The Parker Solar Probe is no stranger to the sun. On January 17th, the NASA spacecraft will make its seventh close pass to our star, which is within 14 million kilometers of its scorching surface.
And this time, Parker will have plenty of company. A happy sky constellation means that dozens of other observatories are trained on the sun at the same time. Together, these telescopes offer unprecedented views of the Sun and help solve some of our star’s most enduring mysteries.
“This next orbit is really amazing,” says mission project scientist Nour Raouafi of the Johns Hopkins Applied Physics Laboratory in Laurel, Md.
The boss among the spacecraft that will join the guard party is the newcomer Solar Orbiter, which the European Space Agency launched in February 2020 (SN: 02/09/20). As Parker swings past our star this month, Solar Orbiter will be watching from across the sun.
“That’s partly luck,” said solar physicist Timothy Horbury of Imperial College London at a press conference on December 10th at the American Geophysical Union virtual meeting. “Nobody planned to run Parker Solar Probe and Solar Orbiter together. it just came out that way. “
Together, the people of Sungaz will solve long-standing riddles: How the sun generates and controls the solar wind, why solar activity changes over time and how strong solar eruptions can be predicted.
“I think it’s really going to be a revolution,” said Horbury. “We are all incredibly happy to be doing this at this point.”
Work in tandem
The Parker Solar Probe was launched in 2018 and has already had six encounters with the sun (SN: 07/05/18). During its nearly seven-year mission, the probe will eventually swing within 6 million kilometers of the Sun – less than a seventh the distance of mercury from the Sun – and Parker’s heavily shielded instruments will give the sun a better taste of the plasma and charged particles on the outside Atmosphere of the sun, the corona (SN: 07/31/18).
Because Parker is so close, his cameras cannot capture direct images of the sun’s surface. However, Solar Orbiter will get no closer than 42 million kilometers and capture the highest resolution images of the Sun ever. The official science phase of the mission doesn’t begin until November 2021, but the spacecraft has already captured images revealing tiny “campfire” torches that could be helping to warm the corona (SN: 07/16/20).
During Parker’s seventh encounter, January 12-23, Solar Orbiter will observe the sun from a vantage point that is almost the opposite of Parker’s view. Half a dozen other observers will also be watching, including ESA’s BepiColombo spacecraft en route to Mercury and NASA’s veteran solar observer STEREO-A. Both will flank Parker on either side of the sun. And telescopes on Earth will observe from a vantage point about 135 million kilometers behind Parker and will draw a straight line from Earth to the spaceship to the sun.
The situation is similar to Parker’s fourth flyby in January 2020, when nearly 50 observatories along with the probe observed the sun, Raouafi says. These observations led to a special edition of Astronomy & Astrophysics with more than 40 articles. One of the results confirmed that there is a dust-free region around the sun, which was predicted in 1929. “That was amazing,” says Raouafi. “We want to do a campaign that is as good or even better for this run.”
In the wind
At the AGU meeting, the researchers presented new results from Parker’s second year of observation. The results deepen the mystery of the magnetic kinks known as “serpentines” that Parker observed in the solar wind, a constant stream of charged particles flowing away from the sun (SN: 04.12.19), Says Raouafi.
Some observations support the idea that the kinks originate at the base of the corona and are carried to Parker and beyond, like a wave moving along a skipping rope. Others suggest that the switchbacks are created by turbulence in the solar wind itself.
By figuring out which idea is correct, you can determine how the sun creates the solar wind in the first place. “These [switchbacks] could be the key to explaining how the solar wind is heated and accelerated, ”said Raouafi in a lecture recorded for AGU.
With the help of the enlarged images of the solar orbiter and simultaneous measurements of the solar wind, scientists can trace the energetic particles of the wind back to their place of birth on the solar surface. Campfire torches – the “nanoflares” discovered by Solar Orbiter – could even explain the switchbacks, says Horbury.
“The aim is to link tiny transient events like nanoflares to changes in solar winds,” Horbury said at the press conference.
Wake up with the sun
Parker and Solar Orbiter couldn’t have arrived at a better time. “The sun has been very calm for the past few years, at a deep solar minimum,” said Horbury. “But the sun is just beginning to wake up.”
Both spaceships have built up solar activity over the past year. During the sleep phase, the sun shows fewer sunspots and outbreaks like flares and expectorations of coronal masses or CMEs. But when he wakes up, these signs of increasing magnetic activity become more frequent and energetic.
On November 29, Parker observed the strongest flare he had seen in the past three years, followed by a CME whizzing past the spaceship at 1,400 kilometers per second.
“We have so much data from it,” says Raouafi. More CMEs should go past Parker if it’s even closer to the sun. This will tell scientists how these outbreaks are triggered.
Solar Orbiter also got a breakout. On April 19, a CME passed the spacecraft about 20 hours before its effects hit Earth. With existing spacecraft, observers on Earth only receive around 40 minutes of warning before a CME arrives.
“We can see this CME evolve as it moves away from the sun in ways we have never been able to do before,” said Horbury.
Strong CMEs can turn satellites and power grids off, so it is important to have as much advance warning as possible. A future spaceship at Solar Orbiter’s distance from the Sun could help provide this warning.
I’m looking forward to
This orbit marks the first time Parker Solar Probe and Solar Orbiter have observed the sun at the same time, but not the last. “There will be a lot of options like this,” says Raouafi.
He is looking forward to one opportunity in particular: the solar eclipse of 2024. On April 8, 2024, a total solar eclipse will cross North America from Mexico to Newfoundland. Solar scientists plan to make observations all along the path of totality, much like they observed the 2017 total solar eclipse.
During the solar eclipse, the Parker solar probe is on its second closest orbit between 7 and 8 million kilometers from the sun. Parker and Solar Orbiter will be “almost on top of each other,” says Raouafi – both spaceships will be together on one side of the sun when viewed from Earth. Whatever protrusions and other shapes in the corona are visible to observers on Earth, they are aimed directly at the spaceship.
“They will fly through the structure we will see from Earth during the solar eclipse,” says Raouafi. The combined observations will show scientists how features on the sun evolve over time.
“I think it’s a new era,” said Horbury. “The next few years will fundamentally change the way we see the sun.”