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New Dimensions in Transferring Data from the Sea Ice

A quantum leap in data transfers from autonomous monitoring systems (buoys).

  • In Bremerhaven, Starlink satellites have been successfully installed and tested for data transfers from buoys.
  • The greatest challenge in integrating Starlink into autonomous monitoring systems was energy management.
  • The energy problem was solved using extreme energy-saving measures and dynamic data transfer.

Interview with Martin Schiller, an engineer in the Sea-ice Physics Section of the Alfred Wegener Institute, on the latest technological advances in autonomous monitoring systems for sea-ice research.

 

Sea Ice Portal: Mr Schiller, over the past few months you’ve achieved a virtual quantum leap in data transfers for autonomous monitoring systems, or buoys, as you call them. Can you tell us briefly what it’s all about? What will the innovation change?

M. Schiller: That’s right, we also call our autonomous monitoring systems “buoys”, even though most of them can’t float and are deployed on the sea ice. Many of our “buoys” have been transmitting their data to the Sea Ice Portal for years. Normally, this is done via the Iridium SBD Service (SBD: Short Burst Data), a satellite-based two-way service that offers real-time data transfers anywhere on the globe. It’s a straightforward, efficient and packet-based service for frequent, short data transfers between devices and centralised host computer systems and is most effective for relatively small data volumes. But in sea-ice physics, we also work with autonomous monitoring systems that produce extremely large amounts of data. In the past, continuously transmitting this data by satellite was unfortunately too expensive to be feasible. Accordingly, the monitoring systems’ data was stored locally on memory cards, which then had to be physically retrieved. This also meant that if a buoy was lost, its data was lost with it.

During an expedition on the Swedish icebreaker RV Oden in 2023, I first came in touch with the Starlink satellite network from the US aerospace company SpaceX. Given the system’s performance and extremely low operating costs, I wondered whether it could also be used with our data-intensive autonomous monitoring systems.

 

Sea Ice Portal: That’s very general; could you give us some details or examples? What was impossible back then that’s now possible?

M. Schiller: The Iridium SBD Service is packet-based, so it works like sending a text message from your smartphone. Text messages are limited to 168 characters, and it’s the same with SBD. You have to send a number of messages, back-to-back, and each one is relatively expensive. So, if you need to transfer large amounts of data, the costs can quickly add up.

For instance, the autonomous radiation monitoring stations I developed for use on the sea ice produce several MBs of data per day. With Iridium SBD, transferring 1 kB of data costs roughly 1 euro, which means we would have several thousand euros in data-transfer costs for these buoys every day. To transfer these data quantities at a reasonable cost, you need a satellite link that offers high bandwidth and affordable transfer prices.

And that’s where Starlink comes in. Starlink offers global coverage and transfer rates of roughly 50 – 250 MB for downloads and up to 50 MB for uploads. In terms of costs, you have the current basic fee of €72 per month plus a volume-based fee of €2.27 per gigabyte – not per kilo- or megabyte (that is, not a million or thousand times as much)!

 

Sea Ice Portal: What are the greatest challenges with the new system?

M. Schiller: The greatest challenge in integrating Starlink in autonomous monitoring systems is energy management. The systems’ power supply is a 12V battery with a capacity of approximately 100 ampere-hours. An active Starlink antenna needs 30 to 40 W per hour. You don’t have to be a mathematician to see that the Starlink antenna would completely drain the battery in just a few hours. Everyone I talked to in advance told me it was impossible to operate autonomous monitoring stations with Starlink; the power consumption was much too high for them to keep running autonomously for a year, let alone several years.

Another challenge was data management. With our conventional buoys, we could always access the manufacturer’s server, where we could retrieve the data, process it, and ultimately post it on the Sea Ice Portal. The new Starlink integration is an AWI in-house product. The required processes and infrastructure had to first be created by our Computing Centre, ensuring that the data could be published on the Sea Ice Portal.

 

Sea Ice Portal: How did you solve the energy problem?

M. Schiller: Through extreme energy-saving measures and dynamic data transfer. In other words, the data isn’t transferred constantly, but at certain intervals – and the system can define those intervals itself, based on the available energy. We’ve boosted that energy by installing solar panels on the stations. Using the current energy budget, the interval to the next data transfer is calculated. In addition, the system always keeps track of what data has already been transferred, so in the next transmission, only the new, still-unsent data is transferred. In the polar winter, where the available energy is low, up to a week can go by between transfers.

