SET THE CONTROLS FOR THE HEART OF THE SUN
While Earth enjoys an eclipse, a NASA probe is ready to ‘touch the sun’
The sun is having a glamorous year. It’s at solar maximum, the peak of its 11year cycle of storminess. It’s been hurling great blobs of charged particles at Earth on a regular basis, intensifying the high-latitude auroras. And in a particularly flamboyant star turn, the sun on April 8 will hide itself behind the moon, offering tens of millions of people in North America a chance to experience a total solar eclipse.
Overshadowed by all this is a risky NASA mission that’s about to send a spacecraft hurtling practically within spitting distance of the sun.
The Parker Solar Probe, launched in 2018, is designed to “touch the sun,” as NASA puts it. On Dec. 24 the probe will make its closest pass, coming within 3.8 million miles of the surface, having been accelerated by gravity to more than 430,000 miles per hour.
No spacecraft has ever flown so fast, or so close to the sun.
“It is a voyage into the unknown,” said NASA’S top science administrator, Nicola “Nicky” Fox, who tells everyone that “it’s the coolest, hottest mission under the sun.”
At a cost of $1.4 billion,
this mission is not cheap. That NASA would invest so much money and effort is a reminder that the sun, which is so basic to our survival, is not fully understood.
“We live in the atmosphere of the sun. Anything that happens on the sun, we feel the effect here on Earth,” Fox said. “If the sun sneezes, the Earth catches a cold.”
There’s also a more subtle agenda in this mission: advancing American aerospace prowess. The technological innovations can
be applied to future space endeavors at a time when many countries are sending probes to the moon, Mars and elsewhere in the solar system.
“It’s whether we stay at the top of the world, or somebody else will step in,” said Nour Raouafi, project scientist for the mission and an astrophysicist at the Johns Hopkins University Applied Physics Laboratory in Maryland.
His eyes brighten as he describes the amazing feat of this spacecraft: “We will be almost landing on the star.”
How to survive a visit to the sun
Fun fact: You can’t land on the sun. There’s not actually a distinct surface. When scientists talk about the sun’s surface, they are alluding to the “photosphere,” the lowest visible layer of the atmosphere.
At its closest approach on Christmas Eve, the Parker probe will be seven times closer to the sun than any other spacecraft has ventured. NASA engineers hope the public understands that getting this close to the sun is not a day at the beach.
“This is a high-risk mission. When you go into the atmosphere of a star, it is really harsh,” Raouafi said.
The probe is festooned with instruments that are taking measurements of the solar wind, including temperature, density and velocity. The solar wind reaches to the outermost edge of the solar system. Earth is fully immersed in it, but thanks to our planet’s magnetic field, we are usually protected from the most harmful solar radiation.
“We, ourselves, are living in that environment. But we don’t feel it because we have a geomagnetic field that shields us from these hazardous energetic particles and these explosions from the sun,” Raouafi said. “That’s why we have life on Earth.”
The solar wind is protective, too, because it limits the impact of cosmic rays — particles moving at tremendous speed and coming at us from all directions in our galaxy.
What all this illustrates is that space has weather. A highly technological civilization needs to pay attention to space weather, because a burst of solar material called a coronal mass ejection aimed directly at Earth could generate a debilitating geomagnetic storm.
NASA and other government agencies are especially worried about a repeat of what is known as the Carrington Event. In 1859, a coronal mass ejection struck Earth and caused telegraph lines to sing. A similar storm today could cause radio blackouts, knock out satellites or even, in the worst-case scenario, disable the electrical grid.