April 13, 2024

ESA and NASA team up to study solar wind

Science and Exploration

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In preparation for April’s total solar eclipse, the ESA-led Solar Orbiter and the NASA-led Parker Solar Probe are both at their closest approach to the Sun. Tomorrow, they will take the opportunity to team up to study the torrential rain of plasma that it flows from the Sun, fills the Solar System and causes glare and destruction on Earth.

Both the Solar Orbiter and the Parker Solar Probe have very eccentric orbits, meaning they fly close to the Sun to get a close-up look and then fly away to give their onboard technology a chance to recover from the intense heat and radiation. Over the next week, for the first time, the two spacecraft will both be at their closest approach to the Sun – what we call “perihelion” – at the same time.

What’s more, this closer approach coincides with the Solar Orbiter and Parker Solar Probe being at right angles to each other as they look toward the Sun.

Daniel Müller, ESA Solar Orbiter Project Scientist, explains why this positioning is special. “On this day, we have a unique spacecraft configuration, where Solar Orbiter will have its entire suite of instruments pointed at the region of the Sun where the solar wind is produced that will reach Parker Solar Probe a few hours later.”

Scientists will compare data collected by both missions to better understand the properties of the solar wind. Because Solar Orbiter is closest to the Sun, its telescopes will observe with the highest resolution. Parker Solar Probe’s simultaneous approach means that just hours after the solar wind’s source regions have been imaged by Solar Orbiter, plasma from this nearly pure solar wind will be sampled in space by Parker Solar Probe. This will allow scientists to better understand the connection between the Sun and its heliosphere, the enormous bubble of plasma it blows into space.

But wait… at its closest approach, Solar Orbiter is 45 million km from the Sun, while Parker Solar Probe is just 7.3 million km away. So how does Solar Orbiter observe something that later hits the Parker Solar Probe?

To answer this question, we need to look at the difference between remote sensing and in situ instruments. Both missions carry both types of instruments on board, but while Solar Orbiter carries more remote sensing instruments, Parker Solar Probe carries mostly in situ instruments (no current camera technology could look at the Sun from such a close distance and survive).

Remote sensing instruments work like a camera or our eyes; they detect light waves coming from the Sun at different wavelengths. Since light travels at 300,000 km/s, it takes 2.5 minutes to reach Solar Orbiter’s instruments at closest approach.

Meanwhile, Parker Solar Probe’s in situ instruments function more like our nose or taste buds. They directly “taste” the particles and fields in the spacecraft’s immediate vicinity. In this case, Parker Solar Probe will measure solar wind particles moving away from the Sun at speeds exceeding one million kilometers per hour. Although it seems very fast, it is more than 500 times slower than the speed of light.

“In principle, Solar Orbiter alone can use both methods”, highlights Andrei Zhukov, from the Royal Observatory of Belgium, who is working on the joint observations. “However, the Parker Solar Probe gets much closer to the Sun, so it can directly measure the properties of the solar wind – such as its density and temperature – closer to its birthplace, before these properties change during solar radiation. your journey away from the Sun.”

“We will really hit the jackpot if Solar Orbiter observes a coronal mass ejection (CME) toward the Parker Solar Probe,” adds Andrei. “We will then be able to see in great detail the restructuring of the Sun’s outer atmosphere during the CME and compare these observations with the structure seen in situ by the Parker Solar Probe.”

Teamwork makes the dream work

This is just one example of how Solar Orbiter and Parker Solar Probe are working together throughout their missions. Parker Solar Probe’s instruments are designed to collect samples from the Sun’s corona (its outer atmosphere), targeting the region of space where coronal plasma separates to become the solar wind. This gives scientists direct evidence about the conditions of the plasma in that region and helps identify how it is accelerated towards the planets.

In addition to achieving its own scientific goals, Solar Orbiter will provide contextual information to improve understanding of Parker Solar Probe’s in situ measurements. By working together in this way, the two probes will collect complementary data sets, which will allow us to distill more science from the two missions than either could alone.

Learn more about how the missions complement each other here.

Solar Orbiter helps predict total solar eclipse

The thin ring we see around the Sun during a total solar eclipse is its corona. Solar Orbiter data collected over the next week will also be used to predict what shape the corona will take during the next eclipse.

Researchers at Predictive Science Inc. use data from telescopes on and around Earth to create a 3D model of the solar corona. Before each total solar eclipse, they use this data to predict what the Sun’s corona will look like from Earth.

For the first time, Predictive Science will incorporate data from Solar Orbiter’s Polarimetric and Helioseismic Imager (PHI) instrument. This will allow them to add information about the Sun’s magnetic field from a unique point of view to improve their prediction.

The forecast is now available here. It will evolve in real time as we get closer to the eclipse and Solar Orbiter data is added.

April 8 total solar eclipse prediction on March 28, 2024

Don’t do a Galileo – wear eye protection!

The total solar eclipse will cross North America on April 8, 2024, starting at around 11:07 am local time. Total solar eclipses are rare opportunities to see the Sun’s beautiful outer atmosphere, normally obscured by its bright surface. But great care should be taken when wearing eclipse-appropriate sunglasses to avoid eye damage.

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