After more than ten years of preparation, the space mission “Solar Orbiter” will be launched Monday from Cape Canaveral, Florida. A Swiss X-ray telescope, STIX, developed at the University of Applied Sciences of North-West Switzerland (FHNW), will also be on board.
Unless postponed, the space probe will begin its journey Sunday at 11:03 p.m. local time (Monday 5:03 a.m. in Switzerland) aboard an Atlas V rocket. Solar Orbiter is a mission of ESA, the European Space Agency, in close collaboration with its during American, the NASA.
It will approach up to 45 million kilometers from the Sun, or about a quarter of the distance between it and Earth. This should make it possible for the first time to study the polar regions of the sun, hitherto unknown.
Planned over a period of seven years, this mission aims to research the causes of the solar wind, a flow of charged particles, continuously emitted by the Sun and which crosses the entire solar system. The ten on-board instruments will attempt by various coordinated measures to unravel its mysteries.
Solar flares under STIX’s eye
One such instrument is the STIX (Spectrometer Telescope for Imaging X-rays) X-ray telescope. It will record not only images, but also X-ray spectra emitted by the Sun.
This data contains information about the physical states and processes that occur during solar flares, that is, when huge amounts of charged matter and particles are exploded into space.
The solar wind then evolves into a solar storm which, in addition to the northern lights, can also cause disturbances in communication satellites, GPS, planes or electrical networks.
These processes will be at the center of the investigations, indicates professor Säm Krucker, of the FHNW, principal responsible for STIX, questioned by the agency Keystone-ATS.
International consortium
The causes of solar flares are linked to the mystery of the heating of the solar corona, a question to which physicists do not yet have an answer. While the outside atmosphere of the Sun is around a million degrees, the surface itself “only” reaches 6000 degrees.
This seemingly paradoxical phenomenon stems from the fact that the Sun is a dynamo that generates a magnetic field, says Dr. Krucker. Transforming magnetic energy into kinetic energy produces heat, but we still don’t know how this transformation takes place, adds the researcher.
The FHNW University of Engineering in Windisch (AG) is responsible for the development, construction, operation and scientific evaluation of STIX, under the direction of Säm Krucker.
The astrophysicist had already had the idea, 18 years earlier, of an X-ray telescope. Over the past ten years, with his team, he has set up an international consortium which has prepared the instrumentation and the STIX software. Funding for the project was guaranteed by ESA and the Swiss Space Office of the State Secretariat for Training, Research and Innovation (SERI).
Two years before the first measurements
Extreme temperatures are a real challenge for the probe and its instruments: on the face of the Solar Orbiter facing the Sun, it will be more than 500 degrees, while it can be up to -100 degrees on the shadow side.
A massive titanium shield with a specially designed black protective layer will shelter the instruments from the heat of the Sun. This also explains why the probe will initially weigh no less than 1.8 tonnes.
Once launched from Cape Canaveral, the probe will take two years to reach the orbit of the Sun, using gravitational assistance from Earth and Venus. It is scheduled to begin measurement in November 2021 and will be in service until at least December 2025.
Researchers hope to benefit from close synergies with NASA’s Parker Solar Probe mission. The latter is too close to the Sun to use cameras, Mark McCaughrean of ESA told Keystone-ATS. Solar Orbiter will be further away, but will be able to use a wide spectrum of instruments. (Ps / nxp)
Created: 07.02.2020, 11h57
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