Contents The Instrumentation and Future Technologies Technical Committee’s (IFT-TC) second summer school took place in Auckland, New Zealand, from 30 January to 3 February 2023. The IFT Remote Sensing Summer Schools (IFT-R3S) aim to promote future research in remote sensing; connect Master students, junior Ph.D. students, recent graduates, and young professionals with research groups linked to the IFT-TC; and highlight the educational activities of the IEEE Geoscience and Remote Sensing Society (GRSS). The IFT-R3S focuses on remote sensing instrumentation with aspirations to develop and foster expertise and capacity in this sector. As the first technical activity after the recent formation of a New Zealand GRSS Chapter, a primary objective was to foster connections within New Zealand and the Oceania Region and to heighten New Zealand’s visibility and ambitions in the Earth-observing sector.
The first IFT-R3S Summer School was held in Barcelona in July 2019. This was intended to initiate a series of ongoing summer schools (annual or biannual) moving to different towns/continents and hosted by other IFT-TC groups. Accordingly, this summer school, hosted in New Zealand, was first approved and planned for 2020 but was delayed until 2023 due to the COVID-19 pandemic. Like the inaugural IFT-R3S, foremost experts were enlisted to teach the curriculum, which focused on radar remote sensing. The topic list included sensor and mission design and theory and the state of the art in radar, including sounding, altimetry, synthetic aperture radar (SAR), bistatic radar, and signals of opportunity (SoOp). Through a concentrated emphasis on radar remote sensing, we were able to cover topics in deep detail, avoiding keeping the lectures at a superficial overview level. For context, at the opening event, the GRSS and the IFT-TC were introduced to provide a broader overview of the GRSS and the IFT-TC. The in-depth topics for this edition were principles of radar, sounders and altimeters, SAR, SAR interferometry, and reflectometry with GNSS and SoOP. In future IFT-R3S editions, the in-depth topics might vary, allowing the school to progressively cover the full range of IFT-TC working group topics in detail.
The school was open to any interested people, with a specific emphasis on engaging master’s students, junior Ph.D. students, and young professionals with an engineering or similar background. Ideally, this would motivate the consideration of careers in remote sensing in general and instrument and future technologies in particular. We anticipated a majority of students from IEEE Region 10, particularly from New Zealand and Australia.
Hosted by the University of Auckland’s (UoA) Faculty of Engineering, the school was cofunded by the GRSS, the New Zealand Space Agency (NZSA), and the UoA. The UoA provided the venue, logistic support staff, onsite organization (including coffee breaks), and funds to house students. University housing at walking distance from the faculty was available since we scheduled the event during the academic summer break. Students not residing in the Auckland area were provided university housing as a part of their registration. IEEE and NZSA funds were used to support speaker travel, accommodation, and domestic and international scholarships for students.
The application to register for the IFT-R3S was open from 29 September 2022 to 23 2022 December. A total of 42 applicants were affiliated with universities, institutions, or companies from 22 different countries. Formal invitation letters were sent to 33 applicants.
An unexpected finding was that the vast majority of non-New Zealand local applicants were citizens of countries ineligible for the visa waiver/electronic travel authority (ETA). For those countries, and at that time with New Zealand recently reopening its borders, visa processing times were lengthy and unpredictable. Only two of the invited students from non-ETA-eligible countries were successful in attaining visas despite projected visa processing times suggesting otherwise. Several applicants who were offered travel scholarships declined their invitations with concerns that the visa process was too onerous and uncertain. The final number of participants in the summer school was 11. Of these students, eight were living in New Zealand, one was from Thailand, one was from the Philippines, and another was from the United States. All nonlocal students were provided travel scholarships.
