Over the course of a whole day, Norway’s plasma sampler, the multi-Needle Langmuir Probe (m-NLP), is seen being slowly moved around by a robotic arm to be slotted into place on the outside porch of Bartolomeo – the Airbus-operated platform attached to the Columbus laboratory of the International Space Station (ISS).
Since its integration on Bartolomeo in September 2023, the task of this instrument has been to sample its immediate space weather environment by measuring the plasma surrounding the ISS. It does so to an extraordinarily high level of detail, making a few thousand measurements per second.
Plasma, sometimes called ‘the fourth state of matter’ (the other three being solid, liquid, and gas), is essentially an electrically charged gas. Most of the visible matter in space is made of plasma, including the Sun and the radiation particles it throws off during solar flares. On Earth, we can see plasma in the form of auroras or lightning.
The streams of particles flying from the Sun towards Earth are referred to as the solar wind, and they give rise to space weather. “Spectacular events such as solar flares can be accompanied by bursts of energetic particles that can reach Earth’s upper atmosphere and ionosphere, where most of our satellites are operating,” explains Fabrice Cipriani of European Space Agency’s Space Environment and Effects section.
“This form of space radiation can for instance interrupt communication between satellites and the ground or cause a satellite to veer off its orbit. m-NLP helps us understand space weather by detecting electron density around the ISS, down to a resolution of a few meters. As the instrument is operating most of the time, its continuous measurements allow us to monitor the impact of the Sun on our nearby environment.”
“So far, the instrument has given us a wealth of data about the plasma state in mid and low latitudes, at unprecedented resolution,” explains Lasse Clausen, professor for plasma physics at the University of Oslo. “Now we can really start to understand the underlying physical mechanisms that drive space weather effects in this part of the globe. We were also lucky enough to capture the plasma’s response to one of the biggest solar storms in the last years.”
The instrument is gathering data in its own right, but due to its flexibility, it also acts as the blueprint for operational space weather monitoring instruments that are currently being developed within ESA’s Space Situational Awareness programme.
“m-NLP was the first instrument to be slotted onto the Bartholomeo platform,” says Atul Deep, ESA’s experiment system engineer. “This meant that during its integration, various system requirements had to be tested and validated. In this way, our instrument helped prepare the systems for future payloads that will be hosted on the platform.”
Kenza Benamar, ESA’s technology research and development engineer, adds: “The m-NLP technology has potential to be used well beyond low Earth orbit. With modifications such as more radiation-resistant electronics or different coating, such instruments could be part of a future space weather constellation or even venture into deep space. This concept is currently under study in ESA’s Space Situational Awareness Programme,” Kenza adds.
m-NLP was co-funded by ESA’s PRODEX and General Support Technology (GSTP) programmes. Eidsvoll Electronics designed and built the ERIU electronics to interface the m-NLP instrument to the Bartolomeo platform, while the University of Oslo designed the m-NLP electronics and boom system with probes.