What do we need satellites for?

May 23, 2017

Most of the articles we published so far have been focused on the issue of space debris. We learned that it takes the energy of a powerful rocket to put a satellite in orbit around the Earth, and that, once in orbit, a satellite tends to stay there for a very long time. We also saw what it takes to perform a proper decommissioning manoeuvre that prevents the accumulation of debris in orbit, and preserves the safety of people and property on the ground.


However, the existence of this issue demands an answer to an important question: why do we send satellites in space in the first place? Why in the past many satellite missions have been extended far beyond their nominal life, at the expenses of a decommissioning maneuver?


The answer is simple: Because we need them!


Satellites are the backbone of many applications here on Earth.

Credits: NASA.


The Many Uses Of Satellite Technology


Satellite technology is a pillar of an enormous amount of Earth-bound activities. The use of space data is pervasive, yet often hidden to the public eye. In the last 10 years, however, we have seen an increasing number of consumer-facing applications that are enabled by satellite data, and this number is steadily increasing.


There are five major applications of satellite technology: telecommunications, global navigation, earth observation, weather forecast, and scientific investigation. 


A short introduction to satellite applications


TELECOMMUNICATIONS: Global wireless communication is arguably the most ubiquitous and transparent use of satellite technology.


Radio signals and microwaves require line-of-sight, so they are blocked by the curvature of the Earth. A telecommunications satellite is a spacecraft that amplifies and relays telecommunications signals, creating a communication channel between two widely separated locations on Earth.


There are more than 2,000 telecommunications satellites in Earth’s orbit, operated by private and governmental organizations to relay television, telephone, radio, and to extend the reach of Internet to emerging countries and unpopulated areas. 


GLOBAL NAVIGATION: During a conference about the future of satellite navigation, one of the spectators stood up and started to complain about the waste of money in satellite programs. He concluded his remarks by saying something like “What do we need satellite navigation for? My GPS works just fine!”


While this particular individual may have been uniquely misinformed, it is true that global navigation is an application that we have come to take for granted. In the mid 2000s, car navigation became mainstream thanks to cheap, precise, and reliable devices. By the late 2000s, smartphones brought personal navigation into everyone’s pocket. Today we can plan an entire trip from the door of our home to an address thousands of kilometers away with a request to our voice assistant, getting precise information about the length of our trip, the time of arrival, what vehicles we’ll need to take to get there, and where to eat and go to the bathroom.


This magic is made possible by global navigation satellite constellations like US’ Global Positioning System (GPS), Europe’s Galileo, and Russia’s Glonass. These constellations are made up of dozens of spacecraft that are constantly updating our devices with information about their positions around Earth, enabling a precise calculation of our position in terms of latitude, longitude, and elevation.


Besides car and personal navigation, global navigation is essential for ensuring the safety of aviation, cartography, search and rescue, precision farming, marine operations, and much, much more.


A nerd-proof overview of how GPS works


EARTH OBSERVATION: The basic concept behind an Earth observation satellite is pretty straightforward: place a camera pointing downwards on a spacecraft, and start shooting. A satellite camera, however, is very different from a typical point-and-shoot. The first difference is that an Earth observation satellite does not take framed pictures, but continuous scans of stripes of land. The second difference is that modern Earth observation satellites don’t limit themselves to taking pictures in the visible spectrum, they can also see infrared and other wavelengths. Finally, thanks to microwave radar and digital processing, it is possible to create detailed digital elevation maps.


The applications of Earth observation satellite data are incredibly important for monitoring and managing agriculture, forestry, and urban growth. Satellite data are essential in handling the response to natural disasters, enabling the coordination of relief efforts based on the actual needs. Precise imagery allows natural resources management, energy infrastructure optimization, and hundreds of specialized applications.


Google Earth brought satellite imaging to the general public, providing a foundation for hundreds of consumer apps that, in combination with GPS navigation, allow us to always know where we are and make the most of our surroundings.


Spot 7, one of the most advanced Earth observation satellite, and its applications.


WEATHER SATELLITES: The weather satellites are spacecraft specialized in Earth climate monitoring, measuring clouds and cloud systems, city lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, changes in the Earth's vegetation, sea state, ocean color, and ice fields.


While weather forecast cannot help us planning our summer vacations months in advance, they are very effective in monitoring the current weather and forecast with high precision the upcoming 24-48 hours. This ability has an enormous importance in ensuring the safety of Earth’s activities, keeping planes and ships away from major climatic event, monitoring the dynamics of hurricanes, improving logistics planning, and so on.


Until a few years ago these applications were available only to governmental agencies. Nowadays we have apps in our phones that enable us to observe clouds patterns in real time, giving each one of us the ability to avoid or prepare for incoming storms.


Weather satellites enable us to get an incredibly detailed understanding of weather patterns.

Credits: NASA.


SCIENTIFIC INVESTIGATION: The final class of satellites includes one-of-a-kind spacecraft designed for a specific mission to test a scientific hypothesis, investigate a specific phenomenon, and improve our understanding of physics, astrophysics, cosmology, and so forth.


This category includes spacecraft designed to move out of Earth’s orbit to take pictures and measure geological, meteorological, and physical data of other planetary bodies. These kind of missions enable us to measure and confirm the existence of gravitational waves, investigate quantum physics phenomenon, detect dark matter, understand the origin of the universe, test new technologies, and much more.


D-Sat is a member of this family of satellites, thanks to a scientific package that includes three scientific experiments and one orbital technology validation test. D-Sat is therefore a one-of-a-kind mission, and an important “first” in how we deal with the issue of space debris. Learn more about our mission, and help us to make it happen on Kickstarter.


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