rapid and precise targeting of regions that could be really important of national and global resource management, also for disaster and hazard response.

Helen Fricker (41:57.078)
Yes, so it’s stable for the accuracy, which we need, but it’s also agile for this targeting. This is this other capability that’s sort of really different to what we’ve had before.

Austin Madson
Yeah, I’m excited again. I have said it before, but I have my fingers crossed for you. I know, I know it’s really hard work to put these proposals in. What did you say the last one was, a thousand pages? It’s absurd.

Helen Fricker
Yeah, I mean, I can’t actually describe the amount of work. mean, it’s like, you know, obviously I wrote a PhD thesis and obviously that buried me. It’s like that multiplied by about, I don’t know, 250 maybe. It’s hard to quantify. Such an incredible amount of work, a lot of team members involved, a lot of like back and forth, wordsmithing every last letter. And then, oh, you’ve got to write this.

Right, yeah.

You know, summary now, and there’s just lots of things that were thrown at us all along the way during last phase A that we had to deal with. you know, I think the team has actually navigated all of that really well. So I’m super proud of what we’ve accomplished. We actually got nearly 80 letters of support for this mission. Yeah, we’re really, really excited about it. I think that we’re really ready. I just wish all of the missions could win because they’re all needed.

Austin Madson (42:55.438)
Thanks.

Helen Fricker (43:18.23)
That’s the problem.

Well, think now hopefully our listeners are also enthusiastic about the selection of EDGE. Is there anything else you want to talk about as far as future of spaceborne lidar and any of that? know EDGE is a big thing, but do you see any longer term plans or thoughts? in the commercial world too, could be anything. Just happy to pick your brain about this because you’ve been at it for so long.

So this mission, if it gets selected, the launch is slated for September 2030. And it’s a two-year mission. But beyond that, we have the surface topography and vegetation concept study or study that’s going on right now. It’s an incubator. And so that’s kind of the next thing on the horizon, which might have some combination of lidar and radar with the team studying that.

And so I think EDGE is kind of a stepping stone towards that STV program. And then beyond that, sort of, hopefully what we should be aspiring to is that the US leads a global lidar constellation where we map everywhere all the time. I mean, we should be able, such a fundamental parameter, a surface height of the earth, we should be able to map that well. You know, you think about all the things, all the hazards that we’re encountering.

Helen Fricker (44:45.496)
Just having a really good, accurate topographic map and looking at change is enough to tell you a lot of what you know, like flood mapping, iceberg, like where ice shelves are deteriorating, sea level rise, landslides. All these things can be characterized just by looking at surface topography and surface deformation, permafrost degradation, vegetation changes following fires.

Right.

Helen Fricker (45:12.11)
It’s such a fundamental parameter. I think that’s what I love about altimetry is it’s really easy to explain it to people. You’re just mapping the height of the Earth. Everyone knows what the height is, right? You all do little height charts when you’re growing up as kids. And that’s literally what we’re doing. We’re measuring how the Earth is changing and we’re just tracking its height and that’s it. It’s not complicated.

Well, thank you again so much for your time, Dr. Fricker. That’s all I have for this episode and thanks for chatting with us today and thanks to everyone for tuning in. I hope you’re able to learn something about ICESat and ICESat-2 if you didn’t know about them before and I hope you’re as stoked about EDGE as Dr. Fricker is and for the future of spaceborne lidar. Be sure to subscribe to receive episodes automatically via our website or Spotify or Apple Podcasts or whatever your flavor.

Stay tuned for other exciting episodes in the coming weeks and take care out there. Thanks again, Dr. Fricker. We really appreciate your time.

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