When the Hunga Tonga–Hunga Ha’apai volcano explosively erupted in Tonga in January, the world was captivated at first by the images returned from satellites in orbit. But it was the immediate images the general public largely did not see at first that proved far more useful in assessing conditions on the islands of the South Pacific nation in the immediate aftermath — when air travel was not possible.

And this is also true for most natural disasters, including the severe droughts, fires, and floods that have ravaged other parts of the world — in particular the Canadian province of British Columbia, an area — like most of the world — routinely monitored by the RADARSAT-2 and the RADARSAT Constellation SAR (Synthetic Aperture Radar) missions.

SAR allows the various RADARSAT platforms to capture detailed and routine images of every point on Earth’s surface, regardless of weather and environment conditions, daily and with exact ground track repetition every 24 days for RADARSAT-2 and every four days for RADARSAT Constellation.

The first RADARSAT mission launched on November 4, 1995. RADARSAT-1 was a collaborative effort between the United States and Canada, with a sole focus to deliver remote sensing Earth observations through its then-powerful synthetic aperture radar instrument. It was capable of obtaining images night or day through clouds, smoke, and haze.  

Owned and operated by the Canadian Space Agency, the initial lifespan of the project was five years, but it went on to provide service for 18 years.

Backed on knowledge gained and the demand for its imagery, RADARSAT-2 launched on December 14, 2007, with improved resolution range capabilities, from the eight to 100 meters of RADARSAT-1, down to one to 100 meters.

Unlike RADARSAT-1’s launch from Vandenberg Air Force Base, California, on a Delta II rocket, RADARSAT-2 was launched from Baikonur on a Soyuz-FG/Fregat as U.S. agencies believed it was a threat to national security.

June 12, 2019, saw the RADARSAT program return to Vandenberg for launch on a SpaceX Falcon 9 rocket. This time, the RCM (RADARSAT Constellation Mission) consisted of three satellites — smaller than those of the singular RADARSAT-1 and -2 missions.

This trio of RCM craft is tasked with providing more real-time information while reducing the repetitive orbital pass over of an exact location to once every four days

This strategy enables RCM to support the mission’s three pillars: disaster management, maritime surveillance, and ecosystem monitoring.

RADARSAT during payload integration work – via CSA

After weather events like the fires and flooding in British Columbia and the geological event of the underwater volcano eruption in Tonga, NASASpaceflight’s Chris Gebhardt and Nathan Barker spoke with the Canadian Space Agency’s Guennadi Kroupnik, Executive Director, Space Exploitation, to understand the progress of the RADARSAT-2 and RADARSAT Constellation missions and how they assist with these global events.

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“We are actually quite happy with the performance of the RADARSAT Constellation Mission,” said Mr. Kroupnik. “We are fully compatible with the mission requirements, and even some elements of the mission are performing better than expected.”

“One of the examples is thanks to the precise orbit injection by SpaceX and the fact that we, in the course of testing and experiments, demonstrated that we can achieve the same coherent change detection performance [repetitive ground pass over the same location] with a 120-meter radius orbital tube instead of a 100-meter radius orbital tube. The 20-meter difference in radius in the number of maneuvers and use of fuel onboard, giving us hopes for a longer mission duration,” Mr. Kroupnik added.

To specific natural disaster events and how RADARSAT assists relief efforts, “Canada is one of three founding members of the Charter on Space and Major Disasters. And since the establishment of that organization more than 20 years ago, Canada has been contributing synthetic aperture radar imagery to help disaster relief all over the world.”

“We have seen an increase in the number of activations of the charter due to the severe weather events all over the world. If we look globally, there were 50 activations in 2021. Distribution, roughly 60% floods, 40% ocean storms and winds.”

Wow. Amazing that we can now image something like this.. but horrifying for the people of Tonga who are in my thoughts. https://t.co/2jcrfSMtVF

— Jonathan McDowell (@planet4589) January 16, 2022

Recently, the eruption of the underwater volcano in Tonga was quite interesting because we worked in partnership with NASA on that, with the chief scientist of NASA’s weather center. And we managed to take images of the area before the disaster, when the eruption occurred, and after the eruption.”

“And according to NASA, those images represented a first of their kind, high-resolution SAR spotlight images in C-band of the ongoing volcano eruption.”

Specifically related to the extreme drought, fires, and then severe flooding that impacted British Columbia in Canada, Mr. Kroupnik noted that RADARSAT Constellation and RADARSAT-2 were integral in helping teams create maps of the impacted area for search, rescue, recovery, and relief operations. In this particular case, RADARSAT data provided 24 information products and 24 maps published on short notice and with low latency by the Emergency Geomatics Services.