A “Severe Storm”
The summer school commenced with an evening event on Monday, 30 January, which coincided with a local holiday known as Auckland Day. Typically an occasion where the beaches are crowded and there are many yachts sailing, this year was dampened by continuous rain. Just days prior, the international airport had flooded, as had motorways, residences, and businesses. The IFT-R3S was intentionally planned as an in-person event, with hands-on laboratory-based exercises an integral part of the experience. Unfortunately, Auckland airport’s closure coincided with several of the international lecturer’s flights, leaving them unable to secure alternative bookings. Fortunately, all the students were able to make it, although at least one had to relocate due to flooded accommodation. Accordingly, some lecture portions were reconfigured for virtual delivery. We were fortunate in that those conducting hands-on laboratory sessions were able to make it to Auckland.
Although the airport had reopened prior to the commencement of the IFT-R3S, the rain continued throughout, causing havoc throughout Northern New Zealand, including Auckland. Despite these challenges, we gathered for the opening of the second IFT-R3S and the first event of the New Zealand GRSS Chapter. Organizer, IFT-TC Cochair, and New Zealand GRSS Chapter Chair Delwyn Moller welcomed everyone to the event [Figure 1(b)]. This was followed by Prof. Tony Milne, ex-GRSS president, who presented a talk with an Oceania perspective by highlighting the REACT (Remote sensing Environment Analysis and Climate Technologies) technical committee’s role in the Pacific Island Advisory Group’s Group on Earth Observation (GEO) [Figure 1(a)]. Prof Wolfgang Rack, University of Canterbury and IFT-TC UAV working group lead, then gave an introduction to the IFT-TC as the convener of the summer school (Figure 2).
(a) Former IEEE GRSS president Prof. Tony Milne providing a welcome to students and lecturers on behalf of GRSS. (b). Local University of Auckland organizer and New Zealand GRSS Chapter chair opening the IFT summer school.
Participants at the welcoming event at the “Terraces” in the new University of Auckland faculty of engineering building.
While the welcome was in progress, Auckland’s mayor declared a state of emergency, resulting in an order to close public educational institutions, including tertiary institutions, for the upcoming week. However, our school was given special permission by the vice chancellor’s office to continue its operations. With this permission in hand, the Mission Operations Center director for the Te Pūnaha Ātea Space Institute, Chris Jackson, provided an introduction to the institute and guided a tour encompassing the Mission Operations Control Center, clean rooms, and environmental test facilities [Figure 3(a) and (b)]. The evening concluded with continuing hors d’oeuvres and drinks.
Mission Operations Director Chris Jackson conducted a tour of the Te Pūnaha Ātea/Auckland Space Institute’s facilities: (a) the mission control center and (b) environmental test facilities.
The focus of the summer school was on radar remote sensing instrumentation design and principles of operation. The technical program and logistics experienced daily dynamic changes due to the local state of emergency, business closings, and adverse road conditions that posed travel challenges for local technical and support staff. Despite these obstacles, almost the entire originally planned curriculum was successfully covered. In the remainder of the article, we summarize the summer school activities and content.
Day 1: Radar Principles, Altimeters, and Sounders—Introduction to Synthetic Aperture Radar
The first technical day started with several lectures. The first was “Radar Fundamentals” with Prof. Mahta Moghaddam (Figure 4). This was a virtual delivery due to the travel disruptions from the severe storm. Topics covered included an introduction to active remote sensing and the radar equation, followed by methods of target discrimination, including angle, range, and Doppler. Design criteria and trade space with respect to signal-to-noise ratio (SNR), resolution, and ambiguities were introduced. The lecture then continued into the basics of radar scattering with the concepts of surface, volume, and multiple-bounce scatter, including polarimetry and the Stokes matrix. The comprehensive lecture concluded with signal statistics contrasting deterministic and random targets, Rayleigh fading, and speckle.
A virtual lecture on radar principles by Prof. Mahta Moghaddam commenced the technical portion of the summer school.
