The parker solar probe blasted off from cape canaveral air force base on a delta 4 heavy rocket at 3:31 p.m. on Aug. 12, 2018. Parker would be the closest man-made object to the sun, with an estimated distance of 6.1 million kilometers, not only entering the sun's corona for the first time, but also breaking the previous record of 43.432 million kilometers set by the helios 2 probe on April 17, 1976. Parker is close to the sun and operates in the coronal layer, so he will be able to withstand extremely high temperatures. The solar side of the detector needs to withstand a high temperature of 1377 ℃. However, it is very difficult to ensure that the instrument is always at room temperature of tens of degrees. In order to break free from earth's gravity and become a star in the solar system, Parker would also set the record for the fastest speed ever recorded by a man made object, orbiting the sun at an estimated 700,000 kilometers per hour. To set a world record for the closest position to the sun, materials must be found that can withstand temperatures never seen before. To adapt to the extreme heat, the probe will carry a composite thermal shield that will resist the sun's glare.
The probe's heat shield, also known as the thermal protection system, consists of two carbon-reinforced composite layers and a carbon foam sandwiched about 4.5 inches in between. The heat shield faces the sun with a special white coating to reflect as much energy as possible from the sun. The material can withstand temperatures of 2,500 degrees Fahrenheit, keeping the instrument operating at about 85 degrees Fahrenheit. To make the heat shield, NASA filled the resin with "shredded carbon fiber," hardened the resin and heated it in a 3,000c oven, repeating the process four to five times. The front and back of the heat shield are made of this carbon-carbon composite plate, which, in addition to heat insulation, is a lightweight material with superior mechanical strength. Two carbon-carbon plates are thin enough to bend, or even overlap. Between the two layers of carbon-carbon material is a layer of carbon foam about 4.5 inches long, a material commonly used in the medical industry to make replacement bones. The sandwich design holds up the entire structure -- like corrugated cardboard -- and makes the 8-foot-thick heat shield weigh just 160 pounds.
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