ESA satellite proba-1 has celebrated its 20th birthday in orbit and is still in full operation
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today, 20 years later, proba-1, originally intended to survive for only two years, is still continuing as an earth observation mission, Its heritage has provided a guarantee for the development of the next decade
the proba-1, measuring only 60 x 60 x 80 cm, autonomously performs advanced guidance, navigation and control processing and payload resource management. Its two imaging instruments – compact high-resolution imaging spectrometer (Chris) and panchromatic high-resolution camera (HRC) – have provided more than 1000 images of more than 1000 locations. These images are crucial for monitoring some environmental issues, from assessing how different land-use strategies on the Namibian prairie affect vegetation growth to vegetation types on the central Namibian prairie or helping to map and understand the alpine snow cover of Swiss national parks
this microsatellite was developed by ESA’s general support technology program (GSTP) and built by an industrial alliance led by Verhaert in Belgium
proba-1 marks the transformation of European aerospace industry to small missions. Although cube satellites and are becoming more and more common, proba 1 is the first attempt of ESA in small missions. The mission took only three years to complete – an unheard of feat when missions often took more than 10 years to launch. In addition, it marks the beginning of a series of proba satellites, including proba-2, proba-v and proba-3, which are currently being tested
“in its era, it is completely innovative,” recalls Frederic teston, project manager of proba. “In terms of technology, development time and low cost, all these are brand-new.”
in the past 20 years, no major unit has really failed, and all major systems of the spacecraft are still running. The satellite achieved many of ESA’s firsts — from the first to use lithium-ion batteries (now a common technology) to becoming ESA’s first spacecraft with full autonomous capability
this means that it is designed to perform daily tasks almost without help, and the staff of ESA’s ground station in edu, Belgium are rarely involved
generally, the code for autonomously running some tasks, such as altitude and orbit control systems (AOCS), is written in a specific way. First, the functions and actions of this system and every other system on the machine are described and cleared in detail. Then, when engineers are satisfied with them, they are transformed into software specifications, and finally someone writes software specifically for these functions. This is a long cycle, so if something doesn’t work or needs to be changed, it will be a long process
but part of the reason why the proba-1 task can start so quickly is that it avoids this cycle by developing a tool to automatically generate software. In addition, it also allows engineers to quickly change the functions and parts of the system without writing new code
“we have built all models in one software, and people realize that this is the ancestor of MATLAB,” said Pierre Vuilleumier, who once worked in the proba-1 team, “From the radiation or orbit to the magnetic field and the position of the sun. All these are modeled in the tool, so at the end, we press the button and automatically generate the software compiled and connected with the onboard software. The onboard tool has 40000 lines of code and the ground simulator has more than 30000 lines.”
the tool also saves all files in the model, which means it’s easy to train new engineers to use it.
Vuilleumier said: “some myths about code generation continue today, but I believe we broke them 20 years ago.”
this automatic software generation has developed and is now very common in proba tasks. Although productivity has been improved and development time has been shortened, it is still not the mainstream of all tasks.
proba-1 also emphasizes the use of COTS (commercial off the shell) How components, rather than advanced components, can be cost and time efficient, and it also gets real returns – which is increasingly becoming part of ESA’s strategy to develop and improve new space technologies.
“We were the first people to fly lithium batteries. At that time, experts predicted that their life in space was only 6 months at most. Now, 20 years later, we have not noticed any degradation of these batteries. They have a history of 23 years!” Sighed Vuilleumier.
commercial components are generally considered high risk or low reliability, but the proba team shows that through appropriate engineering design, their hardware has lived in a harsh space environment for 20 years and proved their value.
although the development time is as long as This is a short time, but the project is not always smooth sailing. Vuilleumier recalls that a few weeks before the launch, engineers were ready to test on PSLV in India, and they frantically competed to complete the software coding.
“Isn’t it exciting to do something you haven’t done before? When you see something working, there may be five minutes, but before and after that, the pressure is more than excitement. But we show that things don’t always take longer or cost more, which is possible. We show that it’s possible to do faster and cheaper tasks.” Teston said with a smile