“Last year, first the fires and then floods in British Columbia which were having a lot of impact on the life of people and caused a significant loss of property… the RADARSAT Constellation and the RADARSAT-2 data has been in big demand to help teams on the ground to assess the impact of the floods and to charter the best course of actions to mitigate the consequences.”

Part of this rapid response in terms of disaster management from the RADARSAT Constellation Mission specifically stems from how it was designed. While repetitive ground passes over the same area with the same lighting conditions occur every four days for direct comparison of imagery (otherwise known as coherent change detection), the constellation is also capable of seeing the same locations at least daily — which enables more real-time application of the data even if it is not an exact lighting or angle match.

“Having an opportunity to image the same area on a daily basis provides a lot of support to people on the ground because it, in a very dynamic way, provides them with actionable information of what’s happening.”

In fact, RADARSAT Constellation can image 90% of the Earth’s surface daily — except for a small area over the Antarctic. But over the Arctic, “we are taking the whole area four times per day,” noted Mr. Kroupnik. “So that represents a very significant improvement over the previous missions.”

This Arctic coverage provides the opportunity for real-time ice monitoring in support of maritime traffic, monitoring of fisheries, and other elements of the maritime environment.

“RCM, as well as RADARSAT-2, have a very strong maritime domain awareness focus, and a lot of acquisitions are over the three oceans surrounding Canada,” said Mr. Kroupnik. “And one application that has a lot of impact on economic and social aspects in Canada is ice monitoring and ice awareness.”

“It serves in ensuring secure navigation in Canadian waters. It serves to support fisheries as well as to identify illegal fishery activities and oil pollution, for example, as well as surface winds derived by Environment and Climate Change Canada from RCM data fed into the numerical weather prediction models… serving to improve weather forecasting in Canada.”

The St. Lawrence Estuary seen in this radar image acquired by the RADARSAT Constellation Mission on February 28, 2021, when drifting ice floes formed a mosaic in motion. (Credit: CSA)

Even more, “RCM data is used, among other things, in the assessment of the safety of infrastructure,” related Mr. Kroupnik, “especially in the arctic these days where the thawing of permafrost represents a significant challenge to the infrastructure: roads, bridges, and some other elements.”

RCM data is also used to monitor crop production and inventory. 

But this type of remote sensing comes with regulations.

“Remote sensing is regulated in many countries, including in the United States and Canada. And this is why we have a RADARSAT Constellation Mission data policy which tries to reconcile the requirements of the [Remote Sensing Space Systems Act] with the socioeconomic benefits of open data,” said Mr. Kroupnik.  

Public access to RADARSAT images can be obtained via an account with the Earth Observation Data Management System, hosted and managed by Natural Resources Canada.

The second category of access is for vetted users, those who have been screened by the regulator in Canada, Global Affairs Canada. Currently, there are 109 vetted users, including 37 representing Canadian industries, 32 representing Canadian universities, and 18 sharing partners. 

Sharing partners represent the third access point to RADARSAT data: the international partners. “In this particular case, it’s NASA and NOAA who have access to the data from the Earth Observation Data Management System,” said Kroupnik. 

And requests for the data are numerous. “In January, nearly 13,000 images were ordered from the RADARSAT constellation archive per week. We are talking statistics per week,” related Mr. Kroupnik. “It’s not necessarily all the newly acquired images. It could be some archived images.”

“Whereas NASA and NOAA combined ordered roughly 12,000 images. So that shows that RADARSAT Constellation imagery is considered to be of great value for our partners in the United States, and we are very happy about that.”

The future

Waiting until the previous version is due for replacement before beginning work on the next generation is seldom advisable, and that remains true with the RADARSAT program – where future improvements are already in work.

“The design life of the RADARSAT Constellation Mission is seven years. Nevertheless, we have started very focused efforts looking at opportunities to extend the life of RCM,” said Mr. Kroupnik. 

The greater Montreal region. Dark colors show smooth surfaces (water, highways, airport runways); pale and grey indicate developed areas (downtown and the suburbs); brown and green tints are forested areas; and blue-green represents farmland. (Credit: RADARSAT Constellation Mission imagery; Government of Canada)

“But we have also started thinking about a follow-on to RCM. And we were successful in getting $9.8 million dollars in the last federal budget, the federal budget of 2021, to start collaborating on a follow-on to RCM.”

“We have arrangements with several like-minded nations who have capabilities that we can mutually benefit from, as well as thinking about a next generation of a sovereign system to succeed the RADARSAT Constellation in the future.”

Part of those plans will involve not only additional satellites but also an improvement to the ground network as well.

“I’m very happy to tell you that in the same budget, 2021, the government of Canada allocated significant funds, $80 million dollars to, among other things, improve on ground segment capabilities. Especially ground stations including Inuvik satellite facilities, which are very well located in northern Canada.”

(Lead image: The RADARSAT constellation. Credit: MDA)

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