Satellite Data Storage, Collection, and Transmission: How Does it All Work?

Even though we rely on satellites for many tasks, from communication to choosing the quickest routes to work, the actual logic behind spacecraft operation is often overlooked. At the same time, end users’ expectations are constantly increasing — we demand higher speeds, better accuracy, etc.

However, transmitting satellite data to the end user still has its challenges, even though there have been a lot of advances in this area. Below, we explain how satellite data collection, storage, and transmission work, explaining the complex space- and ground-based infrastructures behind the technology we already take for granted.

Collection and satellite data storage in space

Modern satellites carry various equipment for collecting data in space, but in simple terms, those are different types of cameras and sensors. In space, satellites collect data 24/7, and these data are roughly subdivided into housekeeping and scientific. Housekeeping data is ‘internal’ info about satellite temperature, position, and the direction its cameras are pointed at. This information undergoes regular control checks to make sure the spacecraft operates normally.

Scientific data is the information a satellite is built to collect, such as images of our planet or deep space so it can vary greatly depending on the satellite’s mission and design. Most EOS tech today has optical sensors (operating during daylight hours), radars, or infrared cameras. Satellites with optical lenses work pretty much the same as cameras we use on Earth. Spacecraft with radars send signals to an object of study and capture this object’s response. Thermal sensors and infrared cameras capture emitted thermal radiation — but regardless of the actual technology, most information our space tech collects comes in the form of images.

Now, where do satellites store data? Usually, those are solid-state drives (SSDs, like on our terrestrial computers) or specialized memory modules designed to withstand harsh space conditions. Satellite data is usually compressed to save memory and often gets written over after the previous batch has been sent to Earth for analysis. But how is data collected from satellites?

How does satellite data transmission work?

Satellite data transmission is a complex process that requires a carefully-engineered terrestrial infrastructure. Spacecraft placement in orbit is the first decisive parameter here. For example, satellites placed in geosynchronous orbit are in constant sync with our planet, and information from them can be assessed at any time. That’s why they are generally used for communication and navigation.

But satellites placed in sun-synchronous orbit are primarily used for weather forecasts because they sync with the Sun and pass over the same spot on our planet when solar conditions are roughly the same. With such spacecraft, it makes sense to build receiving ground stations closer to the poles because that’s where data transfer is optimal each time a spacecraft passes over a station.

Ground stations are equipped with antennae that receive signals from space. Ground-based antennae are subdivided into high or low, which corresponds to their transfer speeds. Besides, both antennae support two data transfer ties — uplink (sending information to space) and downlink (receiving information from space). Downlink connection is more common, but uplink is also necessary to send commands to a satellite — for example, to readjust its position or fix another malfunction that can be fixed remotely.

When ground stations receive data from satellites over a radio signal, they transfer it to operation centres —  usually over hard lines or virtual networks. Only after this data is processed into readable formats does it reach the end users.

At this point, you may wonder about all those new satellite constellations. Transmitting raw data from each spacecraft in a larger network is clearly counter-productive. So, how the information is transmitted between satellites? Most constellations today use inter-satellite links, allowing them to communicate with each other directly without relaying radio signals from ground stations. That’s why Internet and GPS constellations work so fast. When the data needs to be sent to Earth, it’s sent over a relay satellite — a higher orbiting spacecraft easily accessible from Earth at any time.  

Recent advances in optimizing satellite data

Despite such system complexity, satellite data transmission is not the biggest challenge we face today. Data processing and analysis takes too much time, human effort, and computing power. Fortunately, advances in AI tech are already mitigating this problem. Onboard AI can prioritize which data to store and transmit, which could be crucial in disaster response. Ground stations, too, are learning to operate in next-to-real-time mode thanks to innovative automated systems.

All in all, space systems continue to evolve, which means we may soon find even better ways to collect and transmit satellite data. But the technologies we enjoy today are already impressive, especially considering their fast-paced revolution. In part, we owe such rapid technological pace to space democratization — as more private and research companies today can access satellite data, they always search for ways to optimize budgets, along with tech efficiency. So, keep up with space updates if you don’t want to miss out on upcoming technologies, which will surely be amazing!