Published on 20 February 2020
ALTIUS is a satellite mission developed to face two of the biggest challenges facing humanity today: the increase in greenhouse gases that fuel climate change and the depletion of stratospheric ozone which protects us from ultraviolet (UV) radiation.
This mission initiated by Belgium presents a great opportunity not only to Belgian scientists specializing in the study of the atmosphere but also to the companies—again Belgian—that were very recently tasked by ESA to develop the satellite and its imaging instrument.
Using original observation techniques and innovative technology, ALTIUS, scheduled to launch in 2023, will continuously record high-resolution vertical profiles of ozone and other atmospheric components.
Atmosphere under high surveillance
After decades of sustained development, the number of space missions to analyze the atmosphere has declined considerably, leaving the scientific community with only a handful of useful instruments.
The first signs of a global recovery of the ozone layer actually reveal a complex pattern: trends vary with latitude and altitude, while growing evidence suggests a strong coupling between climate change and the recovery of the ozone layer.
The ozone layer protects life on Earth agains ultraviolet radiation, but it is also a potent greenhouse gas. Satellites can deliver measurements on atmospheric ozone and monitor seasonal changes in distribution. Source: ESA
A better understanding of these patterns is an essential prerequisite for informed political decision-making. To continue to supply atmospheric models, it is mandatory to develop an instrument capable of monitoring, with good vertical resolution, the evolution of ozone as well as other compounds such as nitrogen dioxide (NO2) and aerosols.
These detailed measurements will support broader operational services as well as long-term monitoring and understanding of the atmosphere to help address current serious concerns.
A Belgian tale
ALTIUS is part of the ESA Earth Watch programme, but Belgium is the main contributor. Initiated by the Royal Belgian Institute for Space Aeronomy (BISA) and supported by the Federal Science Policy (BELSPO), the mission represents an excellent opportunity for both scientists and the space industry in our country.
The European Space Agency has just appointed two Belgian companies, QinetiQ and OIP Sensor Systems, as the main contractors respectively for the development and assembly of the satellite and for the production of the on-board scientific instrument.
PROBA 2.00 platform and eagle-eye camera
The satellite will be installed on the P200 omnidirectional platform, the latest generation of the PROBA family. The space missions PROBA-1, PROBA-2, and PROBA-VEGETATION have demonstrated, over their accumulated 35 years, the exceptional performance of this type of small but sturdy platform.
The ALTIUS (Atmospheric Limb Tracker for Investigation of the Upcoming Stratosphere) instrument consists of three independent spectral cameras covering the UV, Visible (VIS) and Near Infrared (NIR) ranges. They can take measurements in different geometries from a low Earth orbit (LEO), which allows them to collect high-resolution concentration profiles. These measurements are made not only by using the scattering of sunlight in the illuminated part of the atmosphere, but also by absorbing the solar spectra during transitions between day and night and the stellar spectra in the nocturnal part of the atmosphere. This approach guarantees continuous measurement capacity over the complete orbit..