NASA Is Going to Dip This Cup Into the Sun’s Corona
When Justin Kasper, a professor of space physics at the University of Michigan, daydreams, he visualizes a spacecraft the size of a Toyota Prius speeding through the sun’s corona—a cloud of superheated plasma. The vessel, NASA’s Solar Probe Plus, will be closer to our star than any manmade object has ever been—only 4 million miles from its surface. There, the sun shines 512 times brighter and is 20 times wider than what we see on earth. Flying at 450,000 miles per hour, the Solar Probe will be the fastest thing we have ever put into space, and the toughest one too—its 4.5-inch-thick carbon foam heat shield, sandwiched between carbon plates, can withstand temperatures of 2,500 degrees Fahrenheit. Operating at around room temperature beneath this shield are computers and other equipment controlling the craft’s path. But the probe’s most important instrument, its Faraday cup, sits outside the shield like a figurehead on a schooner, dipping into the solar wind—a million-mile-an-hour blast of electrons, protons, and helium ions. The size of a tuna can, this cup will record the wind’s composition and direction. The results of its measurements could answer certain outstanding puzzles of astrophysics, key among which is the mystery of why the sun’s corona is hotter than its surface. And understanding the solar wind better may help humans colonize space.
The solar wind is both protective and dangerous. On one hand, it helps create the safe harbor that is our solar system—it protects us from the destructive cosmic rays emanating from the distant supernovas, much like a headland protects a bay from big ocean waves. On the other hand, it can slam massive clouds of charged particles against the earth’s magnetic field, “causing the global bubble of magnetism that surrounds our planet to shake and quiver,” says one NASA site. These storms generate tremendous electrical currents, which can greatly disrupt life on earth. During the famous 1859 solar storm, known as the Carrington Event, telegraph systems across Europe and North America failed, sparks gave operators electric shocks, and telegraph paper caught fire. In today’s world, highly dependent on satellite-to-ground communications, GPS signals, and cell phone connections, a similar electromagnetic storm can wreak havoc of a much greater degree. It is dangerous for space travel, too, interfering with equipment and irradiating astronauts and ships. While NASA has landed humans on the moon and rovers on Mars, sampled the Venusian atmosphere, and crashed a probe into Comet Tempel 1, the sun and its wind remain something of a mystery. With the Solar Probe Plus, the least explored object in our solar system will at last get a close-up.
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