Solar panel test as a key step toward the flight of the ALTIUS satellite
Engineers at Redwire Space’s Belgian facility have spent recent months assembling the satellite platform for the European ALTIUS mission, intended for precise monitoring of ozone and other gases in the stratosphere. The latest technical test – verification of the deployment of two solar wings – marked an important milestone in preparing the spacecraft for operation in orbit, because the solar panels will be the main source of electrical power for the instruments, computer, communications system, and thermal control.
The solar wings must initially be folded so the satellite can fit inside the rocket fairing, and after launch their deployment happens only once, with no possibility of repetition. That is why detailed tests of the release mechanisms, hinges, and latches are carried out on Earth, which ultimately must ensure structural stability and optimal orientation toward the Sun. The European Space Agency previously also published footage of a solar panel deployment test in Belgium (at QinetiQ facilities) during 2021, as part of qualifying the system for the demanding conditions of space.
What was verified in the test and why it matters
The deployment test checks several things at once: that the panels open smoothly and without snagging from the “stowed” configuration, that they reliably lock after deployment, and that they retain the geometry needed for efficient collection of solar energy. In orbit, mechanisms are exposed to thermal shocks and radiation, and materials can change properties over time. That is why, during the satellite integration phase, repeated checks are insisted on – from mechanical functionality to assessing how the entire system will behave in scenarios that cannot be “fixed” once the spacecraft leaves Earth.
At ESA, they emphasize that reliable electrical power supply is a prerequisite for the scientific part of the mission. Without stable power sources there are no continuous measurements, no data transmission to Earth, and no maintaining instrument temperatures within operating limits. In other words, the solar wings are not a “secondary” subsystem, but one of the fundamental conditions for ALTIUS to be able to fulfill its role at all.
ALTIUS: a new European mission for ozone and trace gases
ALTIUS is an acronym for
Atmospheric Limb Tracker for Investigation of the Upcoming Stratosphere – a European Space Agency satellite mission developed within the Earth Watch program. According to ESA, the project is financed primarily with funds from Belgium, with contributions from Canada, Luxembourg, and Romania. The Belgian Platform on Earth Observation (Belspo) additionally states that Belgium is the largest financier of the mission, while the remaining countries participate with smaller shares.
The operational objective of the mission is to systematically monitor the distribution of ozone and selected trace gases in the stratosphere and lower mesosphere and to provide data for long-term trends, evaluation of environmental protection policies, and improvement of atmospheric models. Stratospheric ozone is not important only as a “shield” from ultraviolet radiation, but also as a component that affects the thermal structure of the stratosphere and indirectly the circulation of the atmosphere – so the measurements are also relevant for climate analyses.
“Limb sounding” technique: looking along Earth’s edge instead of toward the ground
Unlike many satellites that observe ozone by looking “downward,” ALTIUS relies on the limb-imaging technique: the instrument observes the atmosphere along Earth’s horizon, through a “thin” layer of air, which enables the creation of vertical concentration profiles by altitude. That method provides valuable information on how ozone changes at different altitudes, not only in the total column above a given point.
According to ESA’s description of the instrument, ALTIUS will have three independent hyperspectral channels observing in the ultraviolet (250–355 nm), visible (440–675 nm), and near-infrared (600–1020 nm) ranges. In the visible and NIR channel, acousto-optic tunable filters are used, while the UV channel is based on Fabry–Pérot interferometry, enabling selection of the wavelengths needed to detect targeted gases and aerosols. In the specialist literature, ALTIUS is described as a continuation of European “limb” measurements after the loss of missions such as Envisat, with an emphasis on operational value and data continuity.
Why ozone is still a topic of public policy
The need to monitor ozone began to gain a global dimension already in the 1970s and 1980s, when scientists detected severe thinning of the ozone layer, especially above Antarctica – a phenomenon that became known to the public as the “ozone hole.” Ozone in the stratosphere absorbs part of the Sun’s UV radiation, especially UV-B, thereby reducing the risk of health consequences such as skin cancer and cataracts, but also impacts on plants and ecosystems.
