An innovative instrument supported by ESA to sample the space weather environment in situ is about to join the International Space Station.
Langmuir’s Norwegian multi-needle probe, m-NLP, to be installed on the ISS’ European-made Bartolomeo platform, an open ‘porch’ to space, will map the ionospheric plasma surrounding the Station in a unprecedented high resolution, performing almost 10,000 measurements per second continuously along its orbit.
After passing its ESA acceptance exam, the instrument was handed over to Altec in Italy to be prepared for launch to the ISS next March.
Meanwhile, another m-NLP is about to head to the Moon aboard the UAE’s Rashid lunar rover, set to launch soon aboard Japan’s Hakuto-R lander on a SpaceX Falcon 9 rocket. .
This m-NLP will study the plasma environment immediately above the lunar surface as the regolith interacts with sunlight, similar to how the other will track the plasma outside the Station.
Plasma is sometimes called “the fourth state of matter”. Here on Earth, this only happens in special circumstances, for example in the form of lightning, the aurora or “pixies” in the upper atmosphere. In the wider Universe, however, the vast majority of matter takes the form of plasma, including our Sun and other stars, and the solar wind that flows from the Sun to interact with Earth, giving rise to “space weather”.
Many Langmuir probes have flown in space, used to measure the properties of plasma, and their design has changed little since their invention in 1924: a series of voltages are applied to the probe, and the collected currents are used to identify the properties of plasma. plasma, such as electron and ion density, as well as temperature.
“A standard Langmuir probe performs a voltage sweep from negative to positive to collect plasma parameters,” says Tore André Bekkeng of Norway’s Eidsvoll Electronics. “But it takes time to perform such a sweep, typically half a second to two seconds. Operating at orbital speeds of around 7 km per second means that you are limited to at most one sample per 3.5 km of space – which is far too coarse to capture these small ionospheric structures which disturb, among other things, the satellite navigation signals and cause these are known as “signal flickers”.
He adds that the Multi-Needle Langmuir Probe (m-NLP) instead extends a quartet of miniature cylinders, each tuned to a different, but fixed, voltage, yielding much tighter spatial resolution – down to less than two meters.
“The idea goes back to the University of Oslo in the late 2000s and was first tested on a sounding rocket in 2008, flying to the top of the atmosphere and back down to gain about 10 minutes flight time”, Toré continues. “We continued on several sounding rockets and then started flying MicroSats and CubeSats – NorSat-1 from Norway and BRIK-II from the Netherlands, which continue to operate to this day – although these versions of the m-NLP perform 1000 and 4000 samples per second respectively, compared to the nearly 10,000 per second achieved with our current design.
The University of Oslo and Eidsvoll Electronics continued to work together on the m-NLP concept and received shared funding to develop an ISS-ready version, through the Science Directorate’s PRODEX program. ESA supporting work on Mission Payloads and ESA Technology Directorate. General Support Technology Program, preparing promising concepts for spaceflight and the open market.
In parallel, the teams also worked on a rad-hard m-NLP version capable of operating in higher orbits, potentially as part of a space weather constellation currently under study. Eidsvoll Electronics designed and built the electronics, while the University took the boom system designed for NorSat-1 and upgraded it for improved performance.
Lasse Clausen of the University of Oslo explains: “Here in Norway, as in other Arctic countries, we have always been fascinated by auroras and their connection to space, and we also operate many aircraft and ships in the northern regions.
“As a result, we rely heavily on global navigation satellite systems like GPS and Galileo. It turns out that auroras and other space weather phenomena cause significant variability in the ionospheric plasma that can seriously disrupt GNSS signals. So if it were possible to measure the state of the ionospheric plasma with multiple m-NLP instruments aboard a fleet of satellites, we could develop a space weather forecast that predicts GNSS signal problems. Such a service would be very valuable to society.
Tore André Bekkeng adds: “PRODEX and GSTP support played a key role in the development of both versions of m-NLP, in particular by allowing us to receive expert advice from ESA and to use Agency Labs. And Eidsvoll Electronics has, through the development of the m-NLP payload for the ISS, gained extensive system-level experience and hired new project managers, system engineers, electronics experts and software developers. The company is also in the procurement phase for a thermal vacuum facility capable of accommodating up to 16 CubeSats units.
“As a result, this contract has significantly strengthened our position for future Norwegian and ESA-led payloads and missions.”
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