On the night (EST) of Dec 26, 2024, the mission operations team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, received the signal of Parker Solar Probe (PSP). The team was out of contact with the spacecraft during closest approach, which occurred on Dec. 24, with Parker Solar Probe zipping just 3.8 million miles from the solar surface while moving about 430,000 miles per hour. Thus confirming its closest approach to the sun and its safety. NASA’s Parker Solar Probe is designed to revolutionize our understanding of the Sun. Parker solar probe has become the first spacecraft to experience the sun to just a tiny distance. Over seven years, the spacecraft will complete 24 orbits around the Sun. The features and achievements of PSP are not limited to here. So, let’s discover these.
Parker Solar Probe was launched on August 12, 2018, from Cape Canaveral Air Force Station, Florida. The mission was designed and managed at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, USA, and Johns Hopkins University Applied Physics Laboratory, Baltimore, Maryland, USA.
Since the mission is designed for a massive celestial body, its achievements are also huge.
At closest approach, Parker Solar Probe hurtles around the Sun at approximately 194 thousand meters per second (for example, it would take only 18.5 seconds from Srinagar to Kanyakumari if we travel at this speed).
Parker Solar Probe was the first NASA mission to be named for a living person, Dr. Eugene Parker, and the first person to predict the existence of the solar wind. In 1958, Dr. Parker developed a theory showing how the Sun’s hot corona – now known to be millions of degrees Fahrenheit – is so hot that it overcomes the Sun’s gravity. According to the theory, the material in the corona expands continuously outwards in all directions, forming a solar wind. Dr. Parker watched the launch with the mission team from Kennedy Space Center in Florida on Aug. 12, 2018. Dr. Parker died on March 15, 2022, at age 94.
Parker Solar Probe has become the first spacecraft to approach the sun to just a small distance of 3.8 million miles. (Distance may seem significant, but if the sun and earth were 1 m apart, then Parker Solar Probe is only four c. m. away from the sun.)
DESIGN AND PROTECTION:
PSP weighs about 685 kilograms, which is relatively light for a spacecraft, but it launched into space aboard one of the most powerful rockets in the world, the United Launch Alliance Delta IV Heavy. That’s because it takes much energy to go to the Sun – 55 times more energy than it takes to go to Mars. Another astonishing fact about PSP is why it isn’t melting. One key to understanding what keeps the spacecraft and its instruments safe is understanding the concept of heat versus temperature. In space, the temperature can be thousands of degrees without providing significant heat to a given object or feeling hot. This is because temperature measures how fast particles move, whereas heat measures the total amount of energy they transfer. Particles may be moving fast (high temperature), but if there are very few, they won’t transfer much energy (low heat). Since space is mostly empty, there are very few particles that can transfer energy to the spacecraft. The corona (heading towards it in the next few lines) through which Parker Solar Probe flies, for example, has an extremely high temperature but very low density. Compared to the visible surface of the Sun, the corona is less dense, so the spacecraft interacts with fewer hot particles and doesn’t receive as much heat. That means that while Parker Solar Probe will be traveling through a space with temperatures of several million degrees, the surface of the heat shield that faces the Sun will only get heated to about 1,400 degrees Celsius. But thousands of degrees Celsius is still too hot. For comparison, lava from volcano eruptions can be anywhere between 700 and 1200 degrees Celsius. To withstand that heat, Parker Solar Probe makes use of a heat shield known as the Thermal Protection System, or TPS, which is 2.4 meters in diameter and about 115 mm thick and can withstand temperatures reaching nearly 1,377 degrees Celsius. With those few inches of thickness just on the other side of the shield, the spacecraft body will sit at a comfortable 30 degrees C.
OBJECTIVES:
Having such a fantastic protection system, PSP can survive in such harsh conditions of the Sun. But why has NASA sent PSP to such harsh conditions? The answer to this question points to many unsolved mysteries about our nearest star that are yet to be solved. These include:
CORONAL HEATING PROBLEM:
The corona is the outermost part of the Sun's atmosphere. The corona is usually hidden by the bright light of the Sun's surface. That makes it difficult to see without using special instruments. However, the corona can be seen during a total solar eclipse. The corona reaches extremely high temperatures. However, the corona is very dim because it is about 10 million times less dense than the Sun’s surface. This low density makes the corona much less bright than the surface of the Sun. The temperature of the corona is more than 1.1 million degrees Celsius, whereas down 1610 K.M., the temperature is about 5,537 degrees Celsius. How the sun manages these figures is always a big mystery in front of scientists. They call it a Coronal Heating Problem. PSP, flying itself in the corona, will seek clues to its behavior and offer the chance for scientists to solve this mystery.
SOLAR WIND:
NASA’s PSP will answer one of the important questions in the field of solar science. What is the origin of the solar wind, and how is it accelerated to speeds of up to 1.8 million miles per hour? The solar wind streams off of the Sun in all directions at speeds of about 400 km/s (about 1 million miles per hour). The source of the solar wind is the Sun's hot corona. It emanates from features of the Sun, such as dark and cool regions called coronal holes and active regions, which are characterized by strong magnetic fields. These regions release solar wind at different speeds and densities. But all release the same basic components of solar wind — electrically charged particles such as protons and electrons. The temperature of the corona is so high that the Sun's gravity cannot hold onto it. This wind fills our entire solar system. When gusts of solar wind arrive at Earth, they can set off beautiful aurora — but at the same time, expose astronauts to radiation, interfere with satellite electronics, and disrupt communications signals like GPS and radio waves. The more we understand the fundamental processes that drive the solar wind, the more we can limit some of these effects.
NEAR LIGHT SPEED PARTICLES:
Parker Solar Probe also is studying how some particles accelerate away from the Sun at mind-boggling speeds – more than half the speed of light, or more than 140 million meters per second! These particles move so fast that they can reach Earth in under half an hour, so they can interfere with electronics on board satellites with very little warning. Thus, studying these particles will help us to prepare for future disasters and to preserve our technology.
According to NASA, PSP has completed 22 orbits around the sun. NASA has planned 24 orbits of PSP around the sun. Parker Solar Probe’s next two close passes of the Sun, at approximately the same distance and speed, will occur on March 22, 2025, and June 19, 2025. PSP has contributed significantly to our understanding of our nearest star. It is the first time we are sampling the sun from its atmosphere, and this is important because what it seems from Earth might not be the actual truth. At the same time, it is also an example of next-level, ground-breaking technology. The Sun, no doubt, is an integral part of our lives. We cannot imagine a day without sun. Being a star is also a danger. Continuous emission of solar winds can effectively destroy our technology. Thus, having as much information as possible about our nearest star is a prerequisite to nurturing our understanding of stars. Also, being a nuclear reactor, if our knowledge about the sun evolves properly, it can provide an enormous amount of energy to mankind. This can enable us to cross the huge barrier of space exploration and travel, which is speed and time.
