Apollo 52, 007 Spy Sats and SAR Today
It all starts with the moon.
This month we’re celebrating the 52nd anniversary of America’s lunar landing with Apollo 11. This mission holds a very special place for team EO59. My grandfather, Richard Picard, was an Apollo engineer who together with his team at General Motors (yes, the automobile industry was mobilised for Apollo) produced and installed the Apollo inertial navigation system. One of the most remarkable things about Apollo that was taught to me as early as I can remember was that it did with solid state electronics tasks that we are still doing today. The heart of many core systems conceived and implemented in the heat of space race have remained the same.
Richard Picard, Apollo navigation engineer
Apollo Radar
The Apollo lunar module, LM, carried on board a sophisticated suite of solid state and FM band radar systems for a number of life critical applications. These systems guided the LM in its docking with the Columbia command module, inspected terrain conditions as the LM floated over the lunar surface to land, and provided range to landing data. These systems were rigorously tested and evolved in an fantastic collaboration of American industry in a tremendously short period of time - five years from contract to landing. These radar systems had a fascinating evolution and problems that are ironically still familiar to current space radar platform operators 50 years later. You can read the official NASA technical note here.
Program schedule.
Apollo Imaging Radar
Apollo didn't only carry onboard radar for docking and landing but also SAR imaging radar to create both a de/polarised view of the lunar surface from a 3.8in wavelength radar array. This was part of a multispectral remote sensing effort that was corroborated with the U.S. Geological Survey and later with collaboration from the Soviet Luna 16 data produced a fascinating report. The imaging results were very similar to what we would see from modern Earth radar imaging systems if they were to observe a desert area absent vegetation with terrain variation. Take a look!
At the same time, another radar was quietly in orbit…
Quill was an ultra-secret mission to develop signals intelligence products (SIGINT) from orbit, similar to Corona. This flight test would be brought to orbit by the resilient Agena launch vehicle with Quill built into the nose cone. It would last 96 hours and Quill would orbit and record radar data to both a magnetic tape that would be jettisoned and captured by an aircraft as it re-entered the atmosphere and a UHF base station. Quill was launched in 1964, around the same time that the Apollo radar systems were in full production. It carried on board a radar system originally developed by Goodyear for the F-4 phantom fighter aircraft. The goal of Quill was much the same as we have today on the Sentinel space craft and all other civilian and military synthetic aperture radar (SAR) space craft. The very first SAR image from non-Soviet sources was printed in the Washington Post in 1960.
Courtesy NRO
The same challenges 50 years later
The data film from Quill would resolve similarly as SAR does today from Sentinel1 and other sensors. Visually it represents not Gaussian static on an untuned television but instead a puzzle of intricate various shaded polygons. The challenge for end-users would be the same, finding ways to develop meaningful information from this result. Quill used a unique approach of converting radar data in real time recording to an optical layer transposed in high resolution on the same record of the tracking camera optical system.
Current reflectivity map example
SAR Truth’ing
Even now, over 50 years later we are still hearing that this technique cannot be possible, how can it be to determine from space motion of 1mm on the planet’s surface? Perhaps we owe this to the very secretive nature of project like Quill to use the technique without public awareness. Again, in a funny twist of fate, the intelligence community used the same techniques we use today to judge the satellite’s accuracy on target - corner reflectors. Of course, the design of these has advanced quite a bit over time but the concept has remained the same. This article on the efficacy of corner reflectors by Dr. Armin Doerry at Sandia national labs is tremendously helpful at understanding how their value and technique. He included a full page dedicated to a quote from Will Rogers which any one working with SAR in its various forms will appreciate.
Image from MDPI
Black Magic
What do you do when you hit a home run? Take the bench and sit it out the next few innings. For decades this has been the fate of SAR programs globally. Time and again they have proven their value but the world is built on interpretation of visual imagery. Engineers and managers are more comfortable with a device they got their hands dirty putting in the ground. There’s an undeniable mystical quality to SAR that gets more cryptic as you add acronyms to the front - InSAR, DinSAR, PSinSAR, PSinSAR/TS. The sensors have advanced, the algorithms and processing techniques as well. However, nothing has moved as fast as the processing and visualisation systems. Our industry of scientists, program managers, software engineers, and production teams have made tremendous leaps in improving understanding of this technique in the past decade. Fuelled more than anything by the openness of Sentinel 1. A SAR platform that is relatively easily to access and learn on. This helps to demystify a technique and a magic that lived in the cloak and dagger world for most of its lift. There’s no better answer to the questions of today than: “Hey, go put a reflector in your backyard and adjust it up or down a half centimetre once in a while and you’ll see it in your PSinSAR/TS data just like you would see your infrastructure move.” No longer are the reflectors in unreachable sites, or the source expensive or obscure, now there is no longer a practical reason for the magic of SAR. Its up to this community but also engineering practitioners to put this tool to use! After all, these space craft are flying over every inch of the Earth every day. The real question is, are you making best use of the invisible data all around you?
Kodak’s role in Quill SAR
Fast Forward
If we were to launch an Apollo program in 2021 it would likely have much the same basic engineering principles but you would see the ‘glass’ of today increasing the understanding, data gathering and interpretation. Quill recorded its data onto Kodak film that was brought back to Earth and rapidly developed for interpretation and comparison to the ground station data. Another great connection to me, being from Rochester and surrounded by Kodak my whole life. Kodak was at the heart of the start of SAR and remote sensing. Today we no longer have to relay on that film to gather and process data. We can use GIS systems that appear on the super computer in your pocket to connect in near realtime to a spacecraft in orbit and relay data to you. Sentinel 1 may be orbiting every 6/12 days but you have countless other spacecraft to choose from now. You can even use TerraSAR-X and literally get realtime data on your smartphone from space, if you want :)
We are American
There is a phrase I heard recently that was simple but accurate. We at EO59 are one of the few commercial InSAR efforts led by an American and a Virginia based company. There’s something undeniably special in the history of our company. We share roots in Estonia, the headquarters of the Soviet space communications program. A group that made countless space firsts. Collaboration, competition, and a spirit that we will overcome any obstacle filled Apollo, Quill, and the team at EO59.
We are here not as single entity but to inspire and push all of the SAR community forward. We see no value in secretive competitive advantages, but rather opening the kimono to build awareness of a technique that can improve the safety, efficiency, and understanding of the world around us. We will build the best visualisation tools, evolve the most advanced AI powered algorithms, use any space craft, and train the best engineering teams. Together with everyone fighting for remote sensing we are writing a chapter in the book of Earth observation built on a personal history of space exploration and remote sensing.
