In a very short time, we human beings have seeded our corner of the universe with all kinds of signs of our existence. We have flung hundreds of satellites into the sky, cloaking the Earth in technology. We sent spacecraft to swing by planets and moons, to orbit them, to roam their surfaces. A few years ago, we reached the invisible line between the end of our solar system and the beginning of everything else, and then pierced it, hurtling into the darkness beyond. This last achievement, humanity’s escape from the solar system, was certainly astonishing, a testament to human ingenuity and engineering. But it was much easier than what we’re trying to do next. The Parker Solar Probe, a NASA mission, will blast off from the Florida coast in the early-morning hours of Saturday. Next month, the spacecraft will reach Venus, its sidekick on a long journey. Parker will swing past the planet seven times, slowing down with each pass. Eventually the probe will end its rendezvous with Venus and move into a closer orbit around the sun, coming within 3.9 million miles of the sun’s surface to graze its edge. It will be more than seven times closer than any probe has flown before. As strange as it may sound, it’s much more difficult to reach the sun than it is to leave the solar system altogether. The Parker team studied its options and settled on Venus. In some ways, the new trajectory works out well. With Jupiter, the probe would have come closer to the sun, but it would have made only two passes. With Venus, the Parker Solar Probe will make 24 passes over its lifetime. The probe will spend more time sampling new territory around the sun and, scientists hope, provide answers to some outstanding questions about our star. NASA has previously launched several satellite missions toward the sun, but the field of heliophysics—the study of the sun’s effects on the solar system—remains quite new. The Parker Solar Probe will fly through one of the most mysterious regions of the sun: the corona, the outer layer of hot plasma stretching millions of miles from the surface, or photosphere. Unlike the photosphere, the corona is visible to the direct eye only during a solar eclipse, like the kind that swept across the United States last year. Scientists don’t know why the corona is so hot; temperatures there can exceed 1.8 million degrees Fahrenheit (1 million degrees Celsius), while the photosphere remains at a comparatively cool 10,000 degrees Fahrenheit (6,000 degrees Celsius). Nor do they know how exactly it generates constant streams of charged particles that unfurl across the entire solar system like tentacles, a phenomenon known as the solar wind. Scientists have spent 60 years thinking about the solar wind. Specifically, Eugene Parker, the American astrophysicist for whom the nasa mission is named, first described the dynamics of solar wind in 1958. “It was something most people couldn’t seem to swallow. They expressed stern disbelief,” Parker told Rebecca Boyle in Air & Space magazine this summer. The disbelief was muffled four years later, when instruments on nasa’s Mariner 2 spacecraft observed the presence of solar wind on the way to Venus. Evidence steadily piled up in the decades that followed, as more spacecraft and satellites launched into the sky and felt the breeze. In 2013, as Voyager 1 departed the solar system, the spacecraft’s instruments detected hints of our sun’s wind as it crashed into the cooler particles of interstellar space. The Parker Solar Probe is better dressed for its fiery occasion than previous spacefarers. The probe wears a carbon-composite shield that is 4.5 inches thick and capable of withstanding external temperatures of nearly 2,500 degrees Fahrenheit (1,377 degrees Celsius). Water will circulate through tubes in the solar arrays and into large radiators, cooling the probe down. An autonomous computer system will gauge the heat outside and tuck some of the spacecraft’s solar panels away, or expose them, based on the surroundings. Safe from the sun’s glare, the probe’s scientific instruments will operate at a balmy 78 degrees Fahrenheit (26 degrees Celsius). The Parker mission is scheduled to end in 2025. After it pings home a final time, the spacecraft will, over the course of many years, succumb to the sun’s gravity. There, beyond the pull of anything else, Parker will dip closer and closer to our star. Under the scorching conditions, it will crumble first into pieces, and then into dust. Years after learning to leave the solar system, humanity will have finally managed to plunge right into the heart of it. Thanks for watching. Dr. ANKUR VICHITRA SCIENCE INDIA https://www.youtube.com/channel/UCA__VaeEj9OKAiUacC9rA3Q