Dr. Brian Pollard delivered the subsequent lecture (in person) on radar applications. He talked about pulse compression and deramp with application to radar altimetry and introduced the idea of achieving subband-width resolution via waveform tracking. This was contrasted with applications introduced by state-of-the-art technology advances in automotive radar for low-cost W-band compact and capable sensors. The lecture further explored range/velocity measurements and the engineering behind landing/proximity operation radars, using a real-world application of the Mars lander design and discrimination of the angle of arrival. The lecture concluded with another illustrative design example: CryoSat. This portion encompassed the concepts of pulse-limited versus beam-limited design while also introducing delay-Doppler techniques.
Following the morning’s foundational lectures, we transitioned to hands-on and consolidation exercises. Prof. Rack introduced his drone-based snow radar and the measurement principle as well as the requirements and challenges for cryospheric applications (especially sea ice thickness) (Figure 5). With this background in place, Prof. Rack conducted a practical exercise to explore bandwidth and range resolution, using a vector network analyzer and a drone antenna [Figure 6(a) and (b)]. The horizontal distance to the corner reflector was measured with a reflector, which the students constructed.
Prof. Wolfgang Rack introducing background material prior to his hands-on exercise.
A practical laboratory exercise for students. (a) Master’s student Aston Taylor configuring the vector network analyzer and (b) measurements of corner reflector distances and sensitivity.
The day of radar foundational principles concluded with a lecture transitioning into SAR. Dr. Michelangelo Villano delivered an in-person lecture on SAR principles, consolidating concepts of radar functionality, resolution, the principle of a synthetic aperture, radar measurement, and data acquisition as well as the principles of range and azimuth compression. The lecture also addressed image distortions such as foreshortening and layover. This set the stage for the following day, which would focus entirely on SAR.
Day 2: All-Day Synthetic Aperture Radar!
Day two continued with Dr. Villano teaching a full day on SAR [Figure 7(a) and (b)]. The morning was dedicated to in-person lectures, while the afternoon transitioned into hands-on practical teaching sessions. The first lecture addressed SAR processing fundamentals, covering the SAR impulse response, the SAR transfer function, derivations related to the orbital geometry of SAR, ground and effective velocities, range history approximations, monochromatic SAR image formation, polychromatic SAR image formation, motion and orbit compensation algorithms, and multilooking.
Dr. Michelangelo Villano teaching SAR principles and practice. (a) laboratory workshop and (b) lecture.
During Session 2, the focus shifted to SAR imaging modes, encompassing a range of standard SAR operation modes like ScanSAR and Spotlight, alongside techniques like azimuth phase coding. The session extended to more advanced concepts, including the implementation of beam steering. SAR data flow, impulse response function, range cell migration, window functions, and speckle were also covered.
The afternoon was composed of two workshops designed to provide students with practical insights into the real-world implications of the lecture content. The initial workshop, led by Dr. Villano, took the form of a computer-based session aimed at deepening the understanding of SAR fundamentals. The workshop covered range and azimuth signals and compression as well as the processing of raw data to produce the SAR image. The exercises required changing signal, system, and processing parameters and observing the impact on output plots.
The second workshop centered on SAR instrument parameters, designed to familiarize the students with the basic parameters of timing, range and azimuth ambiguities, SNR, minimum antenna area constraints, their relationship to typical SAR requirements, and their impact on the system design. The workshop also explicitly assessed how the antenna pattern impacts performance in relation to the aforementioned parameters.
Day 3: Synthetic Aperture Radar Concludes, and Signals of Opportunity Begins
The third technical day commenced with two lectures to conclude the SAR portion of the curriculum. Dr. Scott Hensley delivered virtual presentations on SAR instruments and missions followed by SAR interferometry. The lecture on SAR instruments and missions encompassed not only airborne and spaceborne Earth-observing systems in the past, present, and future but also extended to planetary missions. The SAR portion of the summer school concluded with interferometry, where Dr. Hensley covered the principles of interferometry and interferometric correlation properties and how these might be exploited for geophysical measurements. As a brief interlude, Andrew Johnson, deputy head of the NZSA (cosponsor of the summer school), made a virtual address and welcome (originally intended as an in-person address) (Figure 8).
