In recent weeks, a group of engineers from SRON, Airbus Netherlands and NASA have been busy installing the Dutch aerosol instrument SPEXone on the PACE satellite. PACE will take measurements of oceans and aerosols from 2024 to unravel the impact of particulate matter on climate, among other things. On 23 June, the final screw was tightened. The integration is now officially complete.
At NASA's Goddard Space Flight Center in Maryland, the climate satellite PACE is impatiently waiting for its first measurement instrument. On 8 June, a group of Dutch and US engineers walk into the clean room. SPEXone, together with instruments HARP2 and OCI, will provide the spacecraft with a razor-sharp field of view of the Earth. The aim is to measure ocean colour and map the properties of aerosols. The Dutch SPEXone instrument, together with HARP2, will take aerosol measurements. It is now the first instrument to be integrated on the satellite. SRON and Airbus Netherlands developed SPEXone, with support from TNO.
Aerosols
Aerosols are small particles like soot, ash and desert dust in our atmosphere. They have a major impact on climate change and air pollution. However, their exact role is insufficiently known. Partly because of this, warming scenarios for the year 2100 are as much as three degrees Celsius apart. Most aerosols reflect light. As a result, they have a cooling effect on Earth. But they can also have a warming effect through absorption. SPEXone will determine the properties of aerosols. Think of size, composition, shape and their absorption and reflectivity. It will also help the OCI instrument to measure the colour of the oceans to monitor the amount of plankton. Indeed, this requires a correction due to aerosol scattering.
Tests conducted
In early 2021, the finishing touches were put on SPEXone in the Netherlands, under the watchful eye of then OCW minister Van Engelshoven. It then went on transport to Goddard. Since then, the Dutch team has conducted several tests. It is important to check whether the instrument arrived in one piece and whether it survived months of storage. "But this will be the most exciting moment," says SRON engineer Alexander Eigenraam just before leaving for America. "The alignment listens very closely. It's mainly a precision job to make sure it doesn't sit slightly twisted. We mount SPEXone on a vertical side of the satellite, so that makes it extra tricky. We also have to switch to NASA's test systems and electronics. We have to do that because SPEXone is linked to the satellite from now on, and no outside computers are allowed to be connected to that."
The Dutch SPEXone instrument is a candidate to also become part of the European CO2M satellite, which will map concentrations of CO2 in the Earth's atmosphere. Aerosols affect CO2 measurements, so an aerosol instrument is needed for corrections.
Photo: Dutch and US engineers mount SPEXone on the PACE satellite. Credit: GSFC
Source: SRON
