Solar Orbiter: A spaceship leaves the UK for the sun

It took a little longer than expected, but the Solar Orbiter probe is built and ready for testing.

British engineers are finalizing the satellite before sending it to Germany to begin a year – long testing campaign.

Such attention to detail is necessary because of the harsh conditions that the spacecraft will face when studying the inner workings of our star.

SolO will fly less than 43 million km from the solar surface.

In doing so, the thermal shield located at the front of the European Space Agency (ESA) satellite will have to cope with temperatures up to 600 ° C.

If you think "but I thought we had just launched an investigation to study the sun," you would be right. It was the Parker satellite of the US Space Agency (NASA), which left the Earth in August.

Both missions actually have very similar goals and, on many occasions, will work hand in hand to try to understand what motivates the activity of our star.

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Parker will do it even closer than SolO, less than 7 million km from the solar surface.

This will allow the US probe to sit directly in the outside atmosphere of the sun or crown. It is the place where the "solar wind" – the storm of charged particles (plasma) and the magnetic fields that they carry – are accelerated and expelled into space.

Solar Orbiter, on the other hand, will step back to provide a broader context to what Parker detects.

Daniel Müller is the scientist of the Esa SolO project: "The fundamental scientific question we are trying to answer is how the Sun creates this plasma bubble around it and its evolution over time."

SolO can perform measurements very similar to those of Parker from his "softer" point of view. But, above all, it will also take pictures. The Esa mission heat shield has peepholes that allow telescopes to spy on the sun's roasting surface.

Parker can not do that. If a telescope tried to look beyond its shield, the material would quickly melt at temperatures above 1000 ° C.

"We are getting close enough to Solar Orbiter to be able to implant with certain surfaces of the Sun," says Helen O. Brien, Instrument Manager at Imperial College London. "We can fly over a section to see how it develops, and how the atmosphere that emanates from this area behaves as it passes us in space."

And there is another aspect of SolO's mission that is very different from Parker. The European satellite will use a series of Venus overflights to move gravitationally in an inclined orbit in order to look at the poles of the sun.

It would be a first – we have never had pictures of these areas.

"Although we can not see them, the poles are where the Sun's magnetic field is really important," says Tim Horbury, Solo's principal investigator on the Imperial. "The magnetic field of the Sun is at the center of its dynamics, the magnetic field causes all activity on the Sun."

Solar Orbiter was to be launched this year with Parker, but a number of technical setbacks mean that the European probe will not be launched until February 2020.

The delay is disappointing but it should not hurt the search. It is still expected that SolO and Parker will be able to carry out joint scientific activities for several years.

And in the end, scientists should have a much clearer idea of ​​the drivers behind the Sun's 11-year behavior cycles.

It's important because the biggest explosions of our star will shake the Earth's magnetic field. In the process, communications can be disrupted, satellites in orbit around the planet can be disconnected and power grids will be vulnerable to electrical surges.

Missions like SolO and Parker should improve the forecasting tools for this type of disturbance.

Solar Orbiter was assembled by Airbus at Stevenage. The aerospace giant is pleased with the conclusion of the construction phase of the project.

The engineers had to work hard to keep SolO as clean as possible, ensuring that there was nothing on the spacecraft likely to introduce electrical or magnetic interference to the 10 instruments. the probe – and to avoid dust. "If you collect dust from the lenses of the telescopes and expose them to the sun, you effectively pick up that dust on their surfaces and you will lose science," says Integration Manager Michelle Sprake. "We had challenges and had to find solutions."

Stevenage's team is currently assembling the probe for shipping to the IABG company in Munich, where it will be alternately baked and frozen (parts of the probe in the shadows can go down to minus 180 ° C) to demonstrate ability to withstand extreme temperatures.

SolO will also be shaken and "shouted" by loud speakers. This will prove that he can stand the violence of riding on a rocket.

Assuming Solar Orbiter passes through these tests, the satellite will then be shipped to Florida where NASA has reserved an Atlas vehicle to launch the mission to the sun.

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