In the first afternoon session, Dr. Andrew O’Brien introduced GNSS-R and SoOp (Figure 9). He began by explaining how SoOp can be exploited to form a bistatic radar and then gave examples of missions and instruments, example measurements, and models. Historical applications of SoOp, such as ocean altimetry, soil-moisture measurements, ocean winds, and inland inundation, were presented. Dr. O’Brien’s inspirational talk concluded with insights into current investigations and advances within this growing research field.
As an intersession break, the attendees visited the facilities for the UoA’s Auckland Program for Space Systems (APSS). Jim Hefkey provided an overview of the undergraduate CubeSat mission design competition that brings together multidisciplinary teams to collaboratively formulate and design an end-to-end mission (Figure 10). Rocket Lab supports the program by launching the winning satellite.
The day concluded with Dr. Scott Gleason conducting a lab exercise for GNSS-R Level 1 calibration overview and simulation (Figure 11). Using a simulator, students could generate example GNSS-R observations for a receiver on a satellite in any orbit. These provided the input data needed to perform a calibration with an off-line script.
Day 4: Rocket Lab Tour, Final Lecture, and Pizza!
The final day commenced with a tour of Rocket Lab (Figure 12). Participants were guided through the complete fabrication and assembly facilities, getting a first-hand view of launch vehicles in different stages of assembly. Rocket Lab’s Space Ambassador encouraged those interested to reach out for career opportunities.
The students returned for the last technical lecture, which was given virtually by Prof. Chris Ruf (Figure 13). This lecture concluded the SoOP portion of the course and went through the sensor design process, from science objectives to instrument engineering requirements. The IFT-R3S summer school concluded with a pizza lunch at the APSS lab and a demonstration of the Rongowai airborne GNSS-R mission’s payload operations (Figure 14).
A final wrap-up with pizza in the APSS laboratory and a demonstration of the Rongowai GNSS-R mission payload operations center.
Summary
The second IFT-R3S encountered a series of formidable challenges. Not only was the event delayed by two years, but it took place within a postpandemic context, where there still existed a notable reluctance toward in-person student engagement. Despite these obstacles, the small group that gathered displayed remarkable interest and enthusiasm, and their feedback was uniformly positive.
Focused on remote sensing instrumentation, and encompassing subjects including foundational radar principles, SAR, interferometry, GNSS-R, and SoOp, the summer school’s curriculum was enriched through a combination of hands-on exercises, workshops, and lectures delivered by experts. A field trip to Rocket Lab and tours of the Te Pūnaha Ātea Space Institute facilities and the APSS showcased local sector activities and career pathways.
In a gesture of support, student participants were offered a complimentary one-year GRSS membership. The event also forged new connections between several of the students and mentors, leading to collaborative initiatives. Another noteworthy outcome has been the emergence of active participation from a number of student attendees who have since become engaged members within the Society. Amid a backdrop of uncertainty, the second IFT-R3S brought together a motivated group of individuals, instilling a sense of camaraderie and enthusiasm for the future of Earth observation.
ACKNOWLEDGMENT
The authors and organizer gratefully acknowledge the GRSS, the NZSA, and the University of Auckland’s (UoA’s) Office of Research Science and Integrity, Deputy Vice Chancellor James Metson, for funding the IFT-R3S. In addition, we would like to specifically acknowledge the following individuals, all of whom helped make the summer school a success in extremely trying and unpredictable circumstances: Andrew Johnson, deputy head, New Zealand Space Agency; Chris Jackson for his tour of the Auckland Space Institute Facilities; Jim Hefkey from the Auckland Programme for Space Systems; Prof. Kevin Sowerby, head of the Department of Electrical, Computer and Software Engineering, UoA, for institutional support of the activity; Prof Gerard Rowe, dean of engineering; Felicity Powell, Education Programme lead, Rocket Lab, for an inspiring tour; and Sunita Bhide and Akshat Bisht for their dedicated laboratory technical support at the UoA before and during the summer school.