The European Space Agency (ESA) is undertaking its inaugural managed satellite reentry. After successfully completing its mission and nearly exhausting its fuel, the wind-mapping satellite Aeolus is currently descending towards Earth. Although Aeolus was developed before the existing end-of-life disposal regulations, ESA is making efforts to comply with current best practices by directing the satellite towards an oceanic reentry, thus reducing any potential risk. (Artistic concept of a satellite incinerating during reentry.)
The European Space Agency is spearheading its first-ever satellite reentry with the Aeolus satellite, with the goal to guide it towards an oceanic reentry. Despite the difficulties arising from varying atmospheric conditions due to increased solar activity, the ESA team is leveraging simulations, novel maneuvers, and constant adjustments to ensure the mission concludes safely and successfully.
For the first time in the Main Control Room of ESA in Germany, simulations are being conducted in preparation not for a launch, but for a satellite’s assisted return through Earth’s atmosphere. With the mission accomplished and fuel dwindling, Aeolus is naturally descending.
The Flight Control Team at the mission control will soon issue the final command to the wind-mapping satellite, aiming its reentry towards the ocean to further minimize the already tiny risk from its return. However, in simulations, things aren’t going as expected.
Filipe Metelo and Isabel Rojo during Aeolus reentry simulations. Simulation Officer Filipe comments, “for the teams, these simulations appear to be the real deal.” Credit: ESA
While every mission is unique, launches share many commonalities: a satellite or spacecraft is sent into space by a gravity-defying rocket, it separates and, although the precise sequences vary, it awakens, solar panels are deployed, devices are activated and tested, and its thrusters are ignited to position it where it’s required.
Five years ago, Aeolus was doing just that. Now, with its mission completed, it’s just days away from reentering Earth’s atmosphere. Even though it wasn’t designed for this, teams will strive to guide it on its course.
Aeolus, ESA’s wind mission, offered timely and precise profiles of global winds as well as additional data on aerosols and clouds. The mission boosted our knowledge of atmospheric dynamics. It also supplied invaluable information that improved weather forecasts and contributed to climate research. Credit: ESA/ATG medialab
Aeolus was designed and constructed before the current international guidelines on end-of-life disposal were established, but ESA is still striving to ensure that Aeolus complies with today’s highest standards. It’s the first time ESA’s mission control is attempting such an assisted reentry, with simulations in progress to prepare for any surprises.
Creating a simulation for an assisted reentry: a first for ESA
How do you simulate something you’ve never done before? Simulation Officer Filipe Metelo explains:
“We begin by developing a realistic simulation of the expected behavior from Aeolus during its return, drawing on information from previous reentry scenarios, both controlled and uncontrolled. We use proven ‘telecommands’ and various available software,” explains Filipe.
“We then select certain scenarios that might occur, both probable and improbable, and perform these in the Main Control Room. With a simulated Aeolus and ground system, it feels just like the real thing to our teams.”
Aeolus provided global wind profile observations from space to enhance weather forecast quality. This unique mission also expanded our understanding of atmospheric dynamics and climate processes. Credit: ESA/AOES Medialab
In general, the actual operations should not deviate significantly from the simulated events currently being practiced. However, this reentry comes with more uncertainty than the launches and maneuvers typically performed in this historical room.
Currently, high solar activity levels are causing unpredictable changes in the atmosphere’s thickness, accelerating Aeolus’s return. Therefore, aspects of this campaign are continuously being tweaked as crucial operations approach.
ESA’s Kiruna ground station will maintain contact with Aeolus during critical reentry maneuvers. The station, located at Salmijärvi, 38 km east of Kiruna, in northern Sweden, is equipped for tracking, telemetry, command operations, as well as for data reception, recording, processing, and dissemination. Credit: ESA-S.Corvaja
Significant Maneuvers
The key events in Aeolus’s return will be a series of unprecedented maneuvers that should guide Aeolus towards the least inhabited regions possible, i.e., the ocean.
Should any maneuvers fail to proceed as planned, the responsibility will fall on various ground stations around the world to track Aeolus’s signal. Then, it will be up to ESA’s flight dynamics experts to calculate its orbit and possibly generate new commands for the Flight Control Team to transmit to the satellite.
Illustration showing the reentry and fragmentation of ESA’s Automated Transfer Vehicle resupply spacecraft during a controlled reentry. Credit: ESA
Five simulations in total are planned, which are more like rehearsals dealing with minor issues such as losing contact with Aeolus or parts of the spacecraft reaching unforeseen temperatures, rather than the catastrophic scenarios often presented to teams before a launch.
