solar orbiter approaching the sun space satellite

Solar Orbiter approaches the Sun in preparation for celestial photoshoot

Image credit: ESA

A European Space Agency (ESA) satellite has made its closest approach to the Sun as it prepares to take pictures of our nearest star in unprecedented detail.

Coming within 75 million kilometres of the Sun, about halfway between it and the Earth, the Solar Orbiter’s current objective is simply to prove that its telescopes are ready for future scientific observations.

Other valuable data will also be gleaned from its initial trip including measures of the environment around the spacecraft, such as the magnetic field and the particles making up the solar wind.

ESA will test the spacecraft’s ten science instruments, including the six telescopes on board, which will acquire close-up images of the Sun in unison for the first time.

“We have never taken pictures of the Sun from a closer distance than this,” said ESA’s Solar Orbiter project scientist Daniel Müller.

“There have been higher resolution close-ups, e.g. taken by the four-metre Daniel K Inouye Solar Telescope in Hawaii earlier this year. But from Earth, with the atmosphere between the telescope and the Sun, you can only see a small part of the solar spectrum that you can see from space.”

Nasa’s Parker Solar Probe, launched in 2018, makes closer approaches but it doesn’t carry telescopes capable of looking directly at the Sun.

“Our ultraviolet imaging telescopes have the same spatial resolution as those of Nasa’s Solar Dynamic Observatory (SDO), which takes high-resolution images of the Sun from an orbit close to Earth. Because we are currently at half the distance to the Sun, our images have twice SDO’s resolution during this perihelion,” Müller said.

“For the first time, we will be able to put together the images from all our telescopes and see how they take complementary data of the various parts of the Sun including the surface, the outer atmosphere, or corona, and the wider heliosphere around it.”

Solar Orbiter launched on 10 February this year and is completing its commissioning phase on 15 June. Following that it will commence its cruise phase, which will last until November 2021.

During the main science phase that follows, the spacecraft will get as close as 42 million kilometres to the Sun’s surface, which is closer than the planet Mercury.

Solar Orbiter operators will then use the gravity of Venus to gradually shift the spacecraft’s orbit out of the ecliptic plane, in which the planets of the Solar System orbit.

These fly-by manoeuvres will enable Solar Orbiter to look at the Sun from higher latitudes and get the first ever proper view of its poles.

Studying the activity in the polar regions will help the scientists to better understand the behaviour of the Sun’s magnetic field, which drives the creation of the solar wind that in turn affects the environment of the entire Solar System.

Since the spacecraft is currently 134 million kilometres from Earth, it will take about a week for all perihelion images to be downloaded via ESA’s 35-metre deep-space antenna in Malargüe, Argentina.

The science teams will then process the images before releasing them to the public in mid-July. The data from the in-situ instruments will become public later this year after a careful calibration of all individual sensors.

Earlier this month the Jodrell Bank Observatory in Cheshire took steps to resume its operations after being closed due to the coronavirus lockdown.

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