With all instruments integrated, the first ESA MetOp Second Generation-A, MetOp-SG-A1, weather satellite is now fully assembled and on schedule for liftoff next year. Meanwhile, its sibling, MetOp-SG-B1, is undergoing rigorous testing to ensure that it will withstand the vacuum and extreme temperature swings of space.
As its name implies, the MetOp-SG mission substantially improves on the first series of MetOp satellites. This next generation mission is also different in that it is designed as three successive pairs of A-type and B-type satellites, each type carrying a different, but complementary, suite of instruments.
Working as a pair in polar orbit, they will deliver a wealth of global meteorological information for weather forecasts and climate prediction for more than 20 years.
The importance of accurate weather forecasts cannot be overstated. They are crucial not only for public safety and early warnings, but also for key sectors such as agriculture, transportation, energy management and climate adaptation.
The economic benefits of reliable forecasts are substantial, helping industries reduce risks, improve efficiency and safeguard resources.
Europe therefore has two main weather missions, one in geostationary orbit and one in polar orbit.
The Meteosat satellites, in geostationary orbit hovering 36,000 km above the equator, can monitor rapidly evolving events for now-casting and short-term weather prediction. However, being fixed above the equator means and that parts of Earth close to poles and on the opposite hemisphere are never viewed.
The MetOp satellites, on the other hand, orbit around Earth, from pole to pole, in 50 minutes, and much closer to Earth, at an altitude of 832 km. This allows them to achieve global coverage every day and make more detailed observations.
ESA’s MetOp-SG System and Operations Manager, Fermín Álvarez López, said, “MetOp-SG-A1 has been at Airbus’ facilities in France for around two years where engineers have been carefully integrating its instrument package. With the satellite carrying no less than six measuring instruments this is an extremely complex task and we are thrilled to see the satellite now fully equipped.”
These sensors include an infrared sounding interferometer, a radio occultation instrument and a microwave sounder, which use different techniques to measure atmospheric humidity and temperature, along with an instrument that images aerosols and a multispectral visible and infrared imaging radiometer, and the Copernicus Sentinel-5 instrument that provides data on air pollutants.
ESA’s MetOp-SG Project Manager, Marc Loiselet, said, “We have truly reached an important milestone with MetOp-SG-A1 completely assembled with its comprehensive package of five weather instruments and the Sentinel-5 mission for air-quality monitoring. Our thanks go to the many people involved who have allowed us to reach this point. And we are also well on target for getting its partner MetOp-SG-B1 ready too with engineers now putting it through the complex ‘thermal-vacuum tests’, as they did for the MetOp-SG-A1 satellite last year.”
Extensive time and care are devoted to testing satellites before launch to ensure they function flawlessly in the vacuum of space and endure the extreme temperatures they will face during their years of operation in orbit.
The MetOp satellites are big – each weighing more than 4,000 kg and comparable in size to a small truck. Testing such large satellites requires specialized facilities, and only a few in Europe are equipped with thermal-vacuum chambers big enough. One of these is located at Airbus Defence and Space’s facilities in Toulouse.
ESA’s MetOp-SG Engineering Manager, Enrico Corpaccioli, said, “When open, the thermal-vacuum chamber resembles a section of a road tunnel, and when closed, it looks like a giant pressure cooker. Its operation involves a complex system of motors, pumps, valves and pipelines to simulate the harsh conditions of space. Creating extreme hot and cold temperatures in a vacuum is a challenging process. To achieve this, the chamber is lined with black metal, through which liquid nitrogen, at –192°C, circulates to simulate the coldness of space. The tests consume one truck of liquid nitrogen every day. When testing the satellite’s response to heat, the temperature of the lining can be raised but solar heat is primarily simulated using large, powerful lamps, replicating the intense solar radiation. Patience is also required as the satellite must remain within the chamber for around a month, with the tests running continuously, 24/7. However, this doesn’t mean that the satellite is left alone. More than 100 engineers are busy executing the tests and processing the data over the course of the month.”
