ESA / NASA - Solar Orbiter patch.
Feb. 17, 2020
Magnetic field measurements during Solar Orbiter boom deployment
First measurements by a Solar Orbiter science instrument reached the ground on Thursday 13 February providing a confirmation to the international science teams that the magnetometer on board is in good health following a successful deployment of the spacecraft’s instrument boom.
Solar Orbiter, ESA’s new Sun-exploring spacecraft, launched on Monday 10 February. It carries ten scientific instruments, four of which measure properties of the environment around the spacecraft, especially electromagnetic characteristics of the solar wind, the stream of charged particles flowing from the Sun. Three of these ‘in situ’ instruments have sensors located on the 4.4 m-long boom.
“We measure magnetic fields thousands of times smaller than those we are familiar with on Earth,” says Tim Horbury of Imperial College London, Principal Investigator for the Magnetometer instrument (MAG). “Even currents in electrical wires make magnetic fields far larger than what we need to measure. That’s why our sensors are on a boom, to keep them away from all the electrical activity inside the spacecraft.”
Observing magnetic field as boom deploys
Solar Orbiter instruments
Image above: Solar Orbiter carries ten instruments, some of which consist of multiple instrument packages. Three of the spacecraft's four 'in situ' instruments, which measure the environment in the vicinity of the spacecraft, are located on Solar Orbiter's 4.4 m boom.
Ground controllers at the European Space Operations Centre in Darmstadt, Germany, switched on the magnetometer’s two sensors (one near the end of the boom and the other close to the spacecraft) about 21 hours after liftoff. The instrument recorded data before, during and after the boom’s deployment, allowing the scientists to understand the influence of the spacecraft on measurements in the space environment.
“The data we received shows how the magnetic field decreases from the vicinity of the spacecraft to where the instruments are actually deployed,” adds Tim. “This is an independent confirmation that the boom actually deployed and that the instruments will, indeed, provide accurate scientific measurements in the future.”
As the titanium/carbon-fibre boom stretched out over an overall 30-minute period on Wednesday, almost three days after liftoff, the scientists could observe the level of the magnetic field decrease by about one order of magnitude. While at the beginning they saw mostly the magnetic field of the spacecraft, at the end of the procedure, they got the first glimpse of the significantly weaker magnetic field in the surrounding environment.
Solar Orbiter boom and antenna deployments
“Measuring before, during, and after the boom deployment helps us to identify and characterise signals that are not linked to the solar wind, such as perturbations coming from the spacecraft platform and other instruments,” says Matthieu Kretzschmar, of Laboratoire de Physique et Chimie de l'Environnement et de l'Espace in Orleans, France, Lead Co-investigator behind another sensor located on the boom, the high frequency magnetometer of the Radio and Plasma Waves instrument (RPW) instrument.
“The spacecraft underwent extensive testing on ground to measure its magnetic properties in a special simulation facility, but we couldn’t fully test this aspect until now, in space, because the test equipment usually prevents us from reaching the needed very low level of magnetic field fluctuations,” he adds.
Next, the instruments will have to be calibrated before true science can begin.
Related articles:
Solar Orbiter braves challenging early days
https://orbiterchspacenews.blogspot.com/2020/02/solar-orbiter-braves-challenging-early.html
Liftoff for Solar Orbiter, ESA’s mission to face the Sun up close
https://orbiterchspacenews.blogspot.com/2020/02/liftoff-for-solar-orbiter-esas-mission.html
Related links:
Solar Orbiter: http://www.esa.int/Science_Exploration/Space_Science/Solar_Orbiter
Scientific instruments: https://sci.esa.int/web/solar-orbiter/-/51217-instruments
Images, Text, Credits: ESA; Data: ESA/Solar Orbiter/MAG/ATG media lab.
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