The key policy response was the 1987 Montreal Protocol, an international agreement that gradually phases out substances that deplete ozone. NOAA notes that the Protocol laid the foundations for reducing and phasing out a range of chemicals, and UN scientific assessment mechanisms regularly analyze the state of the ozone layer. The World Meteorological Organization (WMO), citing the scientific assessment under the Montreal Protocol, announced that ozone-layer recovery is proceeding according to plan and highlighted that the phase-out of almost all banned substances is one of the greatest successes of global environmental policy, with additional climate benefits.
That is exactly why continuous satellite monitoring remains important: ozone is recovering, but changes in circulation, stratospheric temperatures, exceptional events (such as major eruptions), and growth in some industrial activities can affect annual oscillations and regional patterns. Data from missions like ALTIUS make it possible to distinguish trends from short-term variations and to “calibrate” atmospheric models based on measurements.
What ALTIUS will measure and who will use the data
ESA states that ALTIUS is conceived as a mission that will, in addition to ozone, monitor other trace gases and contribute to understanding chemical processes in the stratosphere. Limb profiling is especially useful for analyses of vertical distribution, which is crucial for assessments of chemical reactions that depend on temperature, the presence of aerosols, and stratospheric dynamics.
Such data typically end up in:
- operational services for atmosphere and climate, where measurements are used in data assimilation and model validation
- scientific analyses of long-term trends in ozone and related compounds
- evaluations of the effectiveness of international policies regulating ozone-depleting substances
- studies on the links between ozone, stratospheric temperature, and circulation patterns
Industry and institutions: a Belgian backbone, a European program, and international partners
On the industrial side, Redwire in Belgium participates in integrating the satellite platform, and in its announcements the company has highlighted that integrations and tests for multiple ESA missions are carried out at its plant in Kruibeke. On the other hand, the scientific and institutional framework of the mission is strongly tied to the Belgian community – Belspo states that ALTIUS was initiated at the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), which is involved in the development and coordination of the mission.
ESA’s mission pages confirm that ALTIUS is part of the Earth Watch program, and that it is an internationally financed project in which Belgium carries the largest share, with partner contributions from Canada, Luxembourg, and Romania. Such a configuration is not unusual for European missions: the lead financier ensures continuity and strategic interest, while other partners gain access to instruments, scientific results, and industrial contracts.
Timelines: instrument integration and launch plan
After mechanical integration of the platform and checks such as the solar wing test, the next phase is preparing the satellite to receive the main scientific instrument. According to ESA, the platform is ready after integration to host the ALTIUS instrument – a three-channel spectral imager – and ESA project manager Michael Francois emphasized that completion of the platform is an “important milestone” and that delivery and integration of the instrument are expected in the second quarter of 2027.
As for the launch, the mission’s official page (BIRA-IASB) states that liftoff is planned from the space center in Kourou in 2027, while the CEOS database lists the planned date in September 2027 and the mission’s operational framework after launch. Some expert materials and presentations mentioned earlier targets (for example 2025), but available publications related to the mission in 2025 and 2026 emphasize preparations leading toward a 2027 launch, which points to alignment of the schedule with launch capacity availability and completion of qualification of the instrument and platform.
The bigger picture: why such tests matter beyond the space industry
For the public, the story about a solar wing test can seem like a narrow technical detail. However, behind it stands an entire chain: from the ability to power the satellite reliably, through measurement quality, to understanding processes that directly touch health, agriculture, and climate policy. At a time when international institutions emphasize that the ozone layer is recovering thanks to long-standing measures, satellite systems like ALTIUS serve as an independent “dashboard” showing how effective policies are and where new questions arise.
If it does indeed head into orbit in 2027 as planned, ALTIUS will bring the European and global community a new generation of vertical profiles of ozone and related parameters, at a time when continuity of atmospheric measurements is increasingly important – for science and for decisions made at the level of states and international agreements.
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