This summer, NASA's Parker Solar Probe will embark on a mission to "touch the sun."
"Touch" might be a bit of an overstatement — the probe will actually pass 3.8 million miles from the sun's surface. Its primary job is to learn more about the outer atmosphere of the sun, called the corona. Many things about the corona remain a mystery. For example, scientists still aren't sure why the corona of the sun is hotter than its surface. The probe will take a series of images and measurements to figure out how energy and heat move through the corona.
NASA will also study the solar wind, a stream of super high-energy particles released from the corona. The solar wind leaves the sun's atmosphere and zooms past Earth at more than a million miles per hour. It can affect Earth's satellites and cause changes in space weather.
No one knows what causes the solar wind to accelerate to such high speeds. Scientists are hoping that the data they receive from the probe will help them understand the process. In fact, the probe is named for Eugene Parker, the scientist who first developed the theory of a solar wind.
In order to deal with the tremendous heat of the sun, the probe will be protected by a heat shield. The heat shield will face temperatures approaching 2,500 degrees F. But amazingly, if it works correctly, the heat shield will keep the spacecraft's instruments at a relatively pleasant 85 F.
To make sure the probe can withstand the temperature extremes of space, NASA is putting it through thermal vacuum testing. According to Betsy Congdon, a lead engineer on the heat shield from the Johns Hopkins University Applied Physics Laboratory, they test it by "basically hanging this big oven that we've designed over the spacecraft" to simulate the sun.
This will be a historic mission for many reasons. When NASA was founded, they came up with a list of missions that they wanted to accomplish. According to Congdon, "this is the only one that hasn't been done, and people have been working on it for decades."
The launch window for the probe opens on Aug. 11. After it launches from Cape Canaveral, Fla., it will take about seven years to reach the corona. It will be the closest that humanity has ever been to a star.