International Coordination for Spaceborne Synthetic Aperture Radar: A Personal Impression [Technical Committees] | IEEE Journals & Magazine | IEEE Xplore
in IEEE Geoscience and Remote Sensing Magazine, vol. 12, no. 1, pp. 186-189, March 2024, doi: 10.1109/MGRS.2024.3354032.
Abstract: Provides society information that may include news, reviews or technical notes that should be of interest to practitioners and researchers.
URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10461633&isnumber=10461564
I arrived late on a warm autumn night in Frascati, a city near Rome and well known to remote sensing scientists and engineers for being the place to stay when visiting the European Space Agency Centre for Earth Observation (ESA ESRIN) in Italy. Although it was not my first visit to the ESA ESRIN, I was particularly excited to be there as I was going to attend the Second Workshop on International Coordination for Spaceborne Synthetic Aperture Radar [1] on the following day, which was my first “real,” i.e., in person, event after most of the COVID-19 restrictions had been lifted. Actually, this Second Workshop (in my mind, I called it the Elachi Workshop, as explained later) was originally scheduled for May 2020 but had been postponed three times due to the pandemic. As the organizers realized that an in-person participation was crucial to achieve the goals of the workshop, they decided to wait until this was possible.
This article introduces the activities and efforts of the SAR (synthetic aperture radar) Coordination Group and my personal impressions from the workshop. I also emphasize the need for this kind of coordination, possibly motivating similar activities.
It was the former director of NASA’s Jet Propulsion Laboratory (JPL), Charles Elachi, who recognized the need and importance of coordination and cooperation among space agencies. Being committed to remote sensing with SAR, he had the ingenious idea of establishing a workshop as a means to facilitate regular contact and cross fertilization among space agencies.
The key elements of the workshop objectives were to identify
new trends in spaceborne SAR missions
areas where coordination of data acquisitions can lead to improved science processing efficiency
organizational challenges in achieving coordination among agencies
the recommendations needed to acquire spatially and temporally dense SAR datasets.
And further, to discuss
how to maximize scientific/user exploitation of present and planned SAR missions
interest and value in having common test sites for calibration and validation
an optimized systems approach to the overall constellation of planned and proposed missions
the desirability of coordinating future missions and the roles of the commercial and NewSpace sector to achieve future scientific and user objectives
Develop a road map for addressing the aforementioned challenges and development areas
Further promote the international coordination for spaceborne SAR.
Three working groups (WGs) that include radar systems experts, users, and scientists from various organizations have started their activities following the first workshop in 2018 (Figure 1). The preparation of the Second Workshop included adding three thematic areas (TAs) to further deepen collaboration across the WGs’ topics.
I had been aware of the First Workshop held at California Institute of Technology, Pasadena, USA, [2] in 2018, but at the time I did not have the chance to participate. Attending the Workshop was by invitation only to limit the number of participants and ensure an efficient process with committed attendees.
I am an active member of the IEEE Geoscience and Remote Sensing Society (GRSS) [3] and engaged in its Technical Committee (TC) [4] on Instrumentation and Future Technologies (IFT). The IFT is a global, multidisciplinary network of engineers and scientists that emphasizes remote sensing instruments. One of the IFT’s aims is [5]
to foster international cooperation in advancing
the state of the art in geoscience remote sensing
instrumentation and technologies.
Which is in-line with the workshop. Added to this, the GRSS seeks to cooperate with space agencies. The allure of the GRSS is that it supports the engagement of its members, which motivated me to seek being invited to the Workshop as a representative of the GRSS. Getting approval from the TC was straightforward, unbureaucratic, and fast.
Organizing a workshop to be attended by nearly 100 scientists and engineers from almost all the countries and space agencies flying spaceborne SAR sensors, in addition to participants from the commercial sector, is a big piece of work. Moreover, there is no guarantee for success or even fulfillment of its intended purpose. Having been involved in the organization of workshops and conferences, I know that there is more than one possible pitfall, such as not reaching any (or even worse, making superficial) decisions, unengaged and bored participants, too many (possibly irrelevant) talks, diverging off-topic discussions, and participants not getting enough chance to interact, just to name a few.
As I expected, the Workshop cochairs were experienced and very successfully managed to avoid the aforementioned pitfalls. I am convinced that one of the key elements to the success of a workshop is its agenda. The Second Workshop was constructed to guide and engage participants to reach practical and useful recommendations.
After Maurice Borgeaud (see Figure 2) welcomed the participants and introduced the Workshop, Elachi presented the overall progress since the First Workshop. To give an example, the First Workshop formulated four recommendations concerning easy SAR data accessibility, coordinate data acquisition and processing, an optimized constellation system approach, and sharing calibration and test sites. The overall progress is evaluated by the degree to which these recommendations have been addressed or implemented for mutual benefit. (The Workshop program and the presentations are available in [1] and provide detailed information.) Then, the status of each WG was presented:
WG 1: “Present and Future Data,” by Shin-Ichi Sobue [Japan Aerospace Exploration Agency (JAXA)]
WG 2: “Future Imaging Systems,” by Paul Rosen (NASA/JPL)
WG 3: “Data Exploration,” by Bruce Chapman (NASA/JPL) and Heather McNairn (Agri-Food Canada).
Maurice Borgeaud introduces the Workshop and presents the statistics of the participants.
