Human spacecraft “touched” the sun for the first time, successfully traversed the corona with resistance to high temperatures of 1 million degrees Celsius

Human spacecraft “touched” the sun for the first time, successfully traversed the corona with resistance to high temperatures of 1 million degrees Celsius

Whether it is Kuafu’s pursuit of the sun, Houyi’s shooting of the sun in myths and legends, or various telescopes and probes aimed at the sun since modern times, it may mean that human interest in the sun has never faded since ancient times.

Recently, Thomas Zurbuchen, Deputy Director of NASA’s Science Mission Directorate, announced that “The Parker Solar Probe successfully passed through the solar corona on April 28 this year, becoming the first spacecraft in human history to’touch’ the sun. “[1].

The probe was launched in 2018 to observe the internal environment of the sun and reveal the sun’s operating mechanism, thereby providing evidence for solving some long-standing problems in the astronomy community.

On December 14, the related results were published in Physical Review Letters. The paper was titled “Parker Solar Probe Enters the Magnetically Dominated Solar Corona” (Parker Solar Probe Enters the Magnetically Dominated Solar Corona). The first author is Justin C. Kasper (Justin C. Kasper), a professor at the Michigan Institute of Astrophysics and Deputy Chief Technology Officer of BWX Technologies.

The pace of mankind’s “day by day” never stops

Human beings cannot do without sunlight, just as they cannot do without air and water. As the spring rain moisturizes things silently, sunlight plays a vital role in maintaining the circulation of the earth.

In ancient times, the sun was once a man of mythology. The “Huainanzi·Ten Tian Xun” records: “The sunrise is in Yanggu, bathing in Xianchi, and blowing on Fusang, it is the morning light.”

In modern times, with the progress of scientific civilization, we finally know that the sun is actually just an ordinary star in many galaxies in the Milky Way, and the so-called solar luminescence is only its internal nuclear fusion reaction. However, mankind’s curiosity about the sun has not been satisfied by this, but has increasingly wanted to explore its true face hidden under the “heat mask”.

Human spacecraft “touched” the sun for the first time, successfully traversed the corona with resistance to high temperatures of 1 million degrees Celsius

Figure | Image of the corona during a total solar eclipse (Source: NASA)

In the 1990s, the United States launched the Ulysses solar probe to observe the Earth’s poles at close range. After a long flight journey of 17 years, it finally ended its exploration mission perfectly in 2008;

In 2001, the “Origin” probe was successfully launched. It is worth mentioning that the detector successfully collected solar wind particle samples through a collection device;

In 2003, the “Galactic Evolution” probe was successfully launched. This is the first time that humans have made ultraviolet measurements in space outside the Milky Way, providing support for the evolution of many galaxies, including the solar system;

On August 12, 2018, the Parker Solar Probe, the protagonist of this report, was launched at the Kennedy Space Center. Unlike previous spacecraft, NASA has high hopes for it, believing that “this will be the first time that a human probe has come into contact with the sun at such a close distance. It will fly directly into the orbit of the sun’s outer atmosphere and the corona, only 6.5 million from the sun’s surface. kilometer”.

It should be noted that the concept of sending a spacecraft into the magnetized atmosphere of the sun even predates NASA’s creation.

It is reported that the Parker probe is currently known to be the fastest human spacecraft with a speed of almost 400,000 kilometers per hour.

In addition, its name comes from the American astronomer Eugene Parker (Eugene Parker) in recognition of his outstanding contributions to solar wind research.

The probe enters the solar corona for the first time

Although the announcement date is December 14, in fact, the exact time that the Parker probe arrived at the solar corona was April 28, and it stayed for 5 hours.

The main goal of the Parker probe is to understand how the sun works, but this requires it to travel through the sun’s atmosphere and collect solar particles.

The corona is the outermost layer of the sun’s atmosphere, and the temperature can reach 2 million degrees Celsius, but the temperature inside the sun is only about 5,500 degrees Celsius. How to make the spacecraft resist the erosion of high temperature and cross the outer boundary of the sun has therefore become the key.

In order to solve this problem, the research team at the Harvard-Smithsonian Center for Astrophysics (CfA) designed a cup-like detection instrument made of materials with high melting points such as tungsten, niobium, molybdenum and sapphire, even through the corona. It will not melt.

CfA astrophysicist Anthony W. Case said, “The amount of light hitting the Parker Solar Probe determines the temperature of the spacecraft. Although most of the probe is protected by a heat shield, our cup It is one of only two outstanding and unprotected instruments.”

In Case’s view, the Solar Probe Cup itself is an engineering feat.

He further explained, “During the measurement, the cup will be directly exposed to the sun and run at a very high temperature; it is actually hot, and the temperature of the part of the instrument exceeds 1,000 degrees Celsius and emits a red-orange light.”

The final result is that the Solar Probe Cup successfully completed the collection of solar particles, which will help scientists understand the latest developments of the Parker probe and whether it has reached the corona safely.

Human spacecraft “touched” the sun for the first time, successfully traversed the corona with resistance to high temperatures of 1 million degrees Celsius

Figure | Artist’s idea of ​​the Parker probe approaching the sun (Source: NASA)

Based on the data returned by Parker, scientists found an interesting phenomenon, that is, the critical surface of Alvin is not smooth, but has “wrinkles” like old people.

The critical surface of Alvin is located at the position of “the end of the solar atmosphere and the beginning of the solar wind”. Since the sun has no solid surface, this position has become an interface in the conventional sense.

The researchers noticed that the reentry points below the critical surface of Alvin are far less than those above it. This finding may mean that no reentry will form in the corona.

“For decades, we have been observing the sun and its corona. We know that interesting physics is happening there to heat and accelerate the solar wind plasma, but we still can’t say exactly what this physics is.” NASA Parker Sun The probe project scientist Nour Raouafi (Nour Raouafi) said.

“As the Parker Solar Probe now flies into the magnetically dominated corona, we will gain the long-awaited insights into the inner workings of this mysterious region.”


refer to:

1. J. C. Kasper et al. Physical Review Letters127, 255101 (2021).

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