The Sun has played a vital role in the formation of the solar system. It is a source of enormous amount of energy, a portion of which provides Earth with the light and heat necessary to support life. Although scientists have figured out certain properties of the Sun, there are two major questions that still puzzle them – “How is solar wind accelerated?” and “Why is the Sun’s outer atmosphere (known as Corona) hotter than the solar surface?”.
To figure out answers to such questions, NASA in 2009 decided to send a robotic spacecraft to probe the outer corona of the Sun. Although initially the launch was scheduled for 2015, the mission went through several delays and the launch date was finally rescheduled to this Saturday, 11th August, 2018. The mission titled – ‘Parker Solar Probe’ (PSP) will be the first ever probe to reach the low solar corona region. It will determine the structure and dynamics of the Sun’s coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what accelerates the energetic particles.
In other words, the Parker Solar Probe mission will revolutionize our understanding of the Sun.
About the Probe
The process behind making a probe that must face enormous amount of heat and radiation is taking us to the next level of research and development.
The Parker Solar Probe is based on heliophysics and was named after Eugene Parker, who proposed theories on how the Sun gives off energy. He called this cascade of energy – “the solar wind”.
Designed in the Applied Physics Laboratory of Johns Hopkins University, PSP has a launch mass of 685 kg and is 1.0 m x 3.0 m x 2.3 m in dimension. The spacecraft’s systems are designed to endure the extreme radiation and heat near the Sun by the use of a solar shadow-shield. The shield is made of reinforced Carbon-Carbon composite which is designed to withstand extreme temperatures of about 1377 degree celsius. It is hexagonal in shape and is mounted in the Sun-facing side of the spacecraft. Without the protection of the shield, the components of the spacecraft will become inoperative in 1/10 of a second. Also, the instruments are kept cool with continuous water flow which helps in preventing the spacecraft from overheating. As radio communication with Earth will take about 8 minutes, PSP will have to act autonomously and rapidly to protect itself.
According to project scientist Nicky Fox, the team describe it as “the most autonomous spacecraft that has ever flown”.
Trajectory of PSP
The spacecraft is scheduled to make 24 elliptical orbits around the Sun within a 7- years phase with the help of Venus, whose gravity assists will help in gradually shrinking the elliptical orbit, bringing the probe closer to the Sun with every revolution. The scientific studies will be conducted during the intervals when the spacecraft is closest to the sun.
During the course of its trajectory, gravity will make the spacecraft accelerate as it nears perihelion (point in the orbit nearest to the sun) and then slows down again as it reaches its aphelion (point in the orbit farthest to the sun), giving it a around velocity of up to 200 km/s temporarily. Interestingly, this will temporarily make PSP the fastest man-made object to be ever sent in space! Talk about shattering records!
PSP is scheduled to be launched on Saturday, August 11, 2018 at 3:33 am EDT (7:33 am UTC) from Cape Canaveral Air Force Station, Florida, USA. As the trajectory requires high launch energy, the probe will be launched on a Delta IV Heavy class launch vehicle with an additional stage to provide the extra boost that it needs to get into an interplanetary trajectory. The first two stages are both powered by Cryogenic stages and the third stage is powered by a solid propellant rocket.
Humanity has always questioned the hows and whys of the Universe and it is because of the fruitful efforts of the scientists that have enabled us to research and develop instruments capable of performing under extremely hazardous conditions. Every stage of this mission involves great complexity to face the unimaginable and answer questions about the sun which remained unanswered for decades. This first encounter with a star will surely be another ‘giant leap for mankind’.
– Dhiraj Kumar