Set course for the heart of the Sun
The story of space is a story of flag-waving and one-upmanship.
During the Cold War world leaders looked to the stars to outdo rival nations. That’s still true, to a degree, but now they also look to the stars to outdo their own predecessors.
Under Nikita Khrushchev, for example, the Russians were a step ahead of the United States when they put a cosmonaut into orbit in 1961. But more recently, Russia’s President Vladimir Putin outdid Khrushchev by apparently putting a space cadet into the White House.
Meanwhile, under Dwight Eisenhower, John F Kennedy and Richard Nixon, the US outpaced the Soviets by creating Nasa, accelerating the space programme, and going to the moon, where they planted the American flag.
Now, under President Donald Trump, the US is creating a military Space Force, defunding Nasa, and still somehow managing to go to the Sun — where, well, let’s just say he’s very welcome to try to plant a flag.
Geopolitical semaphore is not technically part of the Nasa mission that launched the Parker solar probe sunward this Sunday past.
The probe itself is named for Eugene Parker, who in 1958 predicted the existence of the mysterious phenomenon known as the solar wind — the subject of this project’s mission. Thanks to new heat-shielding materials, the probe can travel closer to the Sun than any previous spacecraft, where scientists hope it will shed light on exactly what’s going on up there.
A plasmic mess of protons, electrons and alpha particles, the solar wind is produced in the searing upper atmosphere of the Sun known as the corona. It “blows” outward from the Sun— wildly, unpredictably — getting faster and faster the further away it gets.
The plasma floods the solar system, forming an interplanetary magnetic field and becoming almost like a stellar weather system in which solar flares and coronal mass ejections spark currents and storms that lash the magnetic fields of the objects in their path.
Like, say, the Earth.
The solar wind is responsible for one of the most awe-inspiring natural phenomena a person can hope to witness in their lifetime: the aurora borealis, or the northern lights. Where the wind meets the magnetosphere, charged particles are pulled into the Earth’s electric field, ionising atmospheric particles and sparking a majestic spectacle of light in the firmament.
Something else the solar wind does is give comets their tails. Solar radiation causes a comet to lose water as steam, carrying particles of dust with it. The force exerted by the solar wind shapes the dust trailing the comet, giving it its distinctive tail shape. And it is through these comet tails that the solar wind gave itself away to the aforementioned Mr Parker, who deduced its existence in 1958 by wondering how these tails could form in what was supposed to be an empty, friction less void.
Solar particles had already been hypothesised 100 years previously, when Richard Carrington and Richard Hodgson simultaneously but independently recorded the first observation of a solar flare on September 1 1859.
Carrington one-upped Hodgson, however, by linking the flare to a geomagnetic storm the next day that threw telegraph systems — humanity’s first electronic network — into complete disarray across Europe and the US.
Auroras similar to the northern lights were seen as far south as the equator, casting the night sky of the Caribbean in prismatic hues bright enough to read by.
Essentially the storm itself was a lot harder to miss than the preceding solar flare. But what Carrington did was link the two, extrapolating from the occurence of one and then the other a solar-terrestrial connection.He did not, however, propose the existence of a pervasive solar wind, leaving that honour to Parker to describe a century later.
The mystery that remains is not just in how the plasma that makes up the wind is produced but also in where it is produced: the corona. The Sun’s upper atmosphere is inexplicably hotter and brighter than its surface, and we’ve been wanting to know why for an awfully long time.
The last time anyone sent a spacecraft to find out, it was Nasa’s Helios B probe, which managed to get just past the orbit of Mercury in 1976 before it burned up at a perihelion (the distance at which it is closest to the Sun) of 43.5-million kilometres.
True to the spirit of stellar one-upmanship, Nasa expects the Parker probe’s Icarean mission to get to within 6.2-million kilometres of the Sun’s surface before the wax on its wings melt.
Thanks to recent breakthroughs in materials technology, the probe’s carbon shielding can withstand temperatures of 1377 ˚C on its Sun-facing side, and maintain a slightly-balmier-than-room-temperature on the inside.
According to Nicola Fox, one of the scientists working on the project,this is where things get interesting, even on its first approach. “We are going to be in uncharted territory,” she told New Scientist. “A ‘here be dragons’ space.”
Coincidentally, this is also almost close enough to plant a flag, Mr President, if you throw it, very very hard indeed* and you are also for some reason on board.
Which, alas, you are not.
But maybe next time.
* No it isn’t. Also it would burn up. And there’s no actual ground to plant it in. It’s the Sun.