Satellite IoT for Science: A Brief on Recent Advances in the Field
Low earth orbit satellite systems are emerging as a critical tool for scientists working in extreme and remote locations.
As a Physical Scientist for the United States Geological Survey (USGS), I work to connect environmental sensors to the cloud in near real-time and in extremely challenging locations. The places I work in usually have no cellular service and are so remote that even long-range radio telemetry (LoRaWAN) is not feasible. In these situations, satellite connection is our only option. While we still use some legacy (geostationary) satellite providers, I have been working to improve our systems by adding emerging LEO (low earth orbit) technologies. Here I will briefly describe what the current options are for LEO systems and how they can be applied to different scientific needs.
When Full Internet Connection is Required
In some cases, a sensor used by a scientist requires proprietary or custom software to be calibrated or accessed remotely. This is the case with many of our water quality and sediment sensors. When building these systems, a full Windows 10 (or 11) PC is required to run the sensor’s software, and a remote desktop view (via satellite internet) is used to manage the device out in the field.
Traditional Geostationary Satellite Internet
To achieve internet connections in remote locations in the past, traditional geostationary satellite connections have been used. There are problems with this type of design, though. The first is that geostationary satellites operate at a great distance from the earth’s surface, significantly slowing internet speeds. We have found with our existing geostationary systems in the Grand Canyon that internet speeds can be as slow as 1.5 kbps and only get as fast as 3 Mbps. A second issue is line-of-sight. In challenging geographic locations, such as the bottom of the canyon or along a mountain side, a poor view of a geostationary satellite can cause internet speeds to be reduced even further, or cause constant signal dropping, resulting in a lack of ability to retrieve sensor data effectively.
New LEO Satellite Internet
New LEO internet services, such as Starlink, are emerging as potential solutions to both of these issues. LEO satellites utilize a mesh network of constantly orbiting satellites to allow for internet connection (at least part of the day) in nearly any location with a view of the sky. Furthermore, because LEO satellites are much closer to the earth’s surface, they can transfer data at much faster rates than geostationary satellites (up to 1 Gbps, according to Starlink). High speed and more stable internet connections will allow for the expansion of current remote sensor systems with emerging technologies such as edge computing and machine learning in real time. While Starlink is the most prominent provider of this service right now, other companies are joining the field, and a robust LEO satellite internet market is likely to exist within the next 5–10 years.
Two Way “Texting” With Sensors
In some cases, sensor data is produced in small packets of bytes, such as weather station or soil moisture data. Full internet connectivity is overkill in these situations, and a simple “texting” approach is the most efficient. Relatively new LEO networks can help to reduce the equipment footprint of these sensor designs and provide dependable upload of data from very challenging locations, without the large infrastructure of satellite internet dishes.
Short-burst Satellite Data
If you have ever used a Garmin satellite communicator while out on a hike, you have used SBD (short-burst data). With the ever expanding LEO networks of both SpaceX (SWARM) and Iridium, it is possible to build satellite communicators to send sensor data to the cloud from nearly any location on Earth. SBD has such wide coverage that on a recent Grand Canyon river trip, I was able to text my wife and receive a response within 1–3 minutes almost anywhere within the canyon. Another advantage of SBD systems is that they consume very little power (compared to traditional satellite internet dishes and modems) and can be easily incorporated into 12V off-grid systems. The current limitations with SBD, though, are small data packet size (less than 250 bytes) and low frequency of data transmission (every 5–10 minutes).
The LEO satellite networks are ever expanding and providing a dramatic shift in both internet coverage and speeds at almost every location on the planet, and the field is shifting monthly. This is a brief update, but I will write more in the future as we test these systems in the field.