Solar ejection: SoloHI camera catches images by accident

The new space observation instrument Solar Orbiter Heliospheric Image – SoloHI, which is part of the mission Solar Orbiter – partnership between NASA and the European Space Agency – ESA -, accidentally captured, on February 12, 2021, a coronal mass ejection (EMC) from the sun. The event took place just over a year after the launch of the mission, whose original purpose is to observe the solar wind, dust and cosmic rays that fill the space between the sun and the planets.

Although it is a brief and grainy view, since the remote sensing of the mission will only work in full performance from November 2021, it is possible to detect the sudden explosion of particles escaping from the Sun, which is out of frame, in the upper corner right of the image. EMC starts in the middle of the video, like a bright explosion, and leaves the screen on the upper left side.

To capture the explosion, the SoloHI used one of its four detectors at less than 15% of its normal cadence, to reduce the amount of data obtained and stored.

Solar “photobomb”

The moment the eruption hit the spacecraft, the Solar Orbiter it had just passed behind the Sun from Earth’s perspective – and was returning from the other side. When the mission was being planned, the team did not expect to be able to record any data before the full operation of the instruments.

“Since we planned this, ground stations and technology have been updated,” said Robin Colaninno, principal investigator at SoloHI at the United States Naval Research Laboratory in Washington, DC, during an interview with NASA’s communications team. “So, actually, we have more downlink time to the mission than what was originally scheduled.” And that is how SoloHI captured its first EMC.

The equipment Extreme Ultraviolet Imager and Metis, from ESA, attached to Solar Orbiter, also captured images from EMC.

NASA’s STEREO-A spacecraft, short for Solar Terrestrial Relations Observatory, also had a glimpse of the event through its COR2 detector, which blocks the bright disk of the Sun to see faint phenomena that occur in the solar wind.

solar ejection

Here on Earth, NASA’s Space Climate Analysis Office from Moon to Mars, modeled EMC to chart its trajectory through the solar system. The positions of the Solar Orbiter, marked with a red diamond, and the STEREO-A, like a red square, reveal their different points of view.

solar ejection

NASA spacecraft have been watching EMCs for decades, but the mission Solar Orbiter can bring insights unpublished. “We have realized in the last 25 years that many things happen to an EMC between the surface of the Sun and the Earth,” said Colaninno. “Therefore, we hope to obtain images with much better resolution of all these output streams, being closer to the Sun”, he emphasized.

The Solar Orbiter mission has already taken the closest photo of the Sun taken to date, using the Ultraviolet Imager, in July 2020. Since then, the star king should only get closer. The mission of Solar Orbiter officially starts in November, when SoloHI and the other remote sensing instruments will be turned on in full science mode.

Learn more about EMCs

Coronal mass ejections from the sun are relatively common – at times of maximum solar activity, there are at least three a day; in times of low solar activity, on average, an ejection occurs every five days.

EMCs are large eruptions of high temperature ionized gas from the solar corona. When they reach the Earth’s magnetic field, they can cause geomagnetic storms, damaging the media and power stations.

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