What makes this reentry special and new is that it modifies the ending of a mission that was initially designed with a different conclusion in mind.
Isabel Rojo, spacecraft operations manager for ESA’s Gaia mission, based at ESOC, the European Space Operations Centre, Darmstadt, Germany. Credit: ESA/J. Mai
“Throughout my career, I’ve participated in over 60 simulations, but this one is uniquely different as we strive to execute the planned operations as accurately and safely as possible but with several uncontrollable unknowns,” Isabel adds.
“I eagerly anticipate transmitting the last command set that will carry out Aeolus’s final maneuver, and seeing them on a normally functioning spacecraft. Once that’s done, our role is finished, and we can only hope for the best. Naturally, I’m anxious to see everything proceed according to plan, and any reentering fragments safely landing in the ocean.”
A Surprising Conclusion to the Impossible Mission
Aeolus Mission Manager Tommaso Parrinello, who is usually based at ESA’s Earth Observation center at ESRIN, Italy, has participated in the simulations at mission control. Since shortly after Aeolus’s launch, he has bridged the gap between Science and Operations and seen not only how demanding it has been to operate this mission, but also why it has been incredibly worthwhile:
“Aeolus is a magical machine that has surprised even the most seasoned engineers globally,” Tommaso concludes.
“Every day, we tackled and solved numerous technical and scientific challenges to ensure we could provide the best data to the meteorological community. But it’s been tough because it’s been new: Aeolus was always intended to be a demonstrator mission, nothing like it had ever been launched into space.”
Just as Aeolus exceeded expectations during its mission, revolutionizing wind profiling and forever improving weather models, its demise is also turning out to be a significant challenge.
To commemorate the end of Aeolus’ extraordinary mission, ESA collaborated with composer Jamie Perera to create a woodwind piece using data that spans the satellite’s life orbiting Earth.
“Only now do we realize that an idea proposed just a year ago has materialized into something real and tangible. We all understand that this reentry is not going to
Table of Contents
Frequently Asked Questions (FAQs) about Aeolus satellite reentry
What is the Aeolus satellite?
The Aeolus satellite is a wind-mapping satellite launched by the European Space Agency (ESA). It has provided timely and accurate profiles of the world’s winds and further information on aerosols and clouds, advancing our understanding of atmospheric dynamics and contributing to climate research.
Why is the Aeolus satellite reentering Earth’s atmosphere?
The Aeolus satellite has completed its mission and is running out of fuel. It is now naturally descending towards Earth. The ESA is performing its first-ever assisted satellite reentry, steering the satellite towards an ocean reentry to minimize any risk.
What challenges does the reentry process pose?
The reentry process poses a number of challenges. Current high levels of solar activity are causing unpredictable fluctuations in the thickness of the atmosphere, which speeds up Aeolus’s return. This adds uncertainty to the operation, and continual adjustments are being made as critical operations approach.
How is the ESA preparing for the satellite’s reentry?
The ESA is utilizing simulations, innovative maneuvers, and continuous adjustments to ensure a safe and successful mission completion. In the Main Control Room in Germany, teams are conducting simulations of the satellite’s assisted return through Earth’s atmosphere.
Was Aeolus designed for an assisted reentry?
No, Aeolus was not originally designed for this. It was constructed before current end-of-life disposal regulations were put in place. However, the ESA is striving to adhere to contemporary best practices by guiding the satellite towards an ocean reentry.
What is the purpose of the simulations conducted by the ESA?
The simulations create a realistic scenario of the behavior expected from Aeolus during its return, using information from past reentry scenarios, both controlled and uncontrolled. They play out specific possible scenarios in the Main Control Room to prepare for the actual event.
What will happen if something doesn’t go as planned during Aeolus’s reentry?
If any of the maneuvers don’t go according to plan, various ground stations around the world will keep track of Aeolus’s signal. ESA’s flight dynamics experts will determine its orbit and potentially produce new commands for the Flight Control Team to send to the satellite.
What was the contribution of Aeolus to scientific research?
Aeolus has made significant contributions to the meteorological community by providing global observations of wind profiles from space. This improved the quality of weather forecasts and advanced our understanding of atmospheric dynamics and climate processes.
More about Aeolus satellite reentry
- European Space Agency (ESA)
- Aeolus Satellite Mission
- Satellite Reentry and Disposal
- Atmospheric Dynamics
- Understanding Climate Processes
