Saturday, March 9, 2019

What is the Parker Solar Probe?

What is the Parker Solar Probe?

Welcome to a new segment of the blog wherein a will
be writing up the history and current events surrounding
10 NASA missions that are active right now. I’ve chosen
the Parker Solar Probe as a starting point because
1) I know very little about it and 2) without the sun we
wouldn’t be here so it seems like an apt place to start. 

The Parker Solar Probe, or PSP as I will refer to it,
was launched on August 12, 2018 with a velocity of 154 km^2/s^2.
The launch vehicle was a Delta IV-Heavy, which is manufactured
by United Launch Alliance, or ULA. The central booster is the
Common Booster Core, and the boosters on the sides are
CBCs as liquid rocket boosters. At liftoff, all three CBCs
thrust at full force for 44 seconds until the central CBC slows
to 55% capacity to conserve fuel. The side boosters burn for
their full lifespan of 242 seconds, where they separate and
the main core throttles back up to full thrust until it burns
out 86 seconds later. The main objective of the PSP is to
provide new data about the sun and its activity as well
as help scientists forecast space-weather events that
could impact life as we know it. The PSP also has goals to
give us more information on the corona. The corona is
the outer atmosphere of the sun which extends for thousands
of miles above the actual surface of the sun. The corona
gradually transforms into the solar wind that floats through
our solar system and leaves radiation burns on objects like
our moon(see my previous post to learn more about the
radiation on the moon). The corona is made up of extremely
hot plasma with the temperature above a million degrees
fahrenheit, which is far hotter than the actual surface of
the sun, which is only about 9940 degrees fahrenheit.
The corona is only visible to the human eye through a
coronagraph, which is still only useful at certain times
when the sun is in the best viewing position. 
The specific science goals of the PSP are as follows: to trace the flow of energy that heats the corona, to find out what accelerates solar wind to determine the structure and dynamics of the plasma and magnetic fields, and to explore mechanisms that accelerate and transport energetic particles. The closest the PSP will be to the sun is a mere 9 solar radii, or about 3.83 million miles, where it will be moving at approximately 430,000 miles per hour. In total, it will orbit the sun 24 times and will use 7 Venus gravity-assisted flybys to achieve this. It will gradually shrink its orbit each time it passes Venus, eventually coming to the aforementioned closest distance from the sun. The PSP will make its last orbit of the sun on June 19, 2025.
I will now attempt to explain the construction and systems of the PSP with the help of pictures because unfortunately I am not versed well enough in spacecraft design(not yet, at least). The PSP is protected by a 2.3m wide 4.5in thick carbon composite shield that can withstand temperatures of up to 2500 F. Its main source of power is solar arrays that are actively cooled to avoid overheating and burnout. The arrays extend and contract according to the PSP’s position near the sun to keep the panels at the safe temperature and pressure. You can learn more about specifics of the panels and the other infrastructure that was used the build the PSP here. 




Next up, we’re going to talk about the experiments that are taking place during the mission and the instruments used to carry out these experiments. There are 4 major experiments, starting with the FIELDS experiment. This experiment will take direct measurements of different aspects of the sun’s atmosphere such as the electric and magnetic fields, the Poynting flux(a vector that represents the energy transfer per unit of area per unit of time), absolute plasma density and electron temperature, spacecraft floating potential and density fluctuations, as well as radio emissions. The IS☉IS, aka the Integrated Science Investigation of the Sun, will make observations of energetic electrons, protons, and heavy ions that are accelerated to high energies in the sun’s atmosphere and inner heliosphere. It will then use this data and correlate it with wind and coronal structures. The Wide-field Imager for Solar Probe, or WISPR, is a collection of telescopes that will take images of the wind, shocks and other structures as they approach the spacecraft. Lastly, the Solar Wind Electrons Alphas and Protons Investigation, or SWEAP, will count the amount of electrons, protons, and helium ions in the wind and will measure their properties of velocity, density and temperature. You can view detailed drawings of these experiments and the instruments they use here. 
Now that we’ve talked about the backstory and building of the PSP, we can talk about what it is doing now. On January 19, 2019, the PSP completed its first orbit of the sun, ending with the first aphelion, or farthest distance from the sun. It will make its second perihelion, or closest approach on April 4. On January 1st, the PSP reached full operational status for the first time, just in time for its first orbit. The craft has been delivering the data from the first orbit via the Deep SPace Network and has already delivered 17 gigabits of data with the full data package from the first orbit arriving in April. The first orbit has been a learning experience for the PSP team. They saw how the PSP would react to the solar environment for the first time and how well the systems would operate. All said, the APL at Johns Hopkins is proud to report that the projections set by the team held up and was correct. The team has yet to analyze all the data but they are excited about the mysteries the data could solve and what other information it will provide us about the sun. You can view a timeline here to see when major events will happen during the PSP’s orbit.

Thank you for reading my commentary and explanation of the Parker Solar Probe. If you want to learn more, you can check out my sources.

http://parkersolarprobe.jhuapl.edu/index.php
https://en.wikipedia.org/wiki/Delta_IV_Heavy
https://scied.ucar.edu/solar-corona
https://en.wikipedia.org/wiki/Poynting_vector


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