In less than two weeks, a spacecraft will pass through the atmosphere of our nearest star as part of its mission to 鈥渢ouch鈥� the sun.
鈥淥n Christmas Eve of this year, the Parker Solar Probe will be the closest human-made object ever to a star,鈥� at Johns Hopkins University said at a meeting of the American Geophysical Union in Washington DC on 10 December. 鈥淲e are at the moment we鈥檝e been waiting for for nearly 60 years.鈥�
The probe will reach its perihelion 鈥� the point in its orbit nearest the sun 鈥� around 11.40am GMT on 24 December. Since the probe was launched in 2018, it has passed near the star 21 times, but this will be its closest visit to date, just 6.2 million kilometres from the sun. The probe will also spend more time within the sun鈥檚 atmosphere than previous passes and is protected from the nearly 1000掳C (1800掳F) temperatures by an 11-centimetre-thick carbon-composite shield.
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By the researchers鈥� estimation, this is close enough to count as touching the sun. 鈥淭here is no surface of the sun,鈥� said Rawafi. 鈥淭he solar corona is the sun. And Parker Solar Probe is flying through it.鈥�
This visit will let the spacecraft take measurements of the sun鈥檚 activity in unprecedented detail, including direct measurements of magnetic waves that may explain why the corona is so much hotter than the sun鈥檚 interior.
These close-up measurements will be especially valuable when combined with data from other instruments observing the sun from further away, such as those aboard the International Space Station. Watching how sun particles change as they leave the heliosphere 鈥� the edge of the sun鈥檚 magnetic influence 鈥� could reveal even more.
鈥淲e can see what Parker flew through and then watch [the gas] evolve as it flows out throughout the heliosphere,鈥� said at the NASA Goddard Space Flight Center in Maryland. It will take several days after 24 December for the probe, moving at 191 kilometres per second, to travel far enough away from the sun鈥檚 interfering radiation to begin transmitting data back to Earth.
Where previous passes occurred during solar minima 鈥� when the sun鈥檚 activity is lowest 鈥� this closest approach will also coincide with a solar maximum. Sunspots, solar wind and storms are most active now, which will help to shed light on this part of the sun鈥檚 cycle. 鈥淢y hope is for the strongest solar storm on record to happen right as the probe is passing through,鈥� said Rawafi.