In terms of saving energy, I cut corners wherever I could. For instance, when you start it up, a Starlink antenna needs a long time to establish a stable and fast Internet connection. When it’s time for the next transfer, the buoy turns on the Starlink antenna and begins checking whether the AWI servers are already responding, even though there’s no stable connection yet. As soon as the system receives a response, the transfer begins. Usually, by the time the transfer has been confirmed by the AWI servers, the antenna still isn’t done warming up. But since the data has already been transmitted and receipt has been confirmed on the AWI’s end, the antenna is shut back off again before ever really getting started. Though this approach isn’t quite in line with Starlink specifications, it avoids unnecessarily long transfer times and therefore unnecessarily high energy consumption. That’s just one of the measures I’ve introduced to help the systems save energy.

 

Sea Ice Portal: And how did you solve data problems like potential data loss?

M. Schiller: Our dynamic data management is a challenge, since we have to make sure data is never lost. Normally, monitoring data is stored in a file, which is transferred. A new file is created for every transfer. But when a transfer fails or is only partially completed, there’s a risk of losing data.

When it comes to the new buoys, the data is stored in a local database and then transferred directly from the database. The system always indicates the latest successfully transferred dataset – so the system always knows what data hasn’t been sent yet and can transmit it to the AWI next time. This even works when there hasn’t been any connection to the AWI for an extended period, or when the connection is unexpectedly lost. All the available data that hasn’t yet been sent is always transferred.

 

Sea Ice Portal: That sounds exciting. I’m sure you’ve already tested it. What are your expectations for future expeditions?

M. Schiller: For about a year now, I’ve had an office at the AWI’s new Technical Centre. On the roof of the building, we have a special testing area with an unrestricted view of the sky. That’s where I set up the systems and ran them through extensive tests (Figures 2 – 4). This included a long-term test: half a year. The tests gave me the chance to fine-tune a number of aspects. Here in Germany, the systems run very reliably. I expect them to do the same in the polar regions.

Figure 2: Weather station with Starlink connection (Gen2 antenna with motor) on the roof of the Technical Centre in Bremerhaven. (photo: Alfred Wegener Institute, Martin Schiller)

Figure 3: Starlink mini-antenna on the radiation station. (photo: Alfred Wegener Institute, Martin Schiller)

Sea Ice Portal: What types of buoy did you design, exactly? When will the systems be deployed, and how will you know if it all really works?

M. Schiller: I’ve made two types of buoy with integrated Starlink technology and tested them in Bremerhaven – a weather station and a radiation station. Both will be installed on the Antarctic sea ice during the current Polarstern expedition HAFOS (PS144). The first tests will take place on the Polarstern, once she’s reached the Antarctic. If the tests are successful, the stations will be deployed directly on  the sea ice. After that, we’ll know quite soon whether or not everything’s working as it should. It will also be interesting when the Polar Night begins. Then, the systems will go into energy-saving mode and only transmit their data once a week. When the winter is over and the sun returns, I’ll be very curious to see how long it takes before the transfer intervals are daily or even hourly again. We plan to deploy further stations with this technology in the summer of 2025, including cameras to gather additional data.

 

Sea Ice Portal: That all sounds great. Where do you anticipate potential problems?

M. Schiller: From a technical standpoint, I think the systems are highly reliable. If technical problems arise, I’m confident that we can solve them. Technical problems are something we can handle. But when it comes to Starlink, we’re talking about a privately-owned company. It’s hard for me to guess how the company will continue to evolve. For example, Starlink uses monthly contracts. Though that offers customers considerable flexibility, it also means the prices and services could change at short notice. There could be new restrictions that we can’t predict today.

 

Sea Ice Portal: Can you offer remote support if something needs changing?

M. Schiller: No, that’s not currently possible. It might be possible in a future version. But to support my colleagues working on the ice, I came up with a solution I call “Starlink On Ice”. It’s a small briefcase with an integrated Starlink antenna, power supply, and Wi-Fi access point. The whole thing only weighs 3 kg and offers high-speed Internet access on the sea ice in a roughly 100-m radius. You just lay the case flat on the ice and can turn it on from the outside. This way, if my colleagues on-site have problems or questions, I can help them in a live videoconference.

 

Sea Ice Portal: Where is this trend headed? What can we expect to see next?

M. Schiller: We currently use the Campbell Scientific Datalogger to manage the gathering and transfer of our monitoring data. One of my colleagues is now working on an in-house solution to replace it. We’re also looking into receiving photos and videos directly from the ice. This could allow us to compare monitoring data with the current conditions on the ice. We’ve just assigned an external provider the task of developing this type of camera buoy. It would also be great if we could monitor or even control devices like our ROVs from Bremerhaven.

Thanks to its global coverage, including the polar regions, Starlink offers an Internet connection with high bandwidth and at very affordable prices, opening up a range of new possibilities for us. It’s a real game-changer, even if it means we have to keep a close eye on the dependencies that come with it.

 

Contact

Martin Schiller (AWI)

Dr Klaus Grosfeld (AWI)

Dr Renate Treffeisen (AWI)

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