multi-Needle Langmuir Probe

Overview

Space weather creates ionospheric plasma effects on satellite instruments, disturbing both communication and navigation satellites in orbit and negatively impacting airtraffic in transpolar flights. The strongest GPS-scintillations occur when plasma clouds enter the polar cap through the auroral oval on the dayside, and exits the polar cap through the auroral oval on the nightside.

EIDEL AS has space qualified the multi-Needle Langmuir Probe (m-NLP) system for 10 years operation on satellites in Low Earth Orbit. The system is designed for high spatial resolution measurements of ionospheric electron density and spacecraft floating potential.

The mulit-Needle Langmuir Probe (m-NLP) is an instrument for measuring electron density and spacecraft floating potential at sampling rates in Low Earth Orbit. Obtaining meter scale resolution of electron density structures and turbulence in the ionosphere for space weather forecasting, geographical distribution of expected scintillation effects and availability forecasting in the coming hours for GNSS.

Background

The m-NLP development was supported through the ESA GSTP programme under ESA Contract No. 4000109393/13/NL/AK. The instrument can sample electron density and spacecraft floating potential at sampling rates up to 5 kHz, i.e., close to meter scale resolution in Low Earth Orbit. The instrument prototype has flight heritage from nine sounding rockets up to 350 km altitude, and an engineering model of the boom system is qualified for the Norsat-1 satellite that was launched on 14 July 2017.

Obtaining meter scale resolution of electron density structures and turbulence in the ionosphere opens up entirely new possibilities for space weather forecasting, e.g., geographical distribution of expected scintillation effects and availability forecasting in the coming hours for GNSS systems.

History of m-NLP at UiO

The University of Oslo has for the last 13 years developed a new Langmuir probe system for high spatial resolution measurements of ionospheric electron density, together with measurements of the spacecraft floating potential. The system consists of four miniaturized cylindrical Langmuir probes, and is therefor referred to as the multi-Needle Langmuir Probe system (m-NLP).

The system is tested on six sounding rockets flights from 2003 – 2012 to altitudes of 350 km, and several upcoming CubeSat mission will have the m-NLP system as the science payload, i.e. the QB50 multi-satellite mission. The advantages of the m-NLP system compared to other Langmuir probes are the unprecedented high sampling rate, and the capability of on-board processing of electron density and spacecraft floating potential with low computational power requirements. For the spacecraft operators this means that the can get valuable info on the plasma conditions around the satellite, as well as the spacecraft charging levels. Both at low telemetry cost, and with high time resolution.