If you think of an artificial satellite, you usually imagine a huge device made of resistant material and weighing tons. However, not all are like this: at the Faculty of Engineering at the National University of La Plata (UNLP) they are making one the size of a lactal loaf of bread that will be able to make atmospheric and soil observations. What it is? Its name is USAT I and it is the first satellite of the UNLP “University Satellite” program.
“It weighs about 4 kilos and measures 10 by 10 by 34 cm, similar to the size of a lactal bread”, he says. Sonia Botta, engineer at the Center for Aerospace Technology (CTA) Faculty, responsible for coordinating the project.
Designed and manufactured by CTA, together with the Electronic Navigation and Telecommunications Systems (SENyT), both from the Faculty of Engineering, this little satellite of the type CubeSat aims to demonstrate the operation of the GNSS system, a tool for navigation and orbital determination, and for measurements using the radio occultation technique.
Botta explains that GNSS is a generic way of calling all satellite constellations that are intended for use in navigation. A popular example is the GPS. “With our GNSS receiver we will be able to detect GPS signals that travel through the atmosphere and the earth”. In this sense, it seeks to prove three things. The first will be to demonstrate its use in navigation, but once the positive result has been obtained, two scientific techniques will be tested: radiooccultation and reflectometry.
The function of the satellite, under this premise, is related to the technological demonstration of scientific Earth observation techniques. “We want it to be able to make atmospheric and terrestrial observations in Argentine territory, but as it is an orbit that covers the whole world, collaboration with other countries is open“, details the coordinator. He adds: “With the satellite in orbit, the mission will be a technological demonstration and will have as payload a GNSS receiver developed by the SENyT group.”
What are the measurement techniques?
O GNSS or GNSS-R reflectometry makes use of GNSS signals reflected from the Earth’s surface. It’s a type of scientific technique that began to be demonstrated on satellites just over a decade ago. It can be used in measurements of soil characteristics such as moisture, vegetation cover or altimetry. In this mode, the receiver and transmitter GNSS satellite work as a bistatic radar. “It is possible to measure how the ground bounce influences the GPS signal. If we manage to detect changes in this signal, we will be able to know, for example, characteristics of the soil, such as humidity, vegetation cover, types of soil and even surface winds in the oceans”, describes the expert.
scientific technique GNSS radio concealment or GNSS-RO it indirectly measures the refraction of the signal emitted by the GNSS satellites in the atmosphere. Depending on the position of the receiver, can be used to study the characteristics of the upper layers of the atmosphere (for example, the ionosphere) or the lower layers (for example, the troposphere). “We can detect atmospheric variables such as pressure, temperature and electron content,” he says.
what will come
In September of last year, the USAT I successfully passed the Critical Design Review (CDR), a fundamental step to start its construction. Procurement is currently being completed to begin building the flight model.
“We are at a very advanced stage where we hope to soon have a complete flight model to start doing all the final tests needed to go into space,” says Botta. He concludes: “The launch date depends on when we finish the satellite and when launch opportunities arise, but We hope to do it before the end of the year, between October and November.”.