This was followed by the presentation on TAs 1 and 2 by Cathleen Jones (NASA/JPL) and Åke Rosenqvist (JAXA) (see Figure 3) just before an extensive coffee break. The keynote talks that followed were “Future Applications of SAR Missions in Cryosphere Science,” by Eric Rignot; “Future SAR Technologies and Mission Concepts,” by Alberto Moreira; and “New Space for SAR,” by Darren Muff. The three talks were an appetizer, presenting the general and new trends in SAR. Later, representatives of the individual space agencies (see Figure 4) presented their SAR activities and future plans, followed by a general discussion that included all the participants. The first day concluded with visit to ESRIN’s Phi-Experience [6] and an icebreaker gathering (see Figure 5).
The conference dinner provided an excellent opportunity for discussion and exchange of ideas
One of the most common mistakes when scheduling the agenda for workshops or meetings is not giving enough time for exchanges among the participants. Instead, most often, the schedule is packed with presentations without giving the audience the opportunity to deepen its understanding or discuss the content. This was different in this Second Workshop. People were gathered in groups and talking. As I walked around, I could hear that most of the discussions were about the context of the Workshop. In my opinion, this is indicative of a successful workshop.
The last years have witnessed several new emerging commercial companies investing and developing their own SAR satellites. The cost of these small instruments is a fraction of that of big and complex SAR systems build and contracted by space agencies. A question (concern) is, if and how NewSpace activities are competing with the SAR activities of space agencies. To answer this question, the first hour of the Workshop’s second day was dedicated to presentations from NewSpace companies, followed by a panel discussion. In short, it was concluded that NewSpace companies and space agencies are complementary as the former have a commercial orientation and serve a different market with (mostly local) products, whereas the latter have a stronger scientific orientation, aiming for global, well-calibrated SAR products.
An effective engineering approach is to divide big “problems” into subtopics that can be solved more easily. Following this reasoning, the main part of the second day was dedicated to splinter meetings, first for each of the WGs, and then for the TAs. A dedicated program was set up for each splinter group, giving the discussion a framework that lead to tangible recommendations, which were then presented on the third and final day of the Workshop.
It is often not easy to comprehend space agencies, which, when viewed by outsiders, seem to be obscure and diverse constructs. Moreover, their higher-level strategies are often influenced by politics and other external factors. Thus, if participants were too high in the hierarchy, they would not be able to understand the technical challenges associated with establishing real cooperation. Engineers and scientists deeply involved in radar instruments or remote sensing data evaluation don’t necessarily have a sufficient impact. The best way to achieve a workshop’s goals is (as always) to carefully choose the participants. Knowing the trends in application, technologies, and industry is crucial to understanding and planning for a successful coordination among space agencies.
Individual workshops, even when carried out at regular intervals, are not the only place/time where the actual coordination occurs. The engagement among space agencies is a continuous process on many levels, mainly initiated by the workshops. The long-term aim of the initiative is to maintain coordination and keep the partners engaged. The presentation reports [1] show that after the First Workshop, several organization and coordination meetings were held in addition to sessions at conferences that included various gatherings and networking. (Incidentally, networking is one of the main purposes of GRSS conferences.) One of the activities after the second meeting was organizing a session on “Coordination and Cooperation of International Spaceborne SAR Missions” at the 2024 IEEE International Geoscience and Remote Sensing Symposium in Pasadena [7].
The questions to be asked are if and what has the International Coordination for Spaceborne SAR achieved? To answer these questions, it should be noted that the achievements may often be subtle and are not necessarily intended to be more visible due to the complex nature of the aforementioned international coordination and cooperation. Nevertheless, for the sake of completeness, here, a few examples are mentioned.
An example from WG 1 on data access is the Disaster Observation Planning Platform, which synergizes different user and operator information layers to support timely disaster response and perform collaborative operations effectively. Further, this WG is working on joint sea ice and oil spill observation by the C and L bands and subsequent analysis of satellite imagery by different space agencies.
Another example, from WG 2, is the specific possibilities and achievements for planned and proposed SAR missions. Here, an optimized systems approach to explore mutual benefits for SAR missions of different space agencies is envisaged. Despite the fact that each organization, understandably, optimizes its SAR system for its own needs, there are opportunities for enhanced or new capabilities, such as
better filling of imaging gaps and higher repeat coverage by a slight adjustment of the orbit, node crossings, or local crossing time
quick responses for time-critical applications.
better continuity of observations over a long (multidecadal) period of time
new multisystem capabilities, including bistatic and multi-interferometric observations
left/right imaging coordination to overcome shadowing.
This has, for example, been successfully implemented for the NASA/Indian Space Research Organisation (NASA-ISRO SAR Mission) [8] and Sentinel-1 [9] missions, which are coordinated to achieve mutual full coverage of Arctic and Antarctica.
An activity of WG 3 is SARCalNet, which, once implemented, will provide reliable, predefined information about SAR calibration targets, both natural and artificial, thus facilitating joint calibration and performance evaluations. SARCalNet will assist postlaunch calibration/validation of SAR sensor data, and, when possible, also provide access to the datasets used to calibrate and monitor the performance of specific sensors. Currently, the Committee on Earth Observation Satellites Working Group on Calibration and Validation SAR subgroup hosts an SAR target database [10].
In conclusion, I can definitely say that cooperation among the space agencies on SAR has been successfully established. The steps taken have already been fruitful and encouraging. The task is to maintain and develop this cooperation. We are already looking forward to the Third Workshop, which is scheduled for the first week of November 2024 and will be hosted by JAXA (Figure 6).
No comments:
Post a Comment