NASA sending craft into sun’s crown

Captain America would envy solar probe’s shield

CAPE CANAVERAL, FLA.— NASA is sending a spacecraft straight into the sun’s glittering crown, an atmospheric region so hot and harsh any normal visitor would wither.

Set to launch early Saturday, the Parker Solar Probe is as heat-resistant as a spacecraft gets, essential for exploring our star closer than ever before. The U.S. got a glimpse of the sun’s glowing, spiky crown, or corona, during last August’s coast-to-coast total solar eclipse. “Well, Parker Solar Probe’s going to be in there,” said project scientist Nicola Fox of Johns Hopkins University.

Here’s why the Parker spacecraft is so tough and why scientists are so hot for this first-ofits-kind mission. Superhero-worthy shield

Parker’s lightweight heat shield is just 11 centimetres thick. But it can withstand1,370 C as well as extreme radiation, thanks to its high-tech carbon. Although the corona reaches millions of degrees, it’s a wispy, tenuous, environment and so the spacecraft won’t need to endure such severe temperatures. The 2.4-metre shield will face the sun during the close solar encounters, shading the sci- ence instruments in the back and keeping them humming at a cool 27 C. Seven years in hot pursuit

The spacecraft’s path to the sun runs past Venus. It will fly by our solar system’s hottest planet seven times over seven years, using the gravity of Venus to shrink its own oval orbit and draw increasingly closer to the sun. The first Venus flyby is in October, followed by the first dip into the sun’s corona in November. There will be 24 orbits between Venus and the sun, with the final three putting Parker closest to the sun, just 6 million kilometres out, in 2024 and 2025. That’s a scant 4 per cent of the 150 million km be- tween Earth and the sun. Breaking records

The records will start falling as soon as Parker takes its first run past the sun. The current closeto-the-sun champ, NASA’s former Helios 2, got within 43 million km in 1976. Parker will come within 25 million km in November and then start beating its own record. Solar science

Our yellow dwarf star is, in many ways, a mystery. The outreaching corona is hundreds of times hotter than the sun’s actual surface, confounding scientists. In addition, physicists don’t know what’s driving the solar wind, the supersonic stream of charged particles constantly blasting away from the sun. Parker the man

Sixty years ago, a young astrophysicist at the University of Chicago, Eugene Parker, proposed the existence of solar wind. Many were skeptical and told him to read up on it first “so you don’t make these killer mistakes,” he recalls. Vindication came with NASA’s Mariner 2 spacecraft in 1962. Parker is now 91 and at Cape Canaveral with his family to witness his first launch — a Delta IV Heavy rocket with the spacecraft bearing his name. It’s the first time NASA has named a spacecraft after someone who